Android Multimedia框架总结（二十二）MediaCodec中C++中创建到start过程及状态变换
上一章介绍MediaCodec中创建到start过程(到jni部分)，从今天开始，将深入源码中看看其c++过程，看下Agenda如下：
- mediacodec.h
- CreateByType
- initMediaCodec中BufferInfo内部类：
- configure过程
- start
BufferInfo在MediaCodec.h中对应是一个结构体
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlinstruct BufferInfo {uint32_t mBufferID;sp<ABuffer> mData;sp<ABuffer> mEncryptedData;sp<IMemory> mSharedEncryptedBuffer;sp<AMessage> mNotify;sp<AMessage> mFormat;bool mOwnedByClient;};
mediacodec.h的方法的声明,位于\frameworks\av\include\media\stagefright下
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlinnamespace android {struct ABuffer;struct AMessage;struct AReplyToken;struct AString;struct CodecBase;struct IBatteryStats;struct ICrypto;class IMemory;struct MemoryDealer;class IResourceManagerClient;class IResourceManagerService;struct PersistentSurface;struct SoftwareRenderer;struct Surface;struct MediaCodec : public AHandler {enum ConfigureFlags {CONFIGURE_FLAG_ENCODE = 1,};enum BufferFlags {BUFFER_FLAG_SYNCFRAME = 1,BUFFER_FLAG_CODECCONFIG = 2,BUFFER_FLAG_EOS = 4,};enum {CB_INPUT_AVAILABLE = 1,CB_OUTPUT_AVAILABLE = 2,CB_ERROR = 3,CB_OUTPUT_FORMAT_CHANGED = 4,CB_RESOURCE_RECLAIMED = 5,};static const pid_t kNoPid = -1;static sp<MediaCodec> CreateByType(const sp<ALooper> &looper, const char *mime, bool encoder, status_t *err = NULL,pid_t pid = kNoPid);static sp<MediaCodec> CreateByComponentName(const sp<ALooper> &looper, const char *name, status_t *err = NULL,pid_t pid = kNoPid);static sp<PersistentSurface> CreatePersistentInputSurface();status_t configure(const sp<AMessage> &format,const sp<Surface> &nativeWindow,const sp<ICrypto> &crypto,uint32_t flags);status_t setCallback(const sp<AMessage> &callback);status_t setOnFrameRenderedNotification(const sp<AMessage> ¬ify);status_t createInputSurface(sp<IGraphicBufferProducer>* bufferProducer);status_t setInputSurface(const sp<PersistentSurface> &surface);status_t start();// Returns to a state in which the component remains allocated but// unconfigured.status_t stop();// Resets the codec to the INITIALIZED state. Can be called after an error// has occured to make the codec usable.status_t reset();// Client MUST call release before releasing final reference to this// object.status_t release();status_t flush();status_t queueInputBuffer(size_t index,size_t offset,size_t size,int64_t presentationTimeUs,uint32_t flags,AString *errorDetailMsg = NULL);status_t queueSecureInputBuffer(size_t index,size_t offset,const CryptoPlugin::SubSample *subSamples,size_t numSubSamples,const uint8_t key[16],const uint8_t iv[16],CryptoPlugin::Mode mode,int64_t presentationTimeUs,uint32_t flags,AString *errorDetailMsg = NULL);status_t dequeueInputBuffer(size_t *index, int64_t timeoutUs = 0ll);status_t dequeueOutputBuffer(size_t *index,size_t *offset,size_t *size,int64_t *presentationTimeUs,uint32_t *flags,int64_t timeoutUs = 0ll);status_t renderOutputBufferAndRelease(size_t index, int64_t timestampNs);status_t renderOutputBufferAndRelease(size_t index);status_t releaseOutputBuffer(size_t index);status_t signalEndOfInputStream();status_t getOutputFormat(sp<AMessage> *format) const;status_t getInputFormat(sp<AMessage> *format) const;status_t getWidevineLegacyBuffers(Vector<sp<ABuffer> > *buffers) const;status_t getInputBuffers(Vector<sp<ABuffer> > *buffers) const;status_t getOutputBuffers(Vector<sp<ABuffer> > *buffers) const;status_t getOutputBuffer(size_t index, sp<ABuffer> *buffer);status_t getOutputFormat(size_t index, sp<AMessage> *format);status_t getInputBuffer(size_t index, sp<ABuffer> *buffer);status_t setSurface(const sp<Surface> &nativeWindow);status_t requestIDRFrame();// Notification will be posted once there "is something to do", i.e.