mpeg_demux.cpp

linux下实现视频播放的播放器

    {

	// If this was already filled
/*	if(pat_entries[entry].valid_pmt)
	    continue;*/

        if(pid != pat_entries[entry].pmtpid) {
	    LOG_MSG("PID not equal 0x%x!", pat_entries[entry].pmtpid);
	    continue;
	}

	if((ndx = ProcessHeader(pat_entries[entry].first_pmt)) < 0)
	    return false;

	// Skip to the start of the section.
	ndx += pkt[ndx] + 1;

	// Now pointing to the start of the section. Check the table id.
	if(pkt[ndx++] != 2) {
	    ERROR_MSG("Table ID not 2!");
	    return false;
	}

	// Check the section syntax indicator.
	if((pkt[ndx] & 0xc0) != 0x80) {
    	    ERROR_MSG("Invalid syntax indicator!");
	    return false;
	}

	// Check and get section length.
	if((pkt[ndx] & 0x0c) != 0) {
	    ERROR_MSG("Section length invalid!");
	    return false;
	}

	length = ((pkt[ndx++] & 0x03) << 8);
	length |= pkt[ndx++];

	DEBUG_MSG("Detected length %d", length);

	if(length > 0x3fd) {
    	    ERROR_MSG("Length is too large!");
    	    return false;
	}

	begin = ndx;
	// Skip the program number
	ndx += 2;

	// We want only current tables.
	if(!(pkt[ndx++] & 0x01)) {
    	    ERROR_MSG("No current tables!");
    	    return false;
	}

	// Get the number of this section.
	number = pkt[ndx++];
	DEBUG_MSG("Number of the current section %d", number);

	// Get the number of the last section.
	last = pkt[ndx++];
	DEBUG_MSG("Number of the last section %d", last);

	// Get the PCRPID.
	pat_entries[entry].pcrpid = (pkt[ndx++] & 0x1f) << 8;
	pat_entries[entry].pcrpid |= pkt[ndx++];
	ERROR_MSG("PCR on PID 0x%x", pat_entries[entry].pcrpid);

	// Skip the descriptors (if any).
	descriptors_length = (pkt[ndx++] & 0x0f) << 8;
	descriptors_length |= pkt[ndx++];
	ndx += descriptors_length;

	MPEG2_Transport_AudioPID = MPEG2_Transport_VideoPID = 0;

	// Now we have the actual program data.
	while (ndx < begin + length - 4)
	{
	    num_streams = pat_entries[entry].num_streams;
	    ERROR_MSG("Found new stream %d, type: 0x%x", num_streams, pkt[ndx]);

	    switch (pkt[ndx++]) {
		case 0x01:
		    pat_entries[entry].streams[num_streams].stream_type = "MPEG1 Video";
		    m_video = true;
		    break;
		case 0x02:
		    pat_entries[entry].streams[num_streams].stream_type = "MPEG2 Video";
		    m_video = true;
		    break;
		case 0x03:
		    pat_entries[entry].streams[num_streams].stream_type = "MPEG1 Audio";
		    m_audio = true;
		    break;
		case 0x04:
		    pat_entries[entry].streams[num_streams].stream_type = "MPEG2 Audio";
		    m_audio = true;
		    break;
		case 0x05:
		    pat_entries[entry].streams[num_streams].stream_type = "Private Sections";
		    break;
		case 0x06:
		case 0x07:
		    pat_entries[entry].streams[num_streams].stream_type = "Teletext/Subtitling";
		    break;
		case 0x0f:
		case 0x11:
		    // The demuxing code is the same for MPEG and AAC.
		    // The only difference will be the filename.
		    // The demuxing code will look at the audio sync word to
		    // decide between the two.
		    //type = 0x04;
		    pat_entries[entry].streams[num_streams].stream_type = "AAC Audio";
		    m_audio = true;
		    break;
		case 0x1b:
		    pat_entries[entry].streams[num_streams].stream_type = "h264 Video";
		    m_video = true;
		    break;
		case 0x81:
		    pat_entries[entry].streams[num_streams].stream_type = "AC3 Audio";
		    break;
		default:
		    pat_entries[entry].streams[num_streams].stream_type = "Other";
		    break;
	    }

	    pat_entries[entry].streams[num_streams].pid = (pkt[ndx++] & 0x1f) << 8;
	    pat_entries[entry].streams[num_streams].pid |= pkt[ndx++] & 0xFF;

