[FFmpeg-devel] [PATCH] mpeg2: remove idct randomisation

[Jason Garrett-Glaser]

On Sun, Jun 20, 2010 at 3:23 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Sun, Jun 20, 2010 at 11:21:28PM +0100, Mans Rullgard wrote:
>> Since the beginning of time, the MPEG2 decoder has XORed the LSB of
>> all block coeffs into the last one, probably to produce a random
>> dithering for masking DCT mismatch errors. ?This patch removes this
>> randomisation. ?As a side-effect, the value of block_last_index is
>> now correct.
>
> This violates the spec

WHAT?!  The spec mandates this?!  Then we should at least fix the
block_last_index value, which is wrong whenever this mode is used.

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