MediaRecorder创建Surface流程学习
16lz
2021-01-26
Android 配置相机流的时候需要给cameraservice传递一个surface对象，
在分析SnapdragonCamera配置HFR录像流的过程中，发现SnapdragonCamera是通过创建MediaRecorder来获取surface的
mMediaRecorder.getSurface()本文主要分析下MediaRecorder创建surface的过程，顺便整理下MediaRecorder的代码逻辑架构
apk 创建代码
//frameworks\base\media\java\android\media private void setUpMediaRecorder(int cameraId) throws IOException { Log.d(TAG, "setUpMediaRecorder"); ... if (mMediaRecorder == null) mMediaRecorder = new MediaRecorder(); mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE); mMediaRecorder.setOutputFormat(mProfile.fileFormat); mMediaRecorder.setOutputFile(fileName); mMediaRecorder.setVideoFrameRate(mProfile.videoFrameRate); mMediaRecorder.setVideoEncodingBitRate(mProfile.videoBitRate); mMediaRecorder.setVideoSize(mProfile.videoFrameWidth, mProfile.videoFrameHeight); mMediaRecorder.setVideoEncoder(videoEncoder); mMediaRecorder.setMaxDuration(mMaxVideoDurationInMs); try { mMediaRecorder.setMaxFileSize(maxFileSize); } catch (RuntimeException exception) { } try { mMediaRecorder.prepare(); } catch (IOException e) { } }进入MediaRecorder.java，主要讲述构造函数MediaRecorder()和prepare()函数
//frameworks\base\media\java\android\media\MediaRecorder.java public MediaRecorder() { .... String packageName = ActivityThread.currentPackageName(); /* Native setup requires a weak reference to our object. * It's easier to create it here than in C++. */ native_setup(new WeakReference<MediaRecorder>(this), packageName, ActivityThread.currentOpPackageName()); } public void prepare() throws IllegalStateException, IOException { ... _prepare(); }_prepare是native 方法，定义如下：
//frameworks\base\media\java\android\media\MediaRecorder.java private native final void native_setup(Object mediarecorder_this, String clientName, String opPackageName) throws IllegalStateException; private native void _prepare() throws IllegalStateException, IOException;进入JNI 层实现
//frameworks\base\media\jni\android_media_MediaRecorder.cppstatic void android_media_MediaRecorder_native_setup(JNIEnv *env, jobject thiz, jobject weak_this, jstring packageName, jstring opPackageName){ ... // 创建MediaRecorder sp<MediaRecorder> mr = new MediaRecorder(String16(opPackageNameStr.c_str())); // create new listener and give it to MediaRecorder sp<JNIMediaRecorderListener> listener = new JNIMediaRecorderListener(env, thiz, weak_this); mr->setListener(listener); // pass client package name for permissions tracking mr->setClientName(clientName);}static void android_media_MediaRecorder_prepare(JNIEnv *env, jobject thiz){ sp<MediaRecorder> mr = getMediaRecorder(env, thiz);//该处获取的surface为null jobject surface = env->GetObjectField(thiz, fields.surface); if (surface != NULL) { .... } //调用mr->prepare()，mediarecoder的surface是在该方法中完成创建的。 process_media_recorder_call(env, mr->prepare(), "java/io/IOException", "prepare failed.");}进到mediarecorder.cpp类
//frameworks\av\media\libmedia\mediarecorder.cpp//构造函数MediaRecorder::MediaRecorder(const String16& opPackageName) : mSurfaceMediaSource(NULL){ ALOGV("constructor"); //获取IMediaPlayerService服务代理对象(实际是BpMediaPlayerService类对象) const sp<IMediaPlayerService> service(getMediaPlayerService()); if (service != NULL) { //通过IMediaPlayerService服务创建IMediaRecorder(实际是BpMediaRecorder类)对象mMediaRecorder mMediaRecorder = service->createMediaRecorder(opPackageName); } if (mMediaRecorder != NULL) { mCurrentState = MEDIA_RECORDER_IDLE; } doCleanUp();}prepare 方法
//frameworks\av\media\libmedia\mediarecorder.cppstatus_t MediaRecorder::prepare(){ ALOGV("prepare"); ... status_t ret = mMediaRecorder->prepare(); ... return ret;}获取IMediaPlayerService服务代理的实现 代码：
// establish binder interface to MediaPlayerService/*static*/const sp<IMediaPlayerService>IMediaDeathNotifier::getMediaPlayerService(){ ALOGV("getMediaPlayerService"); Mutex::Autolock _l(sServiceLock); if (sMediaPlayerService == 0) { sp<IServiceManager> sm = defaultServiceManager(); sp<IBinder> binder; do { binder = sm->getService(String16("media.player")); if (binder != 0) { break; } ALOGW("Media player service not published, waiting..."); usleep(500000); // 0.5 s } while (true); if (sDeathNotifier == NULL) { sDeathNotifier = new DeathNotifier(); } binder->linkToDeath(sDeathNotifier); sMediaPlayerService = interface_cast<IMediaPlayerService>(binder); } ALOGE_IF(sMediaPlayerService == 0, "no media player service!?"); return sMediaPlayerService;}IMediaPlayerService服务实现代码：