	    ERROR_MSG("%s on PID 0x%x", pat_entries[entry].streams[num_streams].stream_type,
						pat_entries[entry].streams[num_streams].pid);

	    // Increment stream counter
	    if(pat_entries[entry].num_streams < MAX_STREAMS - 1) {
		pat_entries[entry].num_streams++;
	    } else {
		ERROR_MSG("MAX_STREAMS reached!");
	    }

	    // Skip the ES descriptors.
	    es_descriptors_length = (pkt[ndx++] & 0x0f) << 8;
	    es_descriptors_length |= pkt[ndx++];
	    ndx += es_descriptors_length;
	}

	pat_entries[entry].first_pmt = false;

	// If this is the last section number, we're done.
	if(number == last)
	    num_valid_pmts++;
    }

    return true;
}


void mpeg_demux::ProcessVideoPacket()
{
    int ndx;
    Packet packet;
    unsigned int flags;

    DEBUG_MSG("Processing video packet..");

    if((ndx = ProcessHeader(m_video)) < 0)
	return;

    // Start packet, we should now look for PES header
    if((pkt[1] & 0x40) >> 6) {
	if((pkt[ndx] == 0x0) && (pkt[ndx + 1] == 0x0) && (pkt[ndx + 2] == 0x1))
	    DEBUG_MSG("PES header found!");
	else {
	    DEBUG_MSG("Not a PES header: 0x%x 0x%x 0x%x", pkt[ndx], pkt[ndx + 1], pkt[ndx + 2]);
	    return;
	}

	// Check for scrambling
	if(pkt[ndx + 6] & 0x60) {
	    ERROR_MSG("PES Scrambling: 0x%x", pkt[ndx + 6] & 0x60);
	}

	// Skip PES header (3 bytes) + stream ID (1 byte)
	// PES packet length (2 bytes) + extension flags (1 byte)
	ndx += 7;

	flags = pkt[ndx++];

	DEBUG_MSG("PES header length %d", pkt[ndx]);

	packet.pes_flag = true;
	// Stop at Packet_Header_Length field & get timestamp
	if((flags & 0x80) && (pkt[ndx] > 4)) {
	    // Ignore bit 33, or mask would be 0x0e
	    packet.pts =  (pkt[ndx+1] & 0x06) << 29;
	    packet.pts |= (pkt[ndx+2]) << 22;
	    packet.pts |= (pkt[ndx+3] & 0xfe) << 14;
	    packet.pts |= (pkt[ndx+4]) << 7;
	    packet.pts |= (pkt[ndx+5] & 0xfe) >> 1;

	    // Convert to ms
	    packet.pts /= 90;
	}

	// Make sure first packet has PTS stamp
	if(m_video && (packet.pts == 0)) {
	    LOG_MSG("Missing PTS timestamp");
	    return;
	}

	// Now, skip rest of PES-header
	ndx += pkt[ndx] + 1;

	/*if(!Start_Flag)
	{
	    // Start_Flag becomes true after the first I frame.
	    // So VideoPTS will be left at the value corresponding to
	    // the first I frame.
	    VideoPTS = pts_stamp;
	}*/

