{"id":590,"date":"2013-06-20T12:32:25","date_gmt":"2013-06-20T04:32:25","guid":{"rendered":"http:\/\/guoh.ai\/lifelog\/?p=590"},"modified":"2013-11-12T12:29:27","modified_gmt":"2013-11-12T04:29:27","slug":"android-mediarecorder-architecture","status":"publish","type":"post","link":"https:\/\/guoh.ai\/lifelog\/2013\/06\/android-mediarecorder-architecture\/","title":{"rendered":"Android MediaRecorder\u7cfb\u7edf\u7ed3\u6784"},"content":{"rendered":"
<p>\u524d\u9762\u6709\u5206\u6790\u8fc7Camera\u7684\u5b9e\u73b0\uff0c\u73b0\u5728\u6765\u770b\u770bMediaRecorder\u7684\u5b9e\u73b0\uff0c\u8fd9\u91cc\u6211\u4e0d\u4f1a\u592a\u53bb\u5173\u6ce8\u5b83\u7684\u5206\u5c42\u7ed3\u6784\uff0c\u6211\u66f4\u5173\u6ce8\u5b83\u7684\u903b\u8f91\uff01<\/p>\n<p>APP\u5c42<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/base\/+\/android-4.2.2_r1.2\/media\/java\/android\/media\/MediaRecorder.java" target="_blank"> \/path\/to\/aosp\/frameworks\/base\/media\/java\/android\/media\/MediaRecorder.java<\/a><br \/>\nJNI\u5c42<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/base\/+\/android-4.2.2_r1.2\/media\/jni\/android_media_MediaRecorder.cpp" target="_blank"> \/path\/to\/aosp\/frameworks\/base\/media\/jni\/android_media_MediaRecorder.cpp<\/a><br \/>\n\u8c03\u7528NATIVE\u5c42\u7684MediaRecorder(\u8fd9\u91cc\u662fBnMediaRecorderClient)<br \/>\nheader<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/av\/+\/android-4.2.2_r1.2\/include\/media\/mediarecorder.h" target="_blank"> \/path\/to\/aosp\/frameworks\/av\/include\/media\/mediarecorder.h<\/a><br \/>\nimplementation <a href="https:\/\/android.googlesource.com\/platform\/frameworks\/av\/+\/android-4.2.2_r1.2\/media\/libmedia\/mediarecorder.cpp" target="_blank">\/path\/to\/aosp\/frameworks\/av\/media\/libmedia\/mediarecorder.cpp<\/a><\/p>\n<pre class="brush: java; title: ; notranslate" title="">MediaRecorder::MediaRecorder() : mSurfaceMediaSource(NULL)\r\n{\r\n ALOGV("constructor");\r\n\r\n const sp<IMediaPlayerService>& service(getMediaPlayerService());\r\n if (service != NULL) {\r\n mMediaRecorder = service->createMediaRecorder(getpid());\r\n }\r\n if (mMediaRecorder != NULL) {\r\n mCurrentState = MEDIA_RECORDER_IDLE;\r\n }\r\n\r\n doCleanUp();\r\n}<\/pre>\n<p>getMediaPlayerService()\u8fd9\u4e2a\u65b9\u6cd5\u4f4d\u4e8e<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/av\/+\/android-4.2.2_r1.2\/include\/media\/IMediaMetadataRetriever.h" target="_blank">\/path\/to\/aosp\/frameworks\/av\/include\/media\/IMediaDeathNotifier.h<\/a><\/p>\n<p>\u83b7\u53d6\u5230MediaPlayerService(\u8fd9\u4e2a\u662fBpMediaPlayerService)\u4e4b\u540e<br \/>\n\u8c03\u7528IMediaPlayerService\u5f53\u4e2d\u7684<\/p>\n<pre class="brush: java; title: ; notranslate" title="">sp<IMediaRecorder> MediaPlayerService::createMediaRecorder(pid_t pid)\r\n{\r\n sp<MediaRecorderClient> recorder = new MediaRecorderClient(this, pid);\r\n wp<MediaRecorderClient> w = recorder;\r\n Mutex::Autolock lock(mLock);\r\n mMediaRecorderClients.add(w);\r\n ALOGV("Create new media recorder client from pid %d", pid);\r\n return recorder;\r\n}<\/pre>\n<p>\u521b\u5efaMediaRecorderClient(\u8fd9\u91cc\u662fBnMediaRecorder)<\/p>\n<p>\u4f46\u662f\u901a\u8fc7binder\u62ff\u5230\u7684\u662fBpMediaRecorder<br \/>\n\u56e0\u4e3a\u6709\u5982\u4e0b\u7684interface_cast\u8fc7\u7a0b<\/p>\n<pre class="brush: java; title: ; notranslate" title="">virtual sp<IMediaRecorder> createMediaRecorder(pid_t pid)\r\n{\r\n Parcel data, reply;\r\n data.writeInterfaceToken(IMediaPlayerService::getInterfaceDescriptor());\r\n data.writeInt32(pid);\r\n remote()->transact(CREATE_MEDIA_RECORDER, data, &reply);\r\n return interface_cast<IMediaRecorder>(reply.readStrongBinder());\r\n}<\/pre>\n<p>\u800cMediaRecorderClient\u5f53\u4e2d\u53c8\u4f1a\u521b\u5efaStagefrightRecorder(MediaRecorderBase)\uff0c\u5b83\u4f4d\u4e8e<br \/>\n<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/av\/+\/android-4.2.2_r1.2\/media\/libmediaplayerservice\/StagefrightRecorder.cpp" target="_blank">\/path\/to\/aosp\/frameworks\/av\/media\/libmediaplayerservice\/StagefrightRecorder.cpp<\/a><\/p>\n<p>\u76ee\u524d\u6211\u4eec\u53ef\u4ee5\u8ba4\u4e3a\u5728APP\/JNI\/NATIVE\u8fd9\u8fb9\u662f\u5728\u4e00\u4e2a\u8fdb\u7a0b\u5f53\u4e2d\uff0c\u5728MediaPlayerService\u5f53\u4e2d\u7684MediaRecorderClient\/StagefrightRecorder\u662f\u5728\u53e6\u5916\u4e00\u4e2a\u8fdb\u7a0b\u5f53\u4e2d\uff0c\u4ed6\u4eec\u4e4b\u95f4\u901a\u8fc7binder\u901a\u4fe1\uff0c\u800c\u4e14Bp\u548cBn\u6211\u4eec\u4e5f\u90fd\u6709\u62ff\u5230\uff0c\u540e\u9762\u6211\u4eec\u5c06\u4e0d\u518d\u4ed4\u7ec6\u533a\u5206Bp\u548cBn\u3002<\/p>\n<blockquote><p>\u5ba2\u6237\u7aef\u8fd9\u8fb9<br \/>\nBnMediaRecorderClient<br \/>\nBpMediaRecorder<br \/>\nBpMediaPlayerService<\/p>\n<p>\u670d\u52a1\u7aef\u8fd9\u8fb9<br \/>\nBpMediaRecorderClient(\u5982\u679c\u9700\u8981\u901a\u77e5\u5ba2\u6237\u7aef\u7684\u8bdd\uff0c\u5b83\u53ef\u4ee5\u83b7\u5f97\u8fd9\u4e2aBp)<br \/>\nBnMediaRecorder<br \/>\nBnMediaPlayerService<\/p><\/blockquote>\n<p>\u8fd9\u6709\u5f20\u56fe(\u70b9\u8fc7\u53bb\u770b\u539f\u59cb\u5927\u56fe)<br \/>\n<a href="https:\/\/www.flickr.com\/photos\/46848122@N08\/9410173938\/" title="Android MediaRecorder Diagram by DeliberateKids, on Flickr" target="_blank"><img src="https:\/\/farm6.staticflickr.com\/5474\/9410173938_9d2028ea46_o.png" width="3942" height="2652" alt="Android MediaRecorder Diagram"><\/a><\/p>\n<p>\u6211\u4eec\u4ee5\u5f00\u59cb\u5f55\u5f71\u4e3a\u4f8b\u5b50\uff0c\u6bd4\u5982start()<\/p>\n<p>\u5728\u8fd9\u91cc\u5c31\u5175\u5206\u4e24\u8def\uff0c\u4e00\u4e2aCameraSource\uff0c\u4e00\u4e2aMPEG4Writer(sp<MediaWriter> mWriter)<br \/>\n\u8fd9\u4e24\u4e2aclass\u90fd\u4f4d\u4e8e<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/av\/+\/android-4.2.2_r1.2\/media\/libstagefright\/" target="_blank">\/path\/to\/aosp\/frameworks\/av\/media\/libstagefright\/<\/a>\u5f53\u4e2d<\/p>\n<pre class="brush: java; title: ; notranslate" title="">status_t StagefrightRecorder::startMPEG4Recording() {\r\n