AudioTrack.h revision 54b6cfa9a9e5b861a9930af873580d6dc20f773c 
1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_AUDIOTRACK_H
18#define ANDROID_AUDIOTRACK_H
19
20#include <stdint.h>
21#include <sys/types.h>
22
23#include <media/IAudioFlinger.h>
24#include <media/IAudioTrack.h>
25#include <media/AudioSystem.h>
26
27#include <utils/RefBase.h>
28#include <utils/Errors.h>
29#include <utils/IInterface.h>
30#include <utils/IMemory.h>
31#include <utils/threads.h>
32
33
34namespace android {
35
36// ----------------------------------------------------------------------------
37
38class audio_track_cblk_t;
39
40// ----------------------------------------------------------------------------
41
42class AudioTrack
43{
44public:
45
46    enum stream_type {
47        DEFAULT     =-1,
48        VOICE_CALL  = 0,
49        SYSTEM      = 1,
50        RING        = 2,
51        MUSIC       = 3,
52        ALARM       = 4,
53        NUM_STREAM_TYPES
54    };
55
56    enum channel_index {
57        MONO   = 0,
58        LEFT   = 0,
59        RIGHT  = 1
60    };
61
62    /* Create Buffer on the stack and pass it to obtainBuffer()
63     * and releaseBuffer().
64     */
65
66    class Buffer
67    {
68    public:
69        enum {
70            MUTE    = 0x00000001
71        };
72        uint32_t    flags;
73        int         channelCount;
74        int         format;
75        size_t      frameCount;
76        size_t      size;
77        union {
78            void*       raw;
79            short*      i16;
80            int8_t*     i8;
81        };
82    };
83
84    /* Returns AudioFlinger's frame count. AudioTrack's buffers will
85     * be created with this size.
86     */
87    static  size_t      frameCount();
88
89    /* As a convenience, if a callback is supplied, a handler thread
90     * is automatically created with the appropriate priority. This thread
91     * invokes the callback when a new buffer becomes availlable.
92     */
93    typedef void (*callback_t)(void* user, const Buffer& info);
94
95    /* Constructs an uninitialized AudioTrack. No connection with
96     * AudioFlinger takes place.
97     */
98                        AudioTrack();
99
100    /* Creates an audio track and registers it with AudioFlinger.
101     * Once created, the track needs to be started before it can be used.
102     * Unspecified values are set to the audio hardware's current
103     * values.
104     */
105
106                        AudioTrack( int streamType,
107                                    uint32_t sampleRate = 0,
108                                    int format          = 0,
109                                    int channelCount    = 0,
110                                    int bufferCount     = 0,
111                                    uint32_t flags      = 0,
112                                    callback_t cbf = 0, void* user = 0);
113
114
115    /* Terminates the AudioTrack and unregisters it from AudioFlinger.
116     * Also destroys all resources assotiated with the AudioTrack.
117     */
118                        ~AudioTrack();
119
120
121    /* Initialize an uninitialized AudioTrack. */
122            status_t    set(int streamType      =-1,
123                            uint32_t sampleRate = 0,
124                            int format          = 0,
125                            int channelCount    = 0,
126                            int bufferCount     = 0,
127                            uint32_t flags      = 0,
128                            callback_t cbf = 0, void* user = 0);
129
130
131    /* Result of constructing the AudioTrack. This must be checked
132     * before using any AudioTrack API (except for set()), using
133     * an uninitialized AudoiTrack prduces undefined results.
134     */
135            status_t    initCheck() const;
136
137    /* Returns this track's latency in nanoseconds or framecount.
138     * This only includes the latency due to the fill buffer size.
139     * In particular, the hardware or driver latencies are not accounted.
140     */
141            nsecs_t     latency() const;
142
143   /* getters, see constructor */
144
145            int         streamType() const;
146            uint32_t    sampleRate() const;
147            int         format() const;
148            int         channelCount() const;
149            int         bufferCount() const;
150
151
152    /* After it's created the track is not active. Call start() to
153     * make it active. If set, the callback will start being called.
