[FFmpeg-devel] [RFC] Expose more legal encoding parameters from AVCodec

Stefano Sabatini stefano.sabatini-lala
Tue Apr 8 15:39:33 CEST 2008


On date Tuesday 2008-04-08 15:20:24 +0200, Michael Niedermayer encoded:
> On Tue, Apr 08, 2008 at 01:17:45PM +0200, Stefano Sabatini wrote:
[...]
> > Excellent, here it is a list of the fields I would like to see
> > implemented each one with a corresponding braindump, please comment on
> > them if you have suggestions/blames regarding them.
> 
> first comment: seperate patches!

Of course, but I wanted to recollect more informations before to send
completely misguided patches ;-)!!
 
> > long_name
> > =========
> > 
> > As in AV{Input|Output}Format, the names could sound
> > something like:
> > 
> 
> > mpeg1video -> "Mpeg 1 video",
> > "wmv2" -> "Windows Media Video version 8"
> > "msmpeg4v2" -> "Mpeg 4 part 2 Microsoft variant version 2"
> > "flv" -> "Flash video"
> > "h264" -> "H.264 aka Mpeg 4 part 10 aka AVC (Advanced Video Codec)"
> 
> Please leave choosing long names to others! Iam fine with adding a long name
> field but i will not waste my time to think about good names and your
> long names are bad with the exception of flash video.

OK, I happily leave this choice to others, ideally to the respective
codecs maintainers.

> [...]
> > supported_video_sizes
> > =====================
> > 
> > There isn't a structure used to define a video size in libavcodec, we
> > could create such thing then have a list as in supported_framerates,
> > otherwise we could use a simple array of strings then use
> > av_parse_video_frame_size() to parse them.
> 
> array of int[2]!
> 
> 
> > 
> > {min|max}_audio_channels
> > ========================
> > 
> > Should express the maximum and minimum number of channels supported by
> > the stream.
> > 
> > I don't know if it makes sense a min_audio_channels field, maybe there
> > is some codec which doesn't support for example less than 2 channels.
> 
> This is rejected until we have proper multichannel support. A min/max is
> almost certainly not usefull.

Also looking at libamr.c I thought about a supported_bitrates field, I
don't know if this could be useful for other codecs as well. It could
be implemented both as a list of integers or as an expression for the
arithmetic evaluator so to gain more flexibility... thoughts?

Thanks for your feedback, best regards.
-- 
Stefano Sabatini
Linux user number 337176 (see http://counter.li.org)




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