int32_t totalBitRate;\r\n status_t err = setupMPEG4Recording(\r\n mOutputFd, mVideoWidth, mVideoHeight,\r\n mVideoBitRate, &totalBitRate, &mWriter);\r\n if (err != OK) {\r\n return err;\r\n }\r\n\r\n int64_t startTimeUs = systemTime() \/ 1000;\r\n sp<MetaData> meta = new MetaData;\r\n setupMPEG4MetaData(startTimeUs, totalBitRate, &meta);\r\n\r\n err = mWriter->start(meta.get());\r\n if (err != OK) {\r\n return err;\r\n }\r\n\r\n return OK;\r\n}<\/pre>\n<pre class="brush: java; title: ; notranslate" title="">status_t StagefrightRecorder::setupMPEG4Recording(\r\n int outputFd,\r\n int32_t videoWidth, int32_t videoHeight,\r\n int32_t videoBitRate,\r\n int32_t *totalBitRate,\r\n sp<MediaWriter> *mediaWriter) {\r\n mediaWriter->clear();\r\n *totalBitRate = 0;\r\n status_t err = OK;\r\n sp<MediaWriter> writer = new MPEG4Writer(outputFd);\r\n\r\n if (mVideoSource < VIDEO_SOURCE_LIST_END) {\r\n\r\n sp<MediaSource> mediaSource;\r\n err = setupMediaSource(&mediaSource); \/\/ very important\r\n if (err != OK) {\r\n return err;\r\n }\r\n\r\n sp<MediaSource> encoder;\r\n err = setupVideoEncoder(mediaSource, videoBitRate, &encoder); \/\/ very important\r\n if (err != OK) {\r\n return err;\r\n }\r\n\r\n writer->addSource(encoder);\r\n *totalBitRate += videoBitRate;\r\n }\r\n\r\n \/\/ Audio source is added at the end if it exists.\r\n \/\/ This help make sure that the "recoding" sound is suppressed for\r\n \/\/ camcorder applications in the recorded files.\r\n if (!mCaptureTimeLapse && (mAudioSource != AUDIO_SOURCE_CNT)) {\r\n err = setupAudioEncoder(writer); \/\/ very important\r\n if (err != OK) return err;\r\n *totalBitRate += mAudioBitRate;\r\n }\r\n\r\n ...\r\n\r\n writer->setListener(mListener);\r\n *mediaWriter = writer;\r\n return OK;\r\n}<\/pre>\n<pre class="brush: java; title: ; notranslate" title="">\r\n\/\/ Set up the appropriate MediaSource depending on the chosen option\r\nstatus_t StagefrightRecorder::setupMediaSource(\r\n sp<MediaSource> *mediaSource) {\r\n if (mVideoSource == VIDEO_SOURCE_DEFAULT\r\n || mVideoSource == VIDEO_SOURCE_CAMERA) {\r\n sp<CameraSource> cameraSource;\r\n status_t err = setupCameraSource(&cameraSource);\r\n if (err != OK) {\r\n return err;\r\n }\r\n *mediaSource = cameraSource;\r\n } else if (mVideoSource == VIDEO_SOURCE_GRALLOC_BUFFER) {\r\n \/\/ If using GRAlloc buffers, setup surfacemediasource.\r\n \/\/ Later a handle to that will be passed\r\n \/\/ to the client side when queried\r\n status_t err = setupSurfaceMediaSource();\r\n if (err != OK) {\r\n return err;\r\n }\r\n *mediaSource = mSurfaceMediaSource;\r\n } else {\r\n return INVALID_OPERATION;\r\n }\r\n return OK;\r\n}<\/pre>\n<pre class="brush: java; title: ; notranslate" title="">status_t StagefrightRecorder::setupCameraSource(\r\n sp<CameraSource> *cameraSource) {\r\n status_t err = OK;\r\n if ((err = checkVideoEncoderCapabilities()) != OK) {\r\n return err;\r\n }\r\n Size videoSize;\r\n videoSize.width = mVideoWidth;\r\n videoSize.height = mVideoHeight;\r\n if (mCaptureTimeLapse) {\r\n if (mTimeBetweenTimeLapseFrameCaptureUs < 0) {\r\n ALOGE("Invalid mTimeBetweenTimeLapseFrameCaptureUs value: %lld",\r\n mTimeBetweenTimeLapseFrameCaptureUs);\r\n return BAD_VALUE;\r\n }\r\n\r\n mCameraSourceTimeLapse = CameraSourceTimeLapse::CreateFromCamera(\r\n mCamera, mCameraProxy, mCameraId,\r\n videoSize, mFrameRate, mPreviewSurface,\r\n mTimeBetweenTimeLapseFrameCaptureUs);\r\n *cameraSource = mCameraSourceTimeLapse;\r\n } else {\r\n *cameraSource = CameraSource::CreateFromCamera(\r\n mCamera, mCameraProxy, mCameraId, videoSize, mFrameRate,\r\n mPreviewSurface, true \/*storeMetaDataInVideoBuffers*\/);\r\n }\r\n mCamera.clear();\r\n mCameraProxy.clear();\r\n if (*cameraSource == NULL) {\r\n return UNKNOWN_ERROR;\r\n }\r\n\r\n if ((*cameraSource)->initCheck() != OK) {\r\n (*cameraSource).clear();\r\n *cameraSource = NULL;\r\n return NO_INIT;\r\n }\r\n\r\n \/\/ When frame rate is not set, the actual frame rate will be set to\r\n \/\/ the current frame rate being used.\r\n if (mFrameRate == -1) {\r\n int32_t frameRate = 0;\r\n CHECK ((*cameraSource)->getFormat()->findInt32(\r\n kKeyFrameRate, &frameRate));\r\n ALOGI("Frame rate is not explicitly set. Use the current frame "\r\n "rate (%d fps)", frameRate);\r\n mFrameRate = frameRate;\r\n }\r\n\r\n CHECK(mFrameRate != -1);\r\n\r\n mIsMetaDataStoredInVideoBuffers =\r\n (*cameraSource)->isMetaDataStoredInVideoBuffers();\r\n\r\n return OK;\r\n}<\/pre>\n<pre class="brush: java; title: ; notranslate" title="">status_t StagefrightRecorder::setupVideoEncoder(\r\n sp<MediaSource> cameraSource,\r\n int32_t videoBitRate,\r\n sp<MediaSource> *source) {\r\n source->clear();\r\n\r\n sp<MetaData> enc_meta = new MetaData;\r\n enc_meta->setInt32(kKeyBitRate, videoBitRate);\r\n enc_meta->setInt32(kKeyFrameRate, mFrameRate);\r\n\r\n switch (mVideoEncoder) {\r\n case VIDEO_ENCODER_H263:\r\n enc_meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_H263);\r\n break;\r\n\r\n case VIDEO_ENCODER_MPEG_4_SP:\r\n enc_meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_MPEG4);\r\n break;\r\n\r\n case VIDEO_ENCODER_H264:\r\n enc_meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);\r\n break;\r\n\r\n default:\r\n CHECK(!"Should not be here, unsupported video encoding.");\r\n break;\r\n }\r\n\r\n sp<MetaData> meta = cameraSource->getFormat();\r\n\r\n int32_t width, height, stride, sliceHeight, colorFormat;\r\n CHECK(meta->findInt32(kKeyWidth, &width));\r\n CHECK(meta->findInt32(kKeyHeight, &height));\r\n CHECK(meta->findInt32(kKeyStride, &stride));\r\n CHECK(meta->findInt32(kKeySliceHeight, &sliceHeight));\r\n CHECK(meta->findInt32(kKeyColorFormat, &colorFormat));\r\n\r\n enc_meta->setInt32(kKeyWidth, width);\r\n enc_meta->setInt32(kKeyHeight, height);\r\n enc_meta->setInt32(kKeyIFramesInterval, mIFramesIntervalSec);\r\n enc_meta->setInt32(kKeyStride, stride);\r\n enc_meta->setInt32(kKeySliceHeight, sliceHeight);\r\n enc_meta->setInt32(kKeyColorFormat, colorFormat);\r\n if (mVideoTimeScale > 0) {\r\n enc_meta->setInt32(kKeyTimeScale, mVideoTimeScale);\r\n }\r\n if (mVideoEncoderProfile != -1) {\r\n enc_meta->setInt32(kKeyVideoProfile, mVideoEncoderProfile);\r\n }\r\n if (mVideoEncoderLevel != -1) {\r\n enc_meta->setInt32(kKeyVideoLevel, mVideoEncoderLevel);\r\n }\r\n\r\n OMXClient client;\r\n CHECK_EQ(client.connect(), (status_t)OK);\r\n\r\n uint32_t encoder_flags = 0;\r\n if (mIsMetaDataStoredInVideoBuffers) {\r\n encoder_flags |= OMXCodec::kStoreMetaDataInVideoBuffers;\r\n }\r\n\r\n \/\/ Do not wait for all the input buffers to become available.