[Theora] Testing libtheora-1.0alpha5

marco marco at math.toronto.edu
Mon Aug 22 20:46:26 PDT 2005


I sent the message below a couple of months ago but I got
no reply. Now that there's more activity perhaps someone
could kindly provide me some guidance. Theora is great
and the developers are doing a wonderful job, so I'd like to
implement the codec in a way which does it justice...

Original post:

I wrote a plugin to enable LiVES (a video editor) to encode
theora/vorbis/ogg files. I'm looking for some advice towards
improving quality. If someone would like to help me
test this please note that you'll need MPlayer, ImageMagick,
sox, the encoder_example from libtheora (somewhere in the PATH),
and Python 2.3.0 (this is fairly all standard stuff).

Consider the following clip:


As you can see there are a lot of obvious artifacts. I generate
this movie using a series on PNG images and the following command

mkfifo -m 0600 stream.yuv
mplayer mf://*.png -mf type=png:fps=29.97002997 -vf dsize=16:9,hqdn3d -vo yuv4mpeg -ao null -nosound &
encoder_example -s 8 -S 7 -f 30000 -F 1001 -v 10 -a 10 -o swath.ogg stream.yuv

Any suggestions on how to improve this? In order to test I'm
making available the LiVES video file (which is essentially a .tgz of the
PNG images):


To encode this you can download the LiVES theora encoder plugin:


and copy it into an empty directory (make sure it's executable). Move swath.lv1
into that same directory and run:

./theora_encoder.py -v -o swath.ogg -a 3 -t hi -L swath.lv1

This will create "swath.ogg". In order to see what the uncomporessed
movie looks like you can run (in that directory):

animate -delay 3.336 *.png

Any suggestions on how to improve the quality? I'm running MPlayer1.0pre7
and libtheora-1.0alpha5.

Thanks for any input!

marco at reimeika.ca
Gunnm: Broken Angel                      http://amv.reimeika.ca
http://reimeika.ca/                      http://photo.reimeika.ca

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