//rc 文件//frameworks\av\media\mediaserver\mediaserver.rcservice media /system/bin/mediaserver class main user media group audio camera inet net_bt net_bt_admin net_bw_acct drmrpc mediadrm ioprio rt 4 writepid /dev/cpuset/foreground/tasks /dev/stune/foreground/tasks进程入口：
//frameworks\av\media\mediaserver\main_mediaserver.cppint main(int argc __unused, char **argv __unused){ signal(SIGPIPE, SIG_IGN); sp<ProcessState> proc(ProcessState::self()); sp<IServiceManager> sm(defaultServiceManager()); ALOGI("ServiceManager: %p", sm.get()); InitializeIcuOrDie(); //将服务注册给IServiceManager MediaPlayerService::instantiate(); ResourceManagerService::instantiate(); registerExtensions(); ProcessState::self()->startThreadPool(); IPCThreadState::self()->joinThreadPool();}MediaPlayerService注册实现代码
//frameworks\av\media\libmediaplayerservice\MediaPlayerService.cppvoid MediaPlayerService::instantiate() { defaultServiceManager()->addService( String16("media.player"), new MediaPlayerService());}至此可以看出，将MediaPlayerService注册给了serviceManager
继续分析 service->createMediaRecorder(opPackageName)
进入到IMediaPlayerService
//frameworks\av\media\libmedia\IMediaPlayerService.cpp virtual sp<IMediaRecorder> createMediaRecorder(const String16 &opPackageName) { Parcel data, reply; data.writeInterfaceToken(IMediaPlayerService::getInterfaceDescriptor()); data.writeString16(opPackageName); //Binder IPC remote()->transact(CREATE_MEDIA_RECORDER, data, &reply); return interface_cast<IMediaRecorder>(reply.readStrongBinder()); }进入到BnMediaPlayerService
status_t BnMediaPlayerService::onTransact( uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags){ switch (code) { .... case CREATE_MEDIA_RECORDER: { CHECK_INTERFACE(IMediaPlayerService, data, reply); const String16 opPackageName = data.readString16(); sp<IMediaRecorder> recorder = createMediaRecorder(opPackageName); reply->writeStrongBinder(IInterface::asBinder(recorder)); return NO_ERROR; } break; .... default: return BBinder::onTransact(code, data, reply, flags); }}进入到BnMediaPlayerService的实现类MediaPlayerService
sp<IMediaRecorder> MediaPlayerService::createMediaRecorder(const String16 &opPackageName){ pid_t pid = IPCThreadState::self()->getCallingPid(); //创建MediaRecorderClient对象 sp<MediaRecorderClient> recorder = new MediaRecorderClient(this, pid, opPackageName); wp<MediaRecorderClient> w = recorder; Mutex::Autolock lock(mLock); mMediaRecorderClients.add(w); ALOGV("Create new media recorder client from pid %d", pid); return recorder;}由此可见mediarecorder.cpp中createMediaRecorder(opPackageName)返回的其实是MediaRecorderClient对应的代理对象BpMediaRecorder。
MediaRecorderClient类继承实现了IMediaRecorder，类图下如：
MediaRecorderClient 内部成员变量mRecorder是在其构造函数中初始创建的，类型为：StagefrightRecorder
//frameworks\av\media\libmediaplayerservice\MediaRecorderClient.cppMediaRecorderClient::MediaRecorderClient(const sp<MediaPlayerService>& service, pid_t pid, const String16& opPackageName){ ALOGV("Client constructor"); mPid = pid; mRecorder = AVMediaServiceFactory::get()->createStagefrightRecorder(opPackageName); mMediaPlayerService = service;}createStagefrightRecorder创建的是StagefrightRecorder
//frameworks\av\media\libmediaplayerservice\StagefrightRecorder.cppStagefrightRecorder *AVMediaServiceFactory::createStagefrightRecorder( const String16 &opPackageName) { return new StagefrightRecorder(opPackageName);}类图如下
MediaRecorderClient是通过mRecorder对象完成prepare等操作的,代码如下：
//frameworks\av\media\libmediaplayerservice\MediaRecorderClient.cppstatus_t MediaRecorderClient::prepare(){ ALOGV("prepare"); Mutex::Autolock lock(mLock); if (mRecorder == NULL) { ALOGE("recorder is not initialized"); return NO_INIT; } return mRecorder->prepare();}进入StagefrightRecorder.cpp
//frameworks\av\media\libmediaplayerservice\StagefrightRecorder.cppstatus_t StagefrightRecorder::prepare() { ALOGV("prepare"); Mutex::Autolock autolock(mLock); //apk配置过mVideoSource为VIDEO_SOURCE_SURFACE if (mVideoSource == VIDEO_SOURCE_SURFACE) { return prepareInternal(); } return OK;}进入prepareInternal()函数,该方法是初始化所需的编码器，本文配置的是setupMPEG4orWEBMRecording