\r\n \/\/ This give timelapse video recording faster response in\r\n \/\/ receiving output from video encoder component.\r\n if (mCaptureTimeLapse) {\r\n encoder_flags |= OMXCodec::kOnlySubmitOneInputBufferAtOneTime;\r\n }\r\n\r\n sp<MediaSource> encoder = OMXCodec::Create(\r\n client.interface(), enc_meta,\r\n true \/* createEncoder *\/, cameraSource,\r\n NULL, encoder_flags);\r\n if (encoder == NULL) {\r\n ALOGW("Failed to create the encoder");\r\n \/\/ When the encoder fails to be created, we need\r\n \/\/ release the camera source due to the camera's lock\r\n \/\/ and unlock mechanism.\r\n cameraSource->stop();\r\n return UNKNOWN_ERROR;\r\n }\r\n\r\n *source = encoder;\r\n\r\n return OK;\r\n}<\/pre>\n<p>\u8fd9\u91cc\u548cOMXCodec\u5173\u8054\u8d77\u6765<br \/>\n\u6709\u4e00\u4e2a\u53ebmedia_codecs.xml\u7684\u914d\u7f6e\u6587\u4ef6\u6765\u8868\u660e\u8bbe\u5907\u652f\u6301\u54ea\u4e9bcodec<\/p>\n<p>\u6211\u4eec\u5f55\u5236MPEG 4\u7684\u65f6\u5019\u8fd8\u4f1a\u6709\u58f0\u97f3\uff0c\u6240\u4ee5\u540e\u9762\u8fd8\u6709\u4e2asetupAudioEncoder\uff0c\u5177\u4f53\u7684\u65b9\u6cd5\u5c31\u4e0d\u5c55\u5f00\u4e86\uff0c\u603b\u4e4b\u5c31\u662f\u628a\u58f0\u97f3\u4e5f\u4f5c\u4e3a\u4e00\u4e2aTrack\u52a0\u5165\u5230MPEG4Writer\u5f53\u4e2d\u53bb\u3002<br \/>\n\u8fd9\u91cc\u63d2\u4e2a\u9898\u5916\u8bdd\uff0cGoogle\u8bf4\u628asetupAudioEncoder\u653e\u5230\u540e\u9762\u662f\u4e3a\u4e86\u907f\u514d\u5f00\u59cb\u5f55\u5f71\u7684\u90a3\u4e00\u4e2a\u63d0\u793a\u58f0\u97f3\u4e5f\u88ab\u5f55\u5236\u8fdb\u53bb\uff0c\u4f46\u662f\u5b9e\u9645\u53d1\u73b0\u5b83\u8fd9\u6837\u505a\u8fd8\u662f\u4f1a\u6709bug\uff0c\u5728\u4e00\u4e9b\u8bbe\u5907\u4e0a\u8fd8\u662f\u4f1a\u628a\u90a3\u58f0\u5f55\u5236\u8fdb\u53bb\uff0c\u8fd9\u4e2a\u9047\u5230\u7684\u90fd\u662f\u9760APP\u81ea\u5df1\u6765\u64ad\u653e\u58f0\u97f3\u6765\u7ed5\u8fc7\u8fd9\u4e2a\u95ee\u9898\u7684\u3002<\/p>\n<p>\u53e6\u5916MPEG4Writer\u5f53\u4e2d\u6709\u4e2a<br \/>\nstart(MetaData*)<br \/>\n\u542f\u52a8\u4e24\u4e2a\u65b9\u6cd5<br \/>\n a) startWriterThread<\/p>\n<p> \u542f\u52a8\u4e00\u4e2athread\u53bb\u5199<\/p>\n<pre class="brush: java; title: ; notranslate" title=""> void MPEG4Writer::threadFunc() {\r\n ALOGV("threadFunc");\r\n\r\n prctl(PR_SET_NAME, (unsigned long)"MPEG4Writer", 0, 0, 0);\r\n\r\n Mutex::Autolock autoLock(mLock);\r\n while (!mDone) {\r\n Chunk chunk;\r\n bool chunkFound = false;\r\n\r\n while (!mDone && !(chunkFound = findChunkToWrite(&chunk))) {\r\n mChunkReadyCondition.wait(mLock);\r\n }\r\n\r\n \/\/ Actual write without holding the lock in order to\r\n \/\/ reduce the blocking time for media track threads.\r\n if (chunkFound) {\r\n mLock.unlock();\r\n writeChunkToFile(&chunk);\r\n mLock.lock();\r\n }\r\n }\r\n\r\n writeAllChunks();\r\n }<\/pre>\n<p> b) startTracks<\/p>\n<pre class="brush: java; title: ; notranslate" title=""> status_t MPEG4Writer::startTracks(MetaData *params) {\r\n for (List<Track *>::iterator it = mTracks.begin();\r\n it != mTracks.end(); ++it) {\r\n status_t err = (*it)->start(params);\r\n\r\n if (err != OK) {\r\n for (List<Track *>::iterator it2 = mTracks.begin();\r\n it2 != it; ++it2) {\r\n (*it2)->stop();\r\n }\r\n\r\n return err;\r\n }\r\n }\r\n return OK;\r\n }<\/pre>\n<p> \u7136\u540e\u8c03\u7528\u6bcf\u4e2aTrack\u7684start\u65b9\u6cd5<\/p>\n<pre class="brush: java; title: ; notranslate" title=""> status_t MPEG4Writer::Track::start(MetaData *params) {\r\n ...\r\n\r\n initTrackingProgressStatus(params);\r\n\r\n ...\r\n\r\n status_t err = mSource->start(meta.get()); \/\/ \u8fd9\u91cc\u4f1a\u53bb\u6267\u884cCameraSource(start)\uff0c\u8fd9\u4e24\u4e2a\u662f\u76f8\u4e92\u5173\u8054\u7684\r\n\r\n ...\r\n\r\n pthread_create(&mThread, &attr, ThreadWrapper, this);\r\n return OK;\r\n }\r\n\r\n void *MPEG4Writer::Track::ThreadWrapper(void *me) {\r\n Track *track = static_cast<Track *>(me);\r\n\r\n status_t err = track->threadEntry();\r\n return (void *) err;\r\n }<\/pre>\n<p> \u901a\u8fc7status_t MPEG4Writer::Track::threadEntry()<br \/>\n \u662f\u65b0\u542f\u52a8\u53e6\u5916\u4e00\u4e2athread\uff0c\u5b83\u91cc\u9762\u4f1a\u901a\u8fc7\u4e00\u4e2a\u5faa\u73af\u6765\u4e0d\u65ad\u8bfb\u53d6CameraSource(read)\u91cc\u9762\u7684\u6570\u636e\uff0cCameraSource\u91cc\u9762\u7684\u6570\u636e\u5f53\u7136\u662f\u4ecedriver\u8fd4\u56de\u8fc7\u6765\u7684(\u53ef\u4ee5\u53c2\u89c1CameraSourceListener\uff0cCameraSource\u7528\u4e00\u4e2a\u53eb\u505amFrameReceived\u7684List\u4e13\u95e8\u5b58\u653e\u4ecedriver\u8fc7\u6765\u7684\u6570\u636e\uff0c\u5982\u679c\u6536\u5230\u6570\u636e\u4f1a\u8c03\u7528mFrameAvailableCondition.signal\uff0c\u82e5\u8fd8\u6ca1\u6709\u5f00\u59cb\u5f55\u5f71\uff0c\u8fd9\u4e2a\u65f6\u5019\u6536\u5230\u7684\u6570\u636e\u662f\u88ab\u4e22\u5f03\u7684\uff0c\u5f53\u7136MediaWriter\u5148\u542f\u52a8\u7684\u662fCameraSource\u7684start\u65b9\u6cd5\uff0c\u518d\u542f\u52a8\u5199Track)\uff0c\u7136\u540e\u5199\u5230\u6587\u4ef6\u5f53\u4e2d\u3002<br \/>\n\u6ce8\u610f\uff1a\u51c6\u786e\u6765\u8bf4\u8fd9\u91ccMPEG4Writer\u8bfb\u53d6\u7684\u662fOMXCodec\u91cc\u7684\u6570\u636e\uff0c\u56e0\u4e3a\u6570\u636e\u5148\u5230CameraSource\uff0ccodec\u8d1f\u8d23\u7f16\u7801\u4e4b\u540e\uff0cMPEG4Writer\u624d\u8d1f\u8d23\u5199\u5230\u6587\u4ef6\u5f53\u4e2d\uff01\u5173\u4e8e\u6570\u636e\u5728CameraSource\/OMXCodec\/MPEG4Writer\u4e4b\u95f4\u662f\u600e\u4e48\u4f20\u9012\u7684\uff0c\u53ef\u4ee5\u53c2\u89c1<a