// an input/output buffer has become available, a format change is// pending, an error is pending.void requestActivityNotification(const sp<AMessage> ¬ify);status_t getName(AString *componentName) const;status_t setParameters(const sp<AMessage> ¶ms);// Create a MediaCodec notification message from a list of rendered or dropped render infos// by adding rendered frame information to a base notification message. Returns the number// of frames that were rendered.static size_t CreateFramesRenderedMessage(std::list<FrameRenderTracker::Info> done, sp<AMessage> &msg);protected:virtual ~MediaCodec();virtual void onMessageReceived(const sp<AMessage> &msg);private:// used by ResourceManagerClientstatus_t reclaim(bool force = false);friend struct ResourceManagerClient;private:enum State {UNINITIALIZED,INITIALIZING,INITIALIZED,CONFIGURING,CONFIGURED,STARTING,STARTED,FLUSHING,FLUSHED,STOPPING,RELEASING,};enum {kPortIndexInput = 0,kPortIndexOutput = 1,};enum {kWhatInit = 'init',kWhatConfigure = 'conf',kWhatSetSurface = 'sSur',kWhatCreateInputSurface = 'cisf',kWhatSetInputSurface = 'sisf',kWhatStart = 'strt',kWhatStop = 'stop',kWhatRelease = 'rele',kWhatDequeueInputBuffer = 'deqI',kWhatQueueInputBuffer = 'queI',kWhatDequeueOutputBuffer = 'deqO',kWhatReleaseOutputBuffer = 'relO',kWhatSignalEndOfInputStream = 'eois',kWhatGetBuffers = 'getB',kWhatFlush = 'flus',kWhatGetOutputFormat = 'getO',kWhatGetInputFormat = 'getI',kWhatDequeueInputTimedOut = 'dITO',kWhatDequeueOutputTimedOut = 'dOTO',kWhatCodecNotify = 'codc',kWhatRequestIDRFrame = 'ridr',kWhatRequestActivityNotification = 'racN',kWhatGetName = 'getN',kWhatSetParameters = 'setP',kWhatSetCallback = 'setC',kWhatSetNotification = 'setN',};enum {kFlagUsesSoftwareRenderer = 1,kFlagOutputFormatChanged = 2,kFlagOutputBuffersChanged = 4,kFlagStickyError = 8,kFlagDequeueInputPending = 16,kFlagDequeueOutputPending = 32,kFlagIsSecure = 64,kFlagSawMediaServerDie = 128,kFlagIsEncoder = 256,kFlagGatherCodecSpecificData = 512,kFlagIsAsync = 1024,kFlagIsComponentAllocated = 2048,kFlagPushBlankBuffersOnShutdown = 4096,};struct BufferInfo {uint32_t mBufferID;sp<ABuffer> mData;sp<ABuffer> mEncryptedData;sp<IMemory> mSharedEncryptedBuffer;sp<AMessage> mNotify;sp<AMessage> mFormat;bool mOwnedByClient;};struct ResourceManagerServiceProxy : public IBinder::DeathRecipient {ResourceManagerServiceProxy(pid_t pid);~ResourceManagerServiceProxy();void init();// implements DeathRecipientvirtual void binderDied(const wp<IBinder>& /*who*/);void addResource(int64_t clientId,const sp<IResourceManagerClient> client,const Vector<MediaResource> &resources);void removeResource(int64_t clientId);bool reclaimResource(const Vector<MediaResource> &resources);private:Mutex mLock;sp<IResourceManagerService> mService;pid_t mPid;};State mState;bool mReleasedByResourceManager;sp<ALooper> mLooper;sp<ALooper> mCodecLooper;sp<CodecBase> mCodec;AString mComponentName;sp<AReplyToken> mReplyID;uint32_t mFlags;status_t mStickyError;sp<Surface> mSurface;SoftwareRenderer *mSoftRenderer;sp<AMessage> mOutputFormat;sp<AMessage> mInputFormat;sp<AMessage> mCallback;sp<AMessage> mOnFrameRenderedNotification;sp<MemoryDealer> mDealer;sp<IResourceManagerClient> mResourceManagerClient;sp<ResourceManagerServiceProxy> mResourceManagerService;bool mBatteryStatNotified;bool mIsVideo;int32_t mVideoWidth;int32_t mVideoHeight;int32_t mRotationDegrees;// initial create parametersAString mInitName;bool mInitNameIsType;bool