Android NuPlayer要点详解
本文将基于Android N源码对NuPlayer做一个详解。NuPlayer是Android中本地和流媒体播放所用的播放器。
1、AHandler机制首先介绍NuPlayer中无处不在的AHandler机制
frameworks/av/include/media/stagefright/foundation/
frameworks/av/media/libstagefright/foundation/
AHandler是Android native层实现的一个异步消息机制,在这个机制中所有的处理都是异步的,将变量封装到一个消息AMessage结构体中,然后放到队列中去,后台专门有一个线程会从这个队列中取出消息然后执行,执行函数就是onMessageReceived。
Ahandler机制包括以下几个类
AMessage消息类,用于构造消息,通过post方法投递出去给ALooper
status_t AMessage::post(int64_t delayUs) { sp looper = mLooper.promote(); if (looper == NULL) { ALOGW("failed to post message as target looper for handler %d is gone.", mTarget); return -ENOENT; } looper->post(this, delayUs); return OK; } void AMessage::deliver() { sp handler = mHandler.promote(); if (handler == NULL) { ALOGW("failed to deliver message as target handler %d is gone.", mTarget); return; } handler->deliverMessage(this); //see AHandler@deliverMessage,前面通过looper post最后就是调用这里的deliever送到handler手里 }
1234567891011121314151617181920AHandler
消息处理类,一般当做父类,继承该类的子类需要实现onMessageReceived方法
void AHandler::deliverMessage(const sp &msg) { onMessageReceived(msg); mMessageCounter++; …. }
12345ALooper
与Ahander一一对应,负责存储消息并分发Ahandler的消息,与AMessage一对多关系
// posts a message on this looper with the given timeout void ALooper::post(const sp &msg, int64_t delayUs) { Mutex::Autolock autoLock(mLock); int64_t whenUs; if (delayUs > 0) { whenUs = GetNowUs() + delayUs; } else { whenUs = GetNowUs(); } List::iterator it = mEventQueue.begin(); while (it != mEventQueue.end() && (*it).mWhenUs <= whenUs) { ++it; } Event event; event.mWhenUs = whenUs; event.mMessage = msg; if (it == mEventQueue.begin()) { mQueueChangedCondition.signal(); } mEventQueue.insert(it, event); } ---------------------------------------------------------- status_t ALooper::start( bool runOnCallingThread, bool canCallJava, int32_t priority) { if (runOnCallingThread) { { Mutex::Autolock autoLock(mLock); if (mThread != NULL || mRunningLocally) { return INVALID_OPERATION; } mRunningLocally = true; } do { } while (loop()); return OK; } Mutex::Autolock autoLock(mLock); if (mThread != NULL || mRunningLocally) { return INVALID_OPERATION; } mThread = new LooperThread(this, canCallJava); status_t err = mThread->run( mName.empty() ? "ALooper" : mName.c_str(), priority); if (err != OK) { mThread.clear(); } return err; } bool ALooper::loop() { Event event; { Mutex::Autolock autoLock(mLock); if (mThread == NULL && !mRunningLocally) { return false; } if (mEventQueue.empty()) { mQueueChangedCondition.wait(mLock); return true; } int64_t whenUs = (*mEventQueue.begin()).mWhenUs; int64_t nowUs = GetNowUs(); if (whenUs > nowUs) { int64_t delayUs = whenUs - nowUs; mQueueChangedCondition.waitRelative(mLock, delayUs * 1000ll); return true; } event = *mEventQueue.begin(); mEventQueue.erase(mEventQueue.begin()); } event.mMessage->deliver(); //see AHandler.deliverMessage ….. return true; }
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091929394LooperThread
此线程调用ALooper的loop方法来分发消息
virtual status_t readyToRun() { mThreadId = androidGetThreadId(); return Thread::readyToRun(); } virtual bool threadLoop() { return mLooper->loop(); }1 2 3 4 5 6 7 8 9 ALooperRoaster
与Handler是一对多的关系, 管理Looper和Handler一一对应关系,负责释放stale handler
ALooper::handler_id ALooperRoster::registerHandler( const sp looper, const sp &handler) { Mutex::Autolock autoLock(mLock); if (handler->id() != 0) { CHECK(!"A handler must only be registered once."); return INVALID_OPERATION; } HandlerInfo info; info.mLooper = looper; info.mHandler = handler; ALooper::handler_id handlerID = mNextHandlerID++;//一对一 mHandlers.add(handlerID, info);//一对多 handler->setID(handlerID, looper); return handlerID; } void ALooperRoster::unregisterHandler(ALooper::handler_id handlerID) { Mutex::Autolock autoLock(mLock); ssize_t index = mHandlers.indexOfKey(handlerID); if (index < 0) { return; } const HandlerInfo &info = mHandlers.valueAt(index); sp handler = info.mHandler.promote(); if (handler != NULL) { handler->setID(0, NULL); } mHandlers.removeItemsAt(index); } void ALooperRoster::unregisterStaleHandlers() { Vector > activeLoopers; { Mutex::Autolock autoLock(mLock); for (size_t i = mHandlers.size(); i > 0;) { i--; const HandlerInfo &info = mHandlers.valueAt(i); sp looper = info.mLooper.promote(); if (looper == NULL) { ALOGV("Unregistering stale handler %d", mHandlers.keyAt(i)); mHandlers.removeItemsAt(i); } else { // At this point 'looper' might be the only sp<> keeping // the object alive. To prevent it from going out of scope // and having ~ALooper call this method again recursively // and then deadlocking because of the Autolock above, add // it to a Vector which will go out of scope after the lock // has been released. activeLoopers.add(looper); } } } }
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667异步消息机制的创建
sp mLooper = new ALooper; //创建一个Alooper实例 sp mHandler = new AHandlerReflector //创建一个Ahandler实例 mLooper->setName(“xxxxx”); //设置looper名字 mLooper->start(false, true, PRIORITY_XXX); //根据参数创建并启动 looper thread mLooper->regiserHandler(mHandler); //register handler 会调用AHandler的setID方法将looper设置到Handler里去