//frameworks\av\media\libmediaplayerservice\StagefrightRecorder.cppstatus_t StagefrightRecorder::prepareInternal() { ALOGV("prepare"); if (mOutputFd < 0) { ALOGE("Output file descriptor is invalid"); return INVALID_OPERATION; } // Get UID and PID here for permission checking mClientUid = IPCThreadState::self()->getCallingUid(); mClientPid = IPCThreadState::self()->getCallingPid(); status_t status = OK; switch (mOutputFormat) { case OUTPUT_FORMAT_DEFAULT: case OUTPUT_FORMAT_THREE_GPP: case OUTPUT_FORMAT_MPEG_4: case OUTPUT_FORMAT_WEBM: //配置pMPEG4orWEBM编码器 status = setupMPEG4orWEBMRecording(); break; case OUTPUT_FORMAT_AMR_NB: case OUTPUT_FORMAT_AMR_WB: status = setupAMRRecording(); break; case OUTPUT_FORMAT_AAC_ADIF: case OUTPUT_FORMAT_AAC_ADTS: status = setupAACRecording(); break; case OUTPUT_FORMAT_RTP_AVP: status = setupRTPRecording(); break; case OUTPUT_FORMAT_MPEG2TS: status = setupMPEG2TSRecording(); break; default: if (handleCustomRecording() != OK) { ALOGE("Unsupported output file format: %d", mOutputFormat); status = UNKNOWN_ERROR; } break; } ALOGV("Recording frameRate: %d captureFps: %f", mFrameRate, mCaptureFps); return status;}setupMPEG4orWEBMRecording代码实现
//frameworks\av\media\libmediaplayerservice\StagefrightRecorder.cppstatus_t StagefrightRecorder::setupMPEG4orWEBMRecording() { mWriter.clear(); mTotalBitRate = 0; status_t err = OK; sp<MediaWriter> writer; sp<MPEG4Writer> mp4writer; if (mOutputFormat == OUTPUT_FORMAT_WEBM) { writer = new WebmWriter(mOutputFd); } else { //创建的是CreateMPEG4Writer writer = mp4writer = AVFactory::get()->CreateMPEG4Writer(mOutputFd); } if (mVideoSource < VIDEO_SOURCE_LIST_END) { setDefaultVideoEncoderIfNecessary(); sp<MediaSource> mediaSource; //创建mediaSource，本文应该是空 err = setupMediaSource(&mediaSource); if (err != OK) { return err; } //创建encoder，下步重点分析 sp<MediaCodecSource> encoder; err = setupVideoEncoder(mediaSource, &encoder); if (err != OK) { return err; } //向MPEG4Writer添加encoder writer->addSource(encoder); mVideoEncoderSource = encoder; mTotalBitRate += mVideoBitRate; } if (mOutputFormat != OUTPUT_FORMAT_WEBM) { // Audio source is added at the end if it exists. // This help make sure that the "recoding" sound is suppressed for // camcorder applications in the recorded files. // TODO Audio source is currently unsupported for webm output; vorbis encoder needed. // disable audio for time lapse recording bool disableAudio = mCaptureFpsEnable && mCaptureFps < mFrameRate; if (!disableAudio && mAudioSource != AUDIO_SOURCE_CNT) { err = setupAudioEncoder(writer); if (err != OK) return err; mTotalBitRate += mAudioBitRate; } if (mCaptureFpsEnable) { mp4writer->setCaptureRate(mCaptureFps); } if (mInterleaveDurationUs > 0) { mp4writer->setInterleaveDuration(mInterleaveDurationUs); } if (mLongitudex10000 > -3600000 && mLatitudex10000 > -3600000) { mp4writer->setGeoData(mLatitudex10000, mLongitudex10000); } } if (mMaxFileDurationUs != 0) { writer->setMaxFileDuration(mMaxFileDurationUs); } if (mMaxFileSizeBytes != 0) { writer->setMaxFileSize(mMaxFileSizeBytes); } if (mVideoSource == VIDEO_SOURCE_DEFAULT || mVideoSource == VIDEO_SOURCE_CAMERA) { mStartTimeOffsetMs = mEncoderProfiles->getStartTimeOffsetMs(mCameraId); } else if (mVideoSource == VIDEO_SOURCE_SURFACE) { // surface source doesn't need large initial delay mStartTimeOffsetMs = 100; } if (mStartTimeOffsetMs > 0) { writer->setStartTimeOffsetMs(mStartTimeOffsetMs); } writer->setListener(mListener); mWriter = writer; return OK;}分析下setupVideoEncoder
status_t StagefrightRecorder::setupVideoEncoder( const sp<MediaSource> &cameraSource, sp<MediaCodecSource> *source) { source->clear(); sp<AMessage> format = new AMessage(); //本文采用的是VIDEO_ENCODER_H264编码？？VIDEO_ENCODER_MPEG_4_SP??待确定 switch (mVideoEncoder) { case VIDEO_ENCODER_H263: format->setString("mime", MEDIA_MIMETYPE_VIDEO_H263); break; case VIDEO_ENCODER_MPEG_4_SP: format->setString("mime", MEDIA_MIMETYPE_VIDEO_MPEG4); break; case VIDEO_ENCODER_H264: format->setString("mime", MEDIA_MIMETYPE_VIDEO_AVC); break; case VIDEO_ENCODER_VP8: format->setString("mime", MEDIA_MIMETYPE_VIDEO_VP8); break; case VIDEO_ENCODER_HEVC: format->setString("mime", MEDIA_MIMETYPE_VIDEO_HEVC); break; default: CHECK(!"Should not be here, unsupported video encoding."); break; } //cameraSource为NULL if (cameraSource != NULL) { sp<MetaData> meta = cameraSource->getFormat(); int32_t