[MPlayer-users] MPlayer-1.0pre8 detecting wrong aspect ratio

[Giacomo Comes]

On Mon, Jul 31, 2006 at 04:27:34PM +0200, Nico Sabbi wrote:
> Raj Kiran Grandhi wrote:
> >On 7/31/06, RC <rcooley at spamcop.net> wrote:
> >>On Mon, 31 Jul 2006 08:21:23 +0530
> >>"Raj Kiran Grandhi" <grkiran at gmail.com> wrote:
> >>
> >>> I find that mplayer detects a wrong aspect ratio for .dat files.
> >>
> >>As a shot in the dark, you might try with -vfm ffmpeg, and see if there
> >>is any change.
> >
> >Thank you. The -vfm ffmpeg now scales the video correctly, but
> >-identify still reports the aspect ratio as 0.0000.
> >
> >I use a script for encoding with mencoder. The script reads the aspect
> >ratio from the output of -identify. Now with this problem, the script
> >fails to detect the aspect ratio, and I am having to provide it
> >manually.
> 
> if it's wrong it's wrong

No Nico,
1.0pre8 and current svn have a BUG.
The bug consists in the fact that mplayer does not detect correctly the
aspect ration of MPEG1 streams.

Example 1: 4/3 (1.33:1) PAL MPEG1 stream
VIDEO:  MPEG1  352x288  (aspect 2)  25.000 fps  1152.0 kbps (144.0 kbyte/s)

1.0pre8 plays it as:
Movie-Aspect is 1.81:1 - prescaling to correct movie aspect.
VO: [xv] 352x288 => 522x288 Planar YV12

1.0pre7 plays it as:
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
VO: [xv] 352x288 => 384x288 Planar YV12


Example 2: 4/3 (1.33:1) NTSC MPEG1 stream
VIDEO:  MPEG1  352x240  (aspect 2)  29.970 fps  1152.0 kbps (144.0 kbyte/s)

1.0pre8 plays it as:
Movie-Aspect is 2.18:1 - prescaling to correct movie aspect.
VO: [xv] 352x240 => 522x240 Planar YV12

1.0pre7 plays it as:
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
VO: [xv] 352x240 => 352x264 Planar YV12

The bug is not limited to 4/3 aspect ratio. Also 16/9 is misdetected.
As already said, this bug breaks also any script that use mplayer to retreive 
the aspect ratio of a movie (therefore a quick fix is welcome).

Giacomo