[FFmpeg-devel] H.261 chroma motion vector rounding.
u at pkh.me
Sun Apr 2 20:46:28 EEST 2017
On Sun, Apr 02, 2017 at 10:17:05AM +0100, Christina Brien wrote:
> Having written a clean-room implementation of H.261 and comparing it to the output of FFMPEG, I have found that FFMPEG is not spec-compliant with regard to negative chroma motion vectors. The spec states that chroma motion vectors are the luma motion vectors divided by two, and rounded *towards zero*. FFMPEG currently rounds towards negative infinity.
> This patch makes FFMPEG compliant, but breaks the regression tests.
I can't comment on the correctness of the patch, but wouldn't
ROUNDED_DIV() macro be more appropriate?
Also, the Changelog is not supposed to include these kind of changes.
-------------- next part --------------
A non-text attachment was scrubbed...
Size: 488 bytes
Desc: not available
More information about the ffmpeg-devel