1 /*
2 **
3 ** Copyright 2015, The Android Open Source Project
4 **
5 ** Licensed under the Apache License, Version 2.0 (the "License");
6 ** you may not use this file except in compliance with the License.
7 ** You may obtain a copy of the License at
8 **
9 **     http://www.apache.org/licenses/LICENSE-2.0
10 **
11 ** Unless required by applicable law or agreed to in writing, software
12 ** distributed under the License is distributed on an "AS IS" BASIS,
13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 ** See the License for the specific language governing permissions and
15 ** limitations under the License.
16 */
17 
18 #ifndef ANDROID_AUDIO_STREAM_OUT_H
19 #define ANDROID_AUDIO_STREAM_OUT_H
20 
21 #include <stdint.h>
22 #include <sys/types.h>
23 
24 #include <system/audio.h>
25 
26 #include "AudioStreamOut.h"
27 
28 namespace android {
29 
30 class AudioHwDevice;
31 
32 /**
33  * Managed access to a HAL output stream.
34  */
35 class AudioStreamOut {
36 public:
37 // AudioStreamOut is immutable, so its fields are const.
38 // For emphasis, we could also make all pointers to them be "const *",
39 // but that would clutter the code unnecessarily.
40     AudioHwDevice * const audioHwDev;
41     audio_stream_out_t *stream;
42     const audio_output_flags_t flags;
43 
44     audio_hw_device_t *hwDev() const;
45 
46     AudioStreamOut(AudioHwDevice *dev, audio_output_flags_t flags);
47 
48     virtual status_t open(
49             audio_io_handle_t handle,
50             audio_devices_t devices,
51             struct audio_config *config,
52             const char *address);
53 
~AudioStreamOut()54     virtual ~AudioStreamOut() { }
55 
56     // Get the bottom 32-bits of the 64-bit render position.
57     status_t getRenderPosition(uint32_t *frames);
58 
59     virtual status_t getRenderPosition(uint64_t *frames);
60 
61     virtual status_t getPresentationPosition(uint64_t *frames, struct timespec *timestamp);
62 
63     /**
64     * Write audio buffer to driver. Returns number of bytes written, or a
65     * negative status_t. If at least one frame was written successfully prior to the error,
66     * it is suggested that the driver return that successful (short) byte count
67     * and then return an error in the subsequent call.
68     *
69     * If set_callback() has previously been called to enable non-blocking mode
70     * the write() is not allowed to block. It must write only the number of
71     * bytes that currently fit in the driver/hardware buffer and then return
72     * this byte count. If this is less than the requested write size the
73     * callback function must be called when more space is available in the
74     * driver/hardware buffer.
75     */
76     virtual ssize_t write(const void *buffer, size_t bytes);
77 
78     /**
79      * @return frame size from the perspective of the application and the AudioFlinger.
80      */
getFrameSize()81     virtual size_t getFrameSize() const { return mHalFrameSize; }
82 
83     /**
84      * @return format from the perspective of the application and the AudioFlinger.
85      */
86     virtual audio_format_t getFormat() const;
87 
88     /**
89      * The HAL may be running at a higher sample rate if, for example, playing wrapped EAC3.
90      * @return sample rate from the perspective of the application and the AudioFlinger.
91      */
92     virtual uint32_t getSampleRate() const;
93 
94     /**
95      * The HAL is in stereo mode when playing multi-channel compressed audio over HDMI.
96      * @return channel mask from the perspective of the application and the AudioFlinger.
97      */
98     virtual audio_channel_mask_t getChannelMask() const;
99 
100 
101     virtual status_t flush();
102     virtual status_t standby();
103 
104 protected:
105     uint64_t             mFramesWritten; // reset by flush
106     uint64_t             mFramesWrittenAtStandby;
107     uint64_t             mRenderPosition; // reset by flush or standby
108     int                  mRateMultiplier;
109     bool                 mHalFormatIsLinearPcm;
110     size_t               mHalFrameSize;
111 };
112 
113 } // namespace android
114 
115 #endif // ANDROID_AUDIO_STREAM_OUT_H
116