C++ BMediaTrack::SeekToTime方法代码示例

int32
MediaView::MediaPlayer(
	void	*arg)
{
	MediaView*		view = (MediaView *)arg;
	BWindow*		window = view->Window();
	BBitmap*		bitmap = view->fBitmap;
	BMediaTrack*	videoTrack = view->fVideoTrack;
	BMediaTrack*	audioTrack = view->fAudioTrack;
	BMediaTrack*	counterTrack = (videoTrack != NULL) ? videoTrack : audioTrack;
	AudioOutput*	audioOutput = view->fAudioOutput;
	void*			adBuffer = view->fAudioDumpingBuffer;
	int64			numFrames = counterTrack->CountFrames();
	int64			numFramesToSkip = 0;
	int64			numSkippedFrames = 0;
	bool			scrubbing = false;
	bool			seekNeeded = false;
	int64			dummy;
	media_header	mh;
	bigtime_t		vStartTime, aStartTime, seekTime, snoozeTime, startTime;
	bigtime_t		curScrubbing, lastScrubbing, lastTime;

	curScrubbing = lastScrubbing = system_time();
	seekTime = 0LL;

	// Main processing loop (handle stop->start->stop)
	while (acquire_sem(view->fPlaySem) == B_OK) {
		release_sem(view->fPlaySem);
		
		// as we are doing stop->start, restart audio if needed.
		if (audioTrack != NULL)
			audioOutput->Play();
		startTime = system_time()-counterTrack->CurrentTime();		

		// This will loop until the end of the stream
		while ((counterTrack->CurrentFrame() < numFrames) || scrubbing) {
		
			// We are in scrub mode
			if (acquire_sem(view->fScrubSem) == B_OK) {
				curScrubbing = system_time();

				// We are entering scrub mode
				if (!scrubbing) {
					if (audioTrack != NULL)
						audioOutput->Stop();
					scrubbing = true;
				}
				// Do a seek.
				seekNeeded = true;
				seekTime = view->fScrubTime;
			}
			// We are not scrubbing
			else if (scrubbing) {
				if (audioTrack != NULL)
					audioOutput->Play();
				scrubbing = false;
			}
			
			// Handle seeking
			if (seekNeeded) {
				if (videoTrack) {
					// Seek the seekTime as close as possible
					vStartTime = seekTime;
					videoTrack->SeekToTime(&vStartTime);
					
					// Read frames until we get less than 50ms ahead.
					lastTime = vStartTime;
					do {
						bitmap->LockBits();
						status_t err = videoTrack->ReadFrames((char*)bitmap->Bits(), &dummy, &mh);
						bitmap->UnlockBits();
						if (err != B_OK) break;
						vStartTime = mh.start_time;
						if ((dummy == 0) || (vStartTime <= lastTime))
							break;
						lastTime = vStartTime;
					} while (seekTime - vStartTime > 50000);
				}
				
				if (audioTrack) {
					// Seek the extractor as close as possible
					aStartTime = seekTime;
					audioOutput->SeekToTime(&aStartTime);
					
					// Read frames until we get less than 50ms ahead.
					lastTime = aStartTime;
					while (seekTime - aStartTime > 50000) {
						if (audioTrack->ReadFrames((char *)adBuffer, &dummy, &mh) != B_OK)
							break;
						aStartTime = mh.start_time;
						if ((dummy == 0) || (aStartTime <= lastTime))
							break;
						lastTime = aStartTime;
					}
				}
				else startTime = system_time() - vStartTime;
				
				// Set the current time
				view->fCurTime = seekTime;	
			
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		printf("MediaConverterApp::_ConvertFile()"
				" - user canceled before transcoding\n");
		ret = B_CANCELED;
	}

	if (ret < B_OK) {
		delete[] audioBuffer;
		delete[] videoBuffer;
		delete outFile;
		return ret;
	}

	outFile->CommitHeader();
	// this is where you would call outFile->AddCopyright(...)

	int64 framesRead;
	media_header mh;
	int32 lastPercent, currPercent;
	float completePercent;
	BString status;

	int64 start;
	int64 end;
	int32 stat = 0;

	// read video from source and write to destination, if necessary
	if (outVidTrack != NULL) {
		lastPercent = -1;
		videoFrameCount = inVidTrack->CountFrames();
		if (endDuration == 0 || endDuration < startDuration) {
			start = 0;
			end = videoFrameCount;
		} else {
			inVidTrack->SeekToTime(&endDuration, stat);
			end = inVidTrack->CurrentFrame();
			inVidTrack->SeekToTime(&startDuration, stat);
			start = inVidTrack->CurrentFrame();
			if (end > videoFrameCount)
				end =  videoFrameCount;
			if (start > end)
				start = 0;
		}

		framesRead = 0;
		for (int64 i = start; (i <= end) && !fCancel; i += framesRead) {
			if ((ret = inVidTrack->ReadFrames(videoBuffer, &framesRead,
					&mh)) != B_OK) {
				fprintf(stderr, "Error reading video frame %" B_PRId64 ": %s\n", i,
						strerror(ret));
				snprintf(status.LockBuffer(128), 128,
						B_TRANSLATE("Error read video frame %" B_PRId64), i);
				status.UnlockBuffer();
				SetStatusMessage(status.String());

				break;
			}

			if ((ret = outVidTrack->WriteFrames(videoBuffer, framesRead,
					mh.u.encoded_video.field_flags)) != B_OK) {
				fprintf(stderr, "Error writing video frame %" B_PRId64 ": %s\n", i,
						strerror(ret));
				snprintf(status.LockBuffer(128), 128,
						B_TRANSLATE("Error writing video frame %" B_PRId64), i);
				status.UnlockBuffer();
				SetStatusMessage(status.String());