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Last updated: November 27, 2013
Copyright © 2013, Google Inc. All rights reserved.
compatibility@android.com
This document enumerates the requirements that must be met in order for devices to be compatible with Android 4.4.
The use of "must", "must not", "required", "shall", "shall not", "should", "should not", "recommended", "may" and "optional" is per the IETF standard defined in RFC2119 [Resources, 1].
As used in this document, a "device implementer" or "implementer" is a person or organization developing a hardware/software solution running Android 4.4. A "device implementation" or "implementation" is the hardware/software solution so developed.
To be considered compatible with Android 4.4, device implementations MUST meet the requirements presented in this Compatibility Definition, including any documents incorporated via reference.
Where this definition or the software tests described in Section 10 is silent, ambiguous, or incomplete, it is the responsibility of the device implementer to ensure compatibility with existing implementations.
For this reason, the Android Open Source Project [Resources, 3] is both the reference and preferred implementation of Android. Device implementers are strongly encouraged to base their implementations to the greatest extent possible on the "upstream" source code available from the Android Open Source Project. While some components can hypothetically be replaced with alternate implementations this practice is strongly discouraged, as passing the software tests will become substantially more difficult. It is the implementer's responsibility to ensure full behavioral compatibility with the standard Android implementation, including and beyond the Compatibility Test Suite. Finally, note that certain component substitutions and modifications are explicitly forbidden by this document.
Many of these resources are derived directly or indirectly from the Android SDK, and will be functionally identical to the information in that SDK's documentation. In any cases where this Compatibility Definition or the Compatibility Test Suite disagrees with the SDK documentation, the SDK documentation is considered authoritative. Any technical details provided in the references included above are considered by inclusion to be part of this Compatibility Definition.
The managed (Dalvik-based) execution environment is the primary vehicle for Android applications. The Android application programming interface (API) is the set of Android platform interfaces exposed to applications running in the managed VM environment. Device implementations MUST provide complete implementations, including all documented behaviors, of any documented API exposed by the Android SDK [Resources, 4].
Device implementations MUST NOT omit any managed APIs, alter API interfaces or signatures, deviate from the documented behavior, or include no-ops, except where specifically allowed by this Compatibility Definition.
This Compatibility Definition permits some types of hardware for which Android includes APIs to be omitted by device implementations. In such cases, the APIs MUST still be present and behave in a reasonable way. See Section 7 for specific requirements for this scenario.
In addition to the managed APIs from Section 3.1, Android also includes a significant runtime-only "soft" API, in the form of such things such as Intents, permissions, and similar aspects of Android applications that cannot be enforced at application compile time.
Device implementers MUST support and enforce all permission constants as documented by the Permission reference page [Resources, 5]. Note that Section 9 lists additional requirements related to the Android security model.
The Android APIs include a number of constants on the android.os.Build
class [Resources, 6] that are intended to describe
the current device. To provide consistent, meaningful values across device
implementations, the table below includes additional restrictions on the
formats of these values to which device implementations MUST conform.
| Parameter | Comments |
| VERSION.RELEASE | The version of the currently-executing Android system, in human-readable format. This field MUST have one of the string values defined in [Resources, 7]. |
| VERSION.SDK | The version of the currently-executing Android system, in a format accessible to third-party application code. For Android 4.4, this field MUST have the integer value 19. |
| VERSION.SDK_INT | The version of the currently-executing Android system, in a format accessible to third-party application code. For Android 4.4, this field MUST have the integer value 19. |
| VERSION.INCREMENTAL | A value chosen by the device implementer designating the specific build of the currently-executing Android system, in human-readable format. This value MUST NOT be re-used for different builds made available to end users. A typical use of this field is to indicate which build number or source-control change identifier was used to generate the build. There are no requirements on the specific format of this field, except that it MUST NOT be null or the empty string (""). |
| BOARD | A value chosen by the device implementer identifying the specific internal
hardware used by the device, in human-readable format. A possible use of this
field is to indicate the specific revision of the board powering the device.
The value of this field MUST be encodable as 7-bit ASCII and match the regular expression
"^[a-zA-Z0-9.,_-]+$". |
| BRAND | A value reflecting the brand name associated with the device as
known to the end users. MUST be in human-readable format and SHOULD represent
the manufacturer of the device or the company brand under which the device is
marketed. The value of this field MUST be encodable as 7-bit ASCII and match the
regular expression "^[a-zA-Z0-9.,_-]+$".
|
| CPU_ABI | The name of the instruction set (CPU type + ABI convention) of native code. See Section 3.3: Native API Compatibility. |
| CPU_ABI2 | The name of the second instruction set (CPU type + ABI convention) of native code. See Section 3.3: Native API Compatibility. |
| DEVICE | A value chosen by the device implementer containing the development name or
code name identifying the configuration of the hardware features and industrial
design of the device. The value of this field MUST be encodable as 7-bit ASCII
and match the regular expression "^[a-zA-Z0-9.,_-]+$".
|
| FINGERPRINT | A string that uniquely identifies this build. It SHOULD be reasonably
human-readable. It MUST follow this template:
$(BRAND)/$(PRODUCT)/$(DEVICE):$(VERSION.RELEASE)/$(ID)/$(VERSION.INCREMENTAL):$(TYPE)/$(TAGS)For example: acme/myproduct/mydevice:4.4/KRT16/3359:userdebug/test-keysThe fingerprint MUST NOT include whitespace characters. If other fields included in the template above have whitespace characters, they MUST be replaced in the build fingerprint with another character, such as the underscore ("_") character. The value of this field MUST be encodable as 7-bit ASCII. |
| HARDWARE | The name of the hardware (from the kernel command line or /proc). It SHOULD be
reasonably human-readable. The value of this field MUST be encodable as 7-bit ASCII and
match the regular expression "^[a-zA-Z0-9.,_-]+$". |
| HOST | A string that uniquely identifies the host the build was built on, in human readable format. There are no requirements on the specific format of this field, except that it MUST NOT be null or the empty string (""). |
| ID | An identifier chosen by the device implementer to refer to a specific
release, in human readable format. This field can be the same as
android.os.Build.VERSION.INCREMENTAL, but SHOULD be a value sufficiently
meaningful for end users to distinguish between software builds. The value of
this field MUST be encodable as 7-bit ASCII and match the regular expression
"^[a-zA-Z0-9.,_-]+$".
|
| MANUFACTURER | The trade name of the Original Equipment Manufacturer (OEM) of the product. There are no requirements on the specific format of this field, except that it MUST NOT be null or the empty string (""). |
| MODEL | A value chosen by the device implementer containing the name of the device as known to the end user. This SHOULD be the same name under which the device is marketed and sold to end users. There are no requirements on the specific format of this field, except that it MUST NOT be null or the empty string (""). |
| PRODUCT | A value chosen by the device implementer containing the development name or
code name of the specific product (SKU) that SHOULD be unique within the same
brand. MUST be human-readable, but is not necessarily intended for view by end
users. The value of this field MUST be encodable as 7-bit ASCII and match the
regular expression "^[a-zA-Z0-9.,_-]+$".
|
| SERIAL | A hardware serial number, which MUST be available. The value of this field MUST be encodable
as 7-bit ASCII and match the regular expression
"^([a-zA-Z0-9]{6,20})$". |
| TAGS | A comma-separated list of tags chosen by the device implementer that
further distinguishes the build. For example, "unsigned,debug". The value of
this field MUST be encodable as 7-bit ASCII and match the regular expression
"^[a-zA-Z0-9.,_-]+$". |
| TIME | A value representing the timestamp of when the build occurred. |
| TYPE | A value chosen by the device implementer specifying the runtime
configuration of the build. This field SHOULD have one of the values
corresponding to the three typical Android runtime configurations: "user",
"userdebug", or "eng". The value of this field MUST be
encodable as 7-bit ASCII and match the regular expression
"^[a-zA-Z0-9.,_-]+$". |
| USER | A name or user ID of the user (or automated user) that generated the build. There are no requirements on the specific format of this field, except that it MUST NOT be null or the empty string (""). |
Device implementations MUST honor Android's loose-coupling Intent system, as described in the sections below. By "honored", it is meant that the device implementer MUST provide an Android Activity or Service that specifies a matching Intent filter and binds to and implements correct behavior for each specified Intent pattern.
The Android upstream project defines a number of core applications, such as contacts, calendar, photo gallery, music player, and so on. Device implementers MAY replace these applications with alternative versions.
However, any such alternative versions MUST honor the same Intent patterns provided by the upstream project. For example, if a device contains an alternative music player, it must still honor the Intent pattern issued by third-party applications to pick a song.
The following applications are considered core Android system applications:
The core Android system applications include various Activity, or Service components that are considered "public". That is, the attribute "android:exported" may be absent, or may have the value "true".
For every Activity or Service defined in one of the core Android system apps that is not marked as non-public via an android:exported attribute with the value "false", device implementations MUST include a component of the same type implementing the same Intent filter patterns as the core Android system app.
In other words, a device implementation MAY replace core Android system apps; however, if it does, the device implementation MUST support all Intent patterns defined by each core Android system app being replaced.
