[MPlayer-dev-eng] more NUT questions

[Loren Merritt]

On Thu, 15 Apr 2004, The Wanderer wrote:

> Moritz Bunkus wrote:
>
>> Hi,
>>
>>> Oh yes, it is done. By the same format you give as example. Ogg
>>> vorbis audio in ogm, is ogg in ogg.
>>
>> Wrong, no one stores an Ogg bitstream inside an Ogg/OGM bitstream.
>> Vorbis is stored directly in an OGM. In fact, a file with a single
>> Vorbis track and no other tracks is the same in Ogg and OGM.
>
> This is the correct behaviour, but I don't think it's necessarily the
> case, any more than people put (say) XviD in OGM instead of XviD in AVI
> in OGM. I believe that what is considerably more likely to happen, given
> the tendency towards the latter, is that people encode a Vorbis file
> separately (which then ends up in its own Ogg container) and then mux
> *that* file, container and all, into an OGM.
>
> It's possible (haven't looked) that this doesn't actually happen, but if
> so I'd be very surprised, since there are AFAIK no Vorbis encoders which
> do not also automatically mux the resulting audio into an Ogg and hence
> no way to get "clean" Vorbis for muxing into another file.
>
> (I'm surprised I'm posting this, after feeling like such an idiot less
> than a hour ago over my idiotic post to the CVS-log list... perhaps I'm
> just a glutton for punishment.)

Yes, Vorbis encoders produce vorbis-in-ogg and movie encoders usually
produce xvid-in-avi, but ogmmerge automatically demuxes any ogg or avi
input files you pass it.

~> ogmmerge -o foo.ogm foo.ogg
Using OGG/OGM demultiplexer for foo.ogg.
OGG/OGM demultiplexer (foo.ogg): using Vorbis audio output module for
stream 1.
~> ls -l
-rw-r--r--    1 loren    users     6785203 Apr 15 10:13 foo.ogg
-rw-r--r--    1 loren    users     6785230 Apr 15 10:40 foo.ogm

--Loren Merritt