1page.title=Media 2@jd:body 3 4<!-- 5 Copyright 2015 The Android Open Source Project 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18--> 19<div id="qv-wrapper"> 20 <div id="qv"> 21 <h2>In this document</h2> 22 <ol id="auto-toc"> 23 </ol> 24 </div> 25</div> 26 27<img style="float: right; margin: 0px 15px 15px 15px;" 28src="images/ape_fwk_hal_media.png" alt="Android Media HAL icon"/> 29 30<p>Android includes Stagefright, a media playback engine at the native level 31that has built-in software-based codecs for popular media formats.</p> 32 33<p>Stagefright audio and video playback features include integration with 34OpenMAX codecs, session management, time-synchronized rendering, transport 35control, and DRM.</p> 36 37<p>Stagefright also supports integration with custom hardware codecs provided by 38you. To set a hardware path to encode and decode media, you must implement a 39hardware-based codec as an OpenMax IL (Integration Layer) component.</p> 40 41<p class="note"><strong>Note:</strong> Stagefright updates can occur through the 42Android <a href="{@docRoot}security/bulletin/index.html">monthly security 43update</a> process and as part of an Android OS release.</p> 44 45<h2 id="architecture">Architecture</h2> 46<p>Media applications interact with the Android native multimedia framework 47according to the following architecture.</p> 48<img src="images/ape_fwk_media.png" alt="Android media architecture" 49id="figure1" /><p class="img-caption"><strong>Figure 1.</strong> Media 50architecture</p> 51 52<dl> 53<dt>Application Framework</dt> 54<dd>At the application framework level is application code that utilizes 55<a href="http://developer.android.com/reference/android/media/package-summary.html">android.media</a> 56APIs to interact with the multimedia hardware.</dd> 57 58<dt>Binder IPC</dt> 59<dd>The Binder IPC proxies facilitate communication over process boundaries. 60They are located in the <code>frameworks/av/media/libmedia</code> directory and 61begin with the letter "I".</dd> 62 63<dt>Native Multimedia Framework</dt> 64<dd>At the native level, Android provides a multimedia framework that utilizes 65the Stagefright engine for audio and video recording and playback. Stagefright 66comes with a default list of supported software codecs and you can implement 67your own hardware codec by using the OpenMax integration layer standard. For 68more implementation details, see the MediaPlayer and Stagefright components 69located in <code>frameworks/av/media</code>.</dd> 70 71<dt>OpenMAX Integration Layer (IL)</dt> 72<dd>The OpenMAX IL provides a standardized way for Stagefright to recognize and 73use custom hardware-based multimedia codecs called components. You must provide 74an OpenMAX plugin in the form of a shared library named 75<code>libstagefrighthw.so</code>. This plugin links Stagefright with your custom 76codec components, which must be implemented according to the OpenMAX IL 77component standard.</dd> 78</dl> 79 80<h2 id="codecs">Implementing custom codecs</h2> 81<p>Stagefright comes with built-in software codecs for common media formats, but 82you can also add your own custom hardware codecs as OpenMAX components. To do 83this, you must create the OMX components and an OMX plugin that hooks together 84your custom codecs with the Stagefright framework. For example components, see 85the <code>hardware/ti/omap4xxx/domx/</code>; for an example plugin for the 86Galaxy Nexus, see <code>hardware/ti/omap4xx/libstagefrighthw</code>.</p> 87 88<p>To add your own codecs:</p> 89<ol> 90<li>Create your components according to the OpenMAX IL component standard. The 91component interface is located in the 92<code>frameworks/native/include/media/OpenMAX/OMX_Component.h</code> file. To 93learn more about the OpenMAX IL specification, refer to the 94<a href="http://www.khronos.org/openmax/">OpenMAX website</a>.</li> 95<li>Create a OpenMAX plugin that links your components with the Stagefright 96service. For the interfaces to create the plugin, see 97<code>frameworks/native/include/media/hardware/OMXPluginBase.h</code> and 98<code>HardwareAPI.h</code> header files.</li> 99<li>Build your plugin as a shared library with the name 100<code>libstagefrighthw.so</code> in your product Makefile. For example: 101<br> 102<p><pre>LOCAL_MODULE := libstagefrighthw</pre></p> 103<p>In your device's Makefile, ensure you declare the module as a product 104package:</p> 105<pre> 106PRODUCT_PACKAGES += \ 107 libstagefrighthw \ 108 ... 109</pre></li></ol> 110 111<h2 id="expose">Exposing codecs to the framework</h2> 112<p>The Stagefright service parses the <code>system/etc/media_codecs.xml</code> 113and <code>system/etc/media_profiles.xml</code> to expose the supported codecs 114and profiles on the device to app developers via the 115<code>android.media.MediaCodecList</code> and 116<code>android.media.CamcorderProfile</code> classes. You must create both files 117in the <code>device/<company>/<device>/</code> directory 118and copy this over to the system image's <code>system/etc</code> directory in 119your device's Makefile. For example:</p> 120<pre> 121PRODUCT_COPY_FILES += \ 122 device/samsung/tuna/media_profiles.xml:system/etc/media_profiles.xml \ 123 device/samsung/tuna/media_codecs.xml:system/etc/media_codecs.xml \ 124</pre> 125 126<p>For complete examples, seee <code>device/samsung/tuna/media_codecs.xml</code> 127and <code>device/samsung/tuna/media_profiles.xml</code> .</p> 128 129<p class="note"><strong>Note:</strong> As of Android 4.1, the 130<code><Quirk></code> element for media codecs is no longer supported.</p> 131