width, height, stride, sliceHeight, colorFormat; CHECK(meta->findInt32(kKeyWidth, &width)); CHECK(meta->findInt32(kKeyHeight, &height)); CHECK(meta->findInt32(kKeyStride, &stride)); CHECK(meta->findInt32(kKeySliceHeight, &sliceHeight)); CHECK(meta->findInt32(kKeyColorFormat, &colorFormat)); format->setInt32("width", width); format->setInt32("height", height); format->setInt32("stride", stride); format->setInt32("slice-height", sliceHeight); format->setInt32("color-format", colorFormat); } else { //HFR走的是该处 format->setInt32("width", mVideoWidth); format->setInt32("height", mVideoHeight); format->setInt32("stride", mVideoWidth); format->setInt32("slice-height", mVideoHeight); format->setInt32("color-format", OMX_COLOR_FormatAndroidOpaque); // set up time lapse/slow motion for surface source if (mCaptureFpsEnable) { if (!(mCaptureFps > 0.)) { ALOGE("Invalid mCaptureFps value: %lf", mCaptureFps); return BAD_VALUE; } format->setDouble("time-lapse-fps", mCaptureFps); } } setupCustomVideoEncoderParams(cameraSource, format); format->setInt32("bitrate", mVideoBitRate); format->setInt32("frame-rate", mFrameRate); format->setInt32("i-frame-interval", mIFramesIntervalSec); if (mVideoTimeScale > 0) { format->setInt32("time-scale", mVideoTimeScale); } if (mVideoEncoderProfile != -1) { format->setInt32("profile", mVideoEncoderProfile); } if (mVideoEncoderLevel != -1) { format->setInt32("level", mVideoEncoderLevel); } uint32_t tsLayers = 1; bool preferBFrames = true; // we like B-frames as it produces better quality per bitrate format->setInt32("priority", 0 /* realtime */); float maxPlaybackFps = mFrameRate; // assume video is only played back at normal speed if (mCaptureFpsEnable) { format->setFloat("operating-rate", mCaptureFps); // enable layering for all time lapse and high frame rate recordings if (mFrameRate / mCaptureFps >= 1.9) { // time lapse preferBFrames = false; tsLayers = 2; // use at least two layers as resulting video will likely be sped up } else if (mCaptureFps > maxPlaybackFps) { // slow-mo //HFR 走的是该出 format->setInt32("high-frame-rate", 1); maxPlaybackFps = mCaptureFps; // assume video will be played back at full capture speed preferBFrames = false; } } for (uint32_t tryLayers = 1; tryLayers <= kMaxNumVideoTemporalLayers; ++tryLayers) { if (tryLayers > tsLayers) { tsLayers = tryLayers; } // keep going until the base layer fps falls below the typical display refresh rate float baseLayerFps = maxPlaybackFps / (1 << (tryLayers - 1)); if (baseLayerFps < kMinTypicalDisplayRefreshingRate / 0.9) { break; } } // mIFramesIntervalSec == 0 means all Intra frame, can't support P/B layers if (tsLayers > 1 && mIFramesIntervalSec != 0) { uint32_t bLayers = std::min(2u, tsLayers - 1); // use up-to 2 B-layers uint32_t pLayers = tsLayers - bLayers; format->setString( "ts-schema", AStringPrintf("android.generic.%u+%u", pLayers, bLayers)); // TODO: some encoders do not support B-frames with temporal layering, and we have a // different preference based on use-case. We could move this into camera profiles. format->setInt32("android._prefer-b-frames", preferBFrames); } if (mMetaDataStoredInVideoBuffers != kMetadataBufferTypeInvalid) { format->setInt32("android._input-metadata-buffer-type", mMetaDataStoredInVideoBuffers); } if (mOutputFormat == OUTPUT_FORMAT_MPEG_4) { format->setInt32("mpeg4-writer", 1); format->setInt32("nal-length", 4); } uint32_t flags = 0; if (cameraSource == NULL) { //hfr 走的是该处 flags |= MediaCodecSource::FLAG_USE_SURFACE_INPUT; } else { // require dataspace setup even if not using surface input format->setInt32("android._using-recorder", 1); } //创建MediaCodecSource对象encoder sp<MediaCodecSource> encoder = MediaCodecSource::Create( mLooper, format, cameraSource, mPersistentSurface, flags); if (encoder == NULL) { ALOGE("Failed to create video encoder"); // When the encoder fails to be created, we need // release the camera source due to the camera's lock // and unlock mechanism. if (cameraSource != NULL) { cameraSource->stop(); } return UNKNOWN_ERROR; } //HFR的cameraSource为NULL，是通过encoder->getGraphicBufferProducer()来获取mGraphicBufferProducer的 if (cameraSource == NULL) { mGraphicBufferProducer = encoder->getGraphicBufferProducer(); } *source = encoder; return OK;}分析下MediaCodecSource::Create(..)
