[NUT-devel] r21189 - trunk/DOCS/tech/nut.txt

[Rich Felker]

On Fri, Nov 24, 2006 at 11:35:24PM +0100, Michael Niedermayer wrote:
> Hi
> 
> On Fri, Nov 24, 2006 at 12:37:31PM -0500, Rich Felker wrote:
> > On Fri, Nov 24, 2006 at 09:05:31AM -0800, Ralph Giles wrote:
> > > On Fri, Nov 24, 2006 at 01:51:34PM +0100, michael wrote:
> > > 
> > > > if anyone disagrees or has suggestions to improve it then shout
> > > 
> > > > +    codec_specific_data SHOULD contain exactly the essential global packets
> > > > +    needed to decode a stream, more specifically it SHOULD NOT contain packets
> > > > +    which contain only non essential metadata like author, title, ...
> > > 
> > > For codecs with required stream-embedded metadata like ours, I think 
> > > this is just making work for the muxer. I'd allow such packets, and
> > > instead say that implementations SHOULD maintain and prefer 
> > > container-level metadata with NUT. The packet should be there, even
> > > if it's minimal.
> > 
> > The packet can be there if it's required by the spec, but the metadata
> > fields should all be blank, and should be completely ignored by any
> > player. I would be in favor of a requirement that a compliant player
> > MUST NOT present user-oriented metadata from codec bitstream 
> 
> hmm, i see 3 possibilities for xiph codecs
> 1. store the metadata packet as is

What does "as is" mean? This packet should be empty in the case of a
new encoding, anyway. The only way it would contain data is when
remuxing from ogg..

> 2. dont store the metadata packet
> 3. store a dummy (empty) metadata packet

IMO option 3 is the best. It's no horrible problem if option 1 happens
sometime in practice, but players should be considered noncompliant if
they use the metadata from these headers.

"Smart" muxers could be vorbis-aware and strip any crap out of the
header before muxing. :)

Rich