As Android is an extensible platform, device implementations MUST allow each Intent pattern referenced in Section 3.2.3.1 to be overridden by third-party applications. The upstream Android open source implementation allows this by default; device implementers MUST NOT attach special privileges to system applications' use of these Intent patterns, or prevent third-party applications from binding to and assuming control of these patterns. This prohibition specifically includes but is not limited to disabling the "Chooser" user interface that allows the user to select between multiple applications which all handle the same Intent pattern.
However, device implementations MAY provide default activities for specific URI patterns (eg. http://play.google.com) if the default activity provides a more specific filter for the data URI. For example, an intent filter specifying the data URI "http://www.android.com" is more specific than the browser filter for "http://". Device implementations MUST provide a user interface for users to modify the default activity for intents.
Device implementations MUST NOT include any Android component that honors any new Intent or Broadcast Intent patterns using an ACTION, CATEGORY, or other key string in the android.* or com.android.* namespace. Device implementers MUST NOT include any Android components that honor any new Intent or Broadcast Intent patterns using an ACTION, CATEGORY, or other key string in a package space belonging to another organization. Device implementers MUST NOT alter or extend any of the Intent patterns used by the core apps listed in Section 3.2.3.1. Device implementations MAY include Intent patterns using namespaces clearly and obviously associated with their own organization.
This prohibition is analogous to that specified for Java language classes in Section 3.6.
Third-party applications rely on the platform to broadcast certain Intents to notify them of changes in the hardware or software environment. Android-compatible devices MUST broadcast the public broadcast Intents in response to appropriate system events. Broadcast Intents are described in the SDK documentation.
Android 4.4 adds settings that allow users to select their default Home and SMS applications. Device implementations MUST provide a similar user settings menu for each, compatible with the Intent filter pattern and API methods described in the SDK documentation [Resources, 91].
Managed code running in Dalvik can call into native code provided in the
application .apk file as an ELF .so file compiled for the appropriate device
hardware architecture. As native code is highly dependent on the underlying
processor technology, Android defines a number of Application Binary
Interfaces (ABIs) in the Android NDK, in the file
docs/CPU-ARCH-ABIS.html. If a device implementation is compatible
with one or more defined ABIs, it SHOULD implement compatibility with the
Android NDK, as below.
If a device implementation includes support for an Android ABI, it:
android.os.Build.CPU_ABI
API and android.os.Build.CPU_ABI2 parameters.android.os.Build.CPU_ABI2, only those ABIs
documented in the latest version of the Android NDK, in the file
docs/CPU-ARCH-ABIS.htmlandroid.os.Build.CPU_ABI, only one of the
ABIs listed belowThe following native code APIs MUST be available to apps that include native code:
Note that future releases of the Android NDK may introduce support for additional ABIs. If a device implementation is not compatible with an existing predefined ABI, it MUST NOT report support for any ABI at all.
Note that device implementations MUST include libGLESv3.so and it MUST symlink (symbolic) link to libGLESv2.so. On device implementations that declare support for OpenGL ES 3.0, libGLESv2.so MUST export the OpenGL ES 3.0 function symbols in addition to the OpenGL ES 2.0 function symbols.
Native code compatibility is challenging. For this reason, it should be repeated that device implementers are VERY strongly encouraged to use the upstream implementations of the libraries listed above to help ensure compatibility.
The Android Open Source implementation uses code from the Chromium
Project to implement the android.webkit.WebView [Resources, 10] . Because it is not feasible
to develop a comprehensive test suite for a web rendering system, device
implementers MUST use the specific upstream build of Chromium in the WebView
implementation. Specifically:
android.webkit.WebView implementations MUST be based
on the Chromium build from the upstream Android Open Source Project for Android 4.4.
This build includes a specific set of functionality and security fixes for the
WebView. [Resources, 83]Mozilla/5.0 (Linux; Android $(VERSION); $(LOCALE); $(MODEL)
Build/$(BUILD)) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0
$(CHROMIUM_VER) Mobile Safari/537.36
android.os.Build.VERSION.RELEASE.android.os.Build.MODEL.android.os.Build.ID.Mobile in the user agent
string.The WebView component SHOULD include support for as much of HTML5 [Resources, 11] as possible.
Device implementations MUST include a standalone Browser application for
general user web browsing. The standalone Browser MAY be based on a
browser technology other than WebKit. However, even if an alternate Browser
application is used, the android.webkit.WebView component
provided to third-party applications MUST be based on WebKit, as described in
Section 3.4.1.
Implementations MAY ship a custom user agent string in the standalone Browser application.
The standalone Browser application (whether based on the upstream WebKit Browser application or a third-party replacement) SHOULD include support for as much of HTML5 [Resources, 11] as possible. Minimally, device implementations MUST support each of these APIs associated with HTML5:
Additionally, device implementations MUST support the HTML5/W3C webstorage API [Resources, 15], and SHOULD support the HTML5/W3C IndexedDB API [Resources, 16]. Note that as the web development standards bodies are transitioning to favor IndexedDB over webstorage, IndexedDB is expected to become a required component in a future version of Android.
The behaviors of each of the API types (managed, soft, native, and web) must be consistent with the preferred implementation of the upstream Android Open Source Project [Resources, 3]. Some specific areas of compatibility are:
The above list is not comprehensive. The Compatibility Test Suite (CTS) tests significant portions of the platform for behavioral compatibility, but not all. It is the responsibility of the implementer to ensure behavioral compatibility with the Android Open Source Project. For this reason, device implementers SHOULD use the source code available via the Android Open Source Project where possible, rather than re-implement significant parts of the system.
Android follows the package and class namespace conventions defined by the Java programming language. To ensure compatibility with third-party applications, device implementers MUST NOT make any prohibited modifications (see below) to these package namespaces:
Prohibited modifications include:
A "publicly exposed element" is any construct which is not decorated with the "@hide" marker as used in the upstream Android source code. In other words, device implementers MUST NOT expose new APIs or alter existing APIs in the namespaces noted above. Device implementers MAY make internal-only modifications, but those modifications MUST NOT be advertised or otherwise exposed to developers.
Device implementers MAY add custom APIs, but any such APIs MUST NOT be in a
namespace owned by or referring to another organization. For instance, device
implementers MUST NOT add APIs to the com.google.* or similar namespace; only
Google may do so. Similarly, Google MUST NOT add APIs to other companies'
namespaces. Additionally, if a device implementation includes custom APIs
outside the standard Android namespace, those APIs MUST be packaged in an
Android shared library so that only apps that explicitly use them (via the
<uses-library> mechanism) are affected by the increased
memory usage of such APIs.
If a device implementer proposes to improve one of the package namespaces above (such as by adding useful new functionality to an existing API, or adding a new API), the implementer SHOULD visit source.android.com and begin the process for contributing changes and code, according to the information on that site.
Note that the restrictions above correspond to standard conventions for naming APIs in the Java programming language; this section simply aims to reinforce those conventions and make them binding through inclusion in this compatibility definition.
Device implementations MUST support the full Dalvik Executable (DEX) bytecode specification and Dalvik Virtual Machine semantics [Resources, 17].
Device implementations MUST configure Dalvik to allocate memory in accordance with the upstream Android platform, and as specified by the following table. (See Section 7.1.1 for screen size and screen density definitions.)
Note that memory values specified below are considered minimum values, and device implementations MAY allocate more memory per application.
| Screen Size | Screen Density | Application Memory |
| small / normal / large | ldpi / mdpi | 16MB |
| small / normal / large | tvdpi / hdpi | 32MB |
| small / normal / large | xhdpi | 64MB |
| small / normal / large | 400dpi | 96MB |
| small / normal / large | xxhdpi | 128MB |
| small / normal / large | xxxhdpi | 256MB |
| xlarge | mdpi | 32MB |
| xlarge | tvdpi / hdpi | 64MB |
| xlarge | xhdpi | 128MB |
| xlarge | 400dpi | 192MB |
| xlarge | xxhdpi | 256MB |
| xlarge | xxxhdpi | 512MB |
Android includes a launcher application (home screen) and support for third party applications to replace the device
launcher (home screen). Device implementations that allow third party applications to replace the device home screen
MUST declare the platform feature android.software.home_screen.
Android defines a component type and corresponding API and lifecycle that allows applications to expose an "AppWidget"
to the end user [Resources, 18]. Device implementations that support embedding widgets on the
home screen MUST meet the following requirements and declare support for platform feature android.software.app_widgets.
Android includes APIs that allow developers to notify users of notable events [Resources, 19], using hardware and software features of the device.
Some APIs allow applications to perform notifications or attract attention using hardware, specifically sound, vibration, and light. Device implementations MUST support notifications that use hardware features, as described in the SDK documentation, and to the extent possible with the device implementation hardware. For instance, if a device implementation includes a vibrator, it MUST correctly implement the vibration APIs. If a device implementation lacks hardware, the corresponding APIs MUST be implemented as no-ops. Note that this behavior is further detailed in Section 7.
Additionally, the implementation MUST correctly render all resources (icons, sound files, etc.) provided for in the APIs [Resources, 20], or in the Status/System Bar icon style guide [Resources, 21]. Device implementers MAY provide an alternative user experience for notifications than that provided by the reference Android Open Source implementation; however, such alternative notification systems MUST support existing notification resources, as above.
