[FFmpeg-devel] Irregular codec

Kostya kostya.shishkov
Mon Jun 30 14:41:08 CEST 2008

On Mon, Jun 30, 2008 at 06:44:55AM -0400, Jesse L. Zamora wrote:
> Benjamin Larsson wrote:
> > On Fri, Jun 27, 2008 at 07:58:11PM -0400, Jesse L. Zamora wrote:
> >   
> >> Hello All,
> >>
> >> I've been writing a demuxer and a decoder for the SMV format (SigmaTel 
> >> Motion Video) for ffmpeg. It begins with a WAV file, then the SMV header 
> >> afterwards, then an array of jpegs. I was trying to get my demuxer to be 
> >> able to read the SMV header, but since it's practically in the middle of 
> >> the file, the buffer is not that big! So I can't read the header through 
> >> the buffer. How can I somehow read in the middle of the file with the 
> >> demuxer_probe(AVProbeData *p) function to be able to read the header 
> >> (especially with demuxer_read_header())?
> >>
> >> Thanks
> >>
> >> Xtreme Kommander
> >>     
> >
> > Hi, can you derive that it is a SMV file from the wav header ?
> >
> > MvH
> > Benjamin Larsson
> I was hoping that I could, but it seems that the WAV header has only 
> fields for WAV.....and the SMV header is in the middle of the file.
> Xtreme Kommander

Since detecting SMV would require seeking after WAV file end (size
specified in RIFF header), it can't be done during probe stage.

I see three ways here:
1) patch WAV demuxer to handle SMV files as well (not nice at all)
2) make WAV demuxer detect SMV files and print warning ("hey, use -f smv")
3) make SMV demuxer and hope users will add -f smv by themselves

and there's always
0) SMV? What's that?

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