[FFmpeg-devel] [PATCH] HAM6/HAM8 support for IFF demuxer/decoder

Sebastian Vater cdgs.basty
Wed May 5 15:18:22 CEST 2010

Martin Storsj? a ?crit :
> Here, you're making the extradata format totally dependent on the layout 
> of the IffExtraContext struct. If you upgrade libavcodec to another 
> version, where this struct has changed, things will break. Implementations 
> on different architectures with different endianess, word lengths or 
> struct packings will have incompatible extradata formats. You should be 
> able to do the demuxing on one machine and the decoding (given codec 
> parameters, AVPackets and extradata) on a completely different machine.
> Therefore, the extradata format for a codec should be fixed and 
> well-defined, since it is part of the external interface for anybody using 
> libavcodec (which is a whole lot more than just libavformat and ffmpeg.c).
> So instead of using a struct for that, manually pack and unpack the values 
> that you need into a few bytes that you've allocated and kept track of. 
> Try to make sure that you won't need to change the format, to keep 
> compatibility.

Do you have good sample on how to use extradata the proper way?


Best regards,
                   :-) Basty/CDGS (-:

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