android nuplayer reset处理流程

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1.NuPlayerDriver::reset()

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mPlayer->resetAsync();// 执行异步reset
while (mResetInProgress) { // 等待reset完成，如果5秒未完成，则会出现ANR
mCondition.wait(mLock);
}

2.NuPlayer::resetAsync()
发送kWhatReset消息

3.kWhatReset消息的处理
NuPlayer::onMessageReceived
case kWhatReset:
(1)如果mFlushingAudio或者mFlushingVideo是AWAITING_DISCONTINUITY状态，执行

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mRenderer->resume();
if (mRenderer != NULL) {
// There's an edge case where the renderer owns all output
// buffers and is paused, therefore the decoder will not read
// more input data and will never encounter the matching
// discontinuity. To avoid this, we resume the renderer.
if (mFlushingAudio == AWAITING_DISCONTINUITY
|| mFlushingVideo == AWAITING_DISCONTINUITY) {
mRenderer->resume();
}
}

(2)如果正在flushing，则推迟执行reset

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if (mFlushingAudio != NONE || mFlushingVideo != NONE) {
// We're currently flushing, postpone the reset until that's
// completed.
LOGV("postponing reset mFlushingAudio=%d, mFlushingVideo=%d",
mFlushingAudio, mFlushingVideo);
mResetPostponed = true; // 设置推迟reset标志
break;
}

(3)如果mAudioDecoder == NULL && mVideoDecoder == NULL，则表示已经执行完reset，则调用
finishReset()

(4)执行audio的flushDecoder

(5)执行video的flushDecoder

(6)设置变量mResetInProgress为true

4.NuPlayer::finishReset()
(1)执行mSource->stop();
(2)执行driver->notifyResetComplete()

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if (mSource != NULL) {
mSource->stop(); // 执行NuPlayer::RTSPSource::stop()函数
mSource.clear();
}
if (mDriver != NULL) {
sp<NuPlayerDriver> driver = mDriver.promote();
if (driver != NULL) {
driver->notifyResetComplete();
}
}

4.1 NuPlayer::RTSPSource::stop()

stop函数发送消息后，断开与服务器的连接需要及时执行完成，否则会超时导致ANR。

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void NuPlayer::RTSPSource::stop() {
sp<AMessage> msg = new AMessage(kWhatDisconnect, mReflector->id());
sp<AMessage> dummy;
msg->postAndAwaitResponse(&dummy); // 最终调用全局变量gLooperRoster的postAndAwaitResponse函数
}

4.2 处理kWhatDisconnect消息

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void NuPlayer::RTSPSource::onMessageReceived(const sp<AMessage> &msg) {
if (msg->what() == kWhatDisconnect) {
uint32_t replyID;
CHECK(msg->senderAwaitsResponse(&replyID)); // 取得replyID
mDisconnectReplyID = replyID;
finishDisconnectIfPossible(); // 断开与服务器的数据链接
return;
}

4.3 NuPlayer::RTSPSource::finishDisconnectIfPossible

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if (mState != DISCONNECTED) {
mHandler->disconnect(); // 执行MyHandler.h的disconnect函数，发送'abor'消息，断开与服务器的链接
return;
}

5.NuPlayerDriver::notifyResetComplete()
设置mResetInProgress为false，则1.中的等待完成，即reset执行结束

6.NuPlayer::flushDecoder

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(audio ? mAudioDecoder : mVideoDecoder)->signalFlush();
mRenderer->flush(audio);

7.NuPlayer::Decoder::signalFlush()
调用mCodec->signalFlush(); 调用的是ACodec的signalFlush函数

8.ACodec::signalFlush()
发送kWhatFlush消息

9.ACodec::UninitializedState::onMessageReceived
case ACodec::kWhatFlush:
发送ACodec::kWhatFlushCompleted消息

10.对ACodec::kWhatFlushCompleted消息的处理位于NuPlayer类中

[cpp] view plain copy

NuPlayer::onMessageReceived
case kWhatVideoNotify:
case kWhatAudioNotify:
...
} else if (what == ACodec::kWhatFlushCompleted) {
bool needShutdown;
if (audio) {
CHECK(IsFlushingState(mFlushingAudio, &needShutdown));
mFlushingAudio = FLUSHED;
} else {
CHECK(IsFlushingState(mFlushingVideo, &needShutdown));
mFlushingVideo = FLUSHED;
mVideoLateByUs = 0;
}
LOGV("decoder %s flush completed", audio ? "audio" : "video");
if (needShutdown) {
LOGV("initiating %s decoder shutdown",
audio ? "audio" : "video");
// 调用Decoder类的initiateShutdown --> ACodec::initiateShutdown() --> 发送kWhatShutdown消息 -->
// 再发送ACodec::kWhatShutdownCompleted消息 --> 回到本函数处理ACodec::kWhatShutdownCompleted消息
(audio ? mAudioDecoder : mVideoDecoder)->initiateShutdown();
if (audio) {
mFlushingAudio = SHUTTING_DOWN_DECODER;
} else {
mFlushingVideo = SHUTTING_DOWN_DECODER;
}
}
finishFlushIfPossible(); //
}
...
} else if (what == ACodec::kWhatShutdownCompleted) {
LOGV("%s shutdown completed", audio ? "audio" : "video");
if (audio) {
mAudioDecoder.clear();
CHECK_EQ((int)mFlushingAudio, (int)SHUTTING_DOWN_DECODER);
mFlushingAudio = SHUT_DOWN;
} else {
mVideoDecoder.clear();
CHECK_EQ((int)mFlushingVideo, (int)SHUTTING_DOWN_DECODER);
mFlushingVideo = SHUT_DOWN;
}
finishFlushIfPossible(); //
}

11.finishFlushIfPossible的处理

[cpp] view plain copy

void NuPlayer::finishFlushIfPossible() {
if (mFlushingAudio != FLUSHED && mFlushingAudio != SHUT_DOWN) {
return;
}
if (mFlushingVideo != FLUSHED && mFlushingVideo != SHUT_DOWN) {
return;
}
LOGV("both audio and video are flushed now.");
if (mTimeDiscontinuityPending) {
mRenderer->signalTimeDiscontinuity(); // 发送消息
mTimeDiscontinuityPending = false;
}
// NuPlayer::Decoder::signalResume --> ACodec::signalResume --> 发送kWhatResume消息 -->
// ACodec::ExecutingState::resume --> ACodec::ExecutingState::submitOutputBuffers -->
// ACodec::BaseState::postFillThisBuffer --> kWhatInputBufferFilled -->
// ACodec::BaseState::onInputBufferFilled
if (mAudioDecoder != NULL) {
mAudioDecoder->signalResume();
}
if (mVideoDecoder != NULL) {
mVideoDecoder->signalResume();
}
mFlushingAudio = NONE;
mFlushingVideo = NONE;
if (mResetInProgress) { // 3.(6)中设置为true了
LOGV("reset completed");
mResetInProgress = false;
finishReset(); // reset执行完成，见4，5的处理
} else if (mResetPostponed) { // 如果3.(2)中设置了推迟执行reset，则重新发送kWhatReset消息
(new AMessage(kWhatReset, id()))->post();
mResetPostponed = false;
} else if (mAudioDecoder == NULL || mVideoDecoder == NULL) {
postScanSources();
}
}