[theora-dev] yuv strides
giles at xiph.org
Wed Dec 27 10:50:33 PST 2006
On Wed, Dec 27, 2006 at 05:33:09PM +0000, Philip Heron wrote:
> "the strides may be negative in some configurations"
> I'm curious when that would be the case or what purpose negative strides
> would have?
The libtheora reference implementation uses this to invert the image.
Theora's native scanline order is bottom-to-top, but the libtheora api
uses top-to-bottom. If you don't have postprocessing turned on, the
decoder will return a yuv_buffer with a negative stride to avoid doing
an extra copy to invert the row order.
We mention it in the documation to warn people they need to handle that
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