theora - Feb 2008 - Poor encoding quality with etheora and aspect ratio problem

Hello,

I wrote a theora video encoder based on etheora (and the examples
provided with it) for Processing IDE (processing.org). I have some
problem with the quality of encoded frames.
eg. http://poux.be/tmp/movie.ogg

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). And if I try to
encode in 1138x480 with ETHEORA_ASPECT_WIDE_SCREEN the width of the
movie is doubled too. So I don't understand. I'd like to have the same
resolution for encoding and for playing.

eg. mplayer output:

Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
[theora @ 0x892a230]Missing extradata!
Could not open codec.
VDecoder init failed :(
Opening video decoder: [theora] Theora/VP3
VDec: vo config request - 640 x 480 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 2.37:1 - prescaling to correct movie aspect.
VO: [xv] 640x480 => 1138x480 Planar YV12 
Selected video codec: [theora] vfm: theora (Theora (free, reworked VP3))
=========================================================================Audio:
no sound

I don"t understand why the movie is resized by the player.

Thaks in advance for your help

-- 
Manuel Dahmen

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  
stretched.

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.)

  -r