12345Post消息
sp msg = new AMessage(kWhatSayGoodbye, mHandler); //在AMessage的构造方法里获取Ahandler对应的Looper并保存 msg->post(); // 调用looper的post方法 Message Post的调用过程 Message::post ↓ ALooper::post mEventQueue.insert mQueueChangedCondition.signal() //如果之前没有event,通知looper thread ↓ ALooper::loop() if (mEventQueue.empty()) { //如果消息队列为空,则等待 mQueueChangedCondition.wait(mLock); return true; } event = *mEventQueue.begin(); event.mMessage->deliver(); ↓ AHandler::deliverMessage ↓ AHandlerReflector:: onMessageReceived ↓ 具体的实现
1234567891011121314151617181920212223NuPlayer
下面就进入我们的正题,NuPlayer
frameworks/av/media/libmediaplayerservice/nuplayer/
NuPlayerDriver是对NuPlayer的封装,继承MediaPlayerInterface接口。通过NuPlayer来实现播放的功能。看这部分代码的方法就是先看NuPlayerDriver里面干了啥,转头就去找NuPlayer里面的实现,一般都要再去NuPlayer的onMessageReceive中看消息的响应,最后回到NuPlayerDriver的各种notify中看流程的周转,下面附上一张播放器状态机流转图
NuPlayerDriver::NuPlayerDriver(pid_t pid) : mState(STATE_IDLE), //对应播放器状态机的初始化状态 mIsAsyncPrepare(false), mAsyncResult(UNKNOWN_ERROR), mSetSurfaceInProgress(false), mDurationUs(-1), mPositionUs(-1), mSeekInProgress(false), mLooper(new ALooper), mPlayerFlags(0), mAtEOS(false), mLooping(false), mAutoLoop(false) { ALOGV("NuPlayerDriver(%p)", this); //和前面所述的异步消息创建机制相符 mLooper->setName("NuPlayerDriver Looper"); mLooper->start( false, /* runOnCallingThread */ true, /* canCallJava */ PRIORITY_AUDIO); //mPlayer即NuPlayer,继承于AHandler mPlayer = AVNuFactory::get()->createNuPlayer(pid); mLooper->registerHandler(mPlayer); mPlayer->setDriver(this); } NuPlayerDriver::~NuPlayerDriver() { ALOGV("~NuPlayerDriver(%p)", this); mLooper->stop(); //整个NuPlayerDriver就是一个大ALooper }1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 AVNuFactory
负责关键组件的create,通过它能看到:
1.每一个NuPlayer对应一个进程
2.数据流从Source-Decoder-Renderer,中间由AMessages驱动
sp AVNuFactory::createNuPlayer(pid_t pid) { return new NuPlayer(pid); } sp AVNuFactory::createPassThruDecoder( const sp ¬ify, const sp &source, const sp &renderer) { return new NuPlayer::DecoderPassThrough(notify, source, renderer); } sp AVNuFactory::createDecoder( const sp ¬ify, const sp &source, pid_t pid, const sp &renderer) { return new NuPlayer::Decoder(notify, source, pid, renderer); } sp AVNuFactory::createRenderer( const sp &sink, const sp ¬ify, uint32_t flags) { return new NuPlayer::Renderer(sink, notify, flags); }
12345678910111213141516171819202122232425
下面分别分析Source, Decoder, Renderer
Source以setDataSource为切入点
status_t NuPlayerDriver::setDataSource(const sp &source) { ALOGV("setDataSource(%p) stream source", this); Mutex::Autolock autoLock(mLock); if (mState != STATE_IDLE) { return INVALID_OPERATION; } mState = STATE_SET_DATASOURCE_PENDING; mPlayer->setDataSourceAsync(source);//因为driver只是NuPlayer的封装,所以还是要去调用NuPlayer完成实际动作 while (mState == STATE_SET_DATASOURCE_PENDING) { mCondition.wait(mLock); } return mAsyncResult; } -------------------------------------- void NuPlayer::setDataSourceAsync(const sp &source) { sp msg = new AMessage(kWhatSetDataSource, this); sp notify = new AMessage(kWhatSourceNotify, this); msg->setObject("source", new StreamingSource(notify, source)); msg->post(); //到了NuPlayer中,也不是直接进行操作,而是先发个消息,验证前面所说的一切都由AMessage驱动 } --------------------------------------- void NuPlayer::onMessageReceived(const sp &msg) { switch (msg->what()) { case kWhatSetDataSource://实际的处理在这里 { ALOGV("kWhatSetDataSource"); CHECK(mSource == NULL); status_t err = OK; sp obj; CHECK(msg->findObject("source", &obj)); if (obj != NULL) { Mutex::Autolock autoLock(mSourceLock); mSource = static_cast(obj.get());//赋值给mSource } else { err = UNKNOWN_ERROR; } CHECK(mDriver != NULL); sp driver = mDriver.promote(); if (driver != NULL) { driver->notifySetDataSourceCompleted(err);//通知driver设置完毕 } break; }...... --------------------------------------- void NuPlayerDriver::notifySetDataSourceCompleted(status_t err) { Mutex::Autolock autoLock(mLock); CHECK_EQ(mState, STATE_SET_DATASOURCE_PENDING); mAsyncResult = err; mState = (err == OK) ? STATE_UNPREPARED : STATE_IDLE;//回到driver中,流转播放器状态进入下一阶段 mCondition.broadcast(); }
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263
下面就来看看具体有哪些source,它们都继承自NuPlayer:Source(NuPlayerSource.h & NuPlayerSource.cpp)
1.HTTP-进一步判断是以下的哪一种:HTTPLiveSource,RTSPSource,GenericSource
2.File-GenericSource
3.StreamSource-StreamingSource
4.DataSource-GenericSource
nuplayer/GenericSource.h & GenericSource.cpp
几个水位 static int64_t kLowWaterMarkUs = 2000000ll; // 2secs static int64_t kHighWaterMarkUs = 5000000ll; // 5secs static int64_t kHighWaterMarkRebufferUs = 15000000ll; // 15secs,这一个是新增加的水位 static const ssize_t kLowWaterMarkBytes = 40000; static const ssize_t kHighWaterMarkBytes = 200000; status_t NuPlayer::GenericSource::initFromDataSource() { init extractor;get track info and metadata } void NuPlayer::GenericSource::prepareAsync() { if (mLooper == NULL) { mLooper = new ALooper; mLooper->setName("generic"); mLooper->start(); mLooper->registerHandler(this); } sp msg = new AMessage(kWhatPrepareAsync, this); msg->post(); } status_t NuPlayer::GenericSource::feedMoreTSData() { return OK; }
