On Mon, Nov 2, 2015 at 6:49 PM, Ganesh Ajjanagadde <gajja...@mit.edu> wrote: > On Mon, Nov 2, 2015 at 6:37 PM, wm4 <nfx...@googlemail.com> wrote: >> On Mon, 2 Nov 2015 14:49:54 -0500 >> Ganesh Ajjanagadde <gajjanaga...@gmail.com> wrote: >> >>> This improves accuracy for the bessel function, and this in turn should >>> improve the quality of the Kaiser window. >> >> >> "Should"? Does it or does it not? If you don't know, why the patch? > > It improves the window in the sense of mathematically matching the > Kaiser window expression due to the improved bessel function accuracy. > That claim I have verified and placed in the commit message with > evidence. > > What that translates into in terms of resampling accuracy, I don't > know. Normally, such things do help reduce the noise floor, but I > don't know an easy way to test via FATE or associated tools. I put > that caveat in the bottom lines of the patch.
Turns out the init speed is definitely improved as well (~20% boost with default settings). I did a cheap trick of calling build filter 1000 times to get a large number of runs. Results (x86-64, Haswell, GNU/Linux): test: fate-swr-resample-dblp-44100-2626 new: 995894468 decicycles in build_filter(loop 1000), 256 runs, 0 skips 1029719302 decicycles in build_filter(loop 1000), 512 runs, 0 skips 984101131 decicycles in build_filter(loop 1000), 1024 runs, 0 skips old: 1250020763 decicycles in build_filter(loop 1000), 256 runs, 0 skips 1246353282 decicycles in build_filter(loop 1000), 512 runs, 0 skips 1220017565 decicycles in build_filter(loop 1000), 1024 runs, 0 skips Thus, this patch has both things going for it luckily. Will leave to the maintainer (Michael I believe) to give details of accuracy benefits as translated to the actual resampling if easily testable, and I will add the perf numbers to the message. > >> _______________________________________________ >> ffmpeg-devel mailing list >> ffmpeg-devel@ffmpeg.org >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