href="http:\/\/guoh.ai\/lifelog\/2013\/06\/interaction-between-stagefright-and-codec\/" target="_blank">http:\/\/guoh.ai\/lifelog\/2013\/06\/interaction-between-stagefright-and-codec\/<\/a>\u5f53\u4e2d\u8bb2Buffer\u7684\u4f20\u8f93\u8fc7\u7a0b\u3002<\/p>\n<p>\u56de\u5934\u518d\u6765\u770b\uff0cStagefright\u505a\u4e86\u4ec0\u4e48\u4e8b\u60c5\uff1f\u6211\u66f4\u89c9\u5f97\u5b83\u53ea\u662f\u4e00\u4e2a\u7c98\u5408\u5242(glue)\u7684\u7528\u5904\uff0c\u5b83\u5de5\u4f5c\u5728MediaPlayerService\u8fd9\u4e00\u5c42\uff0c\u628aMediaSource\uff0cMediaWriter\uff0cCodec\u4ee5\u53ca\u4e0a\u5c42\u7684MediaRecorder\u7ed1\u5b9a\u5728\u4e00\u8d77\uff0c\u8fd9\u5e94\u8be5\u5c31\u662f\u5b83\u6700\u5927\u7684\u4f5c\u7528\uff0cGoogle\u7528\u5b83\u6765\u66ff\u6362Opencore\u4e5f\u662f\u7b26\u5408\u5176\u4e00\u8d2f\u7684\u5de5\u7a0b\u6d3e\u4f5c\u98ce(\u76f8\u6bd4\u590d\u6742\u7684\u5b66\u672f\u6d3e\u800c\u8a00\uff0c\u867d\u7136Google\u5f88\u591a\u4e1c\u897f\u4e5f\u5f88\u590d\u6742\uff0c\u4f46\u662f\u5b83\u4e00\u822c\u90fd\u662f\u4ee5\u5c3d\u91cf\u7b80\u5355\u7684\u65b9\u5f0f\u6765\u89e3\u51b3\u95ee\u9898)\u3002<br \/>\n\u8ba9\u5927\u5bb6\u89c9\u5f97\u6709\u70b9\u4e0d\u4e60\u60ef\u7684\u662f\uff0c\u5b83\u628aMediaRecorder\u653e\u5728MediaPlayerService\u5f53\u4e2d\uff0c\u8fd9\u4e24\u4e2a\u770b\u8d77\u6765\u662f\u5bf9\u7acb\u7684\u4e8b\u60c5\uff0c\u6216\u8005\u67d0\u4e00\u5929\u5b83\u4eec\u4f1a\u6539\u540d\u5b57\uff0c\u6216\u8005\u662f\u4e24\u8005\u5206\u5f00\uff0c\u4e0d\u77e5\u9053\uff5e\uff5e<\/p>\n<p>\u5f53\u7136\u8fd9\u53ea\u662f\u4e2a\u7b80\u5355\u7684\u5927\u4f53\u4ecb\u7ecd\uff0cCodec\u76f8\u5173\u7684\u540e\u9762\u4e89\u53d6\u4e13\u95e8\u6765\u5206\u6790\u4e00\u4e0b\uff01<\/p>\n<p>\u6709\u4e9b\u7ec6\u8282\u7684\u4e1c\u897f\u5728\u8fd9\u91cc\u6ca1\u6709\u5217\u51fa\uff0c\u9700\u8981\u7684\u8bdd\u4f1a\u628a\u4e00\u4e9b\u6ce8\u610f\u70b9\u5217\u51fa\u6765\uff1a<\/p>\n<p>1. \u65f6\u5149\u6d41\u901d\u5f55\u5f71<br \/>\nCameraSource\u5bf9\u5e94\u7684\u5c31\u662fCameraSourceTimeLapse<\/p>\n<p>\u5177\u4f53\u505a\u6cd5\u5c31\u662f\u5728<br \/>\ndataCallbackTimestamp<br \/>\n\u5f53\u4e2d\u6709skipCurrentFrame<\/p>\n<p>\u5f53\u7136\u5b83\u662f\u7528\u4e9b\u53d8\u91cf\u6765\u8bb0\u5f55\u548c\u8ba1\u7b97<br \/>\nmTimeBetweenTimeLapseVideoFramesUs(1E6\/videoFrameRate) \/\/ \u4e24\u4e2aframe\u4e4b\u95f4\u7684\u95f4\u9694\u65f6\u95f4<br \/>\n\u8bb0\u5f55\u4e0a\u4e00\u4e2aframe\u7684(mLastTimeLapseFrameRealTimestampUs) \/\/ \u4e0a\u4e00\u4e2aframe\u53d1\u751f\u7684\u65f6\u95f4<br \/>\n\u7136\u540e\u901a\u8fc7frame rate\u8ba1\u7b97\u51fa\u4e24\u4e2aframe\u4e4b\u95f4\u7684\u76f8\u8ddd\u79bb\u65f6\u95f4\uff0c\u4e2d\u95f4\u7684\u90fd\u900f\u8fc7releaseOneRecordingFrame\u6765drop\u6389<br \/>\n\u4e5f\u5c31\u662f\u8bf4driver\u8fd4\u56de\u7684\u4e1c\u897f\u90fd\u4e0d\u53d8\uff0c\u53ea\u662f\u5728SW\u8fd9\u5c42\u6211\u4eec\u81ea\u5df1\u6765\u5904\u7406\u6389<\/p>\n<p>\u5173\u4e8eTime-lapse\u76f8\u5173\u7684\u53ef\u4ee5\u53c2\u9605<br \/>\n<a href="https:\/\/en.wikipedia.org\/wiki\/Time-lapse_photography" target="_blank">https:\/\/en.wikipedia.org\/wiki\/Time-lapse_photography<\/a><\/p>\n<p>2. \u5f55\u5f71\u5f53\u4e2d\u9700\u8981\u7528\u5230Camera\u7684\u8bdd\u662f\u901a\u8fc7ICameraRecordingProxy\uff0c\u5373Camera\u5f53\u4e2d\u7684RecordingProxy(\u8fd9\u662f\u4e00\u4e2aBnCameraRecordingProxy)<br \/>\n\u5f53\u900f\u8fc7binder\uff0c\u5c06ICameraRecordingProxy\u4f20\u5230\u670d\u52a1\u7aef\u8fdb\u7a0b\u4e4b\u540e\uff0c\u5b83\u5c31\u53d8\u6210\u4e86Bp\uff0c\u5982\u4e0b\uff1a<\/p>\n<pre class="brush: java; title: ; notranslate" title="">case SET_CAMERA: {\r\n ALOGV("SET_CAMERA");\r\n CHECK_INTERFACE(IMediaRecorder, data, reply);\r\n sp<ICamera> camera = interface_cast<ICamera>(data.readStrongBinder());\r\n sp<ICameraRecordingProxy> proxy =\r\n interface_cast<ICameraRecordingProxy>(data.readStrongBinder());\r\n reply->writeInt32(setCamera(camera, proxy));\r\n return NO_ERROR;\r\n} break;<\/pre>\n<p>\u5728CameraSource\u5f53\u4e2d\u4f1a\u8fd9\u6837\u53bb\u4f7f\u7528<\/p>\n<pre class="brush: java; title: ; notranslate" title="">\/\/ We get the proxy from Camera, not ICamera. We need to get the proxy\r\n\/\/ to the remote Camera owned by the application. Here mCamera is a\r\n\/\/ local Camera object created by us. We cannot use the proxy from\r\n\/\/ mCamera here.\r\nmCamera = Camera::create(camera);\r\nif (mCamera == 0) return -EBUSY;\r\nmCameraRecordingProxy = proxy;\r\nmCameraFlags |= FLAGS_HOT_CAMERA;<\/pre>\n<p>\u7591\u95ee\u70b9\uff1a<\/p>\n<p>CameraSource\u5f53\u4e2d\u8fd9\u4e2a<br \/>\n<strong>List<sp<IMemory> > mFramesBeingEncoded;<\/strong><br \/>\n\u6709\u4ec0\u4e48\u7528\uff1f<br \/>\n\u6bcf\u7f16\u7801\u5b8c\u4e00\u4e2aframe\uff0cCameraSource\u5c31\u4f1a\u5c06\u5176\u4fdd\u5b58\u8d77\u6765\uff0cBuffer\u88abrelease\u7684\u65f6\u5019\uff0c\u4f1a\u53cd\u8fc7\u6765release\u6389\u8fd9\u4e9bframe(s)\uff0c\u8fd9\u79cd\u505a\u6cd5\u662f\u4e3a\u4e86\u6548\u7387\u4e48\uff1f\u4e3a\u4ec0\u4e48\u4e0d\u7f16\u7801\u5b8c\u4e00\u4e2aframe\u5c31\u5c06\u5176release\u6389\uff1f<br \/>\n\u53e6\u5916\u4e0d\u5f97\u4e0d\u518d\u611f\u53f9\u4e0bGoogle\u7ecf\u5e38\u7684<strong>delete this;<\/strong>\u884c\u4e3a\uff0c\u7cbe\u5999\uff0c\u4f46\u662f\u770b\u8d77\u6765\u53cd\u5e38\uff01<\/p>\n<\/div>

\u524d\u9762\u6709\u5206\u6790\u8fc7Camera\u7684\u5b9e\u73b0\uff0c\u73b0\u5728\u6765\u770b\u770bMediaRecorder\u7684\u5b9e\u73b0\uff0c\u8fd9\u91cc\u6211\u4e0d\u4f1a\u592a\u53bb\u5173\u6ce8\u5b83\u7684\u5206\u5c42\u7ed3\u6784\uff0c\u6211\u66f4\u5173\u6ce8\u5b83\u7684\u903b\u8f91\uff01<\/p>\n

APP\u5c42 \/path\/to\/aosp\/frameworks\/base\/media\/java\/android\/media\/MediaRecorder.java<\/a>
\nJNI\u5c42 \/path\/to\/aosp\/frameworks\/base\/media\/jni\/android_media_MediaRecorder.cpp<\/a>
\n\u8c03\u7528NATIVE\u5c42\u7684MediaRecorder(\u8fd9\u91cc\u662fBnMediaRecorderClient)
\nheader \/path\/to\/aosp\/frameworks\/av\/include\/media\/mediarecorder.h<\/a>
\nimplementation \/path\/to\/aosp\/frameworks\/av\/media\/libmedia\/mediarecorder.cpp<\/a><\/p>\n

