[NUT-devel] Fourcc spec

[Michael Niedermayer]

Hi

On Sat, Dec 23, 2006 at 03:26:42PM +0200, Oded Shimon wrote:
> On Sat, Dec 23, 2006 at 03:09:24PM +0200, Oded Shimon wrote:
> > On Sat, Dec 23, 2006 at 01:56:29PM +0100, Michael Niedermayer wrote:
> > > if the lists are not normative that i bet every commercial company will
> > > use their own fourcc divx, 3ivx, ...
> > > why?
> > > 1. the company can better claim that its their own supperior technology
> > > 2. they dont need to bother to implement the standard correctly, its enough
> > >    if their decoder matches their encoder, this is what has happened with
> > >    codecs in avi and as its less work = less money it will happen again.
> > >    It didnt happen with mpeg-ps/ts just because there are too many hw
> > >    decoders around which cant be updated that easily all IMHO
> > > 
> > > if my hypothesis turns out to be true then 3. would loose the 
> > > "single fourcc per codec" and ""Sane" codec names" as in practice the
> > > majority of videos would not use the recommanded fourccs
> > > 
> > > so that brings us to option 4 which would require a player to only support
> > > a codec if the one and only standard fourcc where used, if a unknown fourcc
> > > is used demuxing it would be a violation of the spec ...
> > > 
> > > if that would prevent the issue iam not sure though ...
> > 
> > The list IS normative for demuxers, not for muxers. This was already in my 
> > original proposal, I forgot to re-mention it here.
> 
> To spell it out again:
> 
> A muxer SHOULD use the fourcc from the codec list
> A demuxer MUST support the fourcc from the codec list if it supports the 
> codec at all

ive no problem with this its pure bikeshed after all 


> 
> Which means demuxers can have additional fourcc's to the ones in the 
> official list, and a muxer can do whatever it wants. But obviously, both 
> are better off using the official list.

well a demuxer is better off if it uses a complete list with as many fourccs
as possible
and a muxer is normally best off if its files look best on as many players
as possible, this may or may not achieved with the official fourcc, most of
the time though the standard fourcc will be the best choice

additionally there is the capitalistic scum which will always use their own
fourcc as it gives them more control, lets them claim that their codec is
not just standard mpeg4/h264 (keep in mind that their buisness model might
not be to sell encoders/muxers but rather to sell decoders/demuxer in which
case it is not in their interrest that the files can be played by as many
other decoders/demuxers as possible ...)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No great genius has ever existed without some touch of madness. -- Aristotle
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