[FFmpeg-devel] Irregular codec

Måns Rullgård mans
Mon Jun 30 15:36:47 CEST 2008

Benjamin Larsson wrote:
> Kostya wrote:
>> 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?
> Well .smv and wav header -> SMV file, should work also.

What if it really is just a plain wav file, only with a funny name?

M?ns Rullg?rd
mans at mansr.com

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