[MPlayer-users] Re: mplayer -identify with ogm files

[Moritz Bunkus]

Hi.

> I've wondered about that myself. Actually, it seems that several of the 
> MPlayer demuxers don't return correct values. I've often played a DVD 
> and seen the OSD show something like "0:10:30/0:05:0". Is the issue with 
> OGGs that they don't have global indexes like AVIs or MKVs and no 
> absolute timestamps like MPEGs? Could such a thing be added while being 
> backward and forward compatible?

Ogms do not have any index whatsoever. They do contain absolute,
non-wrapping timestamps. So in most cases seeking to the end, finding
the last Ogg page and using its timestamp as the duration should work.

However the Ogg specs say that an Ogg file may be chained, e.g. one
physical file may contain more than one logical Ogg file sequentially
(Ogms with several streams are parallel streams!). In this case the
timestamps start at 0 for each logical Ogg file, so the method mentioned
above will not work. On the other hand I've only seen audio only files
made in this way, e.g. rips of a complete CD in one physical file.

Adding an index would be pretty easy, but I don't see much point to a
mplayer-only feature. And only my ogmmerge would be able to produce such
an index, so other files (coming from Windows) wouldn't benefit from it
at all.

> By the way, did you see my message about -mc and variable framerate
> OGMs?

Yes, but I haven't had time to verify that with the actual demux_ogg.c.

-- 
 ==> Ciao, Mosu (Moritz Bunkus)
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