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

Baptiste Coudurier baptiste.coudurier
Wed Aug 23 15:45:19 CEST 2006


Michael Niedermayer wrote:
> [...]
>> Divx in mov is non standard
> disagree, mov is a generic container like avi, mkv, nut, ...
> futhermore i said already that we cannot and will not drop support for
> non standard stuff, if you keep trolling about this then ill ignore you
> btw, you can fork ffmpeg anytime if you want

Maybe right for mov but I disagree for mp4/3gp. Those are strictly
defined (there is a close saying about non defined atoms which must be
'reserved', mp4 even more strict since stsd 'fourcc' is not a way to
identify codecs, object type id must be used), assume 14496-12 and
supersiding specs are the ref, those formats still evolve and get new
definitions (mjp2, 3g2, mp4). Also www.mp4ra.org defines standard object
type ids.

You cannot put whatever fourcc in it, that's just non standard.

You basically do what you want with avi/nut, dunno about mkv. That is
not the case with mp4/3gp.

That is a point of view. History has proved that a non strict container
leads to ugly hacks (avi, mkv, will see about nut). And yes let's quit

And btw, I do NOT want to drop support, Im trying to find a good fix for
an existing problem, and yes there is a problem. I didn't mean to be
rude or anything, sorry if that was the case.

>> 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.
> there are 3 seperate things here
> 1. altering the public fourcc, that of course is a hack which isnt
>    ideal but it works and is very simple, iam not opposed to apply
>    a patch which changes this if the new system is clean and works

Well, it does NOT completely works since it alters fourcc when I stream
copy. Put mpeg2 in mov (tag 'mpeg') and stream copy to another mov ->
fourcc is upper cased. It might be a bug report if you prefer.

> 2. setting sub_id, this is conceptually wrong and adds a redundant
>    middle layer, sub_id can be used for the version of a standard
>    but not to idently non standard variants -> rejected


> 3. setting the this "sub_id" or a equivalent variable in the demuxer
>    this will break alot and consequently is out of question

Let's stop trolling and end this thread. After all you're the boss.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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