[theora-dev] resolution issues

Mike Melanson melanson at pcisys.net
Tue May 27 11:55:41 PDT 2003

On Tue, 27 May 2003, Henry Mason  wrote:

> On a somewhat related note, is there any reason to 
> encode at dimensions which are multiples of 32 in 
> order to have full superblocks? How much do VP3 
> superblocks play a part in the video compression 
> efficiency?

        Well, a good reason to encode at superblock boundaries is that it
makes an encoder's life (and source code) much simpler...:) Actually, to
make it *really* easy, with no corner cases, the dimensions need to be
divisible by 64 (so the U & V planes line up on 32-sample boundaries).

        I understand that the point of the superblocks and the associated
Hilbert coding scan is to maximize proximate similarities (based on the
principle that pixels close to each other tend to be similar). This will
be true for most of the image frame; only the outlying areas (right and
bottom) will not have the benefit of as many neighboring pixels.

	-Mike Melanson

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