154     */
155            void        start();
156
157    /* Stop a track. If set, the callback will cease being called and
158     * obtainBuffer returns STOPPED. Note that obtainBuffer() still works
159     * and will fill up buffers until the pool is exhausted.
160     */
161            void        stop();
162            bool        stopped() const;
163
164    /* flush a stopped track. All pending buffers are discarded.
165     * This function has no effect if the track is not stoped.
166     */
167            void        flush();
168
169    /* Pause a track. If set, the callback will cease being called and
170     * obtainBuffer returns STOPPED. Note that obtainBuffer() still works
171     * and will fill up buffers until the pool is exhausted.
172     */
173            void        pause();
174
175    /* mute or unmutes this track.
176     * While mutted, the callback, if set, is still called.
177     */
178            void        mute(bool);
179            bool        muted() const;
180
181
182    /* set volume for this track, mostly used for games' sound effects
183     */
184            void        setVolume(float left, float right);
185            void        getVolume(float* left, float* right);
186
187    /* set sample rate for this track, mostly used for games' sound effects
188     */
189            void        setSampleRate(int sampleRate);
190            uint32_t    getSampleRate();
191
192    /* obtains a buffer of "frameCount" frames. The buffer must be
193     * filled entirely. If the track is stopped, obtainBuffer() returns
194     * STOPPED instead of NO_ERROR as long as there are buffers availlable,
195     * at which point NO_MORE_BUFFERS is returned.
196     * Buffers will be returned until the pool (buffercount())
197     * is exhausted, at which point obtainBuffer() will either block
198     * or return WOULD_BLOCK depending on the value of the "blocking"
199     * parameter.
200     */
201
202        enum {
203            NO_MORE_BUFFERS = 0x80000001,
204            STOPPED = 1
205        };
206
207            status_t    obtainBuffer(Buffer* audioBuffer, bool blocking);
208            void        releaseBuffer(Buffer* audioBuffer);
209
210
211    /* As a convenience we provide a write() interface to the audio buffer.
212     * This is implemented on top of lockBuffer/unlockBuffer. For best
213     * performance
214     *
215     */
216            ssize_t     write(const void* buffer, size_t size);
217
218    /*
219     * Dumps the state of an audio track.
220     */
221            status_t dump(int fd, const Vector<String16>& args) const;
222
223private:
224    /* copying audio tracks is not allowed */
225                        AudioTrack(const AudioTrack& other);
226            AudioTrack& operator = (const AudioTrack& other);
227
228    /* a small internal class to handle the callback */
229    class AudioTrackThread : public Thread
230    {
231    public:
232        AudioTrackThread(AudioTrack& receiver);
233    private:
234        friend class AudioTrack;
235        virtual bool        threadLoop();
236        virtual status_t    readyToRun();
237        virtual void        onFirstRef();
238        AudioTrack& mReceiver;
239        Mutex       mLock;
240    };
241
242            bool processAudioBuffer(const sp<AudioTrackThread>& thread);
243
244    sp<IAudioFlinger>       mAudioFlinger;
245    sp<IAudioTrack>         mAudioTrack;
246    sp<IMemory>             mCblkMemory;
247    sp<AudioTrackThread>    mAudioTrackThread;
248
249    float                   mVolume[2];
250    uint32_t                mSampleRate;
251    size_t                  mFrameCount;
252
253    audio_track_cblk_t*     mCblk;
254    uint8_t                 mStreamType;
255    uint8_t                 mFormat;
256    uint8_t                 mBufferCount;
257    uint8_t                 mChannelCount   : 4;
258    uint8_t                 mMuted          : 1;
259    uint8_t                 mReserved       : 2;
260    status_t                mStatus;
261    nsecs_t                 mLatency;
262
263    volatile int32_t        mActive;
264
265    callback_t              mCbf;
266    void*                   mUserData;
267
268    AudioTrack::Buffer      mAudioBuffer;
269    size_t                  mPosition;
270
271    uint32_t                mReservedFBC[4];
272};
273
274
275}; // namespace android
276
277#endif // ANDROID_AUDIOTRACK_H
278