12345678910111213141516171819202122232425262728LiveSession
libstagefright/httplive/LiveSession.h & cpp
// static // Bandwidth Switch Mark Defaults const int64_t LiveSession::kUpSwitchMarkUs = 15000000ll; const int64_t LiveSession::kDownSwitchMarkUs = 20000000ll; const int64_t LiveSession::kUpSwitchMarginUs = 5000000ll; const int64_t LiveSession::kResumeThresholdUs = 100000ll; // Buffer Prepare/Ready/Underflow Marks const int64_t LiveSession::kReadyMarkUs = 5000000ll; const int64_t LiveSession::kPrepareMarkUs = 1500000ll; const int64_t LiveSession::kUnderflowMarkUs = 1000000ll; 与Fetcher,Bandwidth Estimater(和ExoPlayer一样是滑动窗口平均),switching,Buffering相关的操作都在这里1 2 3 4 5 6 7 8 9 10 11 12 13 HTTPLiveSource
nuplayer目录下
enum Flags { // Don't log any URLs.不在log中记录URL kFlagIncognito = 1, }; NuPlayer::HTTPLiveSource::HTTPLiveSource( if (headers) { //也搞了一个header机制 mExtraHeaders = *headers; ssize_t index = mExtraHeaders.indexOfKey(String8("x-hide-urls-from-log")); if (index >= 0) { mFlags |= kFlagIncognito; mExtraHeaders.removeItemsAt(index); } } } --------------------------------------- void NuPlayer::HTTPLiveSource::prepareAsync() { if (mLiveLooper == NULL) { mLiveLooper = new ALooper;//一如既往的ALooper mLiveLooper->setName("http live"); mLiveLooper->start(); mLiveLooper->registerHandler(this); } sp notify = new AMessage(kWhatSessionNotify, this); mLiveSession = new LiveSession( notify, (mFlags & kFlagIncognito) ? LiveSession::kFlagIncognito : 0, mHTTPService); mLiveLooper->registerHandler(mLiveSession); mLiveSession->connectAsync(//HTTPLiveSource包含LiveSession,很多实际的工作都由LiveSession完成 mURL.c_str(), mExtraHeaders.isEmpty() ? NULL : &mExtraHeaders); }
1234567891011121314151617181920212223242526272829303132333435363738394041
ATSParser
frameworks/av/media/libstagefright/mpeg2ts/ATSParser.cpp
就是一个TS Parser,虽然也叫Axx,但是没有消息机制在里面
StreamingSource
nuplayer目录
void NuPlayer::StreamingSource::prepareAsync() { if (mLooper == NULL) { mLooper = new ALooper; mLooper->setName("streaming"); mLooper->start();//何其相似 mLooper->registerHandler(this); } notifyVideoSizeChanged(); notifyFlagsChanged(0); notifyPrepared(); } --------------------------------------- StreamingSource中的数据由onReadBuffer驱动,最后的EOS,Discontiunity等都交给ATSParser去处理,ATSParser又最终交给AnotherPacketSource去做真正的处理.实际上,这里提到的三个Source最后都会用到AnotherPacketSource void NuPlayer::StreamingSource::onReadBuffer() { for (int32_t i = 0; i < kNumListenerQueuePackets; ++i) { char buffer[188]; sp extra; ssize_t n = mStreamListener->read(buffer, sizeof(buffer), &extra);//实际用NuPlayerStreamListener完成工作 if (n == 0) { ALOGI("input data EOS reached."); mTSParser->signalEOS(ERROR_END_OF_STREAM);//EOS了 setError(ERROR_END_OF_STREAM); break; } else if (n == INFO_DISCONTINUITY) { int32_t type = ATSParser::DISCONTINUITY_TIME; int32_t mask; if (extra != NULL && extra->findInt32( IStreamListener::kKeyDiscontinuityMask, &mask)) { if (mask == 0) { ALOGE("Client specified an illegal discontinuity type."); setError(ERROR_UNSUPPORTED); break; } type = mask; } mTSParser->signalDiscontinuity( (ATSParser::DiscontinuityType)type, extra); } else if (n < 0) { break; } else { if (buffer[0] == 0x00) { // XXX legacy if (extra == NULL) { extra = new AMessage; } uint8_t type = buffer[1]; if (type & 2) { int64_t mediaTimeUs; memcpy(&mediaTimeUs, &buffer[2], sizeof(mediaTimeUs)); extra->setInt64(IStreamListener::kKeyMediaTimeUs, mediaTimeUs); } mTSParser->signalDiscontinuity( ((type & 1) == 0) ? ATSParser::DISCONTINUITY_TIME : ATSParser::DISCONTINUITY_FORMATCHANGE, extra); } else { status_t err = mTSParser->feedTSPacket(buffer, sizeof(buffer)); if (err != OK) { ALOGE("TS Parser returned error %d", err); mTSParser->signalEOS(err); setError(err); break; } } } } }
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283AnotherPacketSource
frameworks/av/media/libstagefright/mpeg2ts
可以类比ExoPlayer中的chunk source,同时负责buffer管理,EOS\Discontinuity的处理等等.前面三个Source最后都会落到AnotherPacketSource
bool AnotherPacketSource::hasBufferAvailable(status_t *finalResult) { Mutex::Autolock autoLock(mLock); *finalResult = OK; if (!mEnabled) { return false; } if (!mBuffers.empty()) {//一个ABuffer List,其实就是一个环形缓冲 return true; } *finalResult = mEOSResult; return false; } -------------------------------------- void AnotherPacketSource::queueDiscontinuity( ATSParser::DiscontinuityType type, const sp &extra, bool discard) { Mutex::Autolock autoLock(mLock); if (discard) { // Leave only discontinuities in the queue. …... } mEOSResult = OK; mLastQueuedTimeUs = 0; mLatestEnqueuedMeta = NULL; if (type == ATSParser::DISCONTINUITY_NONE) { return; } mDiscontinuitySegments.push_back(DiscontinuitySegment()); sp buffer = new ABuffer(0); buffer->meta()->setInt32("discontinuity", static_cast(type)); buffer->meta()->setMessage("extra", extra); mBuffers.push_back(buffer); //将记录了discontinuity的ABuffer推入缓冲区中,这样各个Source在从缓冲区读数据的时候就能正确处理discontinuity了 mCondition.signal(); }
