[Bug]: No multi reference frames(>2) supported on DG2

[feiwan1]

Which component impacted?

Encode

Is it regression? Good in old configuration?

None

What happened?

1. Linux OS
2. use gmmlib/media-driver/onevpl gitbub master commit.
3. Run ffmpeg-qsv cmd with multi reference frames(>2)(set with option -refs 3), but the output frames in bitstream only use 2 reference frame at most.
   3.1 AVC encode:
   ffmpeg -v verbose -hwaccel qsv -hwaccel_output_format qsv -f lavfi -i testsrc=size=1280x720 -vf 'format=nv12,hwupload=extra_hw_frames=120' -c:v h264_qsv -refs 3 -rc_mode cqp -q 10 -b_strategy 0 -vframes 100 -y qsv.mp4
   3.2 HEVC encode:
   ffmpeg -v verbose -hwaccel qsv -hwaccel_output_format qsv -f lavfi -i testsrc=size=1280x720 -vf 'format=nv12,hwupload=extra_hw_frames=120' -c:v hevc_qsv -refs 3 -rc_mode cqp -q 10 -b_strategy 0 -vframes 100 -y qsv.mp4
   3.3 AV1 encode:
   ffmpeg -v verbose -hwaccel qsv -hwaccel_output_format qsv -f lavfi -i testsrc=size=1280x720 -vf 'format=nv12,hwupload=extra_hw_frames=120' -c:v av1_qsv -refs 3 -rc_mode cqp -q 10 -b_strategy 0 -vframes 100 -y qsv.mp4
4. While vainfo -a shows that AVC/HEVC/AV1 can support more than 2 reference frames. And same cmd on TGL looks good.

What's the usage scenario when you are seeing the problem?

Transcode for media delivery

What impacted?

No response

Debug Information

No response

Do you want to contribute a patch to fix the issue?

None

[intel-mediadev]

Auto Created VSMGWL-73777 for further analysis.

[feiwan1]

More info, the issue is exist for Low Power mode on TGL too. By adding -low_power 1 in cmdline.