Android includes support for rich notifications, such as interactive Views for ongoing notifications. Device implementations MUST properly display and execute rich notifications, as documented in the Android APIs.
Android includes APIs [Resources, 22] that allow developers to incorporate search into their applications, and expose their application's data into the global system search. Generally speaking, this functionality consists of a single, system-wide user interface that allows users to enter queries, displays suggestions as users type, and displays results. The Android APIs allow developers to reuse this interface to provide search within their own apps, and allow developers to supply results to the common global search user interface.
Device implementations MUST include a single, shared, system-wide search user interface capable of real-time suggestions in response to user input. Device implementations MUST implement the APIs that allow developers to reuse this user interface to provide search within their own applications. Device implementations MUST implement the APIs that allow third-party applications to add suggestions to the search box when it is run in global search mode. If no third-party applications are installed that make use of this functionality, the default behavior SHOULD be to display web search engine results and suggestions.
Applications can use the "Toast" API (defined in [Resources, 23]) to display short non-modal strings to the end user, that disappear after a brief period of time. Device implementations MUST display Toasts from applications to end users in some high-visibility manner.
Android provides "themes" as a mechanism for applications to apply styles across an entire Activity or application.
Android includes a "Holo" theme family as a set of defined styles for application developers to use if they want to match the Holo theme look and feel as defined by the Android SDK [Resources, 24]. Device implementations MUST NOT alter any of the Holo theme attributes exposed to applications [Resources, 25].
Android also includes a "Device Default" theme family as a set of defined styles for application developers to use if they want to match the look and feel of the device theme as defined by the device implementer. Device implementations MAY modify the DeviceDefault theme attributes exposed to applications [Resources, 25].
From version 4.4, Android now supports a new variant theme with translucent system bars, allowing application developers to fill the area behind the status and navigation bar with their app content. To enable a consistent developer experience in this configuration, it is important the status bar icon style is maintained across different device implementations. Therefore, Android device implementations MUST use white for system status icons (such as signal strength and battery level) and notifications issued by the system, unless the icon is indicating a problematic status [Resources, 25].
Android defines a component type and corresponding API and lifecycle that allows applications to expose one or more "Live Wallpapers" to the end user [Resources, 26]. Live Wallpapers are animations, patterns, or similar images with limited input capabilities that display as a wallpaper, behind other applications.
Hardware is considered capable of reliably running live wallpapers if it can run all live wallpapers, with no limitations on functionality, at a reasonable framerate with no adverse affects on other applications. If limitations in the hardware cause wallpapers and/or applications to crash, malfunction, consume excessive CPU or battery power, or run at unacceptably low frame rates, the hardware is considered incapable of running live wallpaper. As an example, some live wallpapers may use an Open GL 1.0 or 2.0 context to render their content. Live wallpaper will not run reliably on hardware that does not support multiple OpenGL contexts because the live wallpaper use of an OpenGL context may conflict with other applications that also use an OpenGL context.
Device implementations capable of running live wallpapers reliably as described above SHOULD implement live wallpapers. Device implementations determined to not run live wallpapers reliably as described above MUST NOT implement live wallpapers.
The upstream Android source code includes a user interface for displaying recent applications using a thumbnail image of the application's graphical state at the moment the user last left the application. Device implementations MAY alter or eliminate this user interface; however, a future version of Android is planned to make more extensive use of this functionality. Device implementations are strongly encouraged to use the upstream Android user interface (or a similar thumbnail-based interface) for recent applications, or else they may not be compatible with a future version of Android.
Android includes support for Input Management and support for third party input method editors.
Device implementations that allow users to use third party input methods on the device MUST declare the platform feature
android.software.input_methods and support IME APIs as defined in the Android SDK documentation.
Device implementations that declare the android.software.input_methods feature MUST provide a user-accessible mechanism
to add and configure third party input methods. Device implementations MUST display the settings interface in response to the
android.settings.INPUT_METHOD_SETTINGS intent.
Android includes support for Remote Control API that lets media applications integrate with playback controls that are displayed in a remote view like the device lock screen [Resources, 74]. Device implementations that support lock screen in the device and allow users to add widgets on the home screen MUST include support for embedding remote controls in the device lock screen [Resources, 69].
Android includes support for interactive screensavers called Dreams [Resources, 76]. Dreams allows users to interact with applications when a charging device is idle, or docked in a desk dock. Device implementations MUST include support for Dreams and provide a settings option for users to configure Dreams.
Location modes MUST be displayed in the Location menu within Settings [Resources, 87]. Location services provided through the
SettingInjectorService introduced in Android 4.4 must be displayed
in the same Location menu [Resources, 89].
Android 4.4 includes support for color emoji characters. Android device implementations MUST provide an input method to the user for the Emoji characters defined in Unicode 6.1 [Resources, 82] and MUST be capable of rendering these emoji characters in color glyph.
Android includes features that allow security-aware applications
to perform device administration functions at the system level, such as enforcing
password policies or performing remote wipe, through the Android Device
Administration API [Resources, 27]. Device
implementations MUST provide an implementation of the DevicePolicyManager
class [Resources, 28]. Device implementations that include support for lock screen
MUST support the full range of device administration policies defined in the Android SDK
documentation [Resources, 27].
Device implementations MAY have a preinstalled application performing device administration functions but this application MUST NOT be set out-of-the box as the default Device Owner app [Resources, 84].
Android provides an accessibility layer that helps users with disabilities to navigate their devices more easily. In addition, Android provides platform APIs that enable accessibility service implementations to receive callbacks for user and system events and generate alternate feedback mechanisms, such as text-to-speech, haptic feedback, and trackball/d-pad navigation [Resources, 29]. Device implementations MUST provide an implementation of the Android accessibility framework consistent with the default Android implementation. Specifically, device implementations MUST meet the following requirements.
android.accessibilityservice
APIs [Resources, 30].AccessibilityEvents
and deliver these events to all registered AccessibilityService
implementations in a manner consistent with the default Android
implementation.android.provider.Settings.ACTION_ACCESSIBILITY_SETTINGS
intent.Additionally, device implementations SHOULD provide an implementation of an accessibility service on the device, and SHOULD provide a mechanism for users to enable the accessibility service during device setup. An open source implementation of an accessibility service is available from the Eyes Free project [Resources, 31].
Android includes APIs that allow applications to make use of text-to-speech (TTS) services, and allows service providers to provide implementations of TTS services [Resources, 32]. Device implementations MUST meet these requirements related to the Android TTS framework:
Device implementations MUST install and run Android ".apk" files as generated by the "aapt" tool included in the official Android SDK [Resources, 33].
Devices implementations MUST NOT extend either the .apk [Resources, 34], Android Manifest [Resources, 35], Dalvik bytecode [Resources, 17], or renderscript bytecode formats in such a way that would prevent those files from installing and running correctly on other compatible devices. Device implementers SHOULD use the reference upstream implementation of Dalvik, and the reference implementation's package management system.
Device implementations MUST include at least one form of audio output, such as speakers, headphone jack, external speaker connection, etc.
Device implementations MUST support the core media formats specified in the Android SDK documentation [Resources, 58] except where explicitly permitted in this document. Specifically, device implementations MUST support the media formats, encoders, decoders, file types and container formats defined in the tables below. All of these codecs are provided as software implementations in the preferred Android implementation from the Android Open Source Project.
Please note that neither Google nor the Open Handset Alliance make any representation that these codecs are unencumbered by third-party patents. Those intending to use this source code in hardware or software products are advised that implementations of this code, including in open source software or shareware, may require patent licenses from the relevant patent holders.
Note that these tables do not list specific bitrate requirements for most video codecs because current device hardware does not necessarily support bitrates that map exactly to the required bitrates specified by the relevant standards. Instead, device implementations SHOULD support the highest bitrate practical on the hardware, up to the limits defined by the specifications.
