Hi On Sun, Dec 24, 2006 at 09:03:00AM +0000, Måns Rullgård wrote:
Oded Shimon <ods15@ods15.dyndns.org> writes:
On Sat, Dec 23, 2006 at 09:13:59PM +0000, M?ns Rullg?rd wrote:
Oded Shimon <ods15@ods15.dyndns.org> writes:
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
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.
This makes no sense at all, but I think you already knew my opinion...
Actually, no, I'm confused by your reply... I was slightly off - the demuxer is better off using as many fourcc's as it wants, but it MUST include also the official list. The muxer, in most cases, is better off using only fourcc's from the official list, so it has garuntee of demuxers supporting it. I fail to see how this does not make sense. I don't know if you noticed, but I'm going through this entire thing only because of you, I personally do not care. So please, present your arguments.
Having a list makes no sense unless it's normative for both sides.
agree though thats a statement and not a argument the argument ("proof" by contradction) is that if the muxer can choose any fourcc for standard mpeg4 (not buggy near mpeg4 ...) then a demuxer cannot support mpeg4 in nut with 100% certainity, theres the very small possibility that mpeg4 would be stored with another new and unknown fourcc ... btw, one interresting goal of the codec id system should be: the system must be generic so that 2 users who otherwise cannot communicate can mux and demux a codec X in nut with high propability of success, without manual intervention and assuming the codec has a de-facto standard fourcc in avi [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Republics decline into democracies and democracies degenerate into despotisms. -- Aristotle