AudioTrack.h revision be916aa1267e2e6b1c148f51d11bcbbc79cb864c
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 <binder/IInterface.h> 30#include <binder/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 enum channel_index { 46 MONO = 0, 47 LEFT = 0, 48 RIGHT = 1 49 }; 50 51 /* Events used by AudioTrack callback function (audio_track_cblk_t). 52 */ 53 enum event_type { 54 EVENT_MORE_DATA = 0, // Request to write more data to PCM buffer. 55 EVENT_UNDERRUN = 1, // PCM buffer underrun occured. 56 EVENT_LOOP_END = 2, // Sample loop end was reached; playback restarted from loop start if loop count was not 0. 57 EVENT_MARKER = 3, // Playback head is at the specified marker position (See setMarkerPosition()). 58 EVENT_NEW_POS = 4, // Playback head is at a new position (See setPositionUpdatePeriod()). 59 EVENT_BUFFER_END = 5 // Playback head is at the end of the buffer. 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 85 /* As a convenience, if a callback is supplied, a handler thread 86 * is automatically created with the appropriate priority. This thread 87 * invokes the callback when a new buffer becomes availlable or an underrun condition occurs. 88 * Parameters: 89 * 90 * event: type of event notified (see enum AudioTrack::event_type). 91 * user: Pointer to context for use by the callback receiver. 92 * info: Pointer to optional parameter according to event type: 93 * - EVENT_MORE_DATA: pointer to AudioTrack::Buffer struct. The callback must not write 94 * more bytes than indicated by 'size' field and update 'size' if less bytes are 95 * written. 96 * - EVENT_UNDERRUN: unused. 97 * - EVENT_LOOP_END: pointer to an int indicating the number of loops remaining. 98 * - EVENT_MARKER: pointer to an uin32_t containing the marker position in frames. 99 * - EVENT_NEW_POS: pointer to an uin32_t containing the new position in frames. 100 * - EVENT_BUFFER_END: unused. 101 */ 102 103 typedef void (*callback_t)(int event, void* user, void *info); 104 105 /* Constructs an uninitialized AudioTrack. No connection with 106 * AudioFlinger takes place. 107 */ 108 AudioTrack(); 109 110 /* Creates an audio track and registers it with AudioFlinger. 111 * Once created, the track needs to be started before it can be used. 112 * Unspecified values are set to the audio hardware's current 113 * values. 114 * 115 * Parameters: 116 * 117 * streamType: Select the type of audio stream this track is attached to 118 * (e.g. AudioSystem::MUSIC). 119 * sampleRate: Track sampling rate in Hz. 120 * format: Audio format (e.g AudioSystem::PCM_16_BIT for signed 121 * 16 bits per sample). 122 * channels: Channel mask: see AudioSystem::audio_channels. 123 * frameCount: Total size of track PCM buffer in frames. This defines the 124 * latency of the track. 125 * flags: Reserved for future use. 126 * cbf: Callback function. If not null, this function is called periodically 127 * to request new PCM data. 128 * notificationFrames: The callback function is called each time notificationFrames PCM 129 * frames have been comsumed from track input buffer. 130 * user Context for use by the callback receiver. 131 */ 132 133 AudioTrack( int streamType, 134 uint32_t sampleRate = 0, 135 int format = 0, 136 int channels = 0, 137 int frameCount = 0, 138 uint32_t flags = 0, 139 callback_t cbf = 0, 140 void* user = 0, 141 int notificationFrames = 0, 142 int sessionId = 0); 143 144 /* Creates an audio track and registers it with AudioFlinger. With this constructor, 145 * The PCM data to be rendered by AudioTrack is passed in a shared memory buffer 146 * identified by the argument sharedBuffer. This prototype is for static buffer playback. 