[FFmpeg-devel] [PATCH 3/4] vaapi_encode_h265: Query encoding block sizes and features

[Fu, Linjie]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Mark Thompson
> Sent: Thursday, March 5, 2020 08:25
> To: ffmpeg-devel at ffmpeg.org
> Subject: [FFmpeg-devel] [PATCH 3/4] vaapi_encode_h265: Query encoding
> block sizes and features
> 
> ---
> Requires <https://github.com/intel/libva/pull/385>.  That isn't upstream, so
> this will need to wait for that and then get at least a fix to the version
> numbering before applying.

The query looks good to me since I'm suffering from the differences of default
parameters allowed for VDENC and VMEPAK in media-driver while adding support
for low power encoding [1] for VAAPI. 

However got several questions:

1. Why not include PPS parameters as well? There are some differences in
cu_qp_delta_enabled_flag and diff_cu_qp_delta_depth supported for VAEntrypointEncSliceLP.

2. Would it be better to only involve the variable parameters for sps/pps... ? This is 
what PR 379 [2] (unfinished) intended to do.

3. The suggested value of SAO enable flag could also be 1 in corresponding code in
media-driver, which would provide 3% BD-Rate improvement with no fps penalty
based on previous experiment with FFmpeg VAAPI.

4. There is separate media_libva_caps for gen11 and gen12, maybe need further update
or centralization for the code in driver. (not tested yet, will do later)

[1] https://github.com/intel-media-ci/ffmpeg-cartwheel/blob/master/patchset/0008-lavc-vaapi_encode_h265-add-support-for-low-power-mod.patch
[2] https://github.com/intel/libva/pull/379

- Linjie