C++ IDeckLinkOutput::EndAudioPreroll方法代码示例

        void setup_audio( ) {
            /* FIXME hard coded default */
            n_channels = 2; 

            audio_in_pipe = new Pipe<AudioPacket *>(OUT_PIPE_SIZE);

            /* FIXME magic 29.97 related number */
            /* Set up empty audio packet for prerolling */
            current_audio_pkt = new AudioPacket(48000, n_channels, 2, 25626);
            samples_written_from_current_audio_pkt = 0;

            assert(deckLinkOutput != NULL);

            if (deckLinkOutput->SetAudioCallback(this) != S_OK) {
                throw std::runtime_error(
                    "Failed to set DeckLink audio callback"
                );
            }

            if (deckLinkOutput->EnableAudioOutput( 
                    bmdAudioSampleRate48kHz, bmdAudioSampleType16bitInteger, 
                    n_channels, bmdAudioOutputStreamContinuous) != S_OK) {
                throw std::runtime_error(
                    "Failed to enable DeckLink audio output"
                );
            }

            audio_preroll_done = 0;

            if (deckLinkOutput->BeginAudioPreroll( ) != S_OK) {
                throw std::runtime_error(
                    "Failed to begin DeckLink audio preroll"
                );
            }

            while (audio_preroll_done == 0) { 
                /* FIXME: busy wait */
            }

            if (deckLinkOutput->EndAudioPreroll( ) != S_OK) {
                throw std::runtime_error(
                    "Failed to end DeckLink audio preroll"
                );
            }
        }

        void setup_audio( ) {
            IOAudioPacket preroll_audio(8008, n_channels);
            preroll_audio.zero( );

            audio_in_pipe = new Pipe<IOAudioPacket *>(OUT_PIPE_SIZE);
            audio_fifo = new AudioFIFO<int16_t>(n_channels);
            audio_fifo->add_packet(&preroll_audio);

            assert(deckLinkOutput != NULL);

            if (deckLinkOutput->SetAudioCallback(this) != S_OK) {
                throw std::runtime_error(
                    "Failed to set DeckLink audio callback"
                );
            }

            if (deckLinkOutput->EnableAudioOutput( 
                    bmdAudioSampleRate48kHz, bmdAudioSampleType16bitInteger, 
                    n_channels, bmdAudioOutputStreamContinuous) != S_OK) {
                throw std::runtime_error(
                    "Failed to enable DeckLink audio output"
                );
            }

            audio_preroll_done = 0;

            if (deckLinkOutput->BeginAudioPreroll( ) != S_OK) {
                throw std::runtime_error(
                    "Failed to begin DeckLink audio preroll"
                );
            }

            while (audio_preroll_done == 0) { 
                /* FIXME: busy wait */
            }

            if (deckLinkOutput->EndAudioPreroll( ) != S_OK) {
                throw std::runtime_error(
                    "Failed to end DeckLink audio preroll"
                );
            }
        }

	HRESULT render( mlt_frame frame )
	{
		HRESULT result = S_OK;
		// Get the audio		
		double speed = mlt_properties_get_double( MLT_FRAME_PROPERTIES(frame), "_speed" );
		if ( speed == 1.0 )
		{
			mlt_audio_format format = mlt_audio_s16;
			int frequency = bmdAudioSampleRate48kHz;
			int samples = mlt_sample_calculator( m_fps, frequency, m_count );
			int16_t *pcm = 0;
			
			if ( !mlt_frame_get_audio( frame, (void**) &pcm, &format, &frequency, &m_channels, &samples ) )
			{
				int count = samples;
				
				if ( !m_isPrerolling )
				{
					uint32_t audioCount = 0;
					uint32_t videoCount = 0;
					
					// Check for resync
					m_deckLinkOutput->GetBufferedAudioSampleFrameCount( &audioCount );
					m_deckLinkOutput->GetBufferedVideoFrameCount( &videoCount );
					
					// Underflow typically occurs during non-normal speed playback.
					if ( audioCount < 1 || videoCount < 1 )
					{
						// Upon switching to normal playback, buffer some frames faster than realtime.
						mlt_log_info( &m_consumer, "buffer underrun: audio buf %u video buf %u frames\n", audioCount, videoCount );
						m_prerollCounter = 0;
					}
					
					// While rebuffering
					if ( isBuffering() )
					{
						// Only append audio to reach the ideal level and not overbuffer.
						int ideal = ( m_preroll - 1 ) * bmdAudioSampleRate48kHz / m_fps;
						int actual = m_fifo->used / m_channels + audioCount;
						int diff = ideal / 2 - actual;
						count = diff < 0 ? 0 : diff < count ? diff : count;
					}
				}
				if ( count > 0 )
					sample_fifo_append( m_fifo, pcm, count * m_channels );
			}
		}
		
		// Create video frames while pre-rolling
		if ( m_isPrerolling )
		{
			createFrame();
			if ( !m_videoFrame )
			{
				mlt_log_error( &m_consumer, "failed to create video frame\n" );
				return S_FALSE;
			}
		}
		
		// Get the video
		if ( mlt_properties_get_int( MLT_FRAME_PROPERTIES( frame ), "rendered") )
		{
			mlt_image_format format = mlt_image_yuv422;
			uint8_t* image = 0;
			uint8_t* buffer = 0;

			if ( !mlt_frame_get_image( frame, &image, &format, &m_width, &m_height, 0 ) )
			{
				m_videoFrame = (IDeckLinkMutableVideoFrame*) mlt_deque_pop_back( m_videoFrameQ );
				m_videoFrame->GetBytes( (void**) &buffer );
				if ( m_displayMode->GetFieldDominance() == bmdUpperFieldFirst )
					// convert lower field first to top field first
					swab( image, buffer + m_width * 2, m_width * ( m_height - 1 ) * 2 );
				else
					swab( image, buffer, m_width * m_height * 2 );
				m_deckLinkOutput->ScheduleVideoFrame( m_videoFrame, m_count * m_duration, m_duration, m_timescale );
				mlt_deque_push_front( m_videoFrameQ, m_videoFrame );
			}
		}
		else
		{
			mlt_log_verbose( &m_consumer, "dropped video frame\n" );
		}
		++m_count;

		// Check for end of pre-roll
		if ( ++m_prerollCounter > m_preroll && m_isPrerolling )
		{
			// Start audio and video output
			m_deckLinkOutput->EndAudioPreroll();
			m_deckLinkOutput->StartScheduledPlayback( 0, m_timescale, 1.0 );
			m_isPrerolling = false;
		}

		return result;
	}