[FFmpeg-devel] [PATCH v2 1/2] libavcodec/mpegvideo_enc: fix multi-threaded motion estimation rounding for mpeg4

[Ramiro Polla]

On Thu, May 9, 2024 at 2:44 AM Michael Niedermayer
<michael at niedermayer.cc> wrote:
> On Wed, May 08, 2024 at 05:19:49PM +0200, Ramiro Polla wrote:
> > ff_init_me() was being called after ff_update_duplicate_context(),
> > which caused the propagation of the initialization to other thread
> > contexts to be delayed by one frame.
> >
> > In the case of mpeg4 (or flipflop_rounding), this would make the
> > hpel_put functions differ between the first thread (which would be
> > correctly initialized) and the other threads (which would be stale
> > from the previous frame).
> > ---
> >  libavcodec/mpegvideo_enc.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
>
> have you confirmed the actual used rounding matches after this
> encoder & decoder side ?

Yes, I just rechecked it. It used to be wrong (only the first slice
would use the correct hpel/qpel functions in the encoder according to
the no_rounding flag in the bitstream).

> if yes then this should be ok

Thanks. Pushed.