[FFmpeg-devel] [PATCH] lavc/vaapi_encode_h265: fix max_transform_hierarchy_depth_inter/intra

[Xiang, Haihao]

On Mon, 2020-04-13 at 13:06 +0000, Fu, Linjie wrote:
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Mark Thompson
> > Sent: Monday, April 13, 2020 20:20
> > To: ffmpeg-devel at ffmpeg.org
> > Subject: Re: [FFmpeg-devel] [PATCH] lavc/vaapi_encode_h265: fix
> > max_transform_hierarchy_depth_inter/intra
> > 
> > On 13/04/2020 05:32, Linjie Fu wrote:
> > > Set the max_transform_hierarchy_depth_inter/intra to 2 by default
> > > based on the Programmer's Reference Manuals (PRM) in [1].
> > > 
> > > Intel Encoder only supports 2 levels of quad-tree. That is:
> > >     - max_transform_hierarchy_depth_inter/intra <= 2.
> > > 
> > > [1] <https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-
> > 
> > kbl-vol10-hevc.pdf>
> > > 
> > > Signed-off-by: Linjie Fu <linjie.fu at intel.com>
> > > ---
> > > Fixed value for intel platform, makes more sense on TGL+ platform.
> > > (If conflict with other driver capability, we may add query support
> > >  later)
> > >  libavcodec/vaapi_encode_h265.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/libavcodec/vaapi_encode_h265.c
> > 
> > b/libavcodec/vaapi_encode_h265.c
> > > index cd48545..d6cb82a 100644
> > > --- a/libavcodec/vaapi_encode_h265.c
> > > +++ b/libavcodec/vaapi_encode_h265.c
> > > @@ -445,8 +445,9 @@ static int
> > 
> > vaapi_encode_h265_init_sequence_params(AVCodecContext *avctx)
> > >      sps->log2_min_luma_transform_block_size_minus2   = 0;
> > >      sps->log2_diff_max_min_luma_transform_block_size = 3;
> > >      // Full transform hierarchy allowed (2-5).
> > > -    sps->max_transform_hierarchy_depth_inter = 3;
> > > -    sps->max_transform_hierarchy_depth_intra = 3;
> > > +    // Default to 2 based on Programmer's Reference Manuals of Intel
> > 
> > graphics
> > > +    sps->max_transform_hierarchy_depth_inter = 2;
> > > +    sps->max_transform_hierarchy_depth_intra = 2;
> > >      // AMP works.
> > >      sps->amp_enabled_flag = 1;
> > >      // SAO and temporal MVP do not work.
> > > 
> > 
> > I don't much like the idea of changing this based on a value in a Kaby Lake
> > document given that the current value hasn't had any problems on Kaby Lake.
> > Can you explain the benefits of changing this?  
> 
> It fixes the encoding issue for HEVC on gen12+ platform.
> We didn't notice this either, until it triggers gpu hang for encoding on Tiger
> Lake (gen12).
> 
> > Can you confirm that it continues to work on all the other currently-working 
> > platforms?
> > 
> 
> Yes, we set up CI and runs full-round tests for conformance and catch
> regression on different
> platforms(CFL/CML/ICL/KBL/SKL).
> 
> Identical fix has been merged in gstreamer-vaapi, no regression is detected on
> other platforms.
> 
https://gitlab.freedesktop.org/gstreamer/gstreamer-vaapi/-/merge_requests/282/diffs?commit_id=17d82e14e78af901f1cd7f2344e173ad6ae6a8a6

Hi Mark,

Till now we didn't see regression with Linjie's patch, do you have any other
concern on Linjie's patch? 

Thanks
Haihao

> 
> - Linjie
> 
> 
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