[Ffmpeg-devel] Re: [PATCH] mpegvideo remove fourcc upper case conversion

Baptiste Coudurier baptiste.coudurier
Wed Aug 23 11:16:22 CEST 2006


Michael Niedermayer wrote:
>> [...]
>> declaring a sub_id for old divx/whatever mpeg4 flavour is cleaner IMHO,
>> and avi demuxer could set it.
> no this has nothing to do with the demuxer, divx in mov, nut, mkv, raw
> mpeg4-es or in mpeg-ps will all need the very same code it belongs to the
> codec, and its not just divx, there are 10 different ones furthermore
> lavc MUST be independant from lavf, not everyone uses lavc with lavf

It DOES since demuxer identifies codec. Lavc chose to handle differently
h263 variants based on their fourcc, it is one way of course, and that
sounds like the old troll about identifying codec/variant by fourcc like
we had about nut. Divx in mov is non standard

IMHO Cleanest way was to identify them by sub_id/codec_id and not to
alter fourcc. Values from the file should be kept as is, at least you
told me that many times and furthermore regarding fourcc.

> [...]
> AVCodecContext.width/height are the _CODEC_ width/height not the user
> croped width/height, if the demuxer doesnt have reliable values it
> MUST NOT set AVCodecContext.width/height, it can set something else
> to "transport" them to the muxer for stream copy but NOT the codec
> width/height its like storing width/height in the audio samplerate and
> number of audio channels
> [...]

I can set them to 0 for H261,H263,MPEG-4. And let decoder init them
correctly. Is that what you want ?
Setting correctly width and height for H261 lotr.mov (352x288), make
quicktime player playing it as 320x200 with black borders, and gray line
under video. I guess h261 qt codec is behaving differently regarding
specs resolutions.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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