| Type | Format / Codec | Encoder | Decoder | Details | File Type(s) / Container Formats |
|---|---|---|---|---|---|
| Audio | MPEG-4 AAC Profile (AAC LC) | REQUIRED for device implementations that include microphone hardware
and define android.hardware.microphone. |
REQUIRED | Support for mono/stereo/5.0/5.1* content with standard sampling rates from 8 to 48 kHz. |
|
| MPEG-4 HE AAC Profile (AAC+) | REQUIRED for device implementations that include microphone hardware and define android.hardware.microphone | REQUIRED | Support for mono/stereo/5.0/5.1* content with standard sampling rates from 16 to 48 kHz. | ||
| MPEG-4 HE AAC v2 Profile (enhanced AAC+) | REQUIRED | Support for mono/stereo/5.0/5.1* content with standard sampling rates from 16 to 48 kHz. | |||
| MPEG-4 Audio Object Type ER AAC ELD (Enhanced Low Delay AAC) | REQUIRED for device implementations that include microphone hardware and define android.hardware.microphone | REQUIRED | Support for mono/stereo content with standard sampling rates from 16 to 48 kHz. | ||
| AMR-NB | REQUIRED for device implementations that include microphone hardware
and define android.hardware.microphone. |
REQUIRED | 4.75 to 12.2 kbps sampled @ 8kHz | 3GPP (.3gp) | |
| AMR-WB | REQUIRED for device implementations that include microphone hardware
and define android.hardware.microphone. |
REQUIRED | 9 rates from 6.60 kbit/s to 23.85 kbit/s sampled @ 16kHz | 3GPP (.3gp) | |
| FLAC | REQUIRED (Android 3.1+) |
Mono/Stereo (no multichannel). Sample rates up to 48 kHz (but up to 44.1 kHz is recommended on devices with 44.1 kHz output, as the 48 to 44.1 kHz downsampler does not include a low-pass filter). 16-bit recommended; no dither applied for 24-bit. | FLAC (.flac) only | ||
| MP3 | REQUIRED | Mono/Stereo 8-320Kbps constant (CBR) or variable bit-rate (VBR) | MP3 (.mp3) | ||
| MIDI | REQUIRED | MIDI Type 0 and 1. DLS Version 1 and 2. XMF and Mobile XMF. Support for ringtone formats RTTTL/RTX, OTA, and iMelody |
|
||
| Vorbis | REQUIRED |
|
|||
| PCM/WAVE | REQUIRED | REQUIRED | 8-bit and 16-bit linear PCM** (rates up to limit of hardware).Devices MUST support sampling rates for raw PCM recording at 8000,16000 and 44100 Hz frequencies | WAVE (.wav) | |
| Image | JPEG | REQUIRED | REQUIRED | Base+progressive | JPEG (.jpg) |
| GIF | REQUIRED | GIF (.gif) | |||
| PNG | REQUIRED | REQUIRED | PNG (.png) | ||
| BMP | REQUIRED | BMP (.bmp) | |||
| WEBP | REQUIRED | REQUIRED | WebP (.webp) | ||
| Video | H.263 | REQUIRED for device implementations that include camera hardware
and define android.hardware.camera or
android.hardware.camera.front. |
REQUIRED |
|
|
| H.264 AVC | REQUIRED for device implementations that include camera hardware
and define android.hardware.camera or
android.hardware.camera.front. |
REQUIRED | Baseline Profile (BP) |
|
|
| MPEG-4 SP | REQUIRED | 3GPP (.3gp) | |||
| VP8**** | REQUIRED (Android 4.3+) |
REQUIRED (Android 2.3.3+) |
WebM (.webm) and Matroska (.mkv, Android 4.0+)*** | ||
| VP9 | REQUIRED (Android 4.4+) |
WebM (.webm) and Matroska (.mkv, Android 4.0+)*** |
Android device implementations that include a rear-facing camera and declare
android.hardware.camera SHOULD support the following H.264 video encoding
profiles.
| SD (Low quality) | SD (High quality) | HD (When supported by hardware) | |
|---|---|---|---|
| Video resolution | 176 x 144 px | 480 x 360 px | 1280 x 720 px |
| Video frame rate | 12 fps | 30 fps | 30 fps |
| Video bitrate | 56 Kbps | 500 Kbps or higher | 2 Mbps or higher |
| Audio codec | AAC-LC | AAC-LC | AAC-LC |
| Audio channels | 1 (mono) | 2 (stereo) | 2 (stereo) |
| Audio bitrate | 24 Kbps | 128 Kbps | 192 Kbps |
Android device implementations that include a rear-facing camera and declare
android.hardware.camera SHOULD support the following VP8 video encoding profiles
| SD (Low quality) | SD (High quality) | HD 720p (When supported by hardware) |
HD 1080p (When supported by hardware) |
|
|---|---|---|---|---|
| Video resolution | 320 x 180 px | 640 x 360 px | 1280 x 720 px | 1920 x 1080 px |
| Video frame rate | 30 fps | 30 fps | 30 fps | 30 fps |
| Video bitrate | 800 Kbps | 2 Mbps | 4 Mbps | 10 Mbps |
Android device implementations SHOULD support the following VP8, VP9 and H.264 video decoding profiles. Device implementations SHOULD also support dynamic video resolution switching within the same stream for VP8, VP9 and H.264 codecs.
| SD (Low quality) | SD (High quality) | HD 720p (When supported by hardware) |
HD 1080p (When supported by hardware) |
|
|---|---|---|---|---|
| Video resolution | 320 x 180 px | 640 x 360 px | 1280 x 720 px | 1920 x 1080 px |
| Video frame rate | 30 fps | 30 fps | 30 fps | 30 fps |
| Video bitrate | 800 Kbps | 2 Mbps | 8 Mbps | 20 Mbps |
When an application has used the android.media.AudioRecord API to
start recording an audio stream, device implementations that include microphone
hardware and declare android.hardware.microphone MUST sample and
record audio with each of these behaviors:
In addition to the above recording specifications, when an application has
started recording an audio stream using the
android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio
source:
From Android 4.4, android.media.MediaRecorder.AudioSource class has a new
audio source: REMOTE_SUBMIX. Devices MUST properly implement the
REMOTE_SUBMIX audio source so that when an application uses the
android.media.AudioRecord API to record from this audio source,
it can capture a mix of all audio streams except for the following:
STREAM_RINGSTREAM_ALARMSTREAM_NOTIFICATIONNote: while some of the requirements outlined above are stated as "SHOULD" since Android 4.3, the Compatibility Definition for a future version is planned to change these to "MUST". That is, these requirements are optional in Android 4.4 but will be required by a future version. Existing and new devices that run Android are very strongly encouraged to meet these requirements, or they will not be able to attain Android compatibility when upgraded to the future version.
If the platform supports noise suppression technologies tuned for speech
recognition, the effect MUST be controllable from the
android.media.audiofx.NoiseSuppressor API. Moreover, the "uuid"
field for the noise suppressor's effect descriptor MUST uniquely identify each
implementation of the noise suppression technology.
Audio latency is the time delay as an audio signal passes through a system. Many classes of applications rely on short latencies, to achieve real-time sound effects.
For the purposes of this section:
/docs/opensles/index.htmlPer Section 5, all compatible device implementations MUST include at least one form of audio output. Device implementations SHOULD meet or exceed these output latency requirements:
If a device implementation meets the requirements of this section
after any initial calibration
when using the OpenSL ES PCM buffer queue API,
for continuous output latency and cold output latency
over at least one supported audio output device, it MAY
report support for low-latency audio, by reporting the feature
"android.hardware.audio.low-latency" via the
android.content.pm.PackageManager class. [Resources, 37] Conversely, if the device
implementation does not meet these requirements it MUST NOT report support for
low-latency audio.
Per Section 7.2.5, microphone hardware may be omitted by device implementations.
Device implementations that include microphone
hardware and declare android.hardware.microphone SHOULD
meet these input audio latency requirements:
Devices MUST support the media network protocols for audio and video playback as specified in the Android SDK documentation [Resources, 58]. Specifically, devices MUST support the following media network protocols:
Device implementations MUST support the Android Developer Tools provided in the Android SDK. Specifically, Android-compatible devices MUST be compatible with:
adb functions as
documented in the Android SDK. The device-side adb daemon MUST
be inactive by default, and there MUST be a user-accessible mechanism to turn
on the Android Debug Bridge.ddms features as documented in the
Android SDK. As ddms uses adb, support for
ddms SHOULD be inactive by default,
but MUST be supported whenever the user has activated the Android Debug
Bridge, as above.Most Linux-based systems and Apple Macintosh systems recognize Android
devices using the standard Android SDK tools, without additional support;
however Microsoft Windows systems typically require a driver for new Android
devices. (For instance, new vendor IDs and sometimes new device IDs require
custom USB drivers for Windows systems.) If a device implementation is
unrecognized by the adb tool as provided in the standard Android
SDK, device implementers MUST provide Windows drivers allowing developers to
connect to the device using the adb protocol. These drivers MUST
be provided for Windows XP, Windows Vista, Windows 7, and Windows 8, in both 32-bit and
64-bit versions.
Android includes support for developers to configure application development-related settings. Device implementations MUST honor the android.settings.APPLICATION_DEVELOPMENT_SETTINGS intent to show application development-related settings [Resources, 77]. The upstream Android implementation hides the Developer Options menu by default, and enables users to launch Developer Options after pressing seven (7) times on the Settings > About Device > Build Number menu item. Device implementations MUST provide a consistent experience for Developer Options. Specifically, device implementations MUST hide Developer Options by default and MUST provide a mechanism to enable Developer Options that is consistent with the upstream Android implementation.
Android 4.4 introduces ART, an experimental Android runtime, accessible within the Developer Options menu for preview. Device implementations SHOULD include ART (libart.so) and support dual boot from Developer Options, but MUST keep Dalvik (libdvm.so) as the default runtime.
If a device includes a particular hardware component that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. If an API in the SDK interacts with a hardware component that is stated to be optional and the device implementation does not possess that component:
A typical example of a scenario where these requirements apply is the telephony API: even on non-phone devices, these APIs must be implemented as reasonable no-ops.
