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Comparing YUV conversion approaches.
This is comparing different ways to do the YUV conversion. We are doing it in both 420p and 444p since 444p is a fairer binary image comparison. The takeaway should be to use the libswscale filter. The code to generate these files is here.
| YUV420p encodes YUV444p encodes (Chrome Only) </div> | Reference PNG Source PNG file YUV420p encodesDefault Encode (terrible) Basic ffmpeg conversion, no colorspace specified, ffmpeg assumes bt601 colorspace. This is a terrible filter, significant color changes from PNG file.
ffmpeg flags to add:Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-basic.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-basic.png"Mean error = 0.0212507 RMS error = 0.0388912 Peak SNR = 28.203 Max error = 0.556863 @ (1815, 1004, B) values are 0, 0, 0.952941 vs 0.0705882, 0.0901961, 0.396078 1792353 pixels (86.4%) over 1e-06 1792353 pixels (86.4%) over 1e-06 FAILURE 'ERROR! Colormatrix filter (close) Using colormatrix filter. colormatrix only supports 8-bit per component images. Visually its getting pretty close.
ffmpeg flags to add: -sws_flags spline+accurate_rnd+full_chroma_int -vf "colormatrix=bt470bg:bt709"Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-colormatrix.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-colormatrix.png"Mean error = 0.00307147 RMS error = 0.0124281 Peak SNR = 38.1119 Max error = 0.568627 @ (1904, 1040, B) values are 0, 0, 1 vs 0.0666667, 0.0588235, 0.431373 1482440 pixels (71.5%) over 1e-06 1482440 pixels (71.5%) over 1e-06 FAILURE 'ERROR! Colorspace filter Using colorspace filter, better quality filter, SIMD so faster too, can support 10-bit too. Visually pretty close to colormatrix, but slight improvement based on colormatrix values.
ffmpeg flags to add: -sws_flags spline+accurate_rnd+full_chroma_int -vf "colorspace=bt709:iall=bt601-6-625:fast=1"Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-colorspace.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-colorspace.png"Mean error = 0.002964 RMS error = 0.0123796 Peak SNR = 38.1459 Max error = 0.564706 @ (1904, 963, B) values are 0, 0, 1 vs 0.0627451, 0.0588235, 0.435294 1473078 pixels (71%) over 1e-06 1473078 pixels (71%) over 1e-06 FAILURE 'ERROR! libswscale filter + flags (best) Using the libswscale library. Seems similar to colorspace, but with image resizing, and levels built in. This also has a number of libswscale parameters. Visually this is close to the above two, but slight improvement based on colormatrix results.
ffmpeg flags to add: -sws_flags spline+accurate_rnd+full_chroma_int+full_chroma_inp -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709"Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-splinecolormatrix.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-splinecolormatrix.png"Mean error = 0.00260747 RMS error = 0.0131948 Peak SNR = 37.592 Max error = 0.627451 @ (1904, 963, B) values are 0, 0, 1 vs 0.054902, 0.0470588, 0.372549 1341240 pixels (64.7%) over 1e-06 1341240 pixels (64.7%) over 1e-06 FAILURE 'ERROR! YUV444p encodes (Chrome Only)Default Encode (terrible) Basic ffmpeg conversion, ffmpeg assumes bt601 colorspace, now at 444. Results look terrible.
ffmpeg flags to add:Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-basic444.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-basic444.png"Mean error = 0.0204761 RMS error = 0.0372786 Peak SNR = 28.5708 Max error = 0.152941 @ (1832, 618, G) values are 0.968628, 0, 0.968628 vs 1, 0.152941, 1 1779568 pixels (85.8%) over 1e-06 1779568 pixels (85.8%) over 1e-06 FAILURE 'ERROR! Colormatrix filter (close) Using colormatrix filter. colormatrix only supports 8-bit per component images. Visually pretty close, but still off.
ffmpeg flags to add: -sws_flags spline+accurate_rnd+full_chroma_int -vf "colormatrix=bt470bg:bt709"Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444colormatrix2.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444colormatrix2.png"Mean error = 0.00153716 RMS error = 0.00270346 Peak SNR = 51.3616 Max error = 0.0117647 @ (1389, 462, R) values are 0, 0.733333, 0.690196 vs 0.0117647, 0.737255, 0.694118 1434882 pixels (69.2%) over 1e-06 1434882 pixels (69.2%) over 1e-06 FAILURE 'ERROR! Colorspace filter Using colorspace filter, better quality filter, SIMD so faster too, can support 10-bit too. Visually slight differences, but getting closer.
ffmpeg flags to add: -sws_flags spline+accurate_rnd+full_chroma_int -vf "colorspace=bt709:iall=bt601-6-625:fast=1"Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444colorspace.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444colorspace.png"Mean error = 0.00143352 RMS error = 0.0025418 Peak SNR = 51.8972 Max error = 0.0117647 @ (916, 308, B) values are 0.388235, 0.486275, 0.305882 vs 0.392157, 0.490196, 0.317647 1429294 pixels (68.9%) over 1e-06 1429294 pixels (68.9%) over 1e-06 FAILURE 'ERROR! libswscale filter + flags (Match) Using the libswscale library. Seems similar to colorspace, but with image resizing, and levels built in. This also has a number of libswscale parameters. Looking at the oiio difference, this is the first one that has an identical result to the input image.
ffmpeg flags to add: -sws_flags spline+accurate_rnd+full_chroma_int+full_chroma_inp -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709"Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444out_color_matrix.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444out_color_matrix.png"Mean error = 0.00105769 RMS error = 0.00204785 Peak SNR = 53.774 Max error = 0.0078432 @ (1217, 1037, B) values are 0.294118, 0.294118, 0.745098 vs 0.294118, 0.298039, 0.752941 1276800 pixels (61.6%) over 1e-06 1276800 pixels (61.6%) over 1e-06 FAILURE 'ERROR! libswscale filter + flags full-range (Match) Using the libswscale library. Seems similar to colorspace, but with image resizing, and levels built in. This also has a number of libswscale parameters. Looking at the oiio difference, this is the first one that has an identical result to the input image.
ffmpeg flags to add: -sws_flags spline+accurate_rnd+full_chroma_int+full_chroma_inp -vf "scale=in_range=full:in_color_matrix=bt709:out_range=full:out_color_matrix=bt709"Full creation commandline: OIIO idiff outputidiff -o ./chip-chart-yuvconvert/chip-chart-1080-noiccdiff.png ../sourceimages/chip-chart-1080-noicc.png ./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444out_color_matrixfull.png b'Comparing "../sourceimages/chip-chart-1080-noicc.png" and "./chip-chart-yuvconvert/chip-chart-1080-noicc-spline444out_color_matrixfull.png"Mean error = 0.0193162 RMS error = 0.0297635 Peak SNR = 30.5263 Max error = 0.0823529 @ (578, 961, R) values are 0.905882, 0.905882, 0.933333 vs 0.988235, 0.984314, 1 1972990 pixels (95.1%) over 1e-06 1972990 pixels (95.1%) over 1e-06 FAILURE 'ERROR! |