From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 8F530450F1 for ; Fri, 6 Jan 2023 17:56:20 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 09B9C68BD18; Fri, 6 Jan 2023 19:56:17 +0200 (EET) Received: from mail-vk1-f170.google.com (mail-vk1-f170.google.com [209.85.221.170]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id A5E1668BAAC for ; Fri, 6 Jan 2023 19:56:10 +0200 (EET) Received: by mail-vk1-f170.google.com with SMTP id v81so932780vkv.5 for ; Fri, 06 Jan 2023 09:56:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:subject:message-id:date:from:in-reply-to:references:mime-version :from:to:cc:subject:date:message-id:reply-to; bh=awwilG4DegkGXYa9rcIwkNJnAo9QXapY8Urb6mVeV9U=; b=A+cpl4BJ/YgH2WDpUKQlFIjei36UWWk0GLvyxoHQGJAYfyjIFi7bXMRDwooNBTOANB UHP11cTHdcLMQ/US7OQm/bNZw1kiOZZafW8UjTEwkSW2XClBrEDLW8MJ/iyo9Mu/uuT2 sd7GCTpCWgOgHsjQrcDX8BKFd21WQi4gsXEmiX5JWBJEnb2MII7dFi1bBQyf2E2msj+Z q3MyqI1by3I5zWRSHS29HQXQH27bm/BlyYmC1cIB5+ZjtV84svqMwWwYit9BxO0NxJki x1mWUZ/+t8gqE5T1yyG4eb1/hM68OUpPlVZ8k+IiRfXMpCultYjMDbOGRWRPGie1H1nh RYsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:subject:message-id:date:from:in-reply-to:references:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=awwilG4DegkGXYa9rcIwkNJnAo9QXapY8Urb6mVeV9U=; b=dBP+9vKrM4J/6iZINFQXVSCl3n8v5JcsnDJyQqOyzEL3WtNha/u9JqVPRQt0/4fBdq Dr4Q/OfHUM5tk91pxbw2c24aRSnyeH8lSJeLxRXZW0guTZZZqE8jYj4+8HhL1nJfWLYL XE4fLUoxCZLIaYRbhs/s3LNEQoAUoUuNpHKlns2CHGWG8OPNZpBhyMl6Qi8kRfdF14Ih +ULhn6CNsy6aZJINqKrfwHyBKTMe1XDkKad4DOBaIgASlqBfFGViI+VNK8L6y4JDRkBi fYvHbgFrAFHB67u0iQ1xXfn7+TPpvHhO5AgAu4eQcj//vzibAZFFcFKM/NAb34hnq8UI uLpw== X-Gm-Message-State: AFqh2krNGWm8H2y5SooIESw1fp9wEYjEVrvc4jmFG8LhpuSzy7mJ8eCh IuUe+UiqwEXXDU0I94m6ep+mEjMQl5sPZv5aUi/48DBn X-Google-Smtp-Source: AMrXdXt/sWLjvDGI6+lYYW8COBgWkfzoLn9fweqgtXm6H+17BZAvfk7z18N25Dpp3/2lrxurz+nlKdJuDrM6Hjpj6xM= X-Received: by 2002:a1f:4507:0:b0:3d5:6102:b5b8 with SMTP id s7-20020a1f4507000000b003d56102b5b8mr4169967vka.17.1673027768326; Fri, 06 Jan 2023 09:56:08 -0800 (PST) MIME-Version: 1.0 References: <20230105205342.GE4028235@pb2> <20230106172506.GG4028235@pb2> In-Reply-To: <20230106172506.GG4028235@pb2> From: Paul B Mahol Date: Fri, 6 Jan 2023 19:01:06 +0100 Message-ID: To: FFmpeg development discussions and patches X-Content-Filtered-By: Mailman/MimeDel 2.1.29 Subject: Re: [FFmpeg-devel] [PATCH] libswresample: avoid s16p internal processing format X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: 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. > > also what actually is the optimal frequency response of this filter ? > with a 22khz cutoff, a 22.1khz sine should be silence is that > really subjectively better than a 21.9khz sine ? > Iam not sure about this. Has someone done actual hearing tests with > actual real audio? the sinc filter originates from the idea of lossless > reconstruction of frequencies below nyquist if iam not mistaken, but humans > are not trying to losslessly restore a block of frequencies. A human > listener > generally wants to enjoy listening to some media. Has someone looked into > what is actually best for that real use case ? > This question matters because with it we can tune the filter parameters to > target humans. > > But lets push the doubts about choosing resampling purely based on > frequency > analysis away. > swresample has several parameters with which you can tune this: > we have a filter_size, if thats bigger you should get closer to the ideal > sinc. Theres phase_shift which may reduce the (i assume) unhearable > aliasing. > And cutoff which should allow to tune the (i assume) hearable > reflection/attenuation tradeoff also theres filter_type to allow you to > tune the > window function. > > If there are issues reported by people using their ears, please provide > more > details, iam interrested in these cases. > > > > > > > > > This change should be limited to the case that benefits, this would > force > > > this > > > even without resampling in some cases. > > > > > > > It is forced only if sample rates between input and output differs. > > If iam not mistaken it affects rematrixing without resampling too > How so? I really doubt that this patch do that. > > 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 > ..." > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".