Device implementations MUST accurately report accurate hardware configuration
information via the getSystemAvailableFeatures() and
hasSystemFeature(String) methods on the
android.content.pm.PackageManager class. [Resources, 37]
Android includes facilities that automatically adjust application assets and UI layouts appropriately for the device, to ensure that third-party applications run well on a variety of hardware configurations [Resources, 38]. Devices MUST properly implement these APIs and behaviors, as detailed in this section.
The units referenced by the requirements in this section are defined as follows:
pixels = dps * (density / 160).Screen Size
The Android UI framework supports a variety of different screen sizes, and
allows applications to query the device screen size (aka "screen layout") via
android.content.res.Configuration.screenLayout with the
SCREENLAYOUT_SIZE_MASK. Device implementations MUST report the
correct screen size as defined in the Android SDK documentation
[Resources, 38] and determined by the upstream
Android platform. Specifically, device implementations must report the correct
screen size according to the following logical density-independent pixel (dp)
screen dimensions.
In addition, devices MUST have screen sizes of at least 2.5 inches in physical diagonal size.
Devices MUST NOT change their reported screen size at any time.
Applications optionally indicate which screen sizes they support via the
<supports-screens> attribute in the AndroidManifest.xml
file. Device implementations MUST correctly honor applications' stated support
for small, normal, large, and xlarge screens, as described in the Android
SDK documentation.
Screen Aspect Ratio
The aspect ratio MUST be a value from 1.3333 (4:3) to 1.86 (roughly 16:9)
Screen Density
The Android UI framework defines a set of standard logical densities to
help application developers target application resources. Device
implementations MUST report one of the following logical Android framework
densities through the android.util.DisplayMetrics APIs, and MUST
execute applications at this standard density.
Device implementations MUST report correct values for all display metrics
defined in android.util.DisplayMetrics [Resources, 39].
Devices MUST support dynamic orientation by applications to either portrait or landscape screen orientation. That is, the device must respect the application's request for a specific screen orientation. Device implementations MAY select either portrait or landscape orientation as the default.
Devices MUST report the correct value for the device's current orientation, whenever queried via the android.content.res.Configuration.orientation, android.view.Display.getOrientation(), or other APIs.
Devices MUST NOT change the reported screen size or density when changing orientation.
Devices MUST report which screen orientations they support (
android.hardware.screen.portrait and/or
android.hardware.screen.landscape) and MUST report at least one
supported orientation. For example, a device with a fixed-orientation
landscape screen, such as a television or laptop, MUST only report
android.hardware.screen.landscape.
Device implementations MUST support both OpenGL ES 1.0 and 2.0, as embodied and detailed in the Android SDK documentations. Device implementations SHOULD support OpenGL ES 3.0 on devices capable of supporting OpenGL ES 3.0. Device implementations MUST also support Android Renderscript, as detailed in the Android SDK documentation [Resources, 8].
Device implementations MUST also correctly identify themselves as supporting OpenGL ES 1.0, OpenGL ES 2.0, or OpenGL ES 3.0. That is:
GLES10.getString() method)
MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0 Device implementations MAY implement any desired OpenGL ES extensions. However, device implementations MUST report via the OpenGL ES managed and native APIs all extension strings that they do support, and conversely MUST NOT report extension strings that they do not support.
Note that Android includes support for applications to optionally
specify that they require specific OpenGL texture compression formats. These
formats are typically vendor-specific. Device implementations are not required
by Android to implement any specific texture compression format. However,
they SHOULD accurately report any texture compression formats that they do
support, via the getString() method in the OpenGL API.
Android includes a mechanism for applications to declare that they
wanted to enable hardware acceleration for 2D graphics at the Application,
Activity, Window or View level through the use of a manifest tag
android:hardwareAccelerated or direct API calls
[Resources, 9].
In Android 4.4, device implementations MUST enable hardware acceleration by
default, and MUST disable hardware acceleration if the developer so requests
by setting android:hardwareAccelerated="false" or disabling
hardware acceleration directly through the Android View APIs.
In addition, device implementations MUST exhibit behavior consistent with the Android SDK documentation on hardware acceleration [Resources, 9].
Android includes a TextureView object that lets developers
directly integrate hardware-accelerated OpenGL ES textures as rendering targets
in a UI hierarchy. Device implementations MUST support the TextureView
API, and MUST exhibit consistent behavior with the upstream Android
implementation.
Android includes support for EGL_ANDROID_RECORDABLE, a EGLConfig attribute
that indicates whether the EGLConfig supports rendering to an ANativeWindow that records images to a video.
Device implementations MUST support EGL_ANDROID_RECORDABLE extension [Resources, 79].
Android specifies a "compatibility mode" in which the framework operates in an 'normal' screen size equivalent (320dp width) mode for the benefit of legacy applications not developed for old versions of Android that pre-date screen-size independence. Device implementations MUST include support for legacy application compatibility mode as implemented by the upstream Android open source code. That is, device implementations MUST NOT alter the triggers or thresholds at which compatibility mode is activated, and MUST NOT alter the behavior of the compatibility mode itself.
Device implementation screens are classified as one of two types:
Fixed-Pixel Device Implementations
Fixed-pixel device implementations MAY use screens of any pixel dimensions, provided that they meet the requirements defined this Compatibility Definition.
Fixed-pixel implementations MAY include a video output port for use with an external display. However, if that display is ever used for running apps, the device MUST meet the following requirements:
For example, a tablet that is 7" diagonal size with a 1024x600 pixel resolution is considered a fixed-pixel large mdpi display implementation. If it contains a video output port that displays at 720p or 1080p the device implementation MUST scale the output so that applications are only executed in a large mdpi window, regardless of whether the fixed-pixel display or video output port is in use.
Variable-Pixel Device Implementations
Variable-pixel device implementations MUST support at least one of 1280x720, 1920x1080, or 3840x2160 (that is, 720p, 1080p, or 4K). Device implementations with variable-pixel displays MUST NOT support any other screen configuration or mode. Device implementations with variable-pixel screens MAY change screen configuration or mode at runtime or boot-time. For example, a user of a set-top box may replace a 720p display with a 1080p display, and the device implementation may adjust accordingly.
Additionally, variable-pixel device implementations MUST report the following configuration buckets for these pixel dimensions:
For clarity, device implementations with variable pixel dimensions are restricted to 720p, 1080p, or 4K in Android 4.4, and MUST be configured to report screen size and density buckets as noted above.
The Android platform includes APIs that allow applications to render rich graphics to the display. Devices MUST support all of these APIs as defined by the Android SDK unless specifically allowed in this document. Specifically:
Android includes support for secondary display to enable media sharing capabilities and
developer APIs for accessing external displays. If a device supports an external display either via
a wired, wireless or an embedded additional display connection then the device implementation MUST
implement the display manager API as described in the Android SDK documentation [Resources, 75].
Device implementations that support secure video output and are capable of supporting secure surfaces MUST declare support
for Display.FLAG_SECURE. Specifically, device implementations that declare support for Display.FLAG_SECURE,
MUST support HDCP 2.x or higher for Miracast wireless displays or HDCP 1.2 or higher for wired displays. The upstream
Android open source implementation includes support for wireless (Miracast) and wired (HDMI) displays that satisfies this requirement.
Device implementations:
android.content.res.Configuration.keyboard
[Resources, 40] (that is, QWERTY, or 12-key)Device implementations:
android.content.res.Configuration.navigation
[Resources, 40]The Home, Recents and Back functions are essential to the Android navigation paradigm. Device implementations MUST make these functions available to the user at all times when running applications. These functions MAY be implemented via dedicated physical buttons (such as mechanical or capacitive touch buttons), or MAY be implemented using dedicated software keys on a distinct portion of the screen, gestures, touch panel, etc. Android supports both implementations. All of these functions MUST be accessible with a single action (e.g. tap, double-click or gesture) when visible.
The Back and Recents functions SHOULD have a visible button or icon unless hidden together with other navigation functions in full-screen mode. The Home function MUST have a visible button or icon unless hidden together with other navigation functions in full-screen mode.
The Menu function is deprecated in favor of action bar since Android 4.0.
Device implementations SHOULD NOT implement a dedicated physical button for
the Menu function. If the physical Menu button is implemented and the device
is running applications with targetSdkVersion > 10, the device
implementation:
For backwards compatibility, device implementations MUST make available the
Menu function to applications when targetSdkVersion <= 10,
either by a phsyical button, a software key or gestures. This Menu function
should be presented unless hidden together with other navigation functions.
Android supports Assist action [Resources, 63]. Device implementations MUST make the Assist action available to the user at all times when running applications. The Assist action SHOULD be implemented as a long-press on the Home button or a swipe-up gesture on the software Home key. This function MAY be implemented via another physical button, software key or gestures, but MUST be accessible with a single action (e.g. tap, double-click or gesture) when other navigation keys are visible.
Device implementations MAY use a distinct portion of the screen to display the navigation keys, but if so, MUST meet these requirements:
SYSTEM_UI_FLAG_VISIBLE.SYSTEM_UI_FLAG_LOW_PROFILE.SYSTEM_UI_FLAG_HIDE_NAVIGATION.Device implementations SHOULD have a pointer input system of some kind (either mouse-like, or touch). However, if a device
implementation does not support a pointer input system, it MUST NOT report the android.hardware.touchscreen or
android.hardware.faketouch feature constant. Device implementations that do include a pointer input system:
android.content.res.Configuration.touchscreen [Resources, 40]
corresponding to the type of the specific touchscreen on the deviceAndroid includes support for a variety of touch screens, touch pads, and fake touch input devices.