147 * PCM data must be present into memory before the AudioTrack is started. 148 * The Write() and Flush() methods are not supported in this case. 149 * It is recommented to pass a callback function to be notified of playback end by an 150 * EVENT_UNDERRUN event. 151 */ 152 153 AudioTrack( int streamType, 154 uint32_t sampleRate = 0, 155 int format = 0, 156 int channels = 0, 157 const sp<IMemory>& sharedBuffer = 0, 158 uint32_t flags = 0, 159 callback_t cbf = 0, 160 void* user = 0, 161 int notificationFrames = 0, 162 int sessionId = 0); 163 164 /* Terminates the AudioTrack and unregisters it from AudioFlinger. 165 * Also destroys all resources assotiated with the AudioTrack. 166 */ 167 ~AudioTrack(); 168 169 170 /* Initialize an uninitialized AudioTrack. 171 * Returned status (from utils/Errors.h) can be: 172 * - NO_ERROR: successful intialization 173 * - INVALID_OPERATION: AudioTrack is already intitialized 174 * - BAD_VALUE: invalid parameter (channels, format, sampleRate...) 175 * - NO_INIT: audio server or audio hardware not initialized 176 * */ 177 status_t set(int streamType =-1, 178 uint32_t sampleRate = 0, 179 int format = 0, 180 int channels = 0, 181 int frameCount = 0, 182 uint32_t flags = 0, 183 callback_t cbf = 0, 184 void* user = 0, 185 int notificationFrames = 0, 186 const sp<IMemory>& sharedBuffer = 0, 187 bool threadCanCallJava = false, 188 int sessionId = 0); 189 190 191 /* Result of constructing the AudioTrack. This must be checked 192 * before using any AudioTrack API (except for set()), using 193 * an uninitialized AudioTrack produces undefined results. 194 * See set() method above for possible return codes. 195 */ 196 status_t initCheck() const; 197 198 /* Returns this track's latency in milliseconds. 199 * This includes the latency due to AudioTrack buffer size, AudioMixer (if any) 200 * and audio hardware driver. 201 */ 202 uint32_t latency() const; 203 204 /* getters, see constructor */ 205 206 int streamType() const; 207 int format() const; 208 int channelCount() const; 209 uint32_t frameCount() const; 210 int frameSize() const; 211 sp<IMemory>& sharedBuffer(); 212 213 214 /* After it's created the track is not active. Call start() to 215 * make it active. If set, the callback will start being called. 216 */ 217 void start(); 218 219 /* Stop a track. If set, the callback will cease being called and 220 * obtainBuffer returns STOPPED. Note that obtainBuffer() still works 221 * and will fill up buffers until the pool is exhausted. 222 */ 223 void stop(); 224 bool stopped() const; 225 226 /* flush a stopped track. All pending buffers are discarded. 227 * This function has no effect if the track is not stoped. 228 */ 229 void flush(); 230 231 /* Pause a track. If set, the callback will cease being called and 232 * obtainBuffer returns STOPPED. Note that obtainBuffer() still works 233 * and will fill up buffers until the pool is exhausted. 234 */ 235 void pause(); 236 237 /* mute or unmutes this track. 238 * While mutted, the callback, if set, is still called. 239 */ 240 void mute(bool); 241 bool muted() const; 242 243 244 /* set volume for this track, mostly used for games' sound effects 245 * left and right volumes. Levels must be <= 1.0. 246 */ 247 status_t setVolume(float left, float right); 248 void getVolume(float* left, float* right); 249 250 /* set the send level for this track. An auxiliary effect should be attached 251 * to the track with attachEffect(). Level must be <= 1.0. 252 */ 253 status_t setSendLevel(float level); 254 void getSendLevel(float* level); 255 256 /* set sample rate for this track, mostly used for games' sound effects 257 */ 258 status_t setSampleRate(int sampleRate); 259 uint32_t getSampleRate(); 260 261 /* Enables looping and sets the start and end points of looping. 