[FFmpeg-devel] [PATCH 1/3] avutil: Add NV24 and NV42 pixel formats

[Fu, Linjie]

> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Carl Eugen Hoyos
> Sent: Sunday, May 12, 2019 18:45
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH 1/3] avutil: Add NV24 and NV42 pixel
> formats
> 
> Am So., 12. Mai 2019 um 05:38 Uhr schrieb Fu, Linjie <linjie.fu at intel.com>:
> 
> > I'm working on adding support for HEVC 4:2:2/ 4:4:4, 8/10 bit, in vaapi
> decoding.
> > And I'm aslo thinking of add some new pix_fmt for packed FourCC:
> > 444 8 bit :  AYUV
> > 444 10 bit: Y410
> > 422 10 bit: Y210
> 
> Do I understand correctly that for 420 8 bit, vaapi produces the
> decoded image in a planar format but for 444 8 bit (and 10 bit),
> you decided that a packed format makes more sense?
> (Aren't luma and chroma stored independently in hevc?)
> 

It's true that for 420 8 bit, the decoded image is in planar format.
But as to 444 8 bit(and 10 bit), as far as I know in  media driver , the decoded image is produced in packed format.
See:
https://github.com/intel/media-driver/blob/8773ef5e82e8a151e1bcfef317f7808f319c91c2/media_driver/linux/gen11/ddi/media_libva_caps_g11.cpp#L842

        else if(profile == VAProfileHEVCMain444 || profile == VAProfileVP9Profile1)
        {
            attribs[i].type = VASurfaceAttribPixelFormat;
            attribs[i].value.type = VAGenericValueTypeInteger;
            attribs[i].flags = VA_SURFACE_ATTRIB_GETTABLE | VA_SURFACE_ATTRIB_SETTABLE;
            attribs[i].value.value.i = VA_FOURCC_AYUV;
            i++;
        }

> Note that no matter what you do with the decoded image, there
> will be a (measurable) performance hit because of the needed
> transformation into something (planar) that other filters and
> encoders understand.

Agree, the directly decoded format is better. 
And it's also one of the reasons I'd like to add these packed formats.

Linjie