MediaRecorder::MediaRecorder() : mSurfaceMediaSource(NULL)\r\n{\r\n    ALOGV("constructor");\r\n\r\n    const sp<IMediaPlayerService>& service(getMediaPlayerService());\r\n    if (service != NULL) {\r\n        mMediaRecorder = service->createMediaRecorder(getpid());\r\n    }\r\n    if (mMediaRecorder != NULL) {\r\n        mCurrentState = MEDIA_RECORDER_IDLE;\r\n    }\r\n\r\n    doCleanUp();\r\n}<\/pre>\n
getMediaPlayerService()\u8fd9\u4e2a\u65b9\u6cd5\u4f4d\u4e8e\/path\/to\/aosp\/frameworks\/av\/include\/media\/IMediaDeathNotifier.h<\/a><\/p>\n
\u83b7\u53d6\u5230MediaPlayerService(\u8fd9\u4e2a\u662fBpMediaPlayerService)\u4e4b\u540e
\n\u8c03\u7528IMediaPlayerService\u5f53\u4e2d\u7684<\/p>\n
sp<IMediaRecorder> MediaPlayerService::createMediaRecorder(pid_t pid)\r\n{\r\n    sp<MediaRecorderClient> recorder = new MediaRecorderClient(this, pid);\r\n    wp<MediaRecorderClient> w = recorder;\r\n    Mutex::Autolock lock(mLock);\r\n    mMediaRecorderClients.add(w);\r\n    ALOGV("Create new media recorder client from pid %d", pid);\r\n    return recorder;\r\n}<\/pre>\n
\u521b\u5efaMediaRecorderClient(\u8fd9\u91cc\u662fBnMediaRecorder)<\/p>\n
\u4f46\u662f\u901a\u8fc7binder\u62ff\u5230\u7684\u662fBpMediaRecorder
\n\u56e0\u4e3a\u6709\u5982\u4e0b\u7684interface_cast\u8fc7\u7a0b<\/p>\n
virtual sp<IMediaRecorder> createMediaRecorder(pid_t pid)\r\n{\r\n    Parcel data, reply;\r\n    data.writeInterfaceToken(IMediaPlayerService::getInterfaceDescriptor());\r\n    data.writeInt32(pid);\r\n    remote()->transact(CREATE_MEDIA_RECORDER, data, &reply);\r\n    return interface_cast<IMediaRecorder>(reply.readStrongBinder());\r\n}<\/pre>\n
\u800cMediaRecorderClient\u5f53\u4e2d\u53c8\u4f1a\u521b\u5efaStagefrightRecorder(MediaRecorderBase)\uff0c\u5b83\u4f4d\u4e8e
\n\/path\/to\/aosp\/frameworks\/av\/media\/libmediaplayerservice\/StagefrightRecorder.cpp<\/a><\/p>\n
\u76ee\u524d\u6211\u4eec\u53ef\u4ee5\u8ba4\u4e3a\u5728APP\/JNI\/NATIVE\u8fd9\u8fb9\u662f\u5728\u4e00\u4e2a\u8fdb\u7a0b\u5f53\u4e2d\uff0c\u5728MediaPlayerService\u5f53\u4e2d\u7684MediaRecorderClient\/StagefrightRecorder\u662f\u5728\u53e6\u5916\u4e00\u4e2a\u8fdb\u7a0b\u5f53\u4e2d\uff0c\u4ed6\u4eec\u4e4b\u95f4\u901a\u8fc7binder\u901a\u4fe1\uff0c\u800c\u4e14Bp\u548cBn\u6211\u4eec\u4e5f\u90fd\u6709\u62ff\u5230\uff0c\u540e\u9762\u6211\u4eec\u5c06\u4e0d\u518d\u4ed4\u7ec6\u533a\u5206Bp\u548cBn\u3002<\/p>\n
\u5ba2\u6237\u7aef\u8fd9\u8fb9
\nBnMediaRecorderClient
\nBpMediaRecorder
\nBpMediaPlayerService<\/p>\n
\u670d\u52a1\u7aef\u8fd9\u8fb9
\nBpMediaRecorderClient(\u5982\u679c\u9700\u8981\u901a\u77e5\u5ba2\u6237\u7aef\u7684\u8bdd\uff0c\u5b83\u53ef\u4ee5\u83b7\u5f97\u8fd9\u4e2aBp)
\nBnMediaRecorder
\nBnMediaPlayerService<\/p><\/blockquote>\n
\u8fd9\u6709\u5f20\u56fe(\u70b9\u8fc7\u53bb\u770b\u539f\u59cb\u5927\u56fe)
\n\"Android<\/a><\/p>\n
\u6211\u4eec\u4ee5\u5f00\u59cb\u5f55\u5f71\u4e3a\u4f8b\u5b50\uff0c\u6bd4\u5982start()<\/p>\n
\u5728\u8fd9\u91cc\u5c31\u5175\u5206\u4e24\u8def\uff0c\u4e00\u4e2aCameraSource\uff0c\u4e00\u4e2aMPEG4Writer(sp mWriter)
\n\u8fd9\u4e24\u4e2aclass\u90fd\u4f4d\u4e8e\/path\/to\/aosp\/frameworks\/av\/media\/libstagefright\/<\/a>\u5f53\u4e2d<\/p>\n
status_t StagefrightRecorder::startMPEG4Recording() {\r\n    int32_t totalBitRate;\r\n    status_t err = setupMPEG4Recording(\r\n            mOutputFd, mVideoWidth, mVideoHeight,\r\n            mVideoBitRate, &totalBitRate, &mWriter);\r\n    if (err != OK) {\r\n        return err;\r\n    }\r\n\r\n    int64_t startTimeUs = systemTime() \/ 1000;\r\n    sp<MetaData> meta = new MetaData;\r\n    setupMPEG4MetaData(startTimeUs, totalBitRate, &meta);\r\n\r\n    err = mWriter->start(meta.get());\r\n    if (err != OK) {\r\n        return err;\r\n    }\r\n\r\n    return OK;\r\n}<\/pre>\n
status_t StagefrightRecorder::setupMPEG4Recording(\r\n        int outputFd,\r\n        int32_t videoWidth, int32_t videoHeight,\r\n        int32_t videoBitRate,\r\n        int32_t *totalBitRate,\r\n        sp<MediaWriter> *mediaWriter) {\r\n    mediaWriter->clear();\r\n    *totalBitRate = 0;\r\n    status_t err = OK;\r\n    sp<MediaWriter> writer = new MPEG4Writer(outputFd);\r\n\r\n    if (mVideoSource < VIDEO_SOURCE_LIST_END) {\r\n\r\n        sp<MediaSource> mediaSource;\r\n        err = setupMediaSource(&mediaSource); \/\/ very important\r\n        if (err != OK) {\r\n            return err;\r\n        }\r\n\r\n        sp<MediaSource> encoder;\r\n        err = setupVideoEncoder(mediaSource, videoBitRate, &encoder); \/\/ very important\r\n        if (err != OK) {\r\n            return err;\r\n        }\r\n\r\n        writer->addSource(encoder);\r\n        *totalBitRate += videoBitRate;\r\n    }\r\n\r\n    \/\/ Audio source is added at the end if it exists.\r\n    \/\/ This help make sure that the "recoding" sound is suppressed for\r\n    \/\/ camcorder applications in the recorded files.\r\n    if (!mCaptureTimeLapse && (mAudioSource != AUDIO_SOURCE_CNT)) {\r\n        err = setupAudioEncoder(writer); \/\/ very important\r\n        if (err != OK) return err;\r\n        *totalBitRate += mAudioBitRate;\r\n    }\r\n\r\n    ...\r\n\r\n    writer->setListener(mListener);\r\n    *mediaWriter = writer;\r\n    return OK;\r\n}<\/pre>\n
\r\n\/\/ Set up the appropriate MediaSource depending on the chosen option\r\nstatus_t StagefrightRecorder::setupMediaSource(\r\n                      sp<MediaSource> *mediaSource) {\r\n    if (mVideoSource == VIDEO_SOURCE_DEFAULT\r\n            || mVideoSource == VIDEO_SOURCE_CAMERA) {\r\n        sp<CameraSource> cameraSource;\r\n        status_t err = setupCameraSource(&cameraSource);\r\n        if (err != OK) {\r\n            return err;\r\n        }\r\n        *mediaSource = cameraSource;\r\n    } else if (mVideoSource == VIDEO_SOURCE_GRALLOC_BUFFER) {\r\n        \/\/ If using GRAlloc buffers, setup surfacemediasource.\r\n        \/\/ Later a handle to that will be passed\r\n        \/\/ to the client side when queried\r\n        status_t err = setupSurfaceMediaSource();\r\n        if (err != OK) {\r\n            return err;\r\n        }\r\n        *mediaSource = mSurfaceMediaSource;\r\n    } else {\r\n        return INVALID_OPERATION;\r\n    }\r\n    return OK;\r\n}<\/pre>\n