mInitIsEncoder;// configure parametersp<AMessage> mConfigureMsg;// Used only to synchronize asynchronous getBufferAndFormat// across all the other (synchronous) buffer state change// operations, such as de/queueIn/OutputBuffer, start and// stop/flush/reset/release.Mutex mBufferLock;ListmAvailPortBuffers[2]; Vector<BufferInfo> mPortBuffers[2];int32_t mDequeueInputTimeoutGeneration;sp<AReplyToken> mDequeueInputReplyID;int32_t mDequeueOutputTimeoutGeneration;sp<AReplyToken> mDequeueOutputReplyID;sp<ICrypto> mCrypto;List<sp<ABuffer> > mCSD;sp<AMessage> mActivityNotify;bool mHaveInputSurface;bool mHavePendingInputBuffers;MediaCodec(const sp<ALooper> &looper, pid_t pid);static status_t PostAndAwaitResponse(const sp<AMessage> &msg, sp<AMessage> *response);void PostReplyWithError(const sp<AReplyToken> &replyID, int32_t err);status_t init(const AString &name, bool nameIsType, bool encoder);void setState(State newState);void returnBuffersToCodec();void returnBuffersToCodecOnPort(int32_t portIndex);size_t updateBuffers(int32_t portIndex, const sp<AMessage> &msg);status_t onQueueInputBuffer(const sp<AMessage> &msg);status_t onReleaseOutputBuffer(const sp<AMessage> &msg);ssize_t dequeuePortBuffer(int32_t portIndex);status_t getBufferAndFormat(size_t portIndex, size_t index,sp<ABuffer> *buffer, sp<AMessage> *format);bool handleDequeueInputBuffer(const sp<AReplyToken> &replyID, bool newRequest = false);bool handleDequeueOutputBuffer(const sp<AReplyToken> &replyID, bool newRequest = false);void cancelPendingDequeueOperations();void extractCSD(const sp<AMessage> &format);status_t queueCSDInputBuffer(size_t bufferIndex);status_t handleSetSurface(const sp<Surface> &surface);status_t connectToSurface(const sp<Surface> &surface);status_t disconnectFromSurface();void postActivityNotificationIfPossible();void onInputBufferAvailable();void onOutputBufferAvailable();void onError(status_t err, int32_t actionCode, const char *detail = NULL);void onOutputFormatChanged();status_t onSetParameters(const sp<AMessage> ¶ms);status_t amendOutputFormatWithCodecSpecificData(const sp<ABuffer> &buffer);void updateBatteryStat();bool isExecuting() const;uint64_t getGraphicBufferSize();void addResource(const String8 &type, const String8 &subtype, uint64_t value);bool hasPendingBuffer(int portIndex);bool hasPendingBuffer();/* called to get the last codec error when the sticky flag is set.* if no such codec error is found, returns UNKNOWN_ERROR.*/inline status_t getStickyError() const {return mStickyError != 0 ? mStickyError : UNKNOWN_ERROR;}inline void setStickyError(status_t err) {mFlags |= kFlagStickyError;mStickyError = err;}DISALLOW_EVIL_CONSTRUCTORS(MediaCodec);};} // namespace android
CreateByType
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlin// staticsp<MediaCodec> MediaCodec::CreateByType(const sp<ALooper> &looper, const char *mime, bool encoder, status_t *err, pid_t pid) {sp<MediaCodec> codec = new MediaCodec(looper, pid);//这果实际上new出MediaCodec对象const status_t ret = codec->init(mime, true /* nameIsType */, encoder);if (err != NULL) {*err = ret;}return ret == OK ? codec : NULL; // NULL deallocates codec.}
接着到init过程
