[MPlayer-users] [Question]Changing aspect ratio when playing a video file

[Reimar Döffinger]

On Fri, Sep 12, 2008 at 12:00:03PM +0200, Nico Sabbi wrote:
> On Friday 12 September 2008 11:50:03 Kan-I Jyo wrote:
> > For I am new to this list, what I am posting might be some kind of
> > cliche to most of you, but I would like to know the basic routine
> > when playing a video file.
> >
> > It is my understanding that when we open a file in a video player,
> > such as (s)mplayer(one of my favorite), the flow would generally
> > goes like:
> >
> > Open a file -> Check file header for some format information ->
> > looking for a appropriate decoding codec -> decoding the data and
> > send them back to video player -> show the strem on screen.
> >
> > If the above to be correct, at which stage(s), would the "changing
> > aspect ratio" opearation would be taken?
> 
> 
> "decode the video" data, unless there's some aspect ratio change
> signalled in the demuxer or stream layer (dvds, at the stream layer,
> sometimes report a different A/R than the one in the video stream,
> but only at the beginning of a title,  not mid-stream)

Hm, you gave the answer to where the aspect ration change "event" is
"created", but that is not where it is processed (which is in vo or vf,
i.e. during output to screen or during filtering).