[gst-devel] re： Re: how to use qtdemux to demux h264 stream from MP4?

[Edward Hervey]

Hi,

  Could you also try applying the following patch fixing qtdemux so
that it outputs h264 buffers with pts instead of dts. If you are
making a software decoder you shouldn't need the dts.
  the patch and explanations are here :
http://bugzilla.gnome.org/show_bug.cgi?id=423283

    Edward

On 3/26/07, jp_liu <jp_liu at astrocom.cn> wrote:
>
>
> zhangfei gao, Hello
>
> My h264 decoder support say that:
> I believe MP4 uses the NAL format (Need to confirm) and hence doesn't have
> the NAL Start codes. One needs to convert that to bytstream format because
> our decoders support only byte-stream format. Also one needs to do this
> while demuxing it from MP4 otherwise the information various slice positions
> would be lost.
>
> So, How should I do?
>
> jp_liu, jp_liu at astrocom.cn
> 2007-03-26
>
> ----- Receiving the following content -----
> From: zhangfei gao
> Receiver: gstreamer-devel
> Time: 2007-03-22, 21:24:01
> Subject: [gst-devel]re： Re: how to use qtdemux to demux h264 stream from
> MP4?
>
>
>
>
>
>
> hi, jp_liu
>
> "h264.c" in ffmpeg has useful information of how to parse "codec_data" which
> get set_caps.
> "codec_data" has all the nal_length, sps data and pps data.
>
> Thanks
> Jan Schmidt <thaytan at noraisin.net> 写道：
> jp_liu wrote:
> > Hello, gstreamer-devel
> >
> > How to use qtdemux to demux h264 stream from MP4?
> > The demuxed h264 stream looks have no startcodes before every NAL
> > Unit. So, Some key information ( such as: SPS PPS ....) is missed. It
> > caused my H264 decoder can not decode the frame which demuxed by qtdemux .
> > How can I solve this problem?
> >
>
> I think the information your decoder is looking for is the stuff
> provided by the 'codec_data' in the caps. This is the header information
> that quicktime stores and provides separately from the actual data stream.
>
> Regards,
> Jan.
>
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-- 
Edward Hervey
Multimedia editing developer / Fluendo S.A.
http://www.pitivi.org/