[theora] Aspect ratio question

Markus Meyer meyer at mesw.de
Wed Jul 23 12:21:17 PDT 2003


despite the warnings on the website ;-) I played with the current CVS
source of theora on Windows 2000 w/ Microsoft Visual C++. The codec and
the "experimental" example programs compiled fine. I also encoded a 33
MB MPEG2 (?) video (3 minute trailer) to a 14 MB .OGG using "mplayer -vo
yuv4mpeg -ao pcm" and the "encoderwin" sample program, and play it with
the "splayer" sample program. Performance was okay on an 2.4GHz P-IV,
although I was using debug binaries under VMWare. No crashes or other
problems so far.

Looking at the directory structure and the code I must say I'm really
impressed, everything is arranged very logical and works as one expects.

At the moment I'm playing a bit with the splayer example program to get
a feel for the API. I also wanted to implement scaling to get the aspect
ratio right. I see that there are some variables inside the info struct:

(1) width/height
(2) offset x/y and frame width/frame height
(3) aspect ratio numerator / denominator

Can you enlighten me on how (1) and (2) fit together? I see that
width/height isn't used at all by splayer at the moment. What should it
do in a complete implementation?

Also, concerning (3), one can encode files at the moment where one of
the numerator and the denominator is zero. Does this case have any
special semantics or is it just so that either both must be zero or both
must have a positive value?


<p>--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'theora-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.

More information about the Theora mailing list