Android(安卓)Media Server - MediaPlayer - prepare - 01 - android

1． MediaPlayer::prepare()

Frameworks/base/media/java/android/media/MediaPlayer.java

public native void prepare() throws IOException,IllegalStateException;

2． android_media_MediaPlayer_prepare ()

Frameworks/base/media/jni/Android_media_MediaPlayer.cpp

static void

android_media_MediaPlayer_prepare(JNIEnv *env, jobject thiz)

{

sp<MediaPlayer> mp = getMediaPlayer(env, thiz);

if (mp == NULL ) {

jniThrowException(env,"java/lang/IllegalStateException", NULL);

return;

}

// Handle the case where the displaysurface was set before the mp was

// initialized. We try again to make itstick.

sp<IGraphicBufferProducer> st = getVideoSurfaceTexture(env, thiz);

mp->setVideoSurfaceTexture(st);

process_media_player_call( env, thiz, mp->prepare(),"java/io/IOException", "Prepare failed." );

}

3． MediaPlayer:: prepare ()

Frameworks/av/media/libmedia/MediaPlayer.cpp

status_tMediaPlayer::prepare()

{

ALOGV("prepare");

Mutex::Autolock _l(mLock);

mLockThreadId = getThreadId();

if (mPrepareSync) {

mLockThreadId = 0;

return -EALREADY;

}

mPrepareSync = true;

status_t ret = prepareAsync_l();

if (ret != NO_ERROR) {

mLockThreadId = 0;

return ret;

}

if (mPrepareSync) {

mSignal.wait(mLock); // wait for prepare done

mPrepareSync = false;

}

ALOGV("prepare complete -status=%d", mPrepareStatus);

mLockThreadId = 0;

return mPrepareStatus;

}

status_tMediaPlayer::prepareAsync_l()

{

if ( (mPlayer != 0) && (mCurrentState & ( MEDIA_PLAYER_INITIALIZED | MEDIA_PLAYER_STOPPED) ) ) {

mPlayer->setAudioStreamType(mStreamType);

mCurrentState = MEDIA_PLAYER_PREPARING;

// mPlayer是一个BpMediaPlayer(BpBinder)对象

returnmPlayer->prepareAsync();

}

ALOGE("prepareAsync called in state%d", mCurrentState);

return INVALID_OPERATION;

}

4． BpMediaPlayer:: prepareAsync()

Frameworks/av/media/libmedia/IMediaPlayer.cpp

class BpMediaPlayer: public BpInterface<IMediaPlayer>

{

status_t prepareAsync()

{

Parcel data, reply;

data.writeInterfaceToken(IMediaPlayer::getInterfaceDescriptor());

// remote() 得到的是BpMediaPlayer(BpBinder)中的BpBinder

remote()->transact(PREPARE_ASYNC, data, &reply);

return reply.readInt32();

}

5． BnMediaPlayer:: onTransact()

Frameworks/av/media/libmedia/IMediaPlayer.cpp

通过Binder机制调用BnMediaPlayer的onTransact()

status_tBnMediaPlayer::onTransact(

uint32_t code, const Parcel& data,Parcel* reply, uint32_t flags)

{

switch (code) {

case DISCONNECT: {

CHECK_INTERFACE(IMediaPlayer, data,reply);

disconnect();

return NO_ERROR;

} break;

case SET_DATA_SOURCE_URL: {

CHECK_INTERFACE(IMediaPlayer, data,reply);

const char* url =data.readCString();

KeyedVector<String8, String8>headers;

int32_t numHeaders =data.readInt32();

for (int i = 0; i < numHeaders;++i) {

String8 key =data.readString8();

String8 value =data.readString8();

headers.add(key, value);

}

reply->writeInt32(setDataSource(url, numHeaders > 0 ? &headers: NULL));

return NO_ERROR;

} break;

case SET_DATA_SOURCE_FD: {

CHECK_INTERFACE(IMediaPlayer, data,reply);

int fd = data.readFileDescriptor();

int64_t offset = data.readInt64();

int64_t length = data.readInt64();

reply->writeInt32(setDataSource(fd, offset, length));

return NO_ERROR;

}

case SET_DATA_SOURCE_STREAM: {

CHECK_INTERFACE(IMediaPlayer, data, reply);

sp<IStreamSource> source =

interface_cast<IStreamSource>(data.readStrongBinder());

reply->writeInt32(setDataSource(source));

return NO_ERROR;

}

case SET_VIDEO_SURFACETEXTURE: {

CHECK_INTERFACE(IMediaPlayer, data,reply);

sp<IGraphicBufferProducer>bufferProducer =

interface_cast<IGraphicBufferProducer>(data.readStrongBinder());

reply->writeInt32(setVideoSurfaceTexture(bufferProducer));

return NO_ERROR;

