[Ffmpeg-devel] Adding a file type, and VIC codecs

Derk-Jan Hartman hartman
Wed Oct 18 02:28:21 CEST 2006

On 17-okt-2006, at 21:06, Michael Niedermayer wrote:
> On Tue, Oct 17, 2006 at 02:58:22PM -0400, Derek Piper wrote:
>> Michael Niedermayer wrote:
>>>> 	Please let me know what the view is on adding VIC codecs.  
>>>> Obviously
>>>> they would be differentiated from the ffmpeg versions, e.g.  
>>>> 'vich261',
>>>> 'vich263'.
>>> what is the difference between vic-h26* and normal h26* ?
>> I guess that's the problem. I don't KNOW what the difference is, I
>> didn't write them. I only know they are not compatible based on  
>> trying
>> to decode one with the other. I was wondering if anyone on this  
>> list had
>> done anything with both of variants so that they might be able to  
>> shed
>> more light on it. It would probably mean a lot of trawling through  
>> code
>> looking for commonalities and seeing where they differ.
> could you provide some file / a dumped vic-h26* stream which is  
> playable
> by the VIC code but not by ffmpeg?
> (you can upload to ftp://upload.mplayerhq.hu)

One of the problems with H261 is that it's possible to have multiple  
video streams in one video bitstream. In teleconferencing clients  
these present itself as sections in the final video frame (a bit like  
a videowall matrix). The separate streams can come from multiple  
locations. ffmpeg currently has no support for this. I'm not sure if  
ffmpeg even COULD merge them into one frame, or alternatively split  
them into multiple tracks.

If I watch VIC/RAT streams on the Mbone with VLC+ffmpeg, I can view  
some of these streams. It's just that all the frames of the different  
ES'es follow eachother in a rapid fashion, with different w x h  
dimensions creating a totally unviewable stream. So it can be done,  
it's just who finds it worth the effort to support this aged protocol.

I have no knowledge about H263 protocol incompatibilities. Although I  
would not be surprised if there were any :D


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