On Thu, Jan 12, 2023 at 03:20:06PM +0100, Paul B Mahol wrote: > On 1/8/23, Michael Niedermayer wrote: > > On Fri, Jan 06, 2023 at 07:04:59PM +0100, Paul B Mahol wrote: > >> On Fri, Jan 6, 2023 at 7:01 PM Paul B Mahol wrote: > >> > >> > > >> > > >> > On Fri, Jan 6, 2023 at 6:25 PM Michael Niedermayer > >> > > >> > wrote: > >> > > >> >> On Thu, Jan 05, 2023 at 11:08:25PM +0100, Paul B Mahol wrote: > >> >> > On Thu, Jan 5, 2023 at 9:53 PM Michael Niedermayer < > >> >> michael@niedermayer.cc> > >> >> > wrote: > >> >> > > >> >> > > On Thu, Jan 05, 2023 at 01:44:10PM +0100, Paul B Mahol wrote: > >> >> > > > Patch attached. > >> >> > > > >> >> > > > swresample.c | 3 ++- > >> >> > > > 1 file changed, 2 insertions(+), 1 deletion(-) > >> >> > > > eee7a0685b44aa867562138a2e2437ecb8844612 > >> >> > > 0001-libswresample-swresample-avoid-s16p-internal-transfe.patch > >> >> > > > From 9c4cd60e2dd41cf98d693c8251f4cfade0807073 Mon Sep 17 > >> >> > > > 00:00:00 > >> >> 2001 > >> >> > > > From: Paul B Mahol > >> >> > > > Date: Thu, 5 Jan 2023 13:40:12 +0100 > >> >> > > > Subject: [PATCH] libswresample/swresample: avoid s16p internal > >> >> transfer > >> >> > > format > >> >> > > > > >> >> > > > Instead use float one by default for sample rate conversions. > >> >> > > > The s16p internal transfer format produces visible and hearable > >> >> > > > quantization artifacts. > >> >> > > > >> >> > > When does this occur and why? > >> >> > > > >> >> > > >> >> > It occurs always. Just compare output with 16bit and > >> >> > int32/float/double. > >> >> > Look at other people report on internet. > >> >> > Look at src.infinitewave.ca > >> >> > >> >> src.infinitewave.ca uses 32bit none of what it shows should touch the > >> >> codepath > >> >> you change. > >> >> > >> >> if we look at src.infinitewave.ca for swr we see 2 types of artifacts > >> >> 1. Aliassing which is at maybe -120db with the actual signal at 0db > >> >> i would like to see some evidence that a human can hear this > >> >> > >> > > >> > For s16p<->s16p it is much lower, around -78dB thus this patch. > >> > > >> > Also for others and reports for swr its is lower than exact -120dB > >> > > >> > > >> > 2. Reflection and attenuation at the transition frequency > >> >> With linear filters there is a tradeof between attenuation of the > >> >> passband, reflection of frequencies beyond, latency and so on > >> >> You can have a perfect sharp cutoff with no attenuation and no > >> >> refelection > >> >> that requires a infinitly long filter. And while this looks best in > >> >> this > >> >> frequency plot, does it actually sound best ? If you can hear -120db > >> >> signals you surely would then also hear the ringing long before a > >> >> gunshot > >> >> from such long filter. > >> >> > >> > > >> One can always change linear FIR to be min phase FIR kernel. > > > > I certainly would welcome a wider range of filters in swr, if you want to > > add > > any low delay sinc approximation or in fact i would welcome any filter > > you want to add. > > There is that afdelaysrc filter patch on ML to add FIR coefficient > generation for fractional delay audio filter that can be also used as > a interpolation FIR filter. And to me it seems better at same number > of taps than already used/available ones in soxr and swr. Please add improvments into swr, if you have any! > > Also I have done prototype of resampling filter using afir filter via > custom filters in filtergraph and it operates at similar speeds like > soxr (in these very non optimized approach) and providing better/wider > frequency output at highest band. Can it be added into swr ? thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Awnsering whenever a program halts or runs forever is On a turing machine, in general impossible (turings halting problem). On any real computer, always possible as a real computer has a finite number of states N, and will either halt in less than N cycles or never halt.