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 <one...@gmail.com> wrote: > > > > > > > On Fri, Jan 6, 2023 at 6:25 PM Michael Niedermayer <mich...@niedermayer.cc> > > 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 < > >> mich...@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 <one...@gmail.com> > >> > > > 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. thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB The real ebay dictionary, page 1 "Used only once" - "Some unspecified defect prevented a second use" "In good condition" - "Can be repaird by experienced expert" "As is" - "You wouldnt want it even if you were payed for it, if you knew ..."
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