SoundPool.cpp revision f6e43bf29084760b39257b2273e0f04c2815fdc5 
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//#define LOG_NDEBUG 0
18#define LOG_TAG "SoundPool"
19#include <utils/Log.h>
20
21//#define USE_SHARED_MEM_BUFFER
22
23// XXX needed for timing latency
24#include <utils/Timers.h>
25
26#include <sys/resource.h>
27#include <media/AudioTrack.h>
28#include <media/mediaplayer.h>
29
30#include "SoundPool.h"
31#include "SoundPoolThread.h"
32
33namespace android
34{
35
36int kDefaultBufferCount = 4;
37uint32_t kMaxSampleRate = 48000;
38uint32_t kDefaultSampleRate = 44100;
39uint32_t kDefaultFrameCount = 1200;
40
41SoundPool::SoundPool(int maxChannels, int streamType, int srcQuality)
42{
43    LOGV("SoundPool constructor: maxChannels=%d, streamType=%d, srcQuality=%d",
44            maxChannels, streamType, srcQuality);
45
46    // check limits
47    mMaxChannels = maxChannels;
48    if (mMaxChannels < 1) {
49        mMaxChannels = 1;
50    }
51    else if (mMaxChannels > 32) {
52        mMaxChannels = 32;
53    }
54    LOGW_IF(maxChannels != mMaxChannels, "App requested %d channels", maxChannels);
55
56    mQuit = false;
57    mDecodeThread = 0;
58    mStreamType = streamType;
59    mSrcQuality = srcQuality;
60    mAllocated = 0;
61    mNextSampleID = 0;
62    mNextChannelID = 0;
63
64    mCallback = 0;
65    mUserData = 0;
66
67    mChannelPool = new SoundChannel[mMaxChannels];
68    for (int i = 0; i < mMaxChannels; ++i) {
69        mChannelPool[i].init(this);
70        mChannels.push_back(&mChannelPool[i]);
71    }
72
73    // start decode thread
74    startThreads();
75}
76
77SoundPool::~SoundPool()
78{
79    LOGV("SoundPool destructor");
80    mDecodeThread->quit();
81    quit();
82
83    Mutex::Autolock lock(&mLock);
84    mChannels.clear();
85    if (mChannelPool)
86        delete [] mChannelPool;
87
88    // clean up samples
89    LOGV("clear samples");
90    mSamples.clear();
91
92    if (mDecodeThread)
93        delete mDecodeThread;
94}
95
96void SoundPool::addToRestartList(SoundChannel* channel)
97{
98    Mutex::Autolock lock(&mRestartLock);
99    mRestart.push_back(channel);
100    mCondition.signal();
101}
102
103int SoundPool::beginThread(void* arg)
104{
105    SoundPool* p = (SoundPool*)arg;
106    return p->run();
107}
108
109int SoundPool::run()
110{
111    mRestartLock.lock();
112    while (!mQuit) {
113        mCondition.wait(mRestartLock);
114        LOGV("awake");
115        if (mQuit) break;
116
117        while (!mRestart.empty()) {
118            SoundChannel* channel;
119            LOGV("Getting channel from list");
120            List<SoundChannel*>::iterator iter = mRestart.begin();
121            channel = *iter;
122            mRestart.erase(iter);
123            if (channel) channel->nextEvent();
124            if (mQuit) break;
125        }
126    }
127
128    mRestart.clear();
129    mCondition.signal();
130    mRestartLock.unlock();
131    LOGV("goodbye");
132    return 0;
133}
134
135void SoundPool::quit()
136{
137    mRestartLock.lock();
138    mQuit = true;
139    mCondition.signal();
140    mCondition.wait(mRestartLock);
141    LOGV("return from quit");
142    mRestartLock.unlock();
143}
144
145bool SoundPool::startThreads()
146{
147    createThreadEtc(beginThread, this, "SoundPoolThread");
148    if (mDecodeThread == NULL)
149        mDecodeThread = new SoundPoolThread(this);
150    return mDecodeThread != NULL;
151}
152
153SoundChannel* SoundPool::findChannel(int channelID)
154{
155    for (int i = 0; i < mMaxChannels; ++i) {
156        if (mChannelPool[i].channelID() == channelID) {
157            return &mChannelPool[i];
158        }
159    }
160    return NULL;
161}
162
