[Ffmpeg-devel] [PATCH] remove special nuv wav tags

[Baptiste Coudurier]

Reimar D?ffinger wrote:
> Hello,
> On Sun, Nov 05, 2006 at 09:13:14PM +0000, M?ns Rullg?rd wrote:
>> Are those two the only allowed codecs?  Then something like this seems
>> much more appropriate:
> 
> I can not find any specification and I have only two samples. But
> e.g. nuvexport is written in a quite generic way and video really seems
> to use the usual riff tags. And in the case of reading I really do not
> see much reason _not_ to involve riff, it won't hurt anyone (that one
> line of code is not that bad, is it?).
> Also, this:
> ast->codec->codec_id = CODEC_ID_PCM_S16LE;
> will not work, read what wav_codec_get_id does...
> 
>> See, no need to involve RIFF tags at all.  RIFF tags are *not* the
>> bloody center of the universe, even if mplayer appears to have been
>> written with that assumption.
> 
> No a lot of applications have been written like that, which makes it at
> least closer to the "center of the universe" than any other way to
> specify codecs.

Well, it seems lavf was not written like that. It uses a sane codec
mapping. Why using libavformat riff.c ?

>> Also, setting AVCodecContext.codec_tag in nuv.c seems a little
>> questionable, given that most of the code treats it as RIFF codec tag,
>> which it is not in this case.
> 
> Either codec_tag is supposed to be riff tags then it should be removed
> or it is supposed to avoid information loss when doing stream copy then
> this is the correct use IMO.
> 

codec_tag is not riff tag, mov sets it too, and seriously I don't see
why demuxer should not set it to what's in the container.

Now lavf exports CODEC_ID which is unique and accurate. That means that
applications using lavf should use CODEC_ID, not codec_tag.
codec_tag is NOT accurate NOR unique.

There is absolutely no reason to use riff.c, to map.

-- 
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
SMARTJOG S.A.                                    http://www.smartjog.com
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
Phone: +33 1 49966312