FFMpeg AV1 Encoding Using Intel Arc GPU tips?

Operating Systems & Open Source Linux
2

I don’t use multipass, so I’ll leave that to someone else, but here’s what I used to optimize AV1 encoding quality on my A380 (on Jellyfin) according to Intel’s quality optimization guide:

-look_ahead_depth 99 \

-look_ahead_depth (LAD) requires -extbrc 1, and recommended value for quality is 40. It also requires -extra_hw_frames to be set to the same value:

-extbrc 1 \
-look_ahead_depth 40 \
-extra_hw_frames 40 \

  -b:v 1M \

For CBR, Intel also recommends to set -bufsize to at least 2 times the bitrate to maximize quality. In this case, 2M should be used. Also -rc_init_occupancy should also be set for initial buffer delay. The recommended value is half of bitrate:

-b:v 1M \
-bufsize 2M \
-rc_init_occupancy 512K \

Other optimizations:

  • -adaptive_i 1 for adaptive scene change detection
  • -adaptive_b 1 for adaptive miniGOP
  • -b_strategy 1 -bf 7 activate full 3 level B-Pyramid. Note that -bf should be set to less value than LAD. (If LAD is 40, then valid value is up to 39.)

So final command (untested):

ffmpeg \
  -i input.mp4 \
  -init_hw_device vaapi=va:/dev/dri/renderD128 \
  -c:v av1_qsv \
  -preset veryslow \
  -extbrc 1 \
  -look_ahead_depth 40 \
  -extra_hw_frames 40 \
  -b:v 1M \
  -bufsize 2M \
  -rc_init_occupancy 512K \
  -low_power 0 \
  -adaptive_i 1 \
  -adaptive_b 1 \
  -b_strategy 1 -bf 7 \
  output.mp4

Typically I run VBR, but this settings halved the encoding speed while giving a much better quality. SVT-AV1 still produces a better result at a smaller filesize however (but it’s wayyyy too slow compared to QSV).

Forcing ExtBRC to use the new EncTools by setting -extbrc 1 -look_ahead_depth 40 (or any value above 1) seems to be what helps with quality on QSV AV1.

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