163SoundChannel* SoundPool::findNextChannel(int channelID)
164{
165    for (int i = 0; i < mMaxChannels; ++i) {
166        if (mChannelPool[i].nextChannelID() == channelID) {
167            return &mChannelPool[i];
168        }
169    }
170    return NULL;
171}
172
173int SoundPool::load(const char* path, int priority)
174{
175    LOGV("load: path=%s, priority=%d", path, priority);
176    Mutex::Autolock lock(&mLock);
177    sp<Sample> sample = new Sample(++mNextSampleID, path);
178    mSamples.add(sample->sampleID(), sample);
179    doLoad(sample);
180    return sample->sampleID();
181}
182
183int SoundPool::load(int fd, int64_t offset, int64_t length, int priority)
184{
185    LOGV("load: fd=%d, offset=%lld, length=%lld, priority=%d",
186            fd, offset, length, priority);
187    Mutex::Autolock lock(&mLock);
188    sp<Sample> sample = new Sample(++mNextSampleID, fd, offset, length);
189    mSamples.add(sample->sampleID(), sample);
190    doLoad(sample);
191    return sample->sampleID();
192}
193
194void SoundPool::doLoad(sp<Sample>& sample)
195{
196    LOGV("doLoad: loading sample sampleID=%d", sample->sampleID());
197    sample->startLoad();
198    mDecodeThread->loadSample(sample->sampleID());
199}
200
201bool SoundPool::unload(int sampleID)
202{
203    LOGV("unload: sampleID=%d", sampleID);
204    Mutex::Autolock lock(&mLock);
205    return mSamples.removeItem(sampleID);
206}
207
208int SoundPool::play(int sampleID, float leftVolume, float rightVolume,
209        int priority, int loop, float rate)
210{
211    LOGV("sampleID=%d, leftVolume=%f, rightVolume=%f, priority=%d, loop=%d, rate=%f",
212            sampleID, leftVolume, rightVolume, priority, loop, rate);
213    sp<Sample> sample;
214    SoundChannel* channel;
215    int channelID;
216
217    // scope for lock
218    {
219        Mutex::Autolock lock(&mLock);
220
221        // is sample ready?
222        sample = findSample(sampleID);
223        if ((sample == 0) || (sample->state() != Sample::READY)) {
224            LOGW("  sample %d not READY", sampleID);
225            return 0;
226        }
227
228        dump();
229
230        // allocate a channel
231        channel = allocateChannel(priority);
232
233        // no channel allocated - return 0
234        if (!channel) {
235            LOGV("No channel allocated");
236            return 0;
237        }
238
239        channelID = ++mNextChannelID;
240    }
241
242    LOGV("channel state = %d", channel->state());
243    channel->play(sample, channelID, leftVolume, rightVolume, priority, loop, rate);
244    return channelID;
245}
246
247SoundChannel* SoundPool::allocateChannel(int priority)
248{
249    List<SoundChannel*>::iterator iter;
250    SoundChannel* channel = NULL;
251
252    // allocate a channel
253    if (!mChannels.empty()) {
254        iter = mChannels.begin();
255        if (priority >= (*iter)->priority()) {
256            channel = *iter;
257            mChannels.erase(iter);
258            LOGV("Allocated active channel");
259        }
260    }
261
262    // update priority and put it back in the list
263    if (channel) {
264        channel->setPriority(priority);
265        for (iter = mChannels.begin(); iter != mChannels.end(); ++iter) {
266            if (priority < (*iter)->priority()) {
267                break;
268            }
269        }
270        mChannels.insert(iter, channel);
271    }
272    return channel;
273}
274
275// move a channel from its current position to the front of the list
276void SoundPool::moveToFront(SoundChannel* channel)
277{
278    for (List<SoundChannel*>::iterator iter = mChannels.begin(); iter != mChannels.end(); ++iter) {
279        if (*iter == channel) {
280            mChannels.erase(iter);
