12.11.2014 14:26, Alexander E. Patrakov пиÑ?еÑ?: > I will recheck the quality separately later today, in order to verify > that it is still as good as in the previous tests. Please don't merge > the patches until this is done. Done. The -mq, -hq and -vhq variants of the resampler never produce audible distortions. The -lq variant sometimes does, by means of suppressing very high frequencies, but this is relevant to artificial tests only, and only if the listener knows that these frequencies are supposed to be there. Thus, quality is on par with speex-float-5, the CPU consumption is even better than with speex-float-1. Conclusion: *** the patches are generally acceptable *** However, because the low-quality and high-quality versions eat very similar amount of CPU time, I'd just expose a single (high or very high) quality setting. All plots are available at: https://yadi.sk/d/GTQYG9qBcfbMe (2.2 MB) Read this in order to interpret them and to understand how they were made: http://lists.freedesktop.org/archives/pulseaudio-discuss/2014-September/021811.html . The room noise has not been taken into account for the plots, so these are worst-case plots. I have not subjected the new resampler to extensive tests on a variety of music. However, here is what various resamplers think about two files that I did test them on: Artist: Ryan Farish Album: Bloom Composition: Anthem of Hope (i.e. track 2 out of 17) FFT size used for the test: 4096 Length of the track: 4 minutes 14 seconds speex-float-1: average distortion = -12.6 dB, maximum = -5.4 dB, at 0:05 speex-float-3: average distortion = -28.3 dB, maximum = -26.1 dB, at 0:10 speex-float-5: average distortion = -42.2 dB, maximum = -37.7 dB, at 0:10 soxr-lq: average distortion = -38.0 dB, maximum = -31.4 dB, at 2:06 soxr-mq: average distortion = -28.1 dB, maximum = -21.2 dB, at 1:45 soxr-hq: average distortion = -39.9 dB, maximum = -38.9 dB, at 3:54 soxr-vhq: average distortion = -40.4 dB, maximum = -39.2 dB, at 1:10 I.e., for music, soxr creates distortions ~40 dB below what a human can notice. For speech, I have used a track from the first audio CD that comes with a "Teach Yourself Malay" book. The track (number 5) is for Unit 1, "Welcome to Singapore!", and is the second of the five tracks for the unit. The track is 1 minute and 12 seconds long. speex-float-1: average distortion = -14.5 dB, maximum = -4.7 dB, at 0:58 speex-float-3: average distortion = -28.9 dB, maximum = -24.9 dB, at 0:58 speex-float-5: average distortion = -43.1 dB, maximum = -36.5 dB, at 0:58 soxr-lq: average distortion = -38.8 dB, maximum = -28.0 dB, at 0:30 soxr-mq: average distortion = -27.7 dB, maximum = -17.3 dB, at 0:55 soxr-hq: average distortion = -40.7 dB, maximum = -39.0 dB, at 1:06 soxr-vhq: average distortion = -41.2 dB, maximum = -39.0 dB, at 0:58 All of the above assumes that the full scale is 92 dB SPL, and that the room is absolutely quiet. So, even in these conditions, a human definitely cannot hear distortions created by any of the resamplers. To test the resamplers according to the psychoacoustical model on the music of your choice, please follow this post: http://lists.freedesktop.org/archives/pulseaudio-discuss/2014-October/021911.html Or, if you just want to regenerate the distortion lines above, download this archive and convert resampler response files to wav: https://yadi.sk/d/4DzqyERYcfeBm (113 MB) The command line is: flac -d sound-files2/*.flac ./music_distortions.py --report-only --resampler-response sound-files2/soxr-vhq.wav --rate-from 44100 --fftsize 4096 --skip 32768 /path/to/your/music/file.mp3 2>/dev/null -- Alexander E. Patrakov
