[theora] [?] About YUV format

[Ralph Giles]

On Wed, Nov 26, 2008 at 12:45 AM, Andrea Fontana <advmail at katamail.com> wrote:

> Hello. I read documentation, but I didn't found anything about encoder
> supported YUV format. Is Y in [0-255] or in [16,235]? And U,V are in
> [16,239]?
> I'm trying to write a fast (with lookup) conversion from RGB -> YUV...

The colour representation is described extensively in chapter 4 of
http://theora.org/doc/Theora.pdf

There are two defined colour spaces and one 'undefined' one. The
format specification describes how to do conversion for the two
defined colour spaces. For files marked 'undefined' you can of course
do what you like.

The format supports the full range [0,255] for all three components,
but for more accurate conversion of the defined spaces, you can target
the typical floor/ceiling levels with Y in [16, 235] and UV in
[16,240).

HTH,
 -r