[Theora] a question about Bitstream Header.

Ralph Giles giles at xiph.org
Sun Oct 31 23:56:48 PST 2004

On Mon, Nov 01, 2004 at 01:36:40PM +0900, Atsuhiko Yamanaka wrote:

> 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.

Can you be more specific about the difference you found? The last 5 bits
of the info header, which specify the chroma subsampling and some as
yet undefined bits which must be zero are read but not checked by the
alpha3 reference implementation. Otherwise they match as far as I know.

> So, my question is 'is it really OK to ignore its formal specification?'.

Well, no. They should match. If they do not then we need to discover
whether it is a bug in the reference implementation or a bug in the
specification document. Ideally you should write the the spec, but
because the spec hasn't had much independent verification yet, it may
contain some errors.


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