[FFmpeg-devel] [PATCH] libavcodec/qsvdec: use the param from decodeHeader to configure surface

[Xiang, Haihao]

On Tue, 2021-04-06 at 07:54 +0000, Chen, Wenbin wrote:
> > -----Original Message-----
> > From: Xiang, Haihao <haihao.xiang at intel.com>
> > Sent: Tuesday, April 6, 2021 2:24 PM
> > To: Chen, Wenbin <wenbin.chen at intel.com>; ffmpeg-devel at ffmpeg.org
> > Subject: Re: [FFmpeg-devel] [PATCH] libavcodec/qsvdec: use the param from
> > decodeHeader to configure surface
> > 
> > On Tue, 2021-03-23 at 06:45 +0000, Chen, Wenbin wrote:
> > > > -----Original Message-----
> > > > From: Xiang, Haihao <haihao.xiang at intel.com>
> > > > Sent: Tuesday, March 23, 2021 12:10 PM
> > > > To: ffmpeg-devel at ffmpeg.org
> > > > Cc: Chen, Wenbin <wenbin.chen at intel.com>
> > > > Subject: Re: [FFmpeg-devel] [PATCH] libavcodec/qsvdec: use the param
> > 
> > from
> > > > decodeHeader to configure surface
> > > > 
> > > > On Mon, 2021-03-22 at 14:31 +0800, wenbin.chen at intel.com wrote:
> > > > > From: "Chen,Wenbin" <wenbin.chen at intel.com>
> > > > > 
> > > > > MSDK recognizes both yuv420p10 and yuv420p9 as MFX_FOURCC_P010,
> > > > 
> > > > but param
> > > > > are different. When decode yuv420p9 video, ffmpeg-qsv will use
> > > > > yuv420p10le to configure surface which is different with param from
> > > > > DecoderHeader and this will lead to error. Now change it use
> > > > > param from decoderHeader to configure surface.
> > > > 
> > > > 
> > > > Both yuv420p10 and yuv420p9 have 3 planes (
> > > > 
> > 
> > https://github.com/FFmpeg/FFmpeg/blob/master/libavutil/pixdesc.c#L1359-
> > > > L1406) ,
> > > > but MFX_FOURCC_P010 has 2 planes only. MSDK doesn't recognizes
> > > > yuv420p10 and
> > > > yuv420p9 as MFX_FOURCC_P010. FFmpeg-qsv uses p010le instead of
> > > > yuv420p10le to
> > > > configure surface for 10bit video.
> > > > 
> > > 
> > > Sorry, I didn't describe the problem well. I mean when MSDK
> > 
> > decodeHeader a
> > > 9bit video
> > > It will return MFX_FOURCC_P010, but its frameInfo is 9bit. However
> > 
> > FFmpeg-qsv
> > > will use P010's parameter
> > > to configure surface which will be 10bit, and if ffmpeg-qsv send 10bit
> > 
> > surface
> > > to decode 9bit video MSDK will report an error.
> > > 
> > 
> > So it will use yuv420p10le for a 9bit video, right? A potential issue here
> > is
> > the depth info will be lost in the pipeline, a filter after qsv decoder will
> > take it as 10bit frame instead of 9bit frame.
> > 
> > Thanks
> > Haihao
> > 
> > 
> 
> Yes, there is a risk of losing depth information. Function ff_qsv_map_fourcc()
> should also takes 
> "FrameInfo.BitDepth" into consideration. This issue is not brought by this
> patch, we may fix it in a new patch.


FFmpeg has already used pixfmt for both memory layout and the used bits in a
frame. I think you should add a new pixfmt for your case, otherwise we won't
know the bit depth when handling a yuv420p10le frame in a filter if using
yuv420p10le for a 9bit video.


> 
> Thanks
> wenbin
> 
> > > > 
> > > > > 
> > > > > Signed-off-by Wenbin Chen <wenbin.chen at intel.com>
> > > > > ---
> > > > >  libavcodec/qsvdec.c | 4 ++--
> > > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/libavcodec/qsvdec.c b/libavcodec/qsvdec.c
> > > > > index 569ccd4fba..3ab48ea7a2 100644
> > > > > --- a/libavcodec/qsvdec.c
> > > > > +++ b/libavcodec/qsvdec.c
> > > > > @@ -309,13 +309,13 @@ static int alloc_frame(AVCodecContext *avctx,
> > > > 
> > > > QSVContext
> > > > > *q, QSVFrame *frame)
> > > > >      if (frame->frame->format == AV_PIX_FMT_QSV) {
> > > > >          frame->surface = *(mfxFrameSurface1*)frame->frame->data[3];
> > > > >      } else {
> > > > > -        frame->surface.Info = q->frame_info;
> > > > > -
> > > > >          frame->surface.Data.PitchLow = frame->frame->linesize[0];
> > > > >          frame->surface.Data.Y        = frame->frame->data[0];
> > > > >          frame->surface.Data.UV       = frame->frame->data[1];
> > > > >      }
> > > > > 
> > > > > +    frame->surface.Info = q->frame_info;
> > > > > +
> > > > >      if (q->frames_ctx.mids) {
> > > > >          ret = ff_qsv_find_surface_idx(&q->frames_ctx, frame);
> > > > >          if (ret < 0)