[theora] Poor encoding quality with etheora and aspect ratio problem

Ralph Giles giles at xiph.org
Fri Feb 29 09:55:22 PST 2008

On 29-Feb-08, at 2:19 AM, Manuel Dahmen wrote:

> And when I play the movie with mplayer or totem, the video resolution
> is changed from 640x480 to 854x480 (when i use  
> ETHEORA_ASPECT_NORMAL in etheora_enc_setup).

This is a bug in etheora. It's passing the frame aspect ratio where  
libtheora expects the pixel aspect ratio, which is why it looks  

For 640x480 computer-sourced video like processing produces, the  
pixels are square anyway, but ETHEORA_ASPECT_PRESERVE is  
unfortunately also wrong (it sets a square frame aspect ratio). So  
you'll just have to wait until the bug is fixed.

(if you want to hack it, change the default aspect_numerator and  
aspect_denominator in etheora.c to 1 and use ASPECT_PRESERVE.)


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