//frameworks\av\media\libstagefright\MediaCodecSource.cppsp<MediaCodecSource> MediaCodecSource::Create( const sp<ALooper> &looper, const sp<AMessage> &format, const sp<MediaSource> &source, const sp<PersistentSurface> &persistentSurface, uint32_t flags) { //创建MediaCodecSource sp<MediaCodecSource> mediaSource = new MediaCodecSource( looper, format, source, persistentSurface, flags); //获取HFR参数，赋值给mediaSource AVUtils::get()->getHFRParams(&mediaSource->mIsHFR, &mediaSource->mBatchSize, format); //mediaSource初始化，mediarecorder获取的sureface就是在该方法中初始化的，稍后会重点分析， if (mediaSource->init() == OK) { return mediaSource; } return NULL;}分析下encoder->getGraphicBufferProducer()
//frameworks\av\media\libstagefright\MediaCodecSource.cppsp<IGraphicBufferProducer> MediaCodecSource::getGraphicBufferProducer() { CHECK(mFlags & FLAG_USE_SURFACE_INPUT); return mGraphicBufferProducer;}至此，可见mMediaRecorder.getSurface()获取的surface实际上获取的是MediaCodecSource.cpp类成员变量mGraphicBufferProducer封装成 的surface对象。
接下来继续分析下，MediaCodecSource.cpp类成员变量mGraphicBufferProducer的初始化过程 其是在MediaCodecSource::Create(…)`中的mediaSource->init()初始化的，代码如下：
//frameworks\av\media\libstagefright\MediaCodecSource.cppstatus_t MediaCodecSource::init() { //初始化 status_t err = initEncoder(); if (err != OK) { releaseEncoder(); } return err;}继续分析initEncoder
//frameworks\av\media\libstagefright\MediaCodecSource.cppstatus_t MediaCodecSource::initEncoder() { mReflector = new AHandlerReflector<MediaCodecSource>(this); mLooper->registerHandler(mReflector); //启动消息循环线程，之后分析AMessage时会用到 mCodecLooper = new ALooper; mCodecLooper->setName("codec_looper"); mCodecLooper->start(); if (mFlags & FLAG_USE_SURFACE_INPUT) { mOutputFormat->setInt32("create-input-buffers-suspended", 1); } AString outputMIME; CHECK(mOutputFormat->findString("mime", &outputMIME)); Vector<AString> matchingCodecs; if (AVUtils::get()->useQCHWEncoder(mOutputFormat, &matchingCodecs)) { ; } else { //寻找与之匹配的Codecs MediaCodecList::findMatchingCodecs( outputMIME.c_str(), true /* encoder */, ((mFlags & FLAG_PREFER_SOFTWARE_CODEC) ? MediaCodecList::kPreferSoftwareCodecs : 0), &matchingCodecs); } status_t err = NO_INIT; for (size_t ix = 0; ix < matchingCodecs.size(); ++ix) { //创建MediaCodec mEncoder = MediaCodec::CreateByComponentName( mCodecLooper, matchingCodecs[ix]); if (mEncoder == NULL) { continue; } ALOGV("output format is '%s'", mOutputFormat->debugString(0).c_str()); mEncoderActivityNotify = new AMessage(kWhatEncoderActivity, mReflector); mEncoder->setCallback(mEncoderActivityNotify); //初始化MediaCodec err = mEncoder->configure( mOutputFormat, NULL /* nativeWindow */, NULL /* crypto */, MediaCodec::CONFIGURE_FLAG_ENCODE); if (err == OK) { break; } mEncoder->release(); mEncoder = NULL; } if (err != OK) { return err; } mEncoder->getOutputFormat(&mOutputFormat); sp<MetaData> meta = new MetaData; convertMessageToMetaData(mOutputFormat, meta); mMeta.lock().set(meta); if (mFlags & FLAG_USE_SURFACE_INPUT) { CHECK(mIsVideo); if (mPersistentSurface != NULL) { // When using persistent surface, we are only interested in the // consumer, but have to use PersistentSurface as a wrapper to // pass consumer over messages (similar to BufferProducerWrapper) err = mEncoder->setInputSurface(mPersistentSurface); } else { //终于到达了创建surface的地方了 err = mEncoder->createInputSurface(&mGraphicBufferProducer); } if (err != OK) { return err; } } sp<AMessage> inputFormat; int32_t usingSwReadOften; mSetEncoderFormat = false; if (mEncoder->getInputFormat(&inputFormat) == OK) { mSetEncoderFormat = true; if (inputFormat->findInt32("using-sw-read-often", &usingSwReadOften) && usingSwReadOften) { // this is a SW encoder; signal source