	// Check that we have a SEQ header (00 00 01 B3 for mpeg2)
	if(m_video) {
	    // Some streams have an extra 00 ??
	    if((pkt[ndx+2] == 0x0) && (pkt[ndx+3] == 0x1)) {
		LOG_MSG("Additional data before ES!");
		ndx++;
	    }

	    if(SeqHeader(pkt+ndx)) {
		DEBUG_MSG("Found Sequence header.");
		m_video = false;
	    } else {
		DEBUG_MSG("No Sequence header at ndx: %d (bytes 0x%x 0x%x 0x%x 0x%x 0x%x)!", ndx, pkt[ndx], pkt[ndx+1], pkt[ndx+2], pkt[ndx+3], pkt[ndx+4]);
		return;
	    }
	}
	DEBUG_MSG("Video PES starts with 0x%x 0x%x 0x%x 0x%x 0x%x", pkt[ndx], pkt[ndx+1], pkt[ndx+2], pkt[ndx+3], pkt[ndx+4]);
    }

    // We are at the start of ES :-)
    // Length is TS_PACKET_SIZE - ndx
    packet.data = pkt+ndx;
    packet.size = TS_PACKET_SIZE - ndx;
    if(videodec) {
	videodec->WriteData(&packet);
	DEBUG_MSG("Wrote %d bytes to video decoder", TS_PACKET_SIZE - ndx);
    } else {
	ERROR_MSG("No video decoder connected!");
    }
}


void mpeg_demux::ProcessAudioPacket()
{
    int ndx;
    Packet packet;
    unsigned int flags;

    DEBUG_MSG("Processing audio packet..");

    if((ndx = ProcessHeader(m_audio)) < 0)
	return;

    // Start packet, we should now look for PES header
    if((pkt[1] & 0x40) >> 6) {
	if((pkt[ndx] == 0x0) && (pkt[ndx + 1] == 0x0) && (pkt[ndx + 2] == 0x1))
	    DEBUG_MSG("PES header found!");
	else {
	    LOG_MSG("No PES header in audio stream!");
	    return;
	}

	// Skip PES header (3 bytes) + stream ID (1 byte)
	// PES packet length (2 bytes) + extension flags (1 byte)
	ndx += 7;

	flags = pkt[ndx++];

	DEBUG_MSG("PES header length %d", pkt[ndx]);

	// Stop at Packet_Header_Length field & get timestamp
	if((flags & 0x80) && (pkt[ndx] > 4)) {
	    // Ignore bit 33, or mask would be 0x0e
	    packet.pts  =  (pkt[ndx+1] & 0x6) << 29;
	    packet.pts |= (pkt[ndx+2]) << 22;
	    packet.pts |= (pkt[ndx+3] & 0xfe) << 14;
	    packet.pts |= (pkt[ndx+4]) << 7;
	    packet.pts |= (pkt[ndx+5] & 0xfe) >> 1;

	    // Convert to ms
	    packet.pts /= 90;
	    DEBUG_MSG("Found PTS %d", packet.pts);
	}

	// Now, skip rest of PES-header
	ndx += pkt[ndx] + 1;

	// Make sure first packet has PTS stamp
	if(m_audio && (packet.pts == 0)) {
	    LOG_MSG("Missing PTS timestamp");
	    return;
	}

	DEBUG_MSG("Audio PES starts with 0x%x 0x%x 0x%x 0x%x 0x%x", pkt[ndx], pkt[ndx+1], pkt[ndx+2], pkt[ndx+3], pkt[ndx+4]);
	packet.pes_flag = true;
	packet.data = pkt+ndx;
	packet.size = TS_PACKET_SIZE - ndx;
	if((audiodec) && (audiodec->WriteData(&packet))) {
	    DEBUG_MSG("Wrote %d bytes to audio decoder", TS_PACKET_SIZE - ndx);
	    m_audio = false;
	} else {
	    LOG_MSG("Audio decoder not ready yet.");
	}
	return;
    }

    // We are at the start of ES :-)
    // Length is TS_PACKET_SIZE - ndx
    packet.data = pkt+ndx;
    packet.size = TS_PACKET_SIZE - ndx;
    if(audiodec) {
	audiodec->WriteData(&packet);
	DEBUG_MSG("Wrote %d bytes to audio decoder", TS_PACKET_SIZE - ndx);
    } else {
	LOG_MSG("No audio decoder connected!");
    }
}