[mythtv-users] Aspect ratio wrong

Michael T. Dean mtdean at thirdcontact.com
Wed Apr 5 23:50:20 UTC 2006


On 04/05/2006 02:28 PM, Greg Stark wrote:

>The aspect ratio seems to be wrong when I play tv on the computer screen.
>
>This is for video grabbed from a PVR-350 from NTSC and played back via X on my
>regular display. I have the playback window set for 800x600.
>
>It appears the default playback has black bars on the top and bottom and the
>display part is stretched horizontally. That's with the aspect mode set to
>"Off". It appears the same if press W to go to 4:3 mode. And of course much
>worse if I go to any of the 16:9 modes.
>
>It appears more or less correct in "Fill" and maybe "4:3 Zoom" though it's
>hard to tell.
>
>I don't remember having this problem previously and I don't think I've changed
>anything since I remember it working.
>  
>
What do you get from:

xdpyinfo | grep -B 3 'dots per inch'

>Why does mythtv set the weird 480x480 mode on the PVR anyways 
>
Because you told it to set that resolution in your recording profile.  
If you don't like it change it.

>and then have to
>stretch it back to the right aspect ratio? If I just play raw video from it
>using mplayer it feeds mpeg in the correct aspect ratio automatically.
>  
>
Remember your monitor typically uses square pixels (resolution aspect 
ratio and physical display's aspect ratio is identical).  Video often 
doesn't (720x480 is 3:2 and is often displayed on a 4:3 TV (even 16:9 
letterboxed is 3:2 on 4:3), unless it's 16:9 or 2.39:1 video in 
anamorphic widescreen--in which case it's displayed in letterboxed 16:9 
or 2.39:1, respectively, on your 4:3 screen.  So, capture ratio and 
output ratio are seldom the same.

Note, however, to get 1:1 ratio between capture resolution and output 
resolution on a 4:3 display, you need to use 640x480.  However, it won't 
really matter...

Mike



More information about the mythtv-users mailing list