to allocate SW readable buffers mEncoderFormat = kDefaultSwVideoEncoderFormat; } else { mEncoderFormat = kDefaultHwVideoEncoderFormat; } if (!inputFormat->findInt32("android._dataspace", &mEncoderDataSpace)) { mEncoderDataSpace = kDefaultVideoEncoderDataSpace; } ALOGV("setting dataspace %#x, format %#x", mEncoderDataSpace, mEncoderFormat); } //启动MediaCodec err = mEncoder->start(); if (err != OK) { return err; } { Mutexed<Output>::Locked output(mOutput); output->mEncoderReachedEOS = false; output->mErrorCode = OK; } return OK;}继续分析surface的创建
//frameworks\av\media\libstagefright\MediaCodec.cppstatus_t MediaCodec::createInputSurface( sp<IGraphicBufferProducer>* bufferProducer) { sp<AMessage> msg = new AMessage(kWhatCreateInputSurface, this); sp<AMessage> response; //是通过发消息kWhatCreateInputSurface来创建的surface的 //靠，还需要研究下AMessage的发送接收！！！哥已晕 status_t err = PostAndAwaitResponse(msg, &response); if (err == NO_ERROR) { // unwrap the sp接下来分下下AMessage机制
启动过程
//frameworks\av\media\libstagefright\MediaCodecSource.cppstatus_t MediaCodecSource::initEncoder() { mReflector = new AHandlerReflector<MediaCodecSource>(this); mLooper->registerHandler(mReflector); //创建ALooper线程 mCodecLooper = new ALooper; mCodecLooper->setName("codec_looper"); mCodecLooper->start(); ... status_t err = NO_INIT; for (size_t ix = 0; ix < matchingCodecs.size(); ++ix) { //将上一步创建的mCodecLooper传入待创建的MediaCodec mEncoder = MediaCodec::CreateByComponentName( mCodecLooper, matchingCodecs[ix]); .... return OK;}// staticsp<MediaCodec> MediaCodec::CreateByComponentName( const sp<ALooper> &looper, const AString &name, status_t *err, pid_t pid, uid_t uid) { VTRACE_CALL(); //将上一步创建的mCodecLooper传入待创建的MediaCodec sp<MediaCodec> codec = new MediaCodec(looper, pid, uid); //进入MediaCodec 的init方法 const status_t ret = codec->init(name, false /* nameIsType */, false /* encoder */); if (err != NULL) { *err = ret; } return ret == OK ? codec : NULL; // NULL deallocates codec.}为方便分析，先给出MediaCodec类图
可见MediaCodec继承AHandler
进入init
status_t MediaCodec::init(const AString &name, bool nameIsType, bool encoder) { ... // 创建的Acode mCodec = GetCodecBase(name, nameIsType); if (mIsVideo) { // video codec needs dedicated looper if (mCodecLooper == NULL) { mCodecLooper = new ALooper; mCodecLooper->setName("CodecLooper"); mCodecLooper->start(false, false, ANDROID_PRIORITY_AUDIO); } mCodecLooper->registerHandler(mCodec); } else { //给上一步骤创建的MediaCodec设置mLooper及ID，将Loop和ID设置给Handle mLooper->registerHandler(mCodec); } mLooper->registerHandler(this); ... return err;}继续分析registerHandler
//frameworks\av\media\libstagefright\foundation\ALooper.cppALooper::handler_id ALooper::registerHandler(const sp<AHandler> &handler) { return gLooperRoster.registerHandler(this, handler);}继续分析registerHandler
//frameworks\av\media\libstagefright\foundation\ALooperRoster.cppALooper::handler_id ALooperRoster::registerHandler( const sp<ALooper> &looper, const sp<AHandler> &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++; mHandlers.add(handlerID, info); handler->setID(handlerID, looper); return handlerID;}继续分析handler->setID()
//frameworks\av\media\libstagefright\foundation\include\media\stagefright\foundation\AHandler.h inline void setID(ALooper::handler_id id, const wp<ALooper> &looper) { mID = id; mLooper = looper; }接着分析AMessage的使用
AMessage创建
//frameworks\av\media\libstagefright\foundation\AMessage.cppAMessage::AMessage(uint32_t what, const sp<const AHandler> &handler) : mWhat(what), mNumItems(0) { setTarget(handler);}接着分析下
void AMessage::setTarget(const sp<const AHandler> &handler) { if (handler == NULL) { mTarget = 0; mHandler.clear(); mLooper.clear(); } else { mTarget = handler->id(); mHandler = handler->getHandler(); mLooper = handler->getLooper(); }}可见，最终通过handler获取了mLooper和id
