avc vdenc doesn't work as expected when using FFmpeg.

[xhaihao]

The slice header in the encoded h264 stream is wrong, ffprobe reports the following errors:

[h264 @ 0x559068a82fa0] illegal modification_of_pic_nums_idc 32
[h264 @ 0x559068a82fa0] decode_slice_header error
[h264 @ 0x559068a82fa0] no frame!
[h264 @ 0x559068a82fa0] illegal modification_of_pic_nums_idc 32
[h264 @ 0x559068a82fa0] decode_slice_header error
[h264 @ 0x559068a82fa0] no frame!
[h264 @ 0x559068a81c30] decoding for stream 0 failed

The command for encoding ' ffmpeg -loglevel debug -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -s:v WxH -i -vf 'format=nv12,hwupload' -low_power 1 -c:v h264_vaapi output.h264'

ffmpeg commit: 00ae5c1d3d87efc7f13b86cce80e139c805db179
media-driver: ef45492
gmmlib: b8d74ac3fcea0dffa901ce62399d43a937212074
libva: 417b0184d4a767721e9b0a5f1597907707f545cf

[XinfengZhang]

from @xhaihao , it is a CNL only issue. trying to reproduce it.

[XinfengZhang]

reproduced, will fix it

[XinfengZhang]

correct one comments, it's is a CNL only issue ---- not verified. maybe also exist with SKL

[Tianhaol]

On SKL, ran the command, the following error was reported.
"xxxx: Invalid data found when processing input"
After specify input format with option -f rawvideo -pix_fmt nv12 , the command can work fine and ffprobe does not report any errors.

[XinfengZhang]

@xhaihao please help to verify whether we can close the issue