On Mon, Nov 02, 2015 at 09:32:13PM -0500, Ganesh Ajjanagadde wrote: > 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.
the patch should be ok its faster, its more accurate [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Everything should be made as simple as possible, but not simpler. -- Albert Einstein
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