接着分析消息发送
status_t AMessage::postAndAwaitResponse(sp<AMessage> *response) { sp<ALooper> looper = mLooper.promote(); if (looper == NULL) { ALOGW("failed to post message as target looper for handler %d is gone.", mTarget); return -ENOENT; } sp<AReplyToken> token = looper->createReplyToken(); if (token == NULL) { ALOGE("failed to create reply token"); return -ENOMEM; } setObject("replyID", token); //给ALoopeer发送消息 looper->post(this, 0 /* delayUs */); //从ALopper中获取结果 return looper->awaitResponse(token, response);}void ALooper::post(const sp<AMessage> &msg, int64_t delayUs) { Mutex::Autolock autoLock(mLock); int64_t whenUs; if (delayUs > 0) { whenUs = GetNowUs() + delayUs; } else { whenUs = GetNowUs(); } List<Event>::iterator it = mEventQueue.begin(); while (it != mEventQueue.end() && (*it).mWhenUs <= whenUs) { ++it; } //根据msg，形成Event Event event; event.mWhenUs = whenUs; event.mMessage = msg; if (it == mEventQueue.begin()) { mQueueChangedCondition.signal(); } //插入消息队列 mEventQueue.insert(it, event);}//frameworks\av\media\libstagefright\foundation\ALooper.cppbool ALooper::loop() { Event event; { ... 取消息 event = *mEventQueue.begin(); mEventQueue.erase(mEventQueue.begin()); }//发消息 event.mMessage->deliver(); // NOTE: It's important to note that at this point our "ALooper" object // may no longer exist (its final reference may have gone away while // delivering the message). We have made sure, however, that loop() // won't be called again. return true;}继续分析deliver
//\frameworks\av\media\libstagefright\foundation\AMessage.cppvoid AMessage::deliver() { sp<AHandler> handler = mHandler.promote(); if (handler == NULL) { ALOGW("failed to deliver message as target handler %d is gone.", mTarget); return; } handler->deliverMessage(this);}继续分析deliverMessage
//frameworks\av\media\libstagefright\foundation\AHandler.cppvoid AHandler::deliverMessage(const sp<AMessage> &msg) { onMessageReceived(msg); ...}进入MediaCodec
//frameworks\av\media\libstagefright\MediaCodec.cppvoid MediaCodec::onMessageReceived(const sp<AMessage> &msg) { VTRACE_METHOD(); switch (msg->what()) { ... case kWhatCreateInputSurface: case kWhatSetInputSurface: { ..... mReplyID = replyID; if (msg->what() == kWhatCreateInputSurface) { //给ACode发送消息创建surface mCodec->initiateCreateInputSurface(); } break; } .... default: TRESPASS(); }}最终进入ACodec.cpp
//frameworks\av\media\libstagefright\ACodec.cppbool ACodec::LoadedState::onMessageReceived(const sp<AMessage> &msg) { bool handled = false; switch (msg->what()) { .... case ACodec::kWhatCreateInputSurface: { onCreateInputSurface(msg); handled = true; break; } ... return handled;}进如创建surface的流程
//frameworks\av\media\libstagefright\ACodec.cppvoid ACodec::LoadedState::onCreateInputSurface( const sp<AMessage> & /* msg */) { ALOGV("onCreateInputSurface"); //创建surface sp<IGraphicBufferProducer> bufferProducer; //mOMX类型是sp mOMX，接下来分析下其创建过程 status_t err = mCodec->mOMX->createInputSurface( &bufferProducer, &mCodec->mGraphicBufferSource); ...}mOMX的创建过程
//frameworks\av\media\libstagefright\ACodec.cppbool ACodec::UninitializedState::onAllocateComponent(const sp<AMessage> &msg) { ALOGV("onAllocateComponent"); .... sp<CodecObserver> observer = new CodecObserver; sp<IOMX> omx; sp<IOMXNode> omxNode; status_t err = NAME_NOT_FOUND; for (size_t matchIndex = 0; matchIndex < matchingCodecs.size(); ++matchIndex) { componentName = matchingCodecs[matchIndex]; OMXClient client; bool trebleFlag; //创建IOMX对象 if (client.connect(owners[matchIndex].c_str(), &trebleFlag) != OK) { mCodec->signalError(OMX_ErrorUndefined, NO_INIT); return false; } //omx 是通过client获取的， omx = client.interface(); ... mCodec->mOMX = omx; mCodec->mOMXNode = omxNode; mCodec->mCallback->onComponentAllocated(mCodec->mComponentName.c_str()); mCodec->changeState(mCodec->mLoadedState); return true;}接着分析下，IOMX对象的创建connect