281            mChannels.push_front(channel);
282            break;
283        }
284    }
285}
286
287void SoundPool::pause(int channelID)
288{
289    LOGV("pause(%d)", channelID);
290    Mutex::Autolock lock(&mLock);
291    SoundChannel* channel = findChannel(channelID);
292    if (channel) {
293        channel->pause();
294    }
295}
296
297void SoundPool::resume(int channelID)
298{
299    LOGV("resume(%d)", channelID);
300    Mutex::Autolock lock(&mLock);
301    SoundChannel* channel = findChannel(channelID);
302    if (channel) {
303        channel->resume();
304    }
305}
306
307void SoundPool::stop(int channelID)
308{
309    LOGV("stop(%d)", channelID);
310    Mutex::Autolock lock(&mLock);
311    SoundChannel* channel = findChannel(channelID);
312    if (channel) {
313        channel->stop();
314    } else {
315        channel = findNextChannel(channelID);
316        if (channel)
317            channel->clearNextEvent();
318    }
319}
320
321void SoundPool::setVolume(int channelID, float leftVolume, float rightVolume)
322{
323    Mutex::Autolock lock(&mLock);
324    SoundChannel* channel = findChannel(channelID);
325    if (channel) {
326        channel->setVolume(leftVolume, rightVolume);
327    }
328}
329
330void SoundPool::setPriority(int channelID, int priority)
331{
332    LOGV("setPriority(%d, %d)", channelID, priority);
333    Mutex::Autolock lock(&mLock);
334    SoundChannel* channel = findChannel(channelID);
335    if (channel) {
336        channel->setPriority(priority);
337    }
338}
339
340void SoundPool::setLoop(int channelID, int loop)
341{
342    LOGV("setLoop(%d, %d)", channelID, loop);
343    Mutex::Autolock lock(&mLock);
344    SoundChannel* channel = findChannel(channelID);
345    if (channel) {
346        channel->setLoop(loop);
347    }
348}
349
350void SoundPool::setRate(int channelID, float rate)
351{
352    LOGV("setRate(%d, %f)", channelID, rate);
353    Mutex::Autolock lock(&mLock);
354    SoundChannel* channel = findChannel(channelID);
355    if (channel) {
356        channel->setRate(rate);
357    }
358}
359
360// call with lock held
361void SoundPool::done(SoundChannel* channel)
362{
363    LOGV("done(%d)", channel->channelID());
364
365    // if "stolen", play next event
366    if (channel->nextChannelID() != 0) {
367        LOGV("add to restart list");
368        addToRestartList(channel);
369    }
370
371    // return to idle state
372    else {
373        LOGV("move to front");
374        moveToFront(channel);
375    }
376}
377
378void SoundPool::setCallback(SoundPoolCallback* callback, void* user)
379{
380    Mutex::Autolock lock(&mCallbackLock);
381    mCallback = callback;
382    mUserData = user;
383}
384
385void SoundPool::notify(SoundPoolEvent event)
386{
387    Mutex::Autolock lock(&mCallbackLock);
388    if (mCallback != NULL) {
389        mCallback(event, this, mUserData);
390    }
391}
392
393void SoundPool::dump()
394{
395    for (int i = 0; i < mMaxChannels; ++i) {
396        mChannelPool[i].dump();
397    }
398}
399
400
401Sample::Sample(int sampleID, const char* url)
402{
403    init();
404    mSampleID = sampleID;
405    mUrl = strdup(url);
406    LOGV("create sampleID=%d, url=%s", mSampleID, mUrl);
407}
408
409Sample::Sample(int sampleID, int fd, int64_t offset, int64_t length)
410{
411    init();
412    mSampleID = sampleID;
413    mFd = dup(fd);
414    mOffset = offset;
415    mLength = length;
416    LOGV("create sampleID=%d, fd=%d, offset=%lld, length=%lld", mSampleID, mFd, mLength, mOffset);
417}
418
419void Sample::init()
420{
421    mData = 0;
422    mSize = 0;
423    mRefCount = 0;
424    mSampleID = 0;
425    mState = UNLOADED;
426    mFd = -1;
427    mOffset = 0;