Touch screen based device implementations are associated with a display [Resources, 81]
such that the user has the impression of directly manipulating items on screen. Since the user is directly touching the screen,
the system does not require any additional affordances to indicate the objects being manipulated.
In contrast, a fake touch interface provides a user input system that approximates a subset of touchscreen capabilities.
For example, a mouse or remote control that drives an on-screen cursor approximates touch, but requires the user to first
point or focus then click. Numerous input devices like the mouse, trackpad, gyro-based air mouse, gyro-pointer, joystick,
and multi-touch trackpad can support fake touch interactions. Android 4.0 includes the feature constant android.hardware.faketouch,
which corresponds to a high-fidelity non-touch (that is, pointer-based) input device such as a mouse or trackpad that can adequately emulate touch-based
input (including basic gesture support), and indicates that the device supports an emulated subset of touchscreen
functionality. Device implementations that declare the fake touch feature MUST meet the fake touch requirements in Section 7.2.5.
Device implementations MUST report the correct feature corresponding to the type of input used. Device implementations that
include a touchscreen (single-touch or better) MUST report the platform feature constant android.hardware.touchscreen.
Device implementations that report the platform feature constant android.hardware.touchscreen MUST also report the platform feature constant
android.hardware.faketouch. Device implementations that do not include a touchscreen (and rely on a pointer device only) MUST NOT report any
touchscreen feature, and MUST report only android.hardware.faketouch if they meet the fake touch requirements in Section 7.2.5.
Device implementations that declare support for android.hardware.faketouch
down or up on the screen [Resources, 80] down and up on an object on the screen, which allows users to emulate tap on an object on the screendown, pointer up, pointer down then pointer up in the same place on an object on the screen
within a time threshold, which allows users to emulate double tap on an object on the screen [Resources, 80]down on an arbitrary point on the screen, pointer move to any other arbitrary point on the screen,
followed by a pointer up, which allows users to emulate a touch dragdown then allow users to quickly move the object to a different position on the screen
and then pointer up on the screen, which allows users to fling an object on the screenDevices that declare support for android.hardware.faketouch.multitouch.distinct MUST meet the requirements for
faketouch above, and MUST also support distinct tracking of two or more independent pointer inputs.
Device implementations MAY omit a microphone. However, if a device
implementation omits a microphone, it MUST NOT report the
android.hardware.microphone feature constant, and must implement
the audio recording API as no-ops, per Section 7.
Conversely, device implementations that do possess a microphone:
android.hardware.microphone feature constantAndroid includes APIs for accessing a variety of sensor types. Devices implementations generally MAY omit these sensors, as provided for in the following subsections. If a device includes a particular sensor type that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. For example, device implementations:
android.content.pm.PackageManager class. [Resources, 37]SensorManager.getSensorList() and similar methodsThe list above is not comprehensive; the documented behavior of the Android SDK is to be considered authoritative.
Some sensor types are synthetic, meaning they can be derived from data provided by one or more other sensors. (Examples include the orientation sensor, and the linear acceleration sensor.) Device implementations SHOULD implement these sensor types, when they include the prerequisite physical sensors.
Android includes a notion of a "streaming" sensor, which is one that returns data continuously, rather than only when the data changes. Device implementations MUST continuously provide periodic data samples for any API indicated by the Android SDK documentation to be a streaming sensor. Note that the device implementations MUST ensure that the sensor stream must not prevent the device CPU from entering a suspend state or waking up from a suspend state.
Device implementations SHOULD include a 3-axis accelerometer. If a device implementation does include a 3-axis accelerometer, it:
Device implementations SHOULD include a 3-axis magnetometer (i.e. compass.) If a device does include a 3-axis magnetometer, it:
Device implementations SHOULD include a GPS receiver. If a device implementation does include a GPS receiver, it SHOULD include some form of "assisted GPS" technique to minimize GPS lock-on time.
Device implementations SHOULD include a gyroscope (i.e. angular change sensor.) Devices SHOULD NOT include a gyroscope sensor unless a 3-axis accelerometer is also included. If a device implementation includes a gyroscope, it:
Device implementations MAY include a barometer (i.e. ambient air pressure sensor.) If a device implementation includes a barometer, it:
Device implementations MAY include an ambient thermometer (i.e. temperature
sensor). If present, it MUST be defined as SENSOR_TYPE_AMBIENT_TEMPERATURE
and it MUST measure the ambient (room) temperature in degrees Celsius.
Device implementations MAY but SHOULD NOT include a CPU temperature sensor.
If present, it MUST be defined as SENSOR_TYPE_TEMPERATURE, it MUST
measure the temperature of the device CPU, and it MUST NOT measure any other
temperature. Note the SENSOR_TYPE_TEMPERATURE sensor type was
deprecated in Android 4.0.
Device implementations MAY include a photometer (i.e. ambient light sensor.)
Device implementations MAY include a proximity sensor. If a device implementation does include a proximity sensor, it MUST measure the proximity of an object in the same direction as the screen. That is, the proximity sensor MUST be oriented to detect objects close to the screen, as the primary intent of this sensor type is to detect a phone in use by the user. If a device implementation includes a proximity sensor with any other orientation, it MUST NOT be accessible through this API. If a device implementation has a proximity sensor, it MUST be have 1-bit of accuracy or more.
"Telephony" as used by the Android APIs and this document refers specifically to hardware related to placing voice calls and sending SMS messages via a GSM or CDMA network. While these voice calls may or may not be packet-switched, they are for the purposes of Android considered independent of any data connectivity that may be implemented using the same network. In other words, the Android "telephony" functionality and APIs refer specifically to voice calls and SMS; for instance, device implementations that cannot place calls or send/receive SMS messages MUST NOT report the "android.hardware.telephony" feature or any sub-features, regardless of whether they use a cellular network for data connectivity.
Android MAY be used on devices that do not include telephony hardware. That is, Android is compatible with devices that are not phones. However, if a device implementation does include GSM or CDMA telephony, it MUST implement full support for the API for that technology. Device implementations that do not include telephony hardware MUST implement the full APIs as no-ops.
Android device implementations SHOULD include support for one or more forms of 802.11 (b/g/a/n, etc.) If a device implementation does include support for 802.11, it MUST implement the corresponding Android API.
Device implementations MUST implement the multicast API as described in the SDK documentation [Resources, 62]. Device implementations that do include Wi-Fi support MUST support multicast DNS (mDNS). Device implementations MUST NOT filter mDNS packets (224.0.0.251) at any time of operation including when the screen is not in an active state.
Device implementations SHOULD include support for Wi-Fi direct (Wi-Fi peer-to-peer). If a device implementation does include support for Wi-Fi direct, it MUST implement the corresponding Android API as described in the SDK documentation [Resources, 68]. If a device implementation includes support for Wi-Fi direct, then it:
Device implementations SHOULD include support for Wi-Fi Tunneled Direct Link Setup (TDLS) as described in the Android SDK Documentation [Resources, 85]. If a device implementation does include support for TDLS and TDLS is enabled by the WiFiManager API, the device:
Device implementations SHOULD include a Bluetooth transceiver. Device implementations that do include a Bluetooth transceiver MUST enable the RFCOMM-based Bluetooth API as described in the SDK documentation and declare hardware feature android.hardware.bluetooth [Resources, 42]. Device implementations SHOULD implement relevant Bluetooth profiles, such as A2DP, AVRCP, OBEX, etc. as appropriate for the device.
Device implementations that do include support for Bluetooth GATT (generic attribute profile) to enable communication with Bluetooth Smart or Smart Ready devices MUST enable the GATT-based Bluetooth API as described in the SDK documentation and declare hardware feature android.hardware.bluetooth_le [Resources, 42].
Device implementations SHOULD include a transceiver and related hardware for Near-Field Communications (NFC). If a device implementation does include NFC hardware, then it:
android.content.pm.PackageManager.hasSystemFeature() method.
[Resources, 37](Note that publicly available links are not available for the JIS, ISO, and NFC Forum specifications cited above.)
Android 4.4 introduces support for NFC Host Card Emulation (HCE) mode. If a device implementation does include an NFC controller capable of HCE and Application ID (AID) routing, then it:
android.hardware.nfc.hce feature constant
Additionally, device implementations MAY include reader/writer support for the following MIFARE technologies.
Note that Android includes APIs for these MIFARE types. If a device implementation supports MIFARE in the reader/writer role, it:
android.content.pm.PackageManager.hasSystemFeature() method.
[Resources, 37] Note that this is not a standard
Android feature, and as such does not appear as a constant on the
PackageManager class.If a device implementation does not include NFC hardware, it MUST NOT
declare the android.hardware.nfc feature from the
android.content.pm.PackageManager.hasSystemFeature() method [Resources, 37], and MUST implement the Android NFC
API as a no-op.
As the classes android.nfc.NdefMessage and
android.nfc.NdefRecord represent a protocol-independent data
representation format, device implementations MUST implement these APIs even
if they do not include support for NFC or declare the android.hardware.nfc
feature.
