[Nouveau] Video Hardware Decoding: Jittery Rectangles on Nvidia GT218 NVA8 VP4.

[Solerman Kaplon]

Às 14:46 de 27/07/2019, Ilia Mirkin escreveu:
> On Sat, Jul 27, 2019 at 7:37 AM Ralph Corderoy <ralph at inputplus.co.uk> wrote:
>> The video plays, CPU load is less (my aim), but there's ‘tearing’ of the
>> picture as if small rectangles that are updates are appearing in the
>> wrong location, off by a little.  If I step through the frames with
>> mpv's ‘.’ and ‘,’ then I've found a pattern: one frame's picture is
>> good, followed by N bad ones where N is 3 or 7, i.e. every 4th or 8th
>> frame is okay.  Don't know if that's a clue or helps someone here
>> recognise a known problem.
<snip>
>> Unfortunately I've never tracked down the cause for this.
>> https://nouveau.freedesktop.org/wiki/VideoAcceleration/ - see note #4.
>>
>> I have, over time, collected some sample videos where this happens in
>> the first few frames. The plan was to do mmt traces of the blob
>> driver, and figure out what it was doing differently.

<snip>

I don't really know anything about hw coding, but looking from the outside, it 
seems some kind of ring buffer with exact 3 frames maybe intended to work kinda 
like using tripple buffering? I know for once that nvidia works better using 
tripple buffering from what I've read from the kwin threads.


Solerman