[Theora] a question about Bitstream Header.

Atsuhiko Yamanaka ymnk at jcraft.com
Sun Oct 31 20:36:40 PST 2004


I have a question about the format of Theora bitstream header.

It seems to me that there are differences between the specification[1]
(version 2004 Oct 1) and its reference implementation in 
libtheora 1.0alpha3 released at 2004 Jun 1.  

I mean that... please refer to Section 6.2 'Identification Header Decode' 
in that specification[1] and the function '_theora_unpack_info()' 
included in 'lib/toplevel.c'[2] of libtheora 1.0alpha3.

In developing some pure Java program[3], I had required to implement 
some function, which converts granulepos to time in pure Java, and needed
to parse Theora header in pure Java.  Now, I have followed the format 
implemented in libtheora 1.0alpha3, and I have done to implement 
that function and confirmed it works well.
So, my question is 'is it really OK to ignore its formal specification?'.
I have heard 'Theora I  pecification' has been frozen and I hope
that specification has not been updated yet.

[1] http://www.theora.org/doc/Theora_I_spec.pdf
[2] http://svn.xiph.org/trunk/theora/lib/toplevel.c
[3] http://www.jcraft.com/jroar/


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