[theora] More examples?

Manuel Dahmen manuel.dahmen at gmail.com
Mon Feb 25 04:31:37 PST 2008


I want to make a program to extract frame from a theora movie as
images. I tried with the decoding example located at theora web site
(dump_video.c. I use it to extract a frame as yuv image but when I try
to convert it to ppm with yuvtoppm program i obtain a strange image
( see http://poux.be/tmp/file.ppm ). I think it's a problem with the
 byte order for yuv, but don't I don't know anything about this format.

I'd like to make a simple program to encode chosen frame into ppm.
Perhaps it's just ordering properly the bytes issued from the
write_video() function in the example and using yuvtoppm to make the

What is the yuv format issued from dump_video.c (444, 422, 420 ?) and
when can I find a not-too-hard-to-understand explanation of this format?

Thanks in advance for your answers.

Manuel Dahmen

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