} break;

casePREPARE_ASYNC: {

CHECK_INTERFACE(IMediaPlayer, data, reply);

reply->writeInt32(prepareAsync());

returnNO_ERROR;

} break;

case START: {

CHECK_INTERFACE(IMediaPlayer, data,reply);

reply->writeInt32(start());

return NO_ERROR;

} break;

case STOP: {

CHECK_INTERFACE(IMediaPlayer, data,reply);

reply->writeInt32(stop());

return NO_ERROR;

} break;

case IS_PLAYING: {

CHECK_INTERFACE(IMediaPlayer, data,reply);

bool state;

status_t ret =isPlaying(&state);

reply->writeInt32(state);

reply->writeInt32(ret);

return NO_ERROR;

} break;

.........................................................

default:

return BBinder::onTransact(code,data, reply, flags);

}

6． MediaPlayerService::Client::prepareAsync()

Frameworks/av/media/libmediaplayerservice/MediaPlayerService.h

Frameworks/av/media/libmediaplayerservice/MediaPlayerService.cpp

classMediaPlayerService : public BnMediaPlayerService

{

class Client;

classClient : public BnMediaPlayer {

// IMediaPlayer interface

virtual void disconnect();

virtual status_t setVideoSurfaceTexture(

constsp<IGraphicBufferProducer>& bufferProducer);

virtual status_t prepareAsync();

virtual status_t start();

virtual status_t stop();

virtual status_t pause();

virtual status_t isPlaying(bool* state);

virtual status_t seekTo(int msec);

virtual status_t getCurrentPosition(int* msec);

virtual status_t setDataSource(constsp<IStreamSource> &source);

…………………………………………

}

status_tMediaPlayerService::Client::prepareAsync()

{

ALOGV("[%d] prepareAsync", mConnId);

// 这个p 是一个StageFrightPlayer对象

sp<MediaPlayerBase> p = getPlayer();

if (p == 0) return UNKNOWN_ERROR;

// 调用StageFrightPlayer对象的prepareAsync()

status_t ret =p->prepareAsync();

#ifCALLBACK_ANTAGONIZER

ALOGD("start Antagonizer");

if (ret == NO_ERROR)mAntagonizer->start();

#endif

return ret;

}

7． StageFrightPlayer::prepareAsync()

Frameworks/av/media/libmediaplayerservice/StageFrightPlayer.cpp

status_tStagefrightPlayer::prepareAsync() {

//StageFrightPlayer对象的mPlayer成员变量是一个AwesomePlayer对象

// 因此调用AwesomePlayer的prepareAsync方法

return mPlayer->prepareAsync();

}

8． AwesomePlayer::prepareAsync()

Frameworks/av/media/libstagefright/AwesomePlayer.cpp

status_tAwesomePlayer::prepareAsync() {

ATRACE_CALL();

Mutex::Autolock autoLock(mLock);

if (mFlags & PREPARING) {

return UNKNOWN_ERROR; // async prepare already pending

}

mIsAsyncPrepare = true;

return prepareAsync_l();

}

status_tAwesomePlayer::prepareAsync_l() {

if (mFlags & PREPARING) {

return UNKNOWN_ERROR; // async prepare already pending

}

if (!mQueueStarted) {

mQueue.start();

mQueueStarted = true;

}

modifyFlags(PREPARING, SET);

mAsyncPrepareEvent= new AwesomeEvent(

this,&AwesomePlayer::onPrepareAsyncEvent);

mQueue.postEvent(mAsyncPrepareEvent);

return OK;

}

voidAwesomePlayer::onPrepareAsyncEvent() {

Mutex::Autolock autoLock(mLock);

if (mFlags & PREPARE_CANCELLED) {

ALOGI("prepare was cancelledbefore doing anything");

abortPrepare(UNKNOWN_ERROR);

return;

}

if (mUri.size() > 0) {

status_t err =finishSetDataSource_l();

if (err != OK) {

abortPrepare(err);

return;

}

if (mVideoTrack != NULL &&mVideoSource == NULL) {

status_t err =initVideoDecoder();

if (err != OK) {

abortPrepare(err);

return;

}

if (mAudioTrack != NULL &&mAudioSource == NULL) {

status_t err =initAudioDecoder();

if (err != OK) {

abortPrepare(err);

return;

}

modifyFlags(PREPARING_CONNECTED, SET);

if (isStreamingHTTP()) {

postBufferingEvent_l();

} else {

finishAsyncPrepare_l();

}

Android(安卓)Media Server - MediaPlayer - prepare - 01

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