12345678910111213141516171819202122232425262728293031323334353637383940414243Decoder
Decoder是如何被初始化的
从NuPlayer::OnStart方法看起 void NuPlayer::onStart(int64_t startPositionUs) { if (!mSourceStarted) { mSourceStarted = true; mSource->start(); } if (startPositionUs > 0) { performSeek(startPositionUs); if (mSource->getFormat(false /* audio */) == NULL) { return; } } ... sp notify = new AMessage(kWhatRendererNotify, this); ++mRendererGeneration; notify->setInt32("generation", mRendererGeneration); //在这里用AVNuFactory初始化Renderer和它对应的Looper mRenderer = AVNuFactory::get()->createRenderer(mAudioSink, notify, flags); mRendererLooper = new ALooper; mRendererLooper->setName("NuPlayerRenderer"); mRendererLooper->start(false, false, ANDROID_PRIORITY_AUDIO); mRendererLooper->registerHandler(mRenderer); //设置Renderer的播放参数 status_t err = mRenderer->setPlaybackSettings(mPlaybackSettings); ... //给Decoder设置Renderer,两者之间的关系建立起来了 if (mVideoDecoder != NULL) { mVideoDecoder->setRenderer(mRenderer); } if (mAudioDecoder != NULL) { mAudioDecoder->setRenderer(mRenderer); } //抛出这一消息 postScanSources(); } -------------------------------------- case kWhatScanSources: { int32_t generation; CHECK(msg->findInt32("generation", &generation)); if (generation != mScanSourcesGeneration) { // Drop obsolete msg. break; } mScanSourcesPending = false; ALOGV("scanning sources haveAudio=%d, haveVideo=%d", mAudioDecoder != NULL, mVideoDecoder != NULL); bool mHadAnySourcesBefore = (mAudioDecoder != NULL) || (mVideoDecoder != NULL); bool rescan = false; // initialize video before audio because successful initialization of // video may change deep buffer mode of audio. //在这里初始化decoder if (mSurface != NULL) { if (instantiateDecoder(false, &mVideoDecoder) == -EWOULDBLOCK) { rescan = true; } } // Don't try to re-open audio sink if there's an existing decoder. if (mAudioSink != NULL && mAudioDecoder == NULL) { if (instantiateDecoder(true, &mAudioDecoder) == -EWOULDBLOCK) { rescan = true; } } if (!mHadAnySourcesBefore && (mAudioDecoder != NULL || mVideoDecoder != NULL)) { // This is the first time we've found anything playable. if (mSourceFlags & Source::FLAG_DYNAMIC_DURATION) { schedulePollDuration(); } } status_t err; if ((err = mSource->feedMoreTSData()) != OK) { if (mAudioDecoder == NULL && mVideoDecoder == NULL) { // We're not currently decoding anything (no audio or // video tracks found) and we just ran out of input data. if (err == ERROR_END_OF_STREAM) { notifyListener(MEDIA_PLAYBACK_COMPLETE, 0, 0); } else { notifyListener(MEDIA_ERROR, MEDIA_ERROR_UNKNOWN, err); } } break; } //postScanSources和ExoPlayer中的doSomeWork一样是一个不断循环运转的东西 if (rescan) { msg->post(100000ll); mScanSourcesPending = true; } break; } --------------------------------------- 在NuPlayer的instantiateDecoder中完成Decoder的初始化 status_t NuPlayer::instantiateDecoder( bool audio, sp *decoder, bool checkAudioModeChange) { ... if (!audio) { AString mime; CHECK(format->findString("mime", &mime)); sp ccNotify = new AMessage(kWhatClosedCaptionNotify, this); if (mCCDecoder == NULL) { mCCDecoder = new CCDecoder(ccNotify); //new字幕解码器 } if (mSourceFlags & Source::FLAG_SECURE) { format->setInt32("secure", true); } if (mSourceFlags & Source::FLAG_PROTECTED) { format->setInt32("protected", true); } float rate = getFrameRate(); if (rate > 0) { format->setFloat("operating-rate", rate * mPlaybackSettings.mSpeed); } } if (audio) { sp notify = new AMessage(kWhatAudioNotify, this); ++mAudioDecoderGeneration; notify->setInt32("generation", mAudioDecoderGeneration); if (checkAudioModeChange) { determineAudioModeChange(format); } if (mOffloadAudio) mSource->setOffloadAudio(true /* offload */); if (mOffloadAudio) { const bool hasVideo = (mSource->getFormat(false /*audio */) != NULL); format->setInt32("has-video", hasVideo); *decoder = AVNuFactory::get()->createPassThruDecoder(notify, mSource, mRenderer);//利用AVNuFactory的方法创建pass through的音频解码器 } else { AVNuUtils::get()->setCodecOutputFormat(format); mSource->setOffloadAudio(false /* offload */); *decoder = AVNuFactory::get()->createDecoder(notify, mSource, mPID, mRenderer);//创建普通的音频解码器 } } else { sp notify = new AMessage(kWhatVideoNotify, this); ++mVideoDecoderGeneration; notify->setInt32("generation", mVideoDecoderGeneration); *decoder = new Decoder( notify, mSource, mPID, mRenderer, mSurface, mCCDecoder); //new视频解码器,这里还会把字幕解码器作为一个参数传进来 // enable FRC if high-quality AV sync is requested, even if not // directly queuing to display, as this will even improve textureview // playback. { char value[PROPERTY_VALUE_MAX]; if (property_get("persist.sys.media.avsync", value, NULL) && (!strcmp("1", value) || !strcasecmp("true", value))) { format->setInt32("auto-frc", 1); } } } (*decoder)->init();//解码器初始化 (*decoder)->configure(format);//解码器配置 // allocate buffers to decrypt widevine source buffers if (!audio && (mSourceFlags & Source::FLAG_SECURE)) { Vector > inputBufs; CHECK_EQ((*decoder)->getInputBuffers(&inputBufs), (status_t)OK); Vector mediaBufs; for (size_t i = 0; i < inputBufs.size(); i++) { const sp &buffer = inputBufs[i]; MediaBuffer *mbuf = new MediaBuffer(buffer->data(), buffer->size()); mediaBufs.push(mbuf); } status_t err = mSource->setBuffers(audio, mediaBufs); if (err != OK) { for (size_t i = 0; i < mediaBufs.size(); ++i) { mediaBufs[i]->release(); } mediaBufs.clear(); ALOGE("Secure source didn't support secure mediaBufs."); return err; } } ... return OK; } ------------------------------------- ------------------------------------- void NuPlayer::Decoder::doFlush(bool notifyComplete) { if (mCCDecoder != NULL) { mCCDecoder->flush();//先flush字幕Decoder } if (mRenderer != NULL) { mRenderer->flush(mIsAudio, notifyComplete); mRenderer->signalTimeDiscontinuity();//再flush Renderer } status_t err = OK; if (mCodec != NULL) { err = mCodec->flush();//最后flush Decoder mCSDsToSubmit = mCSDsForCurrentFormat; // copy operator ++mBufferGeneration; } ... releaseAndResetMediaBuffers();//清空buffer mPaused = true; }
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220DecoderBase
是NuPlayer::Decoder的基类,内部也维护了一个Looper,各种工作也依然是异步消息驱动完成的,只不过各种onMessage的响应方法都是虚函数,需要由子类来做具体的实现.也能看到利用setRenderer方法和Renderer结合到一起的方法
NuPlayer::DecoderBase::DecoderBase(const sp ¬ify) : mNotify(notify), mBufferGeneration(0), mPaused(false), mStats(new AMessage), mRequestInputBuffersPending(false) { // Every decoder has its own looper because MediaCodec operations // are blocking, but NuPlayer needs asynchronous operations. mDecoderLooper = new ALooper; mDecoderLooper->setName("NPDecoder"); mDecoderLooper->start(false, false, ANDROID_PRIORITY_AUDIO); } void NuPlayer::DecoderBase::init() { mDecoderLooper->registerHandler(this); }
12345678910111213141516NuPlayer::Decoder
由相应的onMessage方法处理各种工作 先关注init和configure两个方法,init直接继承自DecoderBase,就是给Looper注册Handler -------------------------------------- void NuPlayer::Decoder::onConfigure(const sp &format) { ... mCodec = AVUtils::get()->createCustomComponentByName(mCodecLooper, mime.c_str(), false /* encoder */, format); if (mCodec == NULL) { //由mimeType创建Decoder mCodec = MediaCodec::CreateByType( mCodecLooper, mime.c_str(), false /* encoder */, NULL /* err */, mPid); } ... //mCodec就是libstagefright中的MediaCodec,没什么可说的 err = mCodec->configure( format, mSurface, NULL /* crypto */, 0 /* flags */); if (err != OK) { ALOGE("Failed to configure %s decoder (err=%d)", mComponentName.c_str(), err); mCodec->release(); mCodec.clear(); handleError(err); return; } rememberCodecSpecificData(format); // the following should work in configured state读Format信息 CHECK_EQ((status_t)OK, mCodec->getOutputFormat(&mOutputFormat)); CHECK_EQ((status_t)OK, mCodec->getInputFormat(&mInputFormat)); mStats->setString("mime", mime.c_str()); mStats->setString("component-name", mComponentName.c_str()); if (!mIsAudio) { int32_t width, height; if (mOutputFormat->findInt32("width", &width) && mOutputFormat->findInt32("height", &height)) { mStats->setInt32("width", width); mStats->setInt32("height", height); } } ... //MediaCodec开始 err = mCodec->start(); if (err != OK) { ALOGE("Failed to start %s decoder (err=%d)", mComponentName.c_str(), err); mCodec->release(); mCodec.clear(); handleError(err); return; } //先把buffer都release置为null releaseAndResetMediaBuffers(); ... } 前面提到NuPlayer::Decoder里面有一个MediaCodec,所以不用再研究具体怎么解码的,关注点在于从这个模块输出的东西是怎样的,以及是怎样输入这个东西的 先来看输出: 当MediaCodec有Available Output的时候,在onMessageReceived中有 case MediaCodec::CB_OUTPUT_AVAILABLE: { int32_t index; size_t offset; size_t size; int64_t timeUs; int32_t flags; CHECK(msg->findInt32("index", &index)); CHECK(msg->findSize("offset", &offset)); CHECK(msg->findSize("size", &size)); CHECK(msg->findInt64("timeUs", &timeUs)); CHECK(msg->findInt32("flags", &flags)); handleAnOutputBuffer(index, offset, size, timeUs, flags); break; } ------------------------------------- bool NuPlayer::Decoder::handleAnOutputBuffer( size_t index, size_t offset, size_t size, int64_t timeUs, int32_t flags) { // CHECK_LT(bufferIx, mOutputBuffers.size()); sp buffer; mCodec->getOutputBuffer(index, &buffer); .... //发送kWhatRenderBuffer消息 sp reply = new AMessage(kWhatRenderBuffer, this); reply->setSize("buffer-ix", index); reply->setInt32("generation", mBufferGeneration); if (eos) { ALOGI("[%s] saw output EOS", mIsAudio ? "audio" : "video"); //EOS了 buffer->meta()->setInt32("eos", true); reply->setInt32("eos", true); } else if (mSkipRenderingUntilMediaTimeUs >= 0) { if (timeUs < mSkipRenderingUntilMediaTimeUs) { ALOGV("[%s] dropping buffer at time %lld as requested.", mComponentName.c_str(), (long long)timeUs); //中间这一段不用render,skip掉 reply->post(); return true; } mSkipRenderingUntilMediaTimeUs = -1; } else if ((flags & MediaCodec::BUFFER_FLAG_DATACORRUPT) && AVNuUtils::get()->dropCorruptFrame()) { ALOGV("[%s] dropping corrupt buffer at time %lld as requested.", mComponentName.c_str(), (long long)timeUs); //本段buffer坏到了,扔掉 reply->post(); return true; } mNumFramesTotal += !mIsAudio; // wait until 1st frame comes out to signal resume complete notifyResumeCompleteIfNecessary(); if (mRenderer != NULL) { // send the buffer to renderer.