262 * 263 * Parameters: 264 * 265 * loopStart: loop start expressed as the number of PCM frames played since AudioTrack start. 266 * loopEnd: loop end expressed as the number of PCM frames played since AudioTrack start. 267 * loopCount: number of loops to execute. Calling setLoop() with loopCount == 0 cancels any pending or 268 * active loop. loopCount = -1 means infinite looping. 269 * 270 * For proper operation the following condition must be respected: 271 * (loopEnd-loopStart) <= framecount() 272 */ 273 status_t setLoop(uint32_t loopStart, uint32_t loopEnd, int loopCount); 274 status_t getLoop(uint32_t *loopStart, uint32_t *loopEnd, int *loopCount); 275 276 277 /* Sets marker position. When playback reaches the number of frames specified, a callback with event 278 * type EVENT_MARKER is called. Calling setMarkerPosition with marker == 0 cancels marker notification 279 * callback. 280 * If the AudioTrack has been opened with no callback function associated, the operation will fail. 281 * 282 * Parameters: 283 * 284 * marker: marker position expressed in frames. 285 * 286 * Returned status (from utils/Errors.h) can be: 287 * - NO_ERROR: successful operation 288 * - INVALID_OPERATION: the AudioTrack has no callback installed. 289 */ 290 status_t setMarkerPosition(uint32_t marker); 291 status_t getMarkerPosition(uint32_t *marker); 292 293 294 /* Sets position update period. Every time the number of frames specified has been played, 295 * a callback with event type EVENT_NEW_POS is called. 296 * Calling setPositionUpdatePeriod with updatePeriod == 0 cancels new position notification 297 * callback. 298 * If the AudioTrack has been opened with no callback function associated, the operation will fail. 299 * 300 * Parameters: 301 * 302 * updatePeriod: position update notification period expressed in frames. 303 * 304 * Returned status (from utils/Errors.h) can be: 305 * - NO_ERROR: successful operation 306 * - INVALID_OPERATION: the AudioTrack has no callback installed. 307 */ 308 status_t setPositionUpdatePeriod(uint32_t updatePeriod); 309 status_t getPositionUpdatePeriod(uint32_t *updatePeriod); 310 311 312 /* Sets playback head position within AudioTrack buffer. The new position is specified 313 * in number of frames. 314 * This method must be called with the AudioTrack in paused or stopped state. 315 * Note that the actual position set is <position> modulo the AudioTrack buffer size in frames. 316 * Therefore using this method makes sense only when playing a "static" audio buffer 317 * as opposed to streaming. 318 * The getPosition() method on the other hand returns the total number of frames played since 319 * playback start. 320 * 321 * Parameters: 322 * 323 * position: New playback head position within AudioTrack buffer. 324 * 325 * Returned status (from utils/Errors.h) can be: 326 * - NO_ERROR: successful operation 327 * - INVALID_OPERATION: the AudioTrack is not stopped. 328 * - BAD_VALUE: The specified position is beyond the number of frames present in AudioTrack buffer 329 */ 330 status_t setPosition(uint32_t position); 331 status_t getPosition(uint32_t *position); 332 333 /* Forces AudioTrack buffer full condition. When playing a static buffer, this method avoids 334 * rewriting the buffer before restarting playback after a stop. 335 * This method must be called with the AudioTrack in paused or stopped state. 336 * 337 * Returned status (from utils/Errors.h) can be: 338 * - NO_ERROR: successful operation 339 * - INVALID_OPERATION: the AudioTrack is not stopped. 340 */ 341 status_t reload(); 342 343 /* returns a handle on the audio output used by this AudioTrack. 