This is a comparison of different CRF values against cpu-used for the libaom av1 encoder. The -cpu-used flag defaults to 1, which gives a very slow but efficient encode. We are finding values of at least 4 still give an excellent quality, but quite a bit faster (although still significantly slower than other encoders. Values of 5 may also be worth considering. In this case we are encoding to 422. If you are ok with 420, do use svt-av1, which is significantly faster.
| Test Name |
Test Results |
Encode Duration |
File Size |
VMAF Harmonic Mean |
PSNR-Y Harmonic Mean |
CAMBI Harmonic Mean |
MS-SSIM Harmonic Mean |
Encode Arguments |
| test_crf-cpu3_crf_10 |
Test frame= 1 fps=0.3 q=0.0 Lsize= 255KiB time=00:00:00.04 bitrate=52199.0kbits/s speed=0.014x elapsed=0:00:02.85 |
14.4241 |
47,459,643 |
99.986624 |
51.00352 |
0.0 |
0.998651 |
-c:v libaom-av1 -color_primaries 1 -color_range 1 -color_trc 2 -colorspace 1 -cpu-used 3 -crf 10 -g 10 -pix_fmt yuv422p10le -row-mt 1 -sws_flags spline+accurate_rnd+full_chroma_int -usage realtime -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709" |
| test_crf-cpu3_crf_16 |
Test frame= 1 fps=0.3 q=0.0 Lsize= 478KiB time=00:00:00.04 bitrate=97818.0kbits/s speed=0.0114x elapsed=0:00:03.51 |
13.0754 |
38,676,012 |
99.975129 |
48.699529 |
0.0 |
0.997647 |
-c:v libaom-av1 -color_primaries 1 -color_range 1 -color_trc 2 -colorspace 1 -cpu-used 3 -crf 16 -g 10 -pix_fmt yuv422p10le -row-mt 1 -sws_flags spline+accurate_rnd+full_chroma_int -usage realtime -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709" |
| test_crf-cpu3_crf_20 |
Test frame= 1 fps=0.2 q=0.0 Lsize= 526KiB time=00:00:00.04 bitrate=107756.0kbits/s speed=0.00957x elapsed=0:00:04.18 |
12.0543 |
36,249,721 |
99.932055 |
47.633492 |
0.0 |
0.996952 |
-c:v libaom-av1 -color_primaries 1 -color_range 1 -color_trc 2 -colorspace 1 -cpu-used 3 -crf 20 -g 10 -pix_fmt yuv422p10le -row-mt 1 -sws_flags spline+accurate_rnd+full_chroma_int -usage realtime -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709" |
| test_crf-cpu3_crf_25 |
Test frame= 1 fps=0.3 q=0.0 Lsize= 563KiB time=00:00:00.04 bitrate=115350.6kbits/s speed=0.0101x elapsed=0:00:03.96 |
11.2775 |
33,986,056 |
99.705027 |
46.406207 |
0.0 |
0.995913 |
-c:v libaom-av1 -color_primaries 1 -color_range 1 -color_trc 2 -colorspace 1 -cpu-used 3 -crf 25 -g 10 -pix_fmt yuv422p10le -row-mt 1 -sws_flags spline+accurate_rnd+full_chroma_int -usage realtime -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709" |
| test_crf-cpu3_crf_30 |
Test frame= 1 fps=0.3 q=0.0 Lsize= 594KiB time=00:00:00.04 bitrate=121678.0kbits/s speed=0.0104x elapsed=0:00:03.82 |
10.5902 |
32,087,593 |
98.963335 |
44.984168 |
0.0 |
0.994263 |
-c:v libaom-av1 -color_primaries 1 -color_range 1 -color_trc 2 -colorspace 1 -cpu-used 3 -crf 30 -g 10 -pix_fmt yuv422p10le -row-mt 1 -sws_flags spline+accurate_rnd+full_chroma_int -usage realtime -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709" |
| test_crf-cpu3_crf_5 |
Test frame= 1 fps=1.0 q=0.0 Lsize= 56KiB time=00:00:00.04 bitrate=11560.8kbits/s speed=0.0395x elapsed=0:00:01.01 |
17.9611 |
76,096,465 |
99.98678 |
54.16812 |
0.0 |
0.999383 |
-c:v libaom-av1 -color_primaries 1 -color_range 1 -color_trc 2 -colorspace 1 -cpu-used 3 -crf 5 -g 10 -pix_fmt yuv422p10le -row-mt 1 -sws_flags spline+accurate_rnd+full_chroma_int -usage realtime -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709" |
Visual Compare
Testing with ffmpeg version: git-2025-07-22-1ce20f55cc on OS:Darwin 24.5.0 Architecture: arm.