428    mLength = 0;
429    mUrl = 0;
430}
431
432Sample::~Sample()
433{
434    LOGV("Sample::destructor sampleID=%d, fd=%d", mSampleID, mFd);
435    if (mFd > 0) {
436        LOGV("close(%d)", mFd);
437        ::close(mFd);
438    }
439    mData.clear();
440    delete mUrl;
441}
442
443status_t Sample::doLoad()
444{
445    uint32_t sampleRate;
446    int numChannels;
447    int format;
448    sp<IMemory> p;
449    LOGV("Start decode");
450    if (mUrl) {
451        p = MediaPlayer::decode(mUrl, &sampleRate, &numChannels, &format);
452    } else {
453        p = MediaPlayer::decode(mFd, mOffset, mLength, &sampleRate, &numChannels, &format);
454        LOGV("close(%d)", mFd);
455        ::close(mFd);
456        mFd = -1;
457    }
458    if (p == 0) {
459        LOGE("Unable to load sample: %s", mUrl);
460        return -1;
461    }
462    LOGV("pointer = %p, size = %u, sampleRate = %u, numChannels = %d",
463            p->pointer(), p->size(), sampleRate, numChannels);
464
465    if (sampleRate > kMaxSampleRate) {
466       LOGE("Sample rate (%u) out of range", sampleRate);
467       return - 1;
468    }
469
470    if ((numChannels < 1) || (numChannels > 2)) {
471        LOGE("Sample channel count (%d) out of range", numChannels);
472        return - 1;
473    }
474
475    //_dumpBuffer(p->pointer(), p->size());
476    uint8_t* q = static_cast<uint8_t*>(p->pointer()) + p->size() - 10;
477    //_dumpBuffer(q, 10, 10, false);
478
479    mData = p;
480    mSize = p->size();
481    mSampleRate = sampleRate;
482    mNumChannels = numChannels;
483    mFormat = format;
484    mState = READY;
485    return 0;
486}
487
488
489void SoundChannel::init(SoundPool* soundPool)
490{
491    mSoundPool = soundPool;
492}
493
494void SoundChannel::play(const sp<Sample>& sample, int nextChannelID, float leftVolume,
495        float rightVolume, int priority, int loop, float rate)
496{
497    AudioTrack* oldTrack;
498
499    LOGV("play %p: sampleID=%d, channelID=%d, leftVolume=%f, rightVolume=%f, priority=%d, loop=%d, rate=%f",
500            this, sample->sampleID(), nextChannelID, leftVolume, rightVolume, priority, loop, rate);
501
502    // if not idle, this voice is being stolen
503    if (mState != IDLE) {
504        LOGV("channel %d stolen - event queued for channel %d", channelID(), nextChannelID);
505        mNextEvent.set(sample, nextChannelID, leftVolume, rightVolume, priority, loop, rate);
506        stop();
507        return;
508    }
509
510    // initialize track
511    int afFrameCount;
512    int afSampleRate;
513    int streamType = mSoundPool->streamType();
514    if (AudioSystem::getOutputFrameCount(&afFrameCount, streamType) != NO_ERROR) {
515        afFrameCount = kDefaultFrameCount;
516    }
517    if (AudioSystem::getOutputSamplingRate(&afSampleRate, streamType) != NO_ERROR) {
518        afSampleRate = kDefaultSampleRate;
519    }
520    int numChannels = sample->numChannels();
521    uint32_t sampleRate = uint32_t(float(sample->sampleRate()) * rate + 0.5);
522    uint32_t totalFrames = (kDefaultBufferCount * afFrameCount * sampleRate) / afSampleRate;
523    uint32_t bufferFrames = (totalFrames + (kDefaultBufferCount - 1)) / kDefaultBufferCount;
524    uint32_t frameCount = 0;
525
526    if (loop) {
527        frameCount = sample->size()/numChannels/((sample->format() == AudioSystem::PCM_16_BIT) ? sizeof(int16_t) : sizeof(uint8_t));
528    }
529
530#ifndef USE_SHARED_MEM_BUFFER
531    // Ensure minimum audio buffer size in case of short looped sample
532    if(frameCount < totalFrames) {
533        frameCount = totalFrames;
534    }
535#endif
536
537    AudioTrack* newTrack;
538
539    // mToggle toggles each time a track is started on a given channel.