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlinstatus_t MediaCodec::init(const AString &name, bool nameIsType, bool encoder) {mResourceManagerService->init();// 保存 初始参数，到时用于resetmInitName = name;mInitNameIsType = nameIsType;mInitIsEncoder = encoder;// 目前视频解码器不能马上从OMX_FillThisBuffer返回，违反OpenMAX规格,直到提醒我们需要入驻另一个第三方的looper释放在事件队列中。if (nameIsType || !strncasecmp(name.c_str(), "omx.", 4)) {//omx.匹配mCodec = new ACodec;//实例化ACodec} else if (!nameIsType&& !strncasecmp(name.c_str(), "android.filter.", 15)) {mCodec = new MediaFilter;// 实例化MediaFilter} else {return NAME_NOT_FOUND;}bool secureCodec = false;if (nameIsType && !strncasecmp(name.c_str(), "video/", 6)) {mIsVideo = true;} else {AString tmp = name;if (tmp.endsWith(".secure")) {secureCodec = true;tmp.erase(tmp.size() - 7, 7);}const sp<IMediaCodecList> mcl = MediaCodecList::getInstance();if (mcl == NULL) {mCodec = NULL; // remove the codec.return NO_INIT; // if called from Java should raise IOException}ssize_t codecIdx = mcl->findCodecByName(tmp.c_str());if (codecIdx >= 0) {const sp<MediaCodecInfo> info = mcl->getCodecInfo(codecIdx);Vector<AString> mimes;info->getSupportedMimes(&mimes);for (size_t i = 0; i < mimes.size(); i++) {if (mimes[i].startsWith("video/")) {mIsVideo = true;break;}}}}if (mIsVideo) {// video codec needs dedicated looperif (mCodecLooper == NULL) {mCodecLooper = new ALooper;mCodecLooper->setName("CodecLooper");//设置名字为CodecLoopermCodecLooper->start(false, false, ANDROID_PRIORITY_AUDIO);}mCodecLooper->registerHandler(mCodec);} else {mLooper->registerHandler(mCodec);}mLooper->registerHandler(this);mCodec->setNotificationMessage(new AMessage(kWhatCodecNotify, this));sp<AMessage> msg = new AMessage(kWhatInit, this);msg->setString("name", name);msg->setInt32("nameIsType", nameIsType);if (nameIsType) {msg->setInt32("encoder", encoder);}status_t err;Vector<MediaResource> resources;const char *type = secureCodec ? kResourceSecureCodec : kResourceNonSecureCodec;const char *subtype = mIsVideo ? kResourceVideoCodec : kResourceAudioCodec;resources.push_back(MediaResource(String8(type), String8(subtype), 1));for (int i = 0; i <= kMaxRetry; ++i) {if (i > 0) {// Don't try to reclaim resource for the first time.if (!mResourceManagerService->reclaimResource(resources)) {break;}}sp<AMessage> response;err = PostAndAwaitResponse(msg, &response);if (!isResourceError(err)) {break;}}return err;}
configure过程
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlinstatus_t MediaCodec::configure(const sp<AMessage> &format,const sp<Surface> &surface,const sp<ICrypto> &crypto,uint32_t flags) {sp<AMessage> msg = new AMessage(kWhatConfigure, this);if (mIsVideo) {format->findInt32("width", &mVideoWidth);format->findInt32("height", &mVideoHeight);if (!format->findInt32("rotation-degrees", &mRotationDegrees)) {mRotationDegrees = 0;}}msg->setMessage("format", format);msg->setInt32("flags", flags);msg->setObject("surface", surface);if (crypto != NULL) {msg->setPointer("crypto", crypto.get());}// save msg for resetmConfigureMsg = msg;status_t err;Vector<MediaResource> resources;const char *type = (mFlags & kFlagIsSecure) ?kResourceSecureCodec : kResourceNonSecureCodec;const char *subtype = mIsVideo ? kResourceVideoCodec : kResourceAudioCodec;resources.push_back(MediaResource(String8(type), String8(subtype), 1));// Don't know the buffer size at this point, but it's fine to use 1 because// the reclaimResource call doesn't consider the requester's buffer size for now.resources.push_back(MediaResource(String8(kResourceGraphicMemory), 1));for (int i = 0; i <= kMaxRetry; ++i) {if (i > 0) {// Don't try to reclaim resource for the first time.if (!mResourceManagerService->reclaimResource(resources)) {break;}}sp<AMessage> response;err = PostAndAwaitResponse(msg, &response);if (err != OK && err != INVALID_OPERATION) {// MediaCodec now set state to UNINITIALIZED upon any fatal error.// To maintain backward-compatibility, do a reset() to put codec// back into INITIALIZED state.// But don't reset if the err is INVALID_OPERATION, which means// the configure failure is due to wrong state.ALOGE("configure failed with err 0x%08x, resetting...", err);reset();}if (!isResourceError(err)) {break;}}return err;}