把Buffer送到Renderer mRenderer->queueBuffer(mIsAudio, buffer, reply); if (eos && !isDiscontinuityPending()) { mRenderer->queueEOS(mIsAudio, ERROR_END_OF_STREAM); } } return true; } -------------------------------------- case kWhatRenderBuffer: { if (!isStaleReply(msg)) { onRenderBuffer(msg); } break; } ------------------------------------- void NuPlayer::Decoder::onRenderBuffer(const sp &msg) { ... if (!mIsAudio) { int64_t timeUs; sp buffer = mOutputBuffers[bufferIx]; buffer->meta()->findInt64("timeUs", &timeUs); if (mCCDecoder != NULL && mCCDecoder->isSelected()) { mCCDecoder->display(timeUs);//字幕显示 } } if (msg->findInt32("render", &render) && render) { int64_t timestampNs; CHECK(msg->findInt64("timestampNs", ×tampNs)); //由MediaCodec的renderOutputBufferAndRelease完成 err = mCodec->renderOutputBufferAndRelease(bufferIx, timestampNs); } else { mNumOutputFramesDropped += !mIsAudio; err = mCodec->releaseOutputBuffer(bufferIx); } ... } 再来看输入 当MediaCodec有Available Input的时候,在onMessageReceived中有 case MediaCodec::CB_INPUT_AVAILABLE: { int32_t index; CHECK(msg->findInt32("index", &index)); handleAnInputBuffer(index); break; } ------------------------------------ bool NuPlayer::Decoder::handleAnInputBuffer(size_t index) { ... sp buffer; mCodec->getInputBuffer(index, &buffer); ... if (index >= mInputBuffers.size()) { for (size_t i = mInputBuffers.size(); i <= index; ++i) { mInputBuffers.add(); mMediaBuffers.add(); mInputBufferIsDequeued.add(); mMediaBuffers.editItemAt(i) = NULL; mInputBufferIsDequeued.editItemAt(i) = false; } } mInputBuffers.editItemAt(index) = buffer; //CHECK_LT(bufferIx, mInputBuffers.size()); if (mMediaBuffers[index] != NULL) { mMediaBuffers[index]->release(); mMediaBuffers.editItemAt(index) = NULL; } mInputBufferIsDequeued.editItemAt(index) = true; if (!mCSDsToSubmit.isEmpty()) { sp msg = new AMessage(); msg->setSize("buffer-ix", index); sp buffer = mCSDsToSubmit.itemAt(0); ALOGI("[%s] resubmitting CSD", mComponentName.c_str()); msg->setBuffer("buffer", buffer); mCSDsToSubmit.removeAt(0); if (!onInputBufferFetched(msg)) { handleError(UNKNOWN_ERROR); return false; } return true; } while (!mPendingInputMessages.empty()) { sp msg = *mPendingInputMessages.begin(); if (!onInputBufferFetched(msg)) { break; } mPendingInputMessages.erase(mPendingInputMessages.begin()); } if (!mInputBufferIsDequeued.editItemAt(index)) { return true; } mDequeuedInputBuffers.push_back(index); onRequestInputBuffers(); return true; } ------------------------------------ bool NuPlayer::Decoder::onInputBufferFetched(const sp &msg) { ... sp buffer; bool hasBuffer = msg->findBuffer("buffer", &buffer); // handle widevine classic source - that fills an arbitrary input buffer MediaBuffer *mediaBuffer = NULL; if (hasBuffer) { //TODO:更多信息,可以研究mediabuffer mediaBuffer = (MediaBuffer *)(buffer->getMediaBufferBase()); if (mediaBuffer != NULL) { // likely filled another buffer than we requested: adjust buffer index size_t ix; for (ix = 0; ix < mInputBuffers.size(); ix++) { const sp &buf = mInputBuffers[ix]; if (buf->data() == mediaBuffer->data()) { // all input buffers are dequeued on start, hence the check if (!mInputBufferIsDequeued[ix]) { ALOGV("[%s] received MediaBuffer for #%zu instead of #%zu", mComponentName.c_str(), ix, bufferIx); mediaBuffer->release(); return false; } // TRICKY: need buffer for the metadata, so instead, set // codecBuffer to the same (though incorrect) buffer to // avoid a memcpy into the codecBuffer codecBuffer = buffer; codecBuffer->setRange( mediaBuffer->range_offset(), mediaBuffer->range_length()); bufferIx = ix; break; } } CHECK(ix < mInputBuffers.size()); } } if (buffer == NULL /* includes !hasBuffer */) { int32_t streamErr = ERROR_END_OF_STREAM; CHECK(msg->findInt32("err", &streamErr) || !hasBuffer); CHECK(streamErr != OK); // attempt to queue EOS status_t err = mCodec->queueInputBuffer( bufferIx, 0, 0, 0, MediaCodec::BUFFER_FLAG_EOS); if (err == OK) { mInputBufferIsDequeued.editItemAt(bufferIx) = false; } else if (streamErr == ERROR_END_OF_STREAM) { streamErr = err; // err will not be ERROR_END_OF_STREAM } if (streamErr != ERROR_END_OF_STREAM) { ALOGE("Stream error for %s (err=%d), EOS %s queued", mComponentName.c_str(), streamErr, err == OK ? "successfully" : "unsuccessfully"); handleError(streamErr); } } else { sp extra; if (buffer->meta()->findMessage("extra", &extra) && extra != NULL) { int64_t resumeAtMediaTimeUs; if (extra->findInt64( "resume-at-mediaTimeUs", &resumeAtMediaTimeUs)) { ALOGI("[%s] suppressing rendering until %lld us", mComponentName.c_str(), (long long)resumeAtMediaTimeUs); mSkipRenderingUntilMediaTimeUs = resumeAtMediaTimeUs; } } int64_t timeUs = 0; uint32_t flags = 