Device implementations MUST include support for one or more forms of data networking. Specifically, device implementations MUST include support for at least one data standard capable of 200Kbit/sec or greater. Examples of technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g, Ethernet, etc.
Device implementations where a physical networking standard (such as Ethernet) is the primary data connection SHOULD also include support for at least one common wireless data standard, such as 802.11 (Wi-Fi).
Devices MAY implement more than one form of data connectivity.
Device implementations MUST have the master auto-sync setting on by default
so that the method getMasterSyncAutomatically() returns
"true" [Resources, 88].
Device implementations SHOULD include a rear-facing camera, and MAY include a front-facing camera. A rear-facing camera is a camera located on the side of the device opposite the display; that is, it images scenes on the far side of the device, like a traditional camera. A front-facing camera is a camera located on the same side of the device as the display; that is, a camera typically used to image the user, such as for video conferencing and similar applications.
Device implementations SHOULD include a rear-facing camera. If a device implementation includes a rear-facing camera, it:
FLASH_MODE_AUTO or
FLASH_MODE_ON attributes of a Camera.Parameters
object. Note that this constraint does not apply to the device's built-in
system camera application, but only to third-party applications using
Camera.PreviewCallback.Device implementations MAY include a front-facing camera. If a device implementation includes a front-facing camera, it:
android.hardware.Camera.setDisplayOrientation() [Resources, 50] method, the camera preview MUST be
mirrored horizontally relative to the orientation specified by the
application.Device implementations MUST implement the following behaviors for the camera-related APIs, for both front- and rear-facing cameras:
android.hardware.Camera.Parameters.setPreviewFormat(int), then the
device MUST use android.hardware.PixelFormat.YCbCr_420_SP for
preview data provided to application callbacks.android.hardware.Camera.PreviewCallback
instance and the system calls the onPreviewFrame() method
when the preview format is YCbCr_420_SP, the data in the byte[]
passed into onPreviewFrame() must further be in the NV21 encoding
format. That is, NV21 MUST be the default.android.graphics.ImageFormat.YV12 constant) for camera previews
for both front- and rear-facing cameras. (The hardware video encoder and camera
may use any native pixel format, but the device implementation MUST support conversion
to YV12.)Device implementations MUST implement the full Camera API included in the
Android SDK documentation [Resources, 51]),
regardless of whether the device includes hardware autofocus or other
capabilities. For instance, cameras that lack autofocus MUST still call any
registered android.hardware.Camera.AutoFocusCallback instances (even though
this has no relevance to a non-autofocus camera.) Note that this does apply
to front-facing cameras; for instance, even though most front-facing cameras
do not support autofocus, the API callbacks must still be "faked" as
described.
Device implementations MUST recognize and honor each parameter name defined
as a constant on the android.hardware.Camera.Parameters class, if the
underlying hardware supports the feature. If the device hardware does not
support a feature, the API must behave as documented. Conversely, Device
implementations MUST NOT honor or recognize string constants passed
to the android.hardware.Camera.setParameters() method other than
those documented as constants on the
android.hardware.Camera.Parameters. That is,
device implementations MUST support all standard Camera parameters if the
hardware allows, and MUST NOT support custom Camera parameter types.
For instance, device implementations that support image capture using high dynamic range (HDR)
imaging techniques MUST support camera parameter Camera.SCENE_MODE_HDR
[Resources, 78]).
Device implementations MUST broadcast the Camera.ACTION_NEW_PICTURE
intent whenever a new picture is taken by the camera and the entry of the picture
has been added to the media store.
Device implementations MUST broadcast the Camera.ACTION_NEW_VIDEO
intent whenever a new video is recorded by the camera and the entry of the picture
has been added to the media store.
Both front- and rear-facing cameras, if present, MUST be oriented so that the long dimension of the camera aligns with the screen's long dimension. That is, when the device is held in the landscape orientation, cameras MUST capture images in the landscape orientation. This applies regardless of the device's natural orientation; that is, it applies to landscape-primary devices as well as portrait-primary devices.
Device implementations MUST have at least 340MB of memory available to the kernel and userspace. The 340MB MUST be in addition to any memory dedicated to hardware components such as radio, video, and so on that is not under the kernel's control.
Device implementations with less than 512MB of memory available to the kernel
and userspace MUST return the value "true" for
ActivityManager.isLowRamDevice().
Device implementations MUST have at least 1GB of non-volatile storage available
for application private data. That is, the /data partition MUST be at
least 1GB. Device implementations that run Android are very strongly encouraged to
have at least 2GB of non-volatile storage for application private data so they will be
able to upgrade to the future platform releases.
The Android APIs include a Download Manager that applications may use to download data files [Resources, 56]. The device implementation of the Download Manager MUST be capable of downloading individual files of at least 100MB in size to the default "cache" location.
Device implementations MUST offer shared storage for applications. The shared storage provided MUST be at least 1GB in size.
Device implementations MUST be configured with shared storage mounted by
default, "out of the box". If the shared storage is not mounted on the Linux
path /sdcard, then the device MUST include a Linux symbolic link
from /sdcard to the actual mount point.
Device implementations MUST enforce as documented the
android.permission.WRITE_EXTERNAL_STORAGE permission on this
shared storage. Shared storage MUST otherwise be writable by any application
that obtains that permission.
Device implementations MAY have hardware for user-accessible removable storage, such as a Secure Digital card. Alternatively, device implementations MAY allocate internal (non-removable) storage as shared storage for apps. The upstream Android Open Source Project includes an implementation that uses internal device storage for shared external storage APIs; device implementations SHOULD use this configuration and software implementation.
Regardless of the form of shared storage used, device implementations MUST provide some mechanism to access the contents of shared storage from a host computer, such as USB mass storage (UMS) or Media Transfer Protocol (MTP). Device implementations MAY use USB mass storage, but SHOULD use Media Transfer Protocol. If the device implementation supports Media Transfer Protocol:
0x00.If the device implementation lacks USB ports, it MUST provide a host computer with access to the contents of shared storage by some other means, such as a network file system.
It is illustrative to consider two common examples. If a device
implementation includes an SD card slot to satisfy the shared storage
requirement, a FAT-formatted SD card 1GB in size or larger MUST be included
with the device as sold to users, and MUST be mounted by default.
Alternatively, if a device implementation uses internal fixed storage to
satisfy this requirement, that storage MUST be 1GB in size or larger
and mounted on /sdcard (or /sdcard
MUST be a symbolic link to the physical location if it is mounted elsewhere.)
Device implementations that include multiple shared storage paths (such as both an SD card slot and shared internal storage) MUST NOT allow Android applications to write to the secondary external storage, except for their package-specific directories on the secondary external storage, but SHOULD expose content from both storage paths transparently through Android's media scanner service and android.provider.MediaStore.
Device implementations SHOULD include a USB client port, and SHOULD include a USB host port.
If a device implementation includes a USB client port:
android.hardware.usb.accessory [Resources,
52]If a device implementation includes a USB host port:
android.hardware.usb.host [Resources, 53]Device implementations MUST implement the Android Debug Bridge. If a device implementation omits a USB client port, it MUST implement the Android Debug Bridge via local-area network (such as Ethernet or 802.11)
Device implementations MUST meet the key performance metrics of an Android- compatible device defined in the table below:
| Metric | Performance Threshold | Comments |
| Application Launch Time | The following applications should launch within the specified time.
|
The launch time is measured as the total time to complete loading the default activity for the application, including the time it takes to start the Linux process, load the Android package into the Dalvik VM, and call onCreate. |
| Simultaneous Applications | When multiple applications have been launched, re-launching an already-running application after it has been launched must take less than the original launch time. |
Device implementations MUST implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs [Resources, 54] in the Android developer documentation. Device implementations MUST support installation of self-signed applications without requiring any additional permissions/certificates from any third parties/authorities. Specifically, compatible devices MUST support the security mechanisms described in the follow sub-sections.
Device implementations MUST support the Android permissions model as defined in the Android developer documentation [Resources, 54]. Specifically, implementations MUST enforce each permission defined as described in the SDK documentation; no permissions may be omitted, altered, or ignored. Implementations MAY add additional permissions, provided the new permission ID strings are not in the android.* namespace.
Device implementations MUST support the Android application sandbox model, in which each application runs as a unique Unix-style UID and in a separate process. Device implementations MUST support running multiple applications as the same Linux user ID, provided that the applications are properly signed and constructed, as defined in the Security and Permissions reference [Resources, 54].
Device implementations MUST support the Android file access permissions model as defined in the Security and Permissions reference [Resources, 54].
Device implementations MAY include runtime environments that execute applications using some other software or technology than the Dalvik virtual machine or native code. However, such alternate execution environments MUST NOT compromise the Android security model or the security of installed Android applications, as described in this section.
Alternate runtimes MUST themselves be Android applications, and abide by the standard Android security model, as described elsewhere in Section 9.
Alternate runtimes MUST NOT be granted access to resources protected by
permissions not requested in the runtime's AndroidManifest.xml file via the
<uses-permission> mechanism.