status_t StagefrightRecorder::setupCameraSource(\r\n        sp<CameraSource> *cameraSource) {\r\n    status_t err = OK;\r\n    if ((err = checkVideoEncoderCapabilities()) != OK) {\r\n        return err;\r\n    }\r\n    Size videoSize;\r\n    videoSize.width = mVideoWidth;\r\n    videoSize.height = mVideoHeight;\r\n    if (mCaptureTimeLapse) {\r\n        if (mTimeBetweenTimeLapseFrameCaptureUs < 0) {\r\n            ALOGE("Invalid mTimeBetweenTimeLapseFrameCaptureUs value: %lld",\r\n                mTimeBetweenTimeLapseFrameCaptureUs);\r\n            return BAD_VALUE;\r\n        }\r\n\r\n        mCameraSourceTimeLapse = CameraSourceTimeLapse::CreateFromCamera(\r\n                mCamera, mCameraProxy, mCameraId,\r\n                videoSize, mFrameRate, mPreviewSurface,\r\n                mTimeBetweenTimeLapseFrameCaptureUs);\r\n        *cameraSource = mCameraSourceTimeLapse;\r\n    } else {\r\n        *cameraSource = CameraSource::CreateFromCamera(\r\n                mCamera, mCameraProxy, mCameraId, videoSize, mFrameRate,\r\n                mPreviewSurface, true \/*storeMetaDataInVideoBuffers*\/);\r\n    }\r\n    mCamera.clear();\r\n    mCameraProxy.clear();\r\n    if (*cameraSource == NULL) {\r\n        return UNKNOWN_ERROR;\r\n    }\r\n\r\n    if ((*cameraSource)->initCheck() != OK) {\r\n        (*cameraSource).clear();\r\n        *cameraSource = NULL;\r\n        return NO_INIT;\r\n    }\r\n\r\n    \/\/ When frame rate is not set, the actual frame rate will be set to\r\n    \/\/ the current frame rate being used.\r\n    if (mFrameRate == -1) {\r\n        int32_t frameRate = 0;\r\n        CHECK ((*cameraSource)->getFormat()->findInt32(\r\n                    kKeyFrameRate, &frameRate));\r\n        ALOGI("Frame rate is not explicitly set. Use the current frame "\r\n             "rate (%d fps)", frameRate);\r\n        mFrameRate = frameRate;\r\n    }\r\n\r\n    CHECK(mFrameRate != -1);\r\n\r\n    mIsMetaDataStoredInVideoBuffers =\r\n        (*cameraSource)->isMetaDataStoredInVideoBuffers();\r\n\r\n    return OK;\r\n}<\/pre>\n
status_t StagefrightRecorder::setupVideoEncoder(\r\n        sp<MediaSource> cameraSource,\r\n        int32_t videoBitRate,\r\n        sp<MediaSource> *source) {\r\n    source->clear();\r\n\r\n    sp<MetaData> enc_meta = new MetaData;\r\n    enc_meta->setInt32(kKeyBitRate, videoBitRate);\r\n    enc_meta->setInt32(kKeyFrameRate, mFrameRate);\r\n\r\n    switch (mVideoEncoder) {\r\n        case VIDEO_ENCODER_H263:\r\n            enc_meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_H263);\r\n            break;\r\n\r\n        case VIDEO_ENCODER_MPEG_4_SP:\r\n            enc_meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_MPEG4);\r\n            break;\r\n\r\n        case VIDEO_ENCODER_H264:\r\n            enc_meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);\r\n            break;\r\n\r\n        default:\r\n            CHECK(!"Should not be here, unsupported video encoding.");\r\n            break;\r\n    }\r\n\r\n    sp<MetaData> meta = cameraSource->getFormat();\r\n\r\n    int32_t width, height, stride, sliceHeight, colorFormat;\r\n    CHECK(meta->findInt32(kKeyWidth, &width));\r\n    CHECK(meta->findInt32(kKeyHeight, &height));\r\n    CHECK(meta->findInt32(kKeyStride, &stride));\r\n    CHECK(meta->findInt32(kKeySliceHeight, &sliceHeight));\r\n    CHECK(meta->findInt32(kKeyColorFormat, &colorFormat));\r\n\r\n    enc_meta->setInt32(kKeyWidth, width);\r\n    enc_meta->setInt32(kKeyHeight, height);\r\n    enc_meta->setInt32(kKeyIFramesInterval, mIFramesIntervalSec);\r\n    enc_meta->setInt32(kKeyStride, stride);\r\n    enc_meta->setInt32(kKeySliceHeight, sliceHeight);\r\n    enc_meta->setInt32(kKeyColorFormat, colorFormat);\r\n    if (mVideoTimeScale > 0) {\r\n        enc_meta->setInt32(kKeyTimeScale, mVideoTimeScale);\r\n    }\r\n    if (mVideoEncoderProfile != -1) {\r\n        enc_meta->setInt32(kKeyVideoProfile, mVideoEncoderProfile);\r\n    }\r\n    if (mVideoEncoderLevel != -1) {\r\n        enc_meta->setInt32(kKeyVideoLevel, mVideoEncoderLevel);\r\n    }\r\n\r\n    OMXClient client;\r\n    CHECK_EQ(client.connect(), (status_t)OK);\r\n\r\n    uint32_t encoder_flags = 0;\r\n    if (mIsMetaDataStoredInVideoBuffers) {\r\n        encoder_flags |= OMXCodec::kStoreMetaDataInVideoBuffers;\r\n    }\r\n\r\n    \/\/ Do not wait for all the input buffers to become available.\r\n    \/\/ This give timelapse video recording faster response in\r\n    \/\/ receiving output from video encoder component.\r\n    if (mCaptureTimeLapse) {\r\n        encoder_flags |= OMXCodec::kOnlySubmitOneInputBufferAtOneTime;\r\n    }\r\n\r\n    sp<MediaSource> encoder = OMXCodec::Create(\r\n            client.interface(), enc_meta,\r\n            true \/* createEncoder *\/, cameraSource,\r\n            NULL, encoder_flags);\r\n    if (encoder == NULL) {\r\n        ALOGW("Failed to create the encoder");\r\n        \/\/ When the encoder fails to be created, we need\r\n        \/\/ release the camera source due to the camera's lock\r\n        \/\/ and unlock mechanism.\r\n        cameraSource->stop();\r\n        return UNKNOWN_ERROR;\r\n    }\r\n\r\n    *source = encoder;\r\n\r\n    return OK;\r\n}<\/pre>\n
\u8fd9\u91cc\u548cOMXCodec\u5173\u8054\u8d77\u6765
\n\u6709\u4e00\u4e2a\u53ebmedia_codecs.xml\u7684\u914d\u7f6e\u6587\u4ef6\u6765\u8868\u660e\u8bbe\u5907\u652f\u6301\u54ea\u4e9bcodec<\/p>\n
\u6211\u4eec\u5f55\u5236MPEG 4\u7684\u65f6\u5019\u8fd8\u4f1a\u6709\u58f0\u97f3\uff0c\u6240\u4ee5\u540e\u9762\u8fd8\u6709\u4e2asetupAudioEncoder\uff0c\u5177\u4f53\u7684\u65b9\u6cd5\u5c31\u4e0d\u5c55\u5f00\u4e86\uff0c\u603b\u4e4b\u5c31\u662f\u628a\u58f0\u97f3\u4e5f\u4f5c\u4e3a\u4e00\u4e2aTrack\u52a0\u5165\u5230MPEG4Writer\u5f53\u4e2d\u53bb\u3002