0; CHECK(buffer->meta()->findInt64("timeUs", &timeUs)); int32_t eos, csd; // we do not expect SYNCFRAME for decoder if (buffer->meta()->findInt32("eos", &eos) && eos) { flags |= MediaCodec::BUFFER_FLAG_EOS; } else if (buffer->meta()->findInt32("csd", &csd) && csd) { flags |= MediaCodec::BUFFER_FLAG_CODECCONFIG; } // copy into codec buffer if (buffer != codecBuffer) { if (buffer->size() > codecBuffer->capacity()) { handleError(ERROR_BUFFER_TOO_SMALL); mDequeuedInputBuffers.push_back(bufferIx); return false; } codecBuffer->setRange(0, buffer->size()); memcpy(codecBuffer->data(), buffer->data(), buffer->size()); } status_t err = mCodec->queueInputBuffer( bufferIx, codecBuffer->offset(), codecBuffer->size(), timeUs, flags); if (err != OK) { if (mediaBuffer != NULL) { mediaBuffer->release(); } ALOGE("Failed to queue input buffer for %s (err=%d)", mComponentName.c_str(), err); handleError(err); } else { mInputBufferIsDequeued.editItemAt(bufferIx) = false; if (mediaBuffer != NULL) { CHECK(mMediaBuffers[bufferIx] == NULL); mMediaBuffers.editItemAt(bufferIx) = mediaBuffer; } } } return true; }不管做什么,最后都是MediaCodec.queueInputBuffer完成了实际工作 ------------------------------------- void NuPlayer::DecoderBase::onRequestInputBuffers() { if (mRequestInputBuffersPending) { return; } // doRequestBuffers() return true if we should request more data if (doRequestBuffers()) { mRequestInputBuffersPending = true; //注意这里,会自己循环调用,不停地request sp msg = new AMessage(kWhatRequestInputBuffers, this); msg->post(10 * 1000ll); } } -------------------------------------- case kWhatRequestInputBuffers: { mRequestInputBuffersPending = false; onRequestInputBuffers(); break; } -------------------------------------- /* * returns true if we should request more data */ bool NuPlayer::Decoder::doRequestBuffers() { // mRenderer is only NULL if we have a legacy widevine source that // is not yet ready. In this case we must not fetch input. if (isDiscontinuityPending() || mRenderer == NULL) { return false; } status_t err = OK; while (err == OK && !mDequeuedInputBuffers.empty()) { size_t bufferIx = *mDequeuedInputBuffers.begin(); sp msg = new AMessage(); msg->setSize("buffer-ix", bufferIx); err = fetchInputData(msg); if (err != OK && err != ERROR_END_OF_STREAM) { // if EOS, need to queue EOS buffer break; } mDequeuedInputBuffers.erase(mDequeuedInputBuffers.begin()); if (!mPendingInputMessages.empty() || !onInputBufferFetched(msg)) { //前面分析过这个方法了 mPendingInputMessages.push_back(msg); } } return err == -EWOULDBLOCK && mSource->feedMoreTSData() == OK; } ------------------------------------- status_t NuPlayer::Decoder::fetchInputData(sp &reply) { sp accessUnit; bool dropAccessUnit; do { //在这里调用source的方法,从而建立起了联系 status_t err = mSource->dequeueAccessUnit(mIsAudio, &accessUnit); ... }while(...) } ------------------------------------
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418
至此,Decoder部分也分析完毕了
Renderernuplayer目录下
Renderer的初始化在NuPlayer::OnStart方法中完成
void NuPlayer::onStart(int64_t startPositionUs) { ... sp notify = new AMessage(kWhatRendererNotify, this); ++mRendererGeneration; notify->setInt32("generation", mRendererGeneration); mRenderer = AVNuFactory::get()->createRenderer(mAudioSink, notify, flags); mRendererLooper = new ALooper; mRendererLooper->setName("NuPlayerRenderer"); mRendererLooper->start(false, false, ANDROID_PRIORITY_AUDIO); mRendererLooper->registerHandler(mRenderer); status_t err = mRenderer->setPlaybackSettings(mPlaybackSettings); …... float rate = getFrameRate(); if (rate > 0) { mRenderer->setVideoFrameRate(rate); } if (mVideoDecoder != NULL) { mVideoDecoder->setRenderer(mRenderer); } if (mAudioDecoder != NULL) { mAudioDecoder->setRenderer(mRenderer); } postScanSources(); }
1234567891011121314151617181920212223242526272829
Renderer的数据输入在NuPlayer::Decoder::handleAnOutputBuffer中完成
bool NuPlayer::Decoder::handleAnOutputBuffer( size_t index, size_t offset, size_t size, int64_t timeUs, int32_t flags) { ... if (mRenderer != NULL) { // send the buffer to renderer.把Buffer送到Renderer mRenderer->queueBuffer(mIsAudio, buffer, reply); if (eos && !isDiscontinuityPending()) { mRenderer->queueEOS(mIsAudio, ERROR_END_OF_STREAM); } } ... } libmediaplayerservice/nuplayer/NuplayerRenderer.cpp mRenderer->queueBuffer最终会调用下面的方法 void NuPlayer::Renderer::onQueueBuffer(const sp &msg) { int32_t audio; CHECK(msg->findInt32("audio", &audio)); if (dropBufferIfStale(audio, msg)) { return; } if (audio) { mHasAudio = true; } else { mHasVideo = true; } if (mHasVideo) { if (mVideoScheduler == NULL) { mVideoScheduler = new VideoFrameScheduler();//初始化VideoFrameSche,用于VSync mVideoScheduler->init(); } } sp buffer; CHECK(msg->findBuffer("buffer", &buffer)); sp notifyConsumed; CHECK(msg->findMessage("notifyConsumed", ¬ifyConsumed)); QueueEntry entry;//可以理解为buffer循环队列的抽象 entry.mBuffer = buffer; entry.mNotifyConsumed = notifyConsumed; entry.mOffset = 0; entry.mFinalResult = OK; entry.mBufferOrdinal = ++mTotalBuffersQueued; //mAudioQueue和mVideoQueue都是List if (audio) { Mutex::Autolock autoLock(mLock); mAudioQueue.push_back(entry); postDrainAudioQueue_l(); } else { mVideoQueue.push_back(entry); postDrainVideoQueue();//每隔一段时间就被调用一次的 } Mutex::Autolock autoLock(mLock); if (!mSyncQueues || mAudioQueue.empty() || mVideoQueue.empty()) { return; } sp firstAudioBuffer = (*mAudioQueue.begin()).mBuffer; sp firstVideoBuffer = (*mVideoQueue.begin()).mBuffer; if (firstAudioBuffer == NULL || firstVideoBuffer == NULL) { // EOS signalled on either queue.