[FFmpeg-devel] RTP mark bit not passed to parse_packet
Thu Jan 15 15:33:43 CET 2009
Alexandre FERRIEUX - FT/RD/SIRP/ASF/SOFTL wrote:
> OK I followed your advice, and it partly works :)
> "Partly", because passing the raw bitstream as is (ie one AV packet per
> RTP packet, after taking care of the headers as specified above), yields
> complaints from the decoder (Bad picture start code...header damaged).
Did you set st->need_parsing = AVSTREAM_PARSE_FULL?
Can you try something like "ffmpeg -i h263.sdp -vcodec copy out.263"
and check if "out.263" is a valid H.263 bitstream?
> So I suspected the decoder wanted whole pictures
Yes, the decoder wants whole pictures, but there is a "parser" between
the demuxer and the decoder, and the parser transforms the bitstream in
a sequence of frames (AFAIK).
Check what the MPEG1VIDEO de-packetiser does: if a frame is split in more
packets, it returns only a part of the frame.
I expect to see the decoder complaining at the beginning of a stream, but
then it should work...
> static int h263_handle_packet(PayloadContext *data,
> AVStream *st,
> AVPacket * pkt,
> uint32_t * timestamp,
> const uint8_t * buf,
> int len, int flags)
> if(buf & 0x04) /* P bit in H263 payload header */
> memcpy(data->buf+2, buf+2, len-2);
> if (flags&RTP_FLAG_M_BIT) /* M bit in RTP header */
> return 0;
I suspect the problem here is that if M is not set you return 0
(which means "packet is returned"), but you do not put anything
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