Alternate runtimes MUST NOT permit applications to make use of features protected by Android permissions restricted to system applications.
Alternate runtimes MUST abide by the Android sandbox model. Specifically:
Alternate runtimes MUST NOT be launched with, be granted, or grant to other applications any privileges of the superuser (root), or of any other user ID.
The .apk files of alternate runtimes MAY be included in the system image of a device implementation, but MUST be signed with a key distinct from the key used to sign other applications included with the device implementation.
When installing applications, alternate runtimes MUST obtain user consent for the Android permissions used by the application. That is, if an application needs to make use of a device resource for which there is a corresponding Android permission (such as Camera, GPS, etc.), the alternate runtime MUST inform the user that the application will be able to access that resource. If the runtime environment does not record application capabilities in this manner, the runtime environment MUST list all permissions held by the runtime itself when installing any application using that runtime.
Android includes support for multiple users and provides support for full user isolation [Resources, 70].
Device implementations MUST meet these requirements related to multi-user support [Resources, 71]:
Each user instance on an Android device MUST have separate and isolated external storage directories. Device implementations MAY store multiple users' data on the same volume or filesystem. However, the device implementation MUST ensure that applications owned by and running on behalf a given user cannot list, read, or write to data owned by any other user. Note that removable media, such as SD card slots, can allow one user to access another's data by means of a host PC. For this reason, device implementations that use removable media for the external storage APIs MUST encrypt the contents of the SD card if multi-user is enabled using a key stored only on non-removable media accessible only to the system. As this will make the media unreadable by a host PC, device implementations will be required to switch to MTP or a similar system to provide host PCs with access to the current user's data. Accordingly, device implementations MAY but SHOULD NOT enable multi-user if they use removable media [Resources, 72] for primary external storage.
Android includes support for warning users for any outgoing premium SMS message [Resources, 73] . Premium SMS messages are text messages sent to a service registered with a carrier that may incur a charge to the user.
Device implementations that declare support for android.hardware.telephony MUST warn users before sending a SMS message to numbers identified by regular expressions defined in /data/misc/sms/codes.xml file in the device.
The upstream Android Open Source Project provides an implementation that satisfies this requirement.
The Android Sandbox includes features that can use the Security-Enhanced Linux (SELinux) mandatory access control (MAC) system and other security features in the Linux kernel. SELinux or any other security features, if implemented below the Android framework:
If any API for configuration of policy is exposed to an application that can affect another application (such as a Device Administration API), the API MUST NOT allow configurations that break compatibility.
Devices MUST implement SELinux and meet the following requirements, which are satisfied by the reference implementation in the upstream Android Open Source Project.
/sepolicy file on the deviceDevice implementations SHOULD retain the default SELinux policy provided in the upstream Android Open Source Project, until they have first audited their additions to the SELinux policy. Device implementations MUST be compatible with the upstream Android Open Source Project.
If the device implements functionality in the system that captures the contents displayed on the screen and/or records the audio stream played on the device, it MUST continuously notify the user whenever this functionality is enabled and actively capturing/recording.
IF the device has lockscreen, the device MUST support full-disk encryption.
Device implementations MUST pass all tests described in this section.
However, note that no software test package is fully comprehensive. For this reason, device implementers are very strongly encouraged to make the minimum number of changes as possible to the reference and preferred implementation of Android available from the Android Open Source Project. This will minimize the risk of introducing bugs that create incompatibilities requiring rework and potential device updates.
Device implementations MUST pass the Android Compatibility Test Suite (CTS) [Resources, 2] available from the Android Open Source Project, using the final shipping software on the device. Additionally, device implementers SHOULD use the reference implementation in the Android Open Source tree as much as possible, and MUST ensure compatibility in cases of ambiguity in CTS and for any reimplementations of parts of the reference source code.
The CTS is designed to be run on an actual device. Like any software, the CTS may itself contain bugs. The CTS will be versioned independently of this Compatibility Definition, and multiple revisions of the CTS may be released for Android 4.4. Device implementations MUST pass the latest CTS version available at the time the device software is completed.
Device implementations MUST correctly execute all applicable cases in the CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite, and is intended to be run by a human operator to test functionality that cannot be tested by an automated system, such as correct functioning of a camera and sensors.
The CTS Verifier has tests for many kinds of hardware, including some hardware that is optional. Device implementations MUST pass all tests for hardware which they possess; for instance, if a device possesses an accelerometer, it MUST correctly execute the Accelerometer test case in the CTS Verifier. Test cases for features noted as optional by this Compatibility Definition Document MAY be skipped or omitted.
Every device and every build MUST correctly run the CTS Verifier, as noted above. However, since many builds are very similar, device implementers are not expected to explicitly run the CTS Verifier on builds that differ only in trivial ways. Specifically, device implementations that differ from an implementation that has passed the CTS Verifier only by the set of included locales, branding, etc. MAY omit the CTS Verifier test.
Device implementers MUST test implementation compatibility using the following open source applications:
Each app above MUST launch and behave correctly on the implementation, for the implementation to be considered compatible.
Device implementations MUST include a mechanism to replace the entirety of the system software. The mechanism need not perform "live" upgrades - that is, a device restart MAY be required.
Any method can be used, provided that it can replace the entirety of the software preinstalled on the device. For instance, any of the following approaches will satisfy this requirement:
The update mechanism used MUST support updates without wiping user data. That is, the update mechanism MUST preserve application private data and application shared data. Note that the upstream Android software includes an update mechanism that satisfies this requirement.
If an error is found in a device implementation after it has been released but within its reasonable product lifetime that is determined in consultation with the Android Compatibility Team to affect the compatibility of third-party applications, the device implementer MUST correct the error via a software update available that can be applied per the mechanism just described.
The following table contains a summary of the changes to the Compatibility Definition in this release.
| Section(s) | Summary of change |
|---|---|
| 3.2.2. Build Parameters | Revised descriptions of BRAND, DEVICE, and PRODUCT. SERIAL is now required. |
| 3.2.3.5. Default App Settings | New section that adds requirement to comply with new default application settings |
| 3.3.1 Application Binary Interfaces | Clarified allowed values for the android.os.Build.CPU_ABI
and android.os.Build.CPU_ABI2 parameters. |
| 3.4.1. WebView Compatibility | Added Chromium as required WebView implementation. |
| 3.7. Virtual Machine Compatibility | Added requirement for xxhdpi and 400dpi screen densities. |
| 3.8.6. Themes | Updated to reflect use of translucent system bars. |
| 3.8.12. Location | New section that adds requirement location settings be centralized. |
| 3.8.13. Unicode | New section that adds requirement for emoji support. |
| 3.9. Device Administration | Noted preinstalled administrative applications cannot be the default Device Owner application. |
| 5.1. Media Codecs | Added VP9 decoder requirement. Added recommended specification for hardware VP8 codecs. |
| 5.3. Video Decoding | Added VP9. Added recommendation for dynamic resolution switching. |
| 5.4. Audio Recording | Added REMOTE_SUBMIX as new required audio source. Made use
of android.media.audiofx.NoiseSuppressor API a requirement. |
| 6.2.1 Experimental | New section that introduces the ART runtime and requires Dalvik as the default runtime. |
| 7.1.1. Screen Configuration | Replaced 1.85 aspect ratio with 1.86. Added 400dpi screen density. |
| 7.1.6. Screen Types | Added 640 dpi (4K) resolution configuration. |
| 7.2.3. Navigation keys | Added Recents function as essential; demoted Menu function in priority. |
| 7.3.6. Thermometer | Added SENSOR_TYPE_AMBIENT_TEMPERATURE as recommended thermometer. |
| 7.4.2.2. Wi-Fi Tunneled Direct Link Setup | New section that adds support for Wi-Fi Tunneled Direct Link Setup (TDLS). |
| 7.4.4. Near-Field Communications | Added Host Card Emulation (HCE) as a requirement. Replaced SNEP GET with Logical Link Control Protocol (LLCP) and added the Bluetooth Object Push Profile as a requirement. |
| 7.4.6. Sync Settings | New section that adds requirement auto-sync data be enabled by default. |
| 7.6.1. Minimum Memory and Storage | Added ActivityManager.isLowRamDevice() setting requirement
for devices with less than 512MB of memory. Increased storage requirements
from 512MB and 1GB to 1GB and 2GB, respectively. |
| 7.6.2. Shared "External" Storage | Editorial fixes such as change of section name, and moved text that fits in this section from section 9.5. Noted applications may write to their package-specific directories on secondary external storage. |
| 7.7. USB | Added requirement all devices report a USB serial number. |
| 9.5. Multi-User Support | Moved non multi-user specific text to section 7.6.2. |
| 9.7. Kernel Security Features | Rewritten to note switch of SELinux to enforcing mode and requirement SELinux output not be rendered in the user interface. |
| 9.8. Privacy | New section that adds requirement audio and video recording must trigger continuous notifications to the user. |
| 9.9. Full-Disk Encryption | New section that adds requirement devices with lockscreen support full-disk encryption. |
| 12. Document Changelog | New section that summarizes changes in the CDD by section. |
You can contact the document authors at compatibility@android.com for clarifications and to bring up any issues that you think the document does not cover.