\n\u8fd9\u91cc\u63d2\u4e2a\u9898\u5916\u8bdd\uff0cGoogle\u8bf4\u628asetupAudioEncoder\u653e\u5230\u540e\u9762\u662f\u4e3a\u4e86\u907f\u514d\u5f00\u59cb\u5f55\u5f71\u7684\u90a3\u4e00\u4e2a\u63d0\u793a\u58f0\u97f3\u4e5f\u88ab\u5f55\u5236\u8fdb\u53bb\uff0c\u4f46\u662f\u5b9e\u9645\u53d1\u73b0\u5b83\u8fd9\u6837\u505a\u8fd8\u662f\u4f1a\u6709bug\uff0c\u5728\u4e00\u4e9b\u8bbe\u5907\u4e0a\u8fd8\u662f\u4f1a\u628a\u90a3\u58f0\u5f55\u5236\u8fdb\u53bb\uff0c\u8fd9\u4e2a\u9047\u5230\u7684\u90fd\u662f\u9760APP\u81ea\u5df1\u6765\u64ad\u653e\u58f0\u97f3\u6765\u7ed5\u8fc7\u8fd9\u4e2a\u95ee\u9898\u7684\u3002<\/p>\n
\u53e6\u5916MPEG4Writer\u5f53\u4e2d\u6709\u4e2a
\nstart(MetaData*)
\n\u542f\u52a8\u4e24\u4e2a\u65b9\u6cd5
\n a) startWriterThread<\/p>\n
    \u542f\u52a8\u4e00\u4e2athread\u53bb\u5199<\/p>\n
    void MPEG4Writer::threadFunc() {\r\n        ALOGV("threadFunc");\r\n\r\n        prctl(PR_SET_NAME, (unsigned long)"MPEG4Writer", 0, 0, 0);\r\n\r\n        Mutex::Autolock autoLock(mLock);\r\n        while (!mDone) {\r\n            Chunk chunk;\r\n            bool chunkFound = false;\r\n\r\n            while (!mDone && !(chunkFound = findChunkToWrite(&chunk))) {\r\n                mChunkReadyCondition.wait(mLock);\r\n            }\r\n\r\n            \/\/ Actual write without holding the lock in order to\r\n            \/\/ reduce the blocking time for media track threads.\r\n            if (chunkFound) {\r\n                mLock.unlock();\r\n                writeChunkToFile(&chunk);\r\n                mLock.lock();\r\n            }\r\n        }\r\n\r\n        writeAllChunks();\r\n    }<\/pre>\n
 b) startTracks<\/p>\n
    status_t MPEG4Writer::startTracks(MetaData *params) {\r\n        for (List<Track *>::iterator it = mTracks.begin();\r\n             it != mTracks.end(); ++it) {\r\n            status_t err = (*it)->start(params);\r\n\r\n            if (err != OK) {\r\n                for (List<Track *>::iterator it2 = mTracks.begin();\r\n                     it2 != it; ++it2) {\r\n                    (*it2)->stop();\r\n                }\r\n\r\n                return err;\r\n            }\r\n        }\r\n        return OK;\r\n    }<\/pre>\n
    \u7136\u540e\u8c03\u7528\u6bcf\u4e2aTrack\u7684start\u65b9\u6cd5<\/p>\n
    status_t MPEG4Writer::Track::start(MetaData *params) {\r\n        ...\r\n\r\n        initTrackingProgressStatus(params);\r\n\r\n        ...\r\n\r\n        status_t err = mSource->start(meta.get()); \/\/ \u8fd9\u91cc\u4f1a\u53bb\u6267\u884cCameraSource(start)\uff0c\u8fd9\u4e24\u4e2a\u662f\u76f8\u4e92\u5173\u8054\u7684\r\n\r\n        ...\r\n\r\n        pthread_create(&mThread, &attr, ThreadWrapper, this);\r\n        return OK;\r\n    }\r\n\r\n    void *MPEG4Writer::Track::ThreadWrapper(void *me) {\r\n        Track *track = static_cast<Track *>(me);\r\n\r\n        status_t err = track->threadEntry();\r\n        return (void *) err;\r\n    }<\/pre>\n
    \u901a\u8fc7status_t MPEG4Writer::Track::threadEntry()
\n    \u662f\u65b0\u542f\u52a8\u53e6\u5916\u4e00\u4e2athread\uff0c\u5b83\u91cc\u9762\u4f1a\u901a\u8fc7\u4e00\u4e2a\u5faa\u73af\u6765\u4e0d\u65ad\u8bfb\u53d6CameraSource(read)\u91cc\u9762\u7684\u6570\u636e\uff0cCameraSource\u91cc\u9762\u7684\u6570\u636e\u5f53\u7136\u662f\u4ecedriver\u8fd4\u56de\u8fc7\u6765\u7684(\u53ef\u4ee5\u53c2\u89c1CameraSourceListener\uff0cCameraSource\u7528\u4e00\u4e2a\u53eb\u505amFrameReceived\u7684List\u4e13\u95e8\u5b58\u653e\u4ecedriver\u8fc7\u6765\u7684\u6570\u636e\uff0c\u5982\u679c\u6536\u5230\u6570\u636e\u4f1a\u8c03\u7528mFrameAvailableCondition.signal\uff0c\u82e5\u8fd8\u6ca1\u6709\u5f00\u59cb\u5f55\u5f71\uff0c\u8fd9\u4e2a\u65f6\u5019\u6536\u5230\u7684\u6570\u636e\u662f\u88ab\u4e22\u5f03\u7684\uff0c\u5f53\u7136MediaWriter\u5148\u542f\u52a8\u7684\u662fCameraSource\u7684start\u65b9\u6cd5\uff0c\u518d\u542f\u52a8\u5199Track)\uff0c\u7136\u540e\u5199\u5230\u6587\u4ef6\u5f53\u4e2d\u3002
\n\u6ce8\u610f\uff1a\u51c6\u786e\u6765\u8bf4\u8fd9\u91ccMPEG4Writer\u8bfb\u53d6\u7684\u662fOMXCodec\u91cc\u7684\u6570\u636e\uff0c\u56e0\u4e3a\u6570\u636e\u5148\u5230CameraSource\uff0ccodec\u8d1f\u8d23\u7f16\u7801\u4e4b\u540e\uff0cMPEG4Writer\u624d\u8d1f\u8d23\u5199\u5230\u6587\u4ef6\u5f53\u4e2d\uff01\u5173\u4e8e\u6570\u636e\u5728CameraSource\/OMXCodec\/MPEG4Writer\u4e4b\u95f4\u662f\u600e\u4e48\u4f20\u9012\u7684\uff0c\u53ef\u4ee5\u53c2\u89c1http:\/\/guoh.ai\/lifelog\/2013\/06\/interaction-between-stagefright-and-codec\/<\/a>\u5f53\u4e2d\u8bb2Buffer\u7684\u4f20\u8f93\u8fc7\u7a0b\u3002<\/p>\n
\u56de\u5934\u518d\u6765\u770b\uff0cStagefright\u505a\u4e86\u4ec0\u4e48\u4e8b\u60c5\uff1f\u6211\u66f4\u89c9\u5f97\u5b83\u53ea\u662f\u4e00\u4e2a\u7c98\u5408\u5242(glue)\u7684\u7528\u5904\uff0c\u5b83\u5de5\u4f5c\u5728MediaPlayerService\u8fd9\u4e00\u5c42\uff0c\u628aMediaSource\uff0cMediaWriter\uff0cCodec\u4ee5\u53ca\u4e0a\u5c42\u7684MediaRecorder\u7ed1\u5b9a\u5728\u4e00\u8d77\uff0c\u8fd9\u5e94\u8be5\u5c31\u662f\u5b83\u6700\u5927\u7684\u4f5c\u7528\uff0cGoogle\u7528\u5b83\u6765\u66ff\u6362Opencore\u4e5f\u662f\u7b26\u5408\u5176\u4e00\u8d2f\u7684\u5de5\u7a0b\u6d3e\u4f5c\u98ce(\u76f8\u6bd4\u590d\u6742\u7684\u5b66\u672f\u6d3e\u800c\u8a00\uff0c\u867d\u7136Google\u5f88\u591a\u4e1c\u897f\u4e5f\u5f88\u590d\u6742\uff0c\u4f46\u662f\u5b83\u4e00\u822c\u90fd\u662f\u4ee5\u5c3d\u91cf\u7b80\u5355\u7684\u65b9\u5f0f\u6765\u89e3\u51b3\u95ee\u9898)\u3002
\n\u8ba9\u5927\u5bb6\u89c9\u5f97\u6709\u70b9\u4e0d\u4e60\u60ef\u7684\u662f\uff0c\u5b83\u628aMediaRecorder\u653e\u5728MediaPlayerService\u5f53\u4e2d\uff0c\u8fd9\u4e24\u4e2a\u770b\u8d77\u6765\u662f\u5bf9\u7acb\u7684\u4e8b\u60c5\uff0c\u6216\u8005\u67d0\u4e00\u5929\u5b83\u4eec\u4f1a\u6539\u540d\u5b57\uff0c\u6216\u8005\u662f\u4e24\u8005\u5206\u5f00\uff0c\u4e0d\u77e5\u9053\uff5e\uff5e<\/p>\n
\u5f53\u7136\u8fd9\u53ea\u662f\u4e2a\u7b80\u5355\u7684\u5927\u4f53\u4ecb\u7ecd\uff0cCodec\u76f8\u5173\u7684\u540e\u9762\u4e89\u53d6\u4e13\u95e8\u6765\u5206\u6790\u4e00\u4e0b\uff01<\/p>\n
\u6709\u4e9b\u7ec6\u8282\u7684\u4e1c\u897f\u5728\u8fd9\u91cc\u6ca1\u6709\u5217\u51fa\uff0c\u9700\u8981\u7684\u8bdd\u4f1a\u628a\u4e00\u4e9b\u6ce8\u610f\u70b9\u5217\u51fa\u6765\uff1a<\/p>\n
