This very slightly improves compression
Found-by: Christophe Gisquet <christophe.gisquet@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

See Ticket2280
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Avoid code duplication and provide faster and better compression.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

19% faster
smaller files
this may also fix possible integer overflows due to previous 32bit useage

Tested with libutvideo and our utvideo decoder, this patch does not change
decoder output in the test
Reviewed-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

The failures on various architectures and compilers on the RGB(A)
tests seem to have been because of one-off YCbCr->RGB conversion
results. This should make the conversion results match on most if
not all code paths.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

Signed-off-by: Anton Khirnov <anton@khirnov.net>