[MPlayer-dev-eng] Demuxer development questions

[Mikhail Ramendik]

Hello,

Nico Sabbi wrote:

> >- Is there a way to pass options to a demuxer? (I mean, let the user
> >specify options that will be passed to it). 

> as in every other option:
> in cfg-common.h add a reference to external variables in the demuxer's 
> source. 

Thanks! This is indeed in the right direction. Looks like I'll have to
look into the lavc decoder code to find out about the suboptions
stricture, but at least this is a start.

> >- Is there a way for a demuxer to create a subtitle layer, along with a
> >video layer? If so, how does the demuxer tell MPlayer that a subtitle
> >layer is present, and where could I get the description of the format in
> >which it should be given? 

> welcome to the hell of subtitles:) Only dvd subs can be pushed to 
> demuxer->sub, all the others
> must be managed indipendently using a subtitle structure (defined in 
> .../subtitle.h) and create
> a function to fill it with text and call vo_osd_changed(OSD_SUBTITLE_TYPE).
> Many demuxers do it.

By a simple search I found three files in libmpdemux that do this call:
Matroska, Ogg, and something called demux_ty_osd.c.

Now I have something to research, ant to try to imitate. Thanks!

> Since you are at it, why don't you add mplayer a sh_subs structure and 
> the relative code to manage
> fifos of subtitles and dispatch them to the right decoders, as is 
> currently done for video and audio?
> It would be very nice :)

I don't feel ready to modify anything in mplayer core (as opposed to a
single demuxer). Besides, non-text (and non-DVD) subtitles are a
somewhat rare thing...

Yours, Mikhail Ramendik