start过程
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlinstatus_t MediaCodec::start() {sp<AMessage> msg = new AMessage(kWhatStart, this);status_t err;Vector<MediaResource> resources;const char *type = (mFlags & kFlagIsSecure) ?kResourceSecureCodec : kResourceNonSecureCodec;const char *subtype = mIsVideo ? kResourceVideoCodec : kResourceAudioCodec;resources.push_back(MediaResource(String8(type), String8(subtype), 1));// Don't know the buffer size at this point, but it's fine to use 1 because// the reclaimResource call doesn't consider the requester's buffer size for now.resources.push_back(MediaResource(String8(kResourceGraphicMemory), 1));for (int i = 0; i <= kMaxRetry; ++i) {if (i > 0) {// Don't try to reclaim resource for the first time.if (!mResourceManagerService->reclaimResource(resources)) {break;}// Recover codec from previous error before retry start.err = reset();if (err != OK) {ALOGE("retrying start: failed to reset codec");break;}sp<AMessage> response;err = PostAndAwaitResponse(mConfigureMsg, &response);if (err != OK) {ALOGE("retrying start: failed to configure codec");break;}}sp<AMessage> response;err = PostAndAwaitResponse(msg, &response);if (!isResourceError(err)) {break;}}return err;}
stop过程
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlinstatus_t MediaCodec::stop() {sp<AMessage> msg = new AMessage(kWhatStop, this);sp<AMessage> response;return PostAndAwaitResponse(msg, &response);}
找到对应的AMessage.cpp,对应同样有一套AHandler.cpp，及ALooper.cpp，这此组成了在c++中一套机制，接口 方法的名字和Java层保持一致。
所有message都在onMessageReceived方法中处理，MediaCodec的各个状态的相关切换。
//create by 逆流的鱼yuiop on 2016/12/11//blog地址：http://blog.csdn.net/hejjunlinvoid MediaCodec::onMessageReceived(const sp<AMessage> &msg) {switch (mState) {case INITIALIZING://初始化中{setState(UNINITIALIZED);break;}case CONFIGURING://配置中{setState(actionCode == ACTION_CODE_FATAL ?UNINITIALIZED : INITIALIZED);break;}case STARTING://start中{setState(actionCode == ACTION_CODE_FATAL ?UNINITIALIZED : CONFIGURED);break;}case STOPPING://停止中case RELEASING://释放中{// Ignore the error, assuming we'll still get// the shutdown complete notification.sendErrorResponse = false;if (mFlags & kFlagSawMediaServerDie) {// MediaServer died, there definitely won't// be a shutdown complete notification after// all.// note that we're directly going from// STOPPING->UNINITIALIZED, instead of the// usual STOPPING->INITIALIZED state.setState(UNINITIALIZED);if (mState == RELEASING) {mComponentName.clear();}(new AMessage)->postReply(mReplyID);}break;}case FLUSHING://刷新中{if (actionCode == ACTION_CODE_FATAL) {setState(UNINITIALIZED);} else {setState((mFlags & kFlagIsAsync) ? FLUSHED : STARTED);}break;}case FLUSHED:case STARTED:{sendErrorResponse = false;setStickyError(err);postActivityNotificationIfPossible();cancelPendingDequeueOperations();if (mFlags & kFlagIsAsync) {onError(err, actionCode);}switch (actionCode) {case ACTION_CODE_TRANSIENT:break;case ACTION_CODE_RECOVERABLE:setState(INITIALIZED);break;default:setState(UNINITIALIZED);break;}break;}default:{sendErrorResponse = false;setStickyError(err);postActivityNotificationIfPossible();// actionCode in an uninitialized state is always fatal.if (mState == UNINITIALIZED) {actionCode = ACTION_CODE_FATAL;}if (mFlags & kFlagIsAsync) {onError(err, actionCode);}switch (actionCode) {case ACTION_CODE_TRANSIENT:break;case ACTION_CODE_RECOVERABLE:setState(INITIALIZED);break;default:setState(UNINITIALIZED);break;}break;}}