[mythtv-users] Wrong aspect Ratio on some videos with internal player

[Daniel Kristjansson]

On Sat, 2009-08-15 at 17:32 +0300, Yianni Vidalis wrote: 
> The problematic videos can be forced to the correct aspect ratio if
> while watching them I choose Adjust Fill --> H. Stretch.
You can actually do better with the Manual Zoom and use the [ and ]
keys to adjust the aspect ratio.

> But it has to be selected for every video every time I watch them.
> Shouldn't mythtv take care of the video dimensions?
Yes, it does for all my recordings. There are four possible reasons
this is not happening (well there are more, but others are unlikely).
 1/ X11 is reporting the wrong screen aspect ratio to MythTV.
    Unlike a lot of video players, MythTV does not assume square
    pixels. This allows you it to present videos with the correct
    aspect ratio on traditional TVs and Plasmas which don't have
    a 1:1 pixel aspect ratio. But this also means that if the display
    does not report correct dimensions and your xorg.conf does not
    have set the display dimension then the aspect ratio used may
    be incorrect.
 2/ There is an incorrect setting somewhere. For instance if you have
    a large height overscan. Then the width overscan should be equally
    large.
 3/ The broadcaster is lying about the aspect ratio in a digital
    broadcast. This is what the manual zoom aspect ratio adjustment
    allows you to correct.
 4/ MythTV is not reading the aspect ratio correctly from the stream.
    This happens with MPEG-1 streams. When we see one of these we tell
    the decoder library that it is actually an MPEG-2 stream. MPEG-1
    and MPEG-2 signal the aspect ratio differently so it will be
    incorrect. We do this because MPEG-1 streams are extremely rare
    in the wild and some broadcasters incorrectly mark MPEG-2 streams
    as MPEG-1.

> Doesn't anyone else face this??
No. With 1 & 2 this wouldn't be present in only some recordings, so
my guess is it is 3 or 4, in which case a short sample will allow
for a diagnosis.

-- Daniel