540    // The toggle is concatenated with the SoundChannel address and passed to AudioTrack
541    // as callback user data. This enables the detection of callbacks received from the old
542    // audio track while the new one is being started and avoids processing them with
543    // wrong audio audio buffer size  (mAudioBufferSize)
544    unsigned long toggle = mToggle ^ 1;
545    void *userData = (void *)((unsigned long)this | toggle);
546    uint32_t channels = (numChannels == 2) ? AudioSystem::CHANNEL_OUT_STEREO : AudioSystem::CHANNEL_OUT_MONO;
547
548#ifdef USE_SHARED_MEM_BUFFER
549    newTrack = new AudioTrack(streamType, sampleRate, sample->format(),
550            channels, sample->getIMemory(), 0, callback, userData);
551#else
552    newTrack = new AudioTrack(streamType, sampleRate, sample->format(),
553            channels, frameCount, 0, callback, userData, bufferFrames);
554#endif
555    if (newTrack->initCheck() != NO_ERROR) {
556        LOGE("Error creating AudioTrack");
557        delete newTrack;
558        return;
559    }
560    LOGV("setVolume %p", newTrack);
561    newTrack->setVolume(leftVolume, rightVolume);
562    newTrack->setLoop(0, frameCount, loop);
563
564    {
565        Mutex::Autolock lock(&mLock);
566        // From now on, AudioTrack callbacks recevieved with previous toggle value will be ignored.
567        mToggle = toggle;
568        oldTrack = mAudioTrack;
569        mAudioTrack = newTrack;
570        mPos = 0;
571        mSample = sample;
572        mChannelID = nextChannelID;
573        mPriority = priority;
574        mLoop = loop;
575        mLeftVolume = leftVolume;
576        mRightVolume = rightVolume;
577        mNumChannels = numChannels;
578        mRate = rate;
579        clearNextEvent();
580        mState = PLAYING;
581        mAudioTrack->start();
582        mAudioBufferSize = newTrack->frameCount()*newTrack->frameSize();
583    }
584
585    LOGV("delete oldTrack %p", oldTrack);
586    delete oldTrack;
587}
588
589void SoundChannel::nextEvent()
590{
591    sp<Sample> sample;
592    int nextChannelID;
593    float leftVolume;
594    float rightVolume;
595    int priority;
596    int loop;
597    float rate;
598
599    // check for valid event
600    {
601        Mutex::Autolock lock(&mLock);
602        nextChannelID = mNextEvent.channelID();
603        if (nextChannelID  == 0) {
604            LOGV("stolen channel has no event");
605            return;
606        }
607
608        sample = mNextEvent.sample();
609        leftVolume = mNextEvent.leftVolume();
610        rightVolume = mNextEvent.rightVolume();
611        priority = mNextEvent.priority();
612        loop = mNextEvent.loop();
613        rate = mNextEvent.rate();
614    }
615
616    LOGV("Starting stolen channel %d -> %d", channelID(), nextChannelID);
617    play(sample, nextChannelID, leftVolume, rightVolume, priority, loop, rate);
618}
619
620void SoundChannel::callback(int event, void* user, void *info)
621{
622    unsigned long toggle = (unsigned long)user & 1;
623    SoundChannel* channel = static_cast<SoundChannel*>((void *)((unsigned long)user & ~1));
624
625    if (channel->mToggle != toggle) {
626        LOGV("callback with wrong toggle");
627        return;
628    }
629    channel->process(event, info);
630}
631
632void SoundChannel::process(int event, void *info)
633{
634    //LOGV("process(%d)", mChannelID);
635    sp<Sample> sample = mSample;
636
637//    LOGV("SoundChannel::process event %d", event);
638
639    if (event == AudioTrack::EVENT_MORE_DATA) {
640       AudioTrack::Buffer* b = static_cast<AudioTrack::Buffer *>(info);
641
642        // check for stop state
643        if (b->size == 0) return;
644
645        if (sample != 0) {
646            // fill buffer
647            uint8_t* q = (uint8_t*) b->i8;
648            size_t count = 0;
649
650            if (mPos < (int)sample->size()) {
651                uint8_t* p = sample->data() + mPos;
