avfilter: add XPSNR filter

Add XPSNR video filter
Register new filter xpsnr.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

1 files changed, 68 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index b1ca9ad2f3..db2f4b7ea7 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -19944,6 +19944,7 @@ pseudocolor="'if(between(val,ymax,amax),lerp(ymin,ymax,(val-ymax)/(amax-ymax)),-
 @end example
 @end itemize
 
+@anchor{psnr}
 @section psnr
 
 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
@@ -26064,6 +26065,73 @@ minimum values, and @code{1} maximum values.
 
 This filter supports all above options as @ref{commands}, excluding option @code{inputs}.
 
+@anchor{xpsnr}
+@section xpsnr
+
+Obtain the average (across all input frames) and minimum (across all color plane averages)
+eXtended Perceptually weighted peak Signal-to-Noise Ratio (XPSNR) between two input videos.
+
+The XPSNR is a low-complexity psychovisually motivated distortion measurement algorithm for
+assessing the difference between two video streams or images. This is especially useful for
+objectively quantifying the distortions caused by video and image codecs, as an alternative
+to a formal subjective test. The logarithmic XPSNR output values are in a similar range as
+those of traditional @ref{psnr} assessments but better reflect human impressions of visual
+coding quality. More details on the XPSNR measure, which essentially represents a blockwise
+weighted variant of the PSNR measure, can be found in the following freely available papers:
+
+@itemize
+@item
+C. R. Helmrich, M. Siekmann, S. Becker, S. Bosse, D. Marpe, and T. Wiegand, "XPSNR: A
+Low-Complexity Extension of the Perceptually Weighted Peak Signal-to-Noise Ratio for
+High-Resolution Video Quality Assessment," in Proc. IEEE Int. Conf. Acoustics, Speech,
+Sig. Process. (ICASSP), virt./online, May 2020. @url{www.ecodis.de/xpsnr.htm}
+
+@item
+C. R. Helmrich, S. Bosse, H. Schwarz, D. Marpe, and T. Wiegand, "A Study of the
+Extended Perceptually Weighted Peak Signal-to-Noise Ratio (XPSNR) for Video Compression
+with Different Resolutions and Bit Depths," ITU Journal: ICT Discoveries, vol. 3, no.
+1, pp. 65 - 72, May 2020. @url{http://handle.itu.int/11.1002/pub/8153d78b-en}
+@end itemize
+
+When publishing the results of XPSNR assessments obtained using, e.g., this FFmpeg filter, a
+reference to the above papers as a means of documentation is strongly encouraged. The filter
+requires two input videos. The first input is considered a (usually not distorted) reference
+source and is passed unchanged to the output, whereas the second input is a (distorted) test
+signal. Except for the bit depth, these two video inputs must have the same pixel format. In
+addition, for best performance, both compared input videos should be in YCbCr color format.
+
+The obtained overall XPSNR values mentioned above are printed through the logging system. In
+case of input with multiple color planes, we suggest reporting of the minimum XPSNR average.
+
+The following parameter, which behaves like the one for the @ref{psnr} filter, is accepted:
+
+@table @option
+@item stats_file, f
+If specified, the filter will use the named file to save the XPSNR value of each individual
+frame and color plane. When the file name equals "-", that data is sent to standard output.
+@end table
+
+This filter also supports the @ref{framesync} options.
+
+@subsection Examples
+@itemize
+@item
+XPSNR analysis of two 1080p HD videos, ref_source.yuv and test_video.yuv, both at 24 frames
+per second, with color format 4:2:0, bit depth 8, and output of a logfile named "xpsnr.log":
+@example
+ffmpeg -s 1920x1080 -framerate 24 -pix_fmt yuv420p -i ref_source.yuv -s 1920x1080 -framerate
+24 -pix_fmt yuv420p -i test_video.yuv -lavfi xpsnr="stats_file=xpsnr.log" -f null -
+@end example
+
+@item
+XPSNR analysis of two 2160p UHD videos, ref_source.yuv with bit depth 8 and test_video.yuv
+with bit depth 10, both at 60 frames per second with color format 4:2:0, no logfile output:
+@example
+ffmpeg -s 3840x2160 -framerate 60 -pix_fmt yuv420p -i ref_source.yuv -s 3840x2160 -framerate
+60 -pix_fmt yuv420p10le -i test_video.yuv -lavfi xpsnr="stats_file=-" -f null -
+@end example
+@end itemize
+
 @anchor{xstack}
 @section xstack
 Stack video inputs into custom layout.