某一个queue空了 syncQueuesDone_l(); return; } int64_t firstAudioTimeUs; int64_t firstVideoTimeUs; CHECK(firstAudioBuffer->meta() ->findInt64("timeUs", &firstAudioTimeUs)); CHECK(firstVideoBuffer->meta() ->findInt64("timeUs", &firstVideoTimeUs)); int64_t diff = firstVideoTimeUs - firstAudioTimeUs; ALOGV("queueDiff = %.2f secs", diff / 1E6); if (diff > 100000ll) { // Audio data starts More than 0.1 secs before video. // Drop some audio.音频超前视频0.1s,丢掉一些音频 (*mAudioQueue.begin()).mNotifyConsumed->post(); mAudioQueue.erase(mAudioQueue.begin()); return; } syncQueuesDone_l(); }
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101
Renderer的数据输出
同样是在postDrainVideoQueue方法中,会抛出kwhatDrainVideoQueue的消息 void NuPlayer::Renderer::postDrainVideoQueue() { …. sp msg = new AMessage(kWhatDrainVideoQueue, this); msg->setInt32("drainGeneration", getDrainGeneration(false /* audio */)); …} case kWhatDrainVideoQueue: { int32_t generation; CHECK(msg->findInt32("drainGeneration", &generation)); if (generation != getDrainGeneration(false /* audio */)) { break; } mDrainVideoQueuePending = false; onDrainVideoQueue(); postDrainVideoQueue(); break; } void NuPlayer::Renderer::onDrainVideoQueue() { ... QueueEntry *entry = &*mVideoQueue.begin(); if (entry->mBuffer == NULL) { // EOS notifyEOS(false /* audio */, entry->mFinalResult); ... return; } int64_t nowUs = ALooper::GetNowUs(); int64_t realTimeUs; int64_t mediaTimeUs = -1; if (mFlags & FLAG_REAL_TIME) { CHECK(entry->mBuffer->meta()->findInt64("timeUs", &realTimeUs)); } else { CHECK(entry->mBuffer->meta()->findInt64("timeUs", &mediaTimeUs)); realTimeUs = getRealTimeUs(mediaTimeUs, nowUs); } bool tooLate = false; if (!mPaused) { //比较媒体时间和wall clock setVideoLateByUs(nowUs - realTimeUs); tooLate = (mVideoLateByUs > 40000); if (tooLate) { ALOGV("video late by %lld us (%.2f secs)", (long long)mVideoLateByUs, mVideoLateByUs / 1E6); } else { int64_t mediaUs = 0; mMediaClock->getMediaTime(realTimeUs, &mediaUs); ALOGV("rendering video at media time %.2f secs", (mFlags & FLAG_REAL_TIME ? realTimeUs : mediaUs) / 1E6);... } } else { setVideoLateByUs(0); ... } // Always render the first video frame while keeping stats on A/V sync. if (!mVideoSampleReceived) { realTimeUs = nowUs; tooLate = false; } entry->mNotifyConsumed->setInt64("timestampNs", realTimeUs * 1000ll); entry->mNotifyConsumed->setInt32("render", !tooLate); entry->mNotifyConsumed->post(); mVideoQueue.erase(mVideoQueue.begin()); entry = NULL; mVideoSampleReceived = true; if (!mPaused) { if (!mVideoRenderingStarted) { mVideoRenderingStarted = true; notifyVideoRenderingStart();//刚刚开始 } Mutex::Autolock autoLock(mLock); notifyIfMediaRenderingStarted_l();//started,和上面的notifyVideoRenderingStart走的基本是同一条路,都会post对应的kwhatxxxx msg,最后回到NuPlayer的onMessage中被处理 } } NuPlayer case kWhatRendererNotify: { ... int32_t what; CHECK(msg->findInt32("what", &what)); //根据what内容的不同能看到各种熟悉的消息 if (what == Renderer::kWhatEOS) { ... if (audio) { mAudioEOS = true; } else { mVideoEOS = true; } if (finalResult == ERROR_END_OF_STREAM) { ALOGV("reached %s EOS", audio ? "audio" : "video"); } else { ALOGE("%s track encountered an error (%d)", audio ? "audio" : "video", finalResult); notifyListener( MEDIA_ERROR, MEDIA_ERROR_UNKNOWN, finalResult); } if ((mAudioEOS || mAudioDecoder == NULL) && (mVideoEOS || mVideoDecoder == NULL)) { notifyListener(MEDIA_PLAYBACK_COMPLETE, 0, 0); } } else if (what == Renderer::kWhatFlushComplete) { int32_t audio; CHECK(msg->findInt32("audio", &audio)); if (audio) { mAudioEOS = false; } else { mVideoEOS = false; } ALOGV("renderer %s flush completed.", audio ? "audio" : "video"); if (audio && (mFlushingAudio == NONE || mFlushingAudio == FLUSHED || mFlushingAudio == SHUT_DOWN)) { // Flush has been handled by tear down. break; } handleFlushComplete(audio, false /* isDecoder */); finishFlushIfPossible(); } else if (what == Renderer::kWhatVideoRenderingStart) { //对应前面的第一个,也就是刚刚开始render notifyListener(MEDIA_INFO, MEDIA_INFO_RENDERING_START, 0); } else if (what == Renderer::kWhatMediaRenderingStart) { ALOGV("media rendering started"); //对应前面的第二个 notifyListener(MEDIA_STARTED, 0, 0); } else if (what == Renderer::kWhatAudioTearDown) { …. } break; } framework\av\include\media // The player just pushed the very first video frame for rendering enum media_info_type { MEDIA_INFO_RENDERING_START = 3, } enum media_event_type { MEDIA_STARTED = 6, }
至此,就完成对android中nuplayer的ahandler机制和source\decoder\renderer三个模块的分析。欢迎互相交流学习。