[FFmpeg-devel] [PATCH] Make MMX2 put_no_rnd_pixels _x2 and _y2 bitexact

[Loren Merritt]

On Sat, 29 May 2010, Reimar D?ffinger wrote:
> On Sat, May 29, 2010 at 08:18:50PM +0200, Stefan Gehrer wrote:
>> On 05/29/2010 12:49 AM, David Conrad wrote:
>>> On May 28, 2010, at 6:34 PM, Stefan Gehrer wrote:
>>>> On 05/29/2010 12:27 AM, David Conrad wrote:
>>>>> On May 28, 2010, at 6:25 PM, Stefan Gehrer wrote:
>>>>>> On 05/28/2010 11:49 PM, David Conrad wrote:
>>>>> The problem is that theora must always be bitexact,
>>>>
>>>> Why is that? If I don't see the difference I would think
>>>> I can decode it with deviation.
>>>
>>> Same reason H.264 must be: it's part of the spec.
>>
>> That doesn't count as an argument. Some people write
>> decoders without having seen any spec :)
>
> I'm also fairly certain that for H.264 the reason is that
> there are real-world cases where you will get (easily)
> visible artefacts otherwise.
> No idea if that can happen for Theora.

Are you referring to some particular approximation that we tried and 
didn't keep?
We do have an option for non-standard-compliant shortcuts in H.264.

--Loren Merritt