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 95A194372F for ; Wed, 26 Oct 2022 19:13:16 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 9119D68BC2D; Wed, 26 Oct 2022 22:13:13 +0300 (EEST) Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 75C7368B883 for ; Wed, 26 Oct 2022 22:13:07 +0300 (EEST) Received: (Authenticated sender: michael@niedermayer.cc) by mail.gandi.net (Postfix) with ESMTPSA id D3F58E0006 for ; Wed, 26 Oct 2022 19:13:05 +0000 (UTC) Date: Wed, 26 Oct 2022 21:13:02 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20221026191302.GG4048598@pb2> References: <2b7f9605-518a-4cda-6503-7842f22fa620@das-werkstatt.com> MIME-Version: 1.0 In-Reply-To: <2b7f9605-518a-4cda-6503-7842f22fa620@das-werkstatt.com> Subject: Re: [FFmpeg-devel] FFV1 slicecrc: "hashxx" instead of "CRC" for speed? 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: multipart/mixed; boundary="===============2198911205169384658==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============2198911205169384658== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="4eRLI4hEmsdu6Npr" Content-Disposition: inline --4eRLI4hEmsdu6Npr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Oct 25, 2022 at 10:31:48PM +0200, Peter B. wrote: > Hi everyone :) >=20 > This is merely a question of interest. Not a request, complaint or trolli= ng > of any kind :) > I'm happy about any answer. I'm curious. >=20 > Would it possibly have a significant impact on coding speed of FFV1's > slicecrc option (Where a CRC is calculated for each frame slice), to use a > faster algorithm instead (if one exists)? > I'm wondering if, for example something like "xxHash" may warrant a try? > (Haven't found CRC vs xxHash benchmarks yet, but I'm still looking) CRC is not a random pick for error detection, CRC has specfic properties like for example that whole classes of errors are guranteed to be detected a random hash will not gurantee that. for example a properly designed 8bit CRC will detect every single 1 byte ch= ange always. a 8 bit hash like taking 8 bits from SHA256 will detect only 255 ou= t of 256 1 byte changes also CRC can be done in parallel if you have cores to spare, you can split a chunk in as many chunks as you want do the CRC for each and combine them wi= th a bit of math and CRC is in the specification so using somehing else would require changing the spec=20 thx [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB He who knows, does not speak. He who speaks, does not know. -- Lao Tsu --4eRLI4hEmsdu6Npr Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEIAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCY1mGtwAKCRBhHseHBAsP q2DyAJ940MDh44K2j7mSTdr/dwGMH/7DjQCfaz11Ao3Y4d7c0b916vNZ3x+92T4= =Da12 -----END PGP SIGNATURE----- --4eRLI4hEmsdu6Npr-- --===============2198911205169384658== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ 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". --===============2198911205169384658==--