344 * 345 * Parameters: 346 * none. 347 * 348 * Returned value: 349 * handle on audio hardware output 350 */ 351 audio_io_handle_t getOutput(); 352 353 /* returns the unique ID associated to this track. 354 * 355 * Parameters: 356 * none. 357 * 358 * Returned value: 359 * AudioTrack ID. 360 */ 361 int getSessionId(); 362 363 364 /* Attach track auxiliary output to specified effect. Used effectId = 0 365 * to detach track from effect. 366 * 367 * Parameters: 368 * 369 * effectId: effectId obtained from AudioEffect::id(). 370 * 371 * Returned status (from utils/Errors.h) can be: 372 * - NO_ERROR: successful operation 373 * - INVALID_OPERATION: the effect is not an auxiliary effect. 374 * - BAD_VALUE: The specified effect ID is invalid 375 */ 376 status_t attachAuxEffect(int effectId); 377 378 /* obtains a buffer of "frameCount" frames. The buffer must be 379 * filled entirely. If the track is stopped, obtainBuffer() returns 380 * STOPPED instead of NO_ERROR as long as there are buffers availlable, 381 * at which point NO_MORE_BUFFERS is returned. 382 * Buffers will be returned until the pool (buffercount()) 383 * is exhausted, at which point obtainBuffer() will either block 384 * or return WOULD_BLOCK depending on the value of the "blocking" 385 * parameter. 386 */ 387 388 enum { 389 NO_MORE_BUFFERS = 0x80000001, 390 STOPPED = 1 391 }; 392 393 status_t obtainBuffer(Buffer* audioBuffer, int32_t waitCount); 394 void releaseBuffer(Buffer* audioBuffer); 395 396 397 /* As a convenience we provide a write() interface to the audio buffer. 398 * This is implemented on top of lockBuffer/unlockBuffer. For best 399 * performance 400 * 401 */ 402 ssize_t write(const void* buffer, size_t size); 403 404 /* 405 * Dumps the state of an audio track. 406 */ 407 status_t dump(int fd, const Vector<String16>& args) const; 408 409private: 410 /* copying audio tracks is not allowed */ 411 AudioTrack(const AudioTrack& other); 412 AudioTrack& operator = (const AudioTrack& other); 413 414 /* a small internal class to handle the callback */ 415 class AudioTrackThread : public Thread 416 { 417 public: 418 AudioTrackThread(AudioTrack& receiver, bool bCanCallJava = false); 419 private: 420 friend class AudioTrack; 421 virtual bool threadLoop(); 422 virtual status_t readyToRun(); 423 virtual void onFirstRef(); 424 AudioTrack& mReceiver; 425 Mutex mLock; 426 }; 427 428 bool processAudioBuffer(const sp<AudioTrackThread>& thread); 429 status_t createTrack(int streamType, 430 uint32_t sampleRate, 431 int format, 432 int channelCount, 433 int frameCount, 434 uint32_t flags, 435 const sp<IMemory>& sharedBuffer, 436 audio_io_handle_t output, 437 bool enforceFrameCount); 438 439 sp<IAudioTrack> mAudioTrack; 440 sp<IMemory> mCblkMemory; 441 sp<AudioTrackThread> mAudioTrackThread; 442 443 float mVolume[2]; 444 float mSendLevel; 445 uint32_t mFrameCount; 446 447 audio_track_cblk_t* mCblk; 448 uint8_t mStreamType; 449 uint8_t mFormat; 450 uint8_t mChannelCount; 451 uint8_t mMuted; 452 uint32_t mChannels; 453 status_t mStatus; 454 uint32_t mLatency; 455 456 volatile int32_t mActive; 457 458 callback_t mCbf; 459 void* mUserData; 460 uint32_t mNotificationFramesReq; // requested number of frames between each notification callback 461 uint32_t mNotificationFramesAct; // actual number of frames between each notification callback 462 sp<IMemory> mSharedBuffer; 463 int mLoopCount; 464 uint32_t mRemainingFrames; 465 uint32_t mMarkerPosition; 466 bool mMarkerReached; 467 uint32_t mNewPosition; 468 uint32_t mUpdatePeriod; 469 uint32_t mFlags; 470 int mSessionId; 471}; 472 473 474}; // namespace android 475 476#endif // ANDROID_AUDIOTRACK_H 477