Results

Compression speed at 1080p:

Metrics

For each comparison algorithms, we plot the quality in dB in function of the mean bits per pixel on a logarithmic scale. We can then visualize which codec gives the best quality at a given bit per pixel (top left is better).

Bits per pixel at equivalent quality according to VMAF

1080p

Bits per pixel at equivalent quality according to Y-PSNR-HVS-M

1080p

Bits per pixel at equivalent quality according to Y-MSSSIM

1080p

Bits per pixel at equivalent quality according to Y-SSIM

1080p

Bits per pixel at equivalent quality according to RGB-SSIM

1080p

CRF equivalences and bitrate reduction at 1080p

In the following table, we try to find equivalences between the CRF values of the various encoders according to a selected metric. We then calculate the expected bitrate reduction for this comparable CRF value.

For example, a x264 encode at CRF 20 would give a PSNR-HVS-M of 42.80. To obtain the same quality with VP9, one should look at the intersection of CRF 20 and "libvpx crf according to psnr-hvs-m", which gives an equivent CRF of 30.60. The column "libvpx % reduction according to psnr-hvs-m" then gives the expected reduction of bitrate, -21.294%.

x264 crf x264 bpp x264 y-ssim x264 rgb-ssim x264 ms-ssim x264 psnr-hvs-m x264 vmaf 16 0.34558 19.90 18.92 25.30 46.84 98.52 17 0.28786 19.31 18.41 24.60 45.79 98.24 18 0.23879 18.76 17.92 23.92 44.77 97.90 19 0.19742 18.22 17.46 23.27 43.77 97.47 20 0.16285 17.71 17.01 22.64 42.80 96.93 21 0.13424 17.21 16.58 22.02 41.85 96.26 22 0.11082 16.72 16.16 21.42 40.92 95.44 23 0.09185 16.25 15.76 20.82 40.00 94.45 24 0.07667 15.79 15.36 20.23 39.09 93.28

x264 crf x264 bpp libaom crf according to y-ssim libaom bpp according to y-ssim libaom % reduction according to y-ssim libaom crf according to rgb-ssim libaom bpp according to rgb-ssim libaom % reduction according to rgb-ssim libaom crf according to ms-ssim libaom bpp according to ms-ssim libaom % reduction according to ms-ssim libaom crf according to psnr-hvs-m libaom bpp according to psnr-hvs-m libaom % reduction according to psnr-hvs-m libaom crf according to vmaf libaom bpp according to vmaf libaom % reduction according to vmaf 16 0.34558 20.06 0.31722 -8.206 23.42 0.24274 -29.76 20.25 0.31217 -9.666 22.47 0.26128 -24.39 23.31 0.24488 -29.14 17 0.28786 23.25 0.24592 -14.571 26.80 0.18969 -34.10 23.31 0.24484 -14.947 25.41 0.20926 -27.31 25.34 0.21043 -26.90 18 0.23879 26.50 0.19369 -18.886 30.10 0.15265 -36.07 26.43 0.19469 -18.466 28.36 0.17069 -28.52 27.62 0.17935 -24.89 19 0.19742 29.71 0.15640 -20.776 33.27 0.12633 -36.01 29.53 0.15824 -19.842 31.27 0.14212 -28.01 30.19 0.15180 -23.11 20 0.16285 32.84 0.12947 -20.497 36.28 0.10661 -34.53 32.57 0.13154 -19.226 34.11 0.12039 -26.07 33.00 0.12827 -21.23 21 0.13424 35.87 0.10909 -18.736 39.12 0.09074 -32.41 35.53 0.11118 -17.182 36.89 0.10302 -23.26 35.93 0.10871 -19.02 22 0.11082 38.77 0.09259 -16.450 41.78 0.07713 -30.40 38.38 0.09466 -14.578 39.58 0.08828 -20.34 38.77 0.09255 -16.49 23 0.09185 41.54 0.07832 -14.731 44.28 0.06501 -29.22 41.12 0.08040 -12.465 42.20 0.07508 -18.26 41.35 0.07926 -13.71 24 0.07667 44.18 0.06546 -14.613 46.62 0.05413 -29.39 43.75 0.06755 -11.897 44.73 0.06290 -17.95 43.54 0.06852 -10.62