1. \u65f6\u5149\u6d41\u901d\u5f55\u5f71
\nCameraSource\u5bf9\u5e94\u7684\u5c31\u662fCameraSourceTimeLapse<\/p>\n
\u5177\u4f53\u505a\u6cd5\u5c31\u662f\u5728
\ndataCallbackTimestamp
\n\u5f53\u4e2d\u6709skipCurrentFrame<\/p>\n
\u5f53\u7136\u5b83\u662f\u7528\u4e9b\u53d8\u91cf\u6765\u8bb0\u5f55\u548c\u8ba1\u7b97
\nmTimeBetweenTimeLapseVideoFramesUs(1E6\/videoFrameRate) \/\/ \u4e24\u4e2aframe\u4e4b\u95f4\u7684\u95f4\u9694\u65f6\u95f4
\n\u8bb0\u5f55\u4e0a\u4e00\u4e2aframe\u7684(mLastTimeLapseFrameRealTimestampUs) \/\/ \u4e0a\u4e00\u4e2aframe\u53d1\u751f\u7684\u65f6\u95f4
\n\u7136\u540e\u901a\u8fc7frame rate\u8ba1\u7b97\u51fa\u4e24\u4e2aframe\u4e4b\u95f4\u7684\u76f8\u8ddd\u79bb\u65f6\u95f4\uff0c\u4e2d\u95f4\u7684\u90fd\u900f\u8fc7releaseOneRecordingFrame\u6765drop\u6389
\n\u4e5f\u5c31\u662f\u8bf4driver\u8fd4\u56de\u7684\u4e1c\u897f\u90fd\u4e0d\u53d8\uff0c\u53ea\u662f\u5728SW\u8fd9\u5c42\u6211\u4eec\u81ea\u5df1\u6765\u5904\u7406\u6389<\/p>\n
\u5173\u4e8eTime-lapse\u76f8\u5173\u7684\u53ef\u4ee5\u53c2\u9605
\nhttps:\/\/en.wikipedia.org\/wiki\/Time-lapse_photography<\/a><\/p>\n
2. \u5f55\u5f71\u5f53\u4e2d\u9700\u8981\u7528\u5230Camera\u7684\u8bdd\u662f\u901a\u8fc7ICameraRecordingProxy\uff0c\u5373Camera\u5f53\u4e2d\u7684RecordingProxy(\u8fd9\u662f\u4e00\u4e2aBnCameraRecordingProxy)
\n\u5f53\u900f\u8fc7binder\uff0c\u5c06ICameraRecordingProxy\u4f20\u5230\u670d\u52a1\u7aef\u8fdb\u7a0b\u4e4b\u540e\uff0c\u5b83\u5c31\u53d8\u6210\u4e86Bp\uff0c\u5982\u4e0b\uff1a<\/p>\n
case SET_CAMERA: {\r\n    ALOGV("SET_CAMERA");\r\n    CHECK_INTERFACE(IMediaRecorder, data, reply);\r\n    sp<ICamera> camera = interface_cast<ICamera>(data.readStrongBinder());\r\n    sp<ICameraRecordingProxy> proxy =\r\n        interface_cast<ICameraRecordingProxy>(data.readStrongBinder());\r\n    reply->writeInt32(setCamera(camera, proxy));\r\n    return NO_ERROR;\r\n} break;<\/pre>\n
\u5728CameraSource\u5f53\u4e2d\u4f1a\u8fd9\u6837\u53bb\u4f7f\u7528<\/p>\n
\/\/ We get the proxy from Camera, not ICamera. We need to get the proxy\r\n\/\/ to the remote Camera owned by the application. Here mCamera is a\r\n\/\/ local Camera object created by us. We cannot use the proxy from\r\n\/\/ mCamera here.\r\nmCamera = Camera::create(camera);\r\nif (mCamera == 0) return -EBUSY;\r\nmCameraRecordingProxy = proxy;\r\nmCameraFlags |= FLAGS_HOT_CAMERA;<\/pre>\n
\u7591\u95ee\u70b9\uff1a<\/p>\n
CameraSource\u5f53\u4e2d\u8fd9\u4e2a
\nList<sp > mFramesBeingEncoded;<\/strong>
\n\u6709\u4ec0\u4e48\u7528\uff1f
\n\u6bcf\u7f16\u7801\u5b8c\u4e00\u4e2aframe\uff0cCameraSource\u5c31\u4f1a\u5c06\u5176\u4fdd\u5b58\u8d77\u6765\uff0cBuffer\u88abrelease\u7684\u65f6\u5019\uff0c\u4f1a\u53cd\u8fc7\u6765release\u6389\u8fd9\u4e9bframe(s)\uff0c\u8fd9\u79cd\u505a\u6cd5\u662f\u4e3a\u4e86\u6548\u7387\u4e48\uff1f\u4e3a\u4ec0\u4e48\u4e0d\u7f16\u7801\u5b8c\u4e00\u4e2aframe\u5c31\u5c06\u5176release\u6389\uff1f
\n\u53e6\u5916\u4e0d\u5f97\u4e0d\u518d\u611f\u53f9\u4e0bGoogle\u7ecf\u5e38\u7684delete this;<\/strong>\u884c\u4e3a\uff0c\u7cbe\u5999\uff0c\u4f46\u662f\u770b\u8d77\u6765\u53cd\u5e38\uff01<\/p>\n<\/div><\/div>","protected":false},"excerpt":{"rendered":"
<p>\u524d\u9762\u6709\u5206\u6790\u8fc7Camera\u7684\u5b9e\u73b0\uff0c\u73b0\u5728\u6765\u770b\u770bMediaRecorder\u7684\u5b9e\u73b0\uff0c\u8fd9\u91cc\u6211\u4e0d\u4f1a\u592a\u53bb\u5173\u6ce8\u5b83\u7684\u5206\u5c42\u7ed3\u6784\uff0c\u6211\u66f4\u5173\u6ce8\u5b83\u7684\u903b\u8f91\uff01<\/p> <p>APP\u5c42<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/base\/+\/android-4.2.2_r1.2\/media\/java\/android\/media\/MediaRecorder.java" target="_blank"> \/path\/to\/aosp\/frameworks\/base\/media\/java\/android\/media\/MediaRecorder.java<\/a><br \/> JNI\u5c42<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/base\/+\/android-4.2.2_r1.2\/media\/jni\/android_media_MediaRecorder.cpp" target="_blank"> \/path\/to\/aosp\/frameworks\/base\/media\/jni\/android_media_MediaRecorder.cpp<\/a><br \/> \u8c03\u7528NATIVE\u5c42\u7684MediaRecorder(\u8fd9\u91cc\u662fBnMediaRecorderClient)<br \/> header<a href="https:\/\/android.googlesource.com\/platform\/frameworks\/av\/+\/android-4.2.2_r1.2\/include\/media\/mediarecorder.h" target="_blank"> \/path\/to\/aosp\/frameworks\/av\/include\/media\/mediarecorder.h<\/a><br \/> implementation <a href="https:\/\/android.googlesource.com\/platform\/frameworks\/av\/+\/android-4.2.2_r1.2\/media\/libmedia\/mediarecorder.cpp" target="_blank">\/path\/to\/aosp\/frameworks\/av\/media\/libmedia\/mediarecorder.cpp<\/a><\/p> <pre class="brush: java; title: ; notranslate" title="">MediaRecorder::MediaRecorder() : mSurfaceMediaSource(NULL) { ALOGV("constructor"); const sp<IMediaPlayerService>& service(getMediaPlayerService()); if (service != NULL) { mMediaRecorder = service->createMediaRecorder(getpid()); } if (mMediaRecorder != NULL) { mCurrentState = MEDIA_RECORDER_IDLE; } doCleanUp(); … Continue reading Android MediaRecorder\u7cfb\u7edf\u7ed3\u6784<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_gfmr_meta_descriptions":[],"_gfmr_multilingual_taxonomy_terms":[],"footnotes":""},"categories":[7,28,34],"tags":[27],"class_list":["post-590","post","type-post","status-publish","format-standard","hentry","category-android","category-cpp","category-multimedia","tag-camera"],"_links":{"self":[{"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/posts\/590","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/comments?post=590"}],"version-history":[{"count":15,"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/posts\/590\/revisions"}],"predecessor-version":[{"id":851,"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/posts\/590\/revisions\/851"}],"wp:attachment":[{"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/media?parent=590"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/categories?post=590"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/guoh.ai\/lifelog\/wp-json\/wp\/v2\/tags?post=590"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}