[FFmpeg-devel] [PATCH 4/6] lavu/hwcontext_vaapi: add vaapi_format_map support for AYUV/Y210/Y410

[Fu, Linjie]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Mark Thompson
> Sent: Friday, September 13, 2019 07:48
> To: ffmpeg-devel at ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH 4/6] lavu/hwcontext_vaapi: add
> vaapi_format_map support for AYUV/Y210/Y410
> 
> On 10/09/2019 17:07, Linjie Fu wrote:
> > There is no VA_RT_FORMAT_AYUV in defined in libva, and currently in
> > media-driver, VA_FOURCC_AYUV is used to represent
> VA_RT_FORMAT_AYUV.
> 
> That doesn't make sense - VA_RT_FORMAT_* is a bit mask, so using
> VA_FOURCC_AYUV looks like a random combination of other values.
> >
> > diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
> > index cf11764..724bbeb 100644
> > --- a/libavutil/hwcontext_vaapi.c
> > +++ b/libavutil/hwcontext_vaapi.c
> > @@ -116,6 +116,15 @@ static const VAAPIFormatDescriptor
> vaapi_format_map[] = {
> >  #endif
> >      MAP(UYVY, YUV422,  UYVY422, 0),
> >      MAP(YUY2, YUV422,  YUYV422, 0),
> > +#ifdef VA_FOURCC_Y210
> > +    MAP(Y210, YUV422_10,Y210, 0),
> > +#endif
> > +#define VA_RT_FORMAT_AYUV VA_FOURCC_AYUV
> > +    MAP(AYUV,   AYUV,     AYUV, 0),
> > +#undef VA_RT_FORMAT_AYUV
> > +#ifdef VA_FOURCC_Y410
> > +    MAP(Y410, YUV444_10,Y410, 0),
> 
> That looks suspicious - you've defined Y410 as having an alpha channel, but
> that render target format doesn't have one.
> 

Reconsider about these concerns and collect some information in driver.

1. VA_RT_FORMAT describes the sampling format, several fourcc may have the
Same VA_RT_FORMAT. (NV12, YV12, I420 have VA_RT_FORMAT_YUV420) 
so YUV444 is good for AYUV, and YUV444_10 is good for Y410. 
(alpha channel is not relevant with the sampling format)

2. In media driver,  mediaFMT is actually used for decode which is decided by expected_fourcc.
DDI_MEDIA_FORMAT mediaFmt = DdiMedia_OsFormatToMediaFormat(expected_fourcc,format);
https://github.com/intel/media-driver/blob/cf80fa0e3c81361696ada1285ea17a417114be47/media_driver/linux/common/ddi/media_libva.cpp#L2222

No declaring for a RT_FORMAT with alpha channel won't do harm to the decode procedure since mediaFMT
is actually mapped by FourCC.

3. in CreateDecAttributes and MediaLibvaCaps::CheckEncRTFormat,
VA_RT_FORMAT_YUV444 and VA_RT_FORMAT_YUV444_10 are used for MAIN444 and MAIN444_10

https://github.com/intel/media-driver/blob/cf80fa0e3c81361696ada1285ea17a417114be47/media_driver/linux/gen11/ddi/media_libva_caps_g11.cpp#L1189

https://github.com/intel/media-driver/blob/cf80fa0e3c81361696ada1285ea17a417114be47/media_driver/linux/common/ddi/media_libva_caps.cpp#L350

3. If no against, I would like to refine the patch for AYUV and Y410 as follow, and resend the patch.
+    MAP(AYUV,   YUV444,     AYUV, 0),
+#ifdef VA_FOURCC_Y410
+    MAP(Y410, YUV444_10,  Y410, 0),
+#endif

Regards,
- linjie