652                count = sample->size() - mPos;
653                if (count > b->size) {
654                    count = b->size;
655                }
656                memcpy(q, p, count);
657                LOGV("fill: q=%p, p=%p, mPos=%u, b->size=%u, count=%d", q, p, mPos, b->size, count);
658            } else if (mPos < mAudioBufferSize) {
659                count = mAudioBufferSize - mPos;
660                if (count > b->size) {
661                    count = b->size;
662                }
663                memset(q, 0, count);
664                LOGV("fill extra: q=%p, mPos=%u, b->size=%u, count=%d", q, mPos, b->size, count);
665            }
666
667            mPos += count;
668            b->size = count;
669            //LOGV("buffer=%p, [0]=%d", b->i16, b->i16[0]);
670        }
671    } else if (event == AudioTrack::EVENT_UNDERRUN) {
672        LOGV("stopping track");
673        stop();
674    } else if (event == AudioTrack::EVENT_LOOP_END) {
675        LOGV("End loop: %d", *(int *)info);
676    }
677}
678
679
680// call with lock held
681void SoundChannel::stop_l()
682{
683    if (mState != IDLE) {
684        setVolume_l(0, 0);
685        LOGV("stop");
686        mAudioTrack->stop();
687        mSample.clear();
688        mState = IDLE;
689        mPriority = IDLE_PRIORITY;
690    }
691}
692
693void SoundChannel::stop()
694{
695    {
696        Mutex::Autolock lock(&mLock);
697        stop_l();
698    }
699    mSoundPool->done(this);
700}
701
702//FIXME: Pause is a little broken right now
703void SoundChannel::pause()
704{
705    Mutex::Autolock lock(&mLock);
706    if (mState == PLAYING) {
707        LOGV("pause track");
708        mState = PAUSED;
709        mAudioTrack->pause();
710    }
711}
712
713void SoundChannel::resume()
714{
715    Mutex::Autolock lock(&mLock);
716    if (mState == PAUSED) {
717        LOGV("resume track");
718        mState = PLAYING;
719        mAudioTrack->start();
720    }
721}
722
723void SoundChannel::setRate(float rate)
724{
725    Mutex::Autolock lock(&mLock);
726    if (mAudioTrack != 0 && mSample.get() != 0) {
727        uint32_t sampleRate = uint32_t(float(mSample->sampleRate()) * rate + 0.5);
728        mAudioTrack->setSampleRate(sampleRate);
729        mRate = rate;
730    }
731}
732
733// call with lock held
734void SoundChannel::setVolume_l(float leftVolume, float rightVolume)
735{
736    mLeftVolume = leftVolume;
737    mRightVolume = rightVolume;
738    if (mAudioTrack != 0) mAudioTrack->setVolume(leftVolume, rightVolume);
739}
740
741void SoundChannel::setVolume(float leftVolume, float rightVolume)
742{
743    Mutex::Autolock lock(&mLock);
744    setVolume_l(leftVolume, rightVolume);
745}
746
747void SoundChannel::setLoop(int loop)
748{
749    Mutex::Autolock lock(&mLock);
750    if (mAudioTrack != 0 && mSample.get() != 0) {
751        mAudioTrack->setLoop(0, mSample->size()/mNumChannels/((mSample->format() == AudioSystem::PCM_16_BIT) ? sizeof(int16_t) : sizeof(uint8_t)), loop);
752        mLoop = loop;
753    }
754}
755
756SoundChannel::~SoundChannel()
757{
758    LOGV("SoundChannel destructor");
759    if (mAudioTrack) {
760        LOGV("stop track");
761        mAudioTrack->stop();
762        delete mAudioTrack;
763    }
764    clearNextEvent();
765    mSample.clear();
766}
767
768void SoundChannel::dump()
769{
770    LOGV("mState = %d mChannelID=%d, mNumChannels=%d, mPos = %d, mPriority=%d, mLoop=%d",
771            mState, mChannelID, mNumChannels, mPos, mPriority, mLoop);
772}
773
774void SoundEvent::set(const sp<Sample>& sample, int channelID, float leftVolume,
775            float rightVolume, int priority, int loop, float rate)
776{
777    mSample =sample;
778    mChannelID = channelID;
779    mLeftVolume = leftVolume;
780    mRightVolume = rightVolume;
781    mPriority = priority;
782    mLoop = loop;
783    mRate =rate;
784}
785
786} // end namespace android
787
788