[MPlayer-dev-eng] [PATCH] Read pts for VCD in demux_mpg.c

[Giacomo Comes]

On Tue, Feb 27, 2007 at 05:16:25PM +0100, Nico Sabbi wrote:
> Nico Sabbi wrote:
> 
> >Nico Sabbi wrote:
> >
> >>
> >>>    {
> >>>@@ -195,7 +196,7 @@
> >>>      float first_pts = read_first_mpeg_pts_at_position(demuxer, 
> >>>demuxer->movi_start);
> >>>      if(first_pts != -1.0)
> >>>      {
> >>>-        float middle_pts = read_first_mpeg_pts_at_position(demuxer, 
> >>>(demuxer->movi_end - demuxer->movi_start)/2);
> >>>+        float middle_pts = read_first_mpeg_pts_at_position(demuxer, 
> >>>(demuxer->movi_end + demuxer->movi_start)/2);
> >>> 
> >>>
> >>
> >>am I blind or this is cosmetics?
> >>
> >sorry, rethorical question :(
> 
> 
> yet, the general notion of middle is (end-start)/2 ; why do you want to 
> change it to (end+start)/2 ?

(end-start)/2 is the distance of the middle from start
(end+start)/2 is the absolute value of middle.

The way middle is used:
float proportion = (middle_pts-first_pts==0) ? -1 : (final_pts-middle_pts)/(middle_pts-first_pts);

suggest that the proper value to use is (end+start)/2.

Ciao
Giacomo