//frameworks\av\media\libstagefright\OMXClient.cppstatus_t OMXClient::connect(const char* name, bool* trebleFlag) { if (property_get_bool("persist.media.treble_omx", true)) { if (trebleFlag != nullptr) { *trebleFlag = true; } return connectTreble(name); } if (trebleFlag != nullptr) { *trebleFlag = false; } //进入的是该函数 return connectLegacy();}status_t OMXClient::connectLegacy() { //获取服务代理对象codecservice sp<IServiceManager> sm = defaultServiceManager(); sp<IBinder> codecbinder = sm->getService(String16("media.codec")); sp<IMediaCodecService> codecservice = interface_cast<IMediaCodecService>(codecbinder); if (codecservice.get() == NULL) { ALOGE("Cannot obtain IMediaCodecService"); return NO_INIT; } //通过codecservice 获取mOMX对象 mOMX = codecservice->getOMX(); if (mOMX.get() == NULL) { ALOGE("Cannot obtain mediacodec IOMX"); return NO_INIT; } return OK;}进入到media.codec服务
服务实现代码：
rc文件：
//frameworks\av\services\mediacodec\android.hardware.media.omx@1.0-service.rcservice mediacodec /vendor/bin/hw/android.hardware.media.omx@1.0-service class main user mediacodec group camera drmrpc mediadrm audio ioprio rt 4 writepid /dev/cpuset/foreground/tasks进程入口：
//frameworks\av\services\mediacodec\main_codecservice.cppint main(int argc __unused, char** argv){ LOG(INFO) << "mediacodecservice starting"; .... if (treble) { ... } else { MediaCodecService::instantiate(); LOG(INFO) << "Non-Treble OMX service created."; } ProcessState::self()->startThreadPool(); IPCThreadState::self()->joinThreadPool();}getOMX实现
//frameworks\av\services\mediacodec\MediaCodecService.cppsp<IOMX> MediaCodecService::getOMX() { Mutex::Autolock autoLock(mOMXLock); if (mOMX.get() == NULL) { //创建OMX对象 mOMX = new OMX(); } //返回OMX对象 return mOMX;}OMX类图如下：
继续分析surface 创建，上一步分析了OMX的创建过程，现在进入OMX createInputSurface创建surface
//frameworks\av\media\libstagefright\omx\OMX.cppstatus_t OMX::createInputSurface( sp<IGraphicBufferProducer> *bufferProducer, sp<IGraphicBufferSource> *bufferSource) { if (bufferProducer == NULL || bufferSource == NULL) { ALOGE("b/25884056"); return BAD_VALUE; } //创建GraphicBufferSource对象，surface就是在该方法创建出来的 sp<GraphicBufferSource> graphicBufferSource = new GraphicBufferSource(); status_t err = graphicBufferSource->initCheck(); if (err != OK) { ALOGE("Failed to create persistent input surface: %s (%d)", strerror(-err), err); return err; } *bufferProducer = graphicBufferSource->getIGraphicBufferProducer(); *bufferSource = new BWGraphicBufferSource(graphicBufferSource); return OK;}//frameworks\av\media\libstagefright\omx\GraphicBufferSource.cppGraphicBufferSource::GraphicBufferSource() { ALOGV("GraphicBufferSource"); String8 name("GraphicBufferSource"); //创建surface，千辛万苦，终于看到了surface的创建的地方了 BufferQueue::createBufferQueue(&mProducer, &mConsumer); mConsumer->setConsumerName(name); // Note that we can't create an sp<...>(this) in a ctor that will not keep a // reference once the ctor ends, as that would cause the refcount of 'this' // dropping to 0 at the end of the ctor. Since all we need is a wp<...> // that's what we create. wp<BufferQueue::ConsumerListener> listener = static_cast<BufferQueue::ConsumerListener*>(this); sp<IConsumerListener> proxy = new BufferQueue::ProxyConsumerListener(listener); mInitCheck = mConsumer->consumerConnect(proxy, false); ... }至此分析完成，mediarecorder创建其内部的surface流程
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