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 0FA26430A7 for ; Fri, 20 May 2022 13:24:04 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id D28CB68B48E; Fri, 20 May 2022 16:24:01 +0300 (EEST) Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id EFA5368B447 for ; Fri, 20 May 2022 16:23:54 +0300 (EEST) Received: from localhost (213-47-68-29.cable.dynamic.surfer.at [213.47.68.29]) (Authenticated sender: michael@niedermayer.cc) by mail.gandi.net (Postfix) with ESMTPSA id CA86220008 for ; Fri, 20 May 2022 13:23:53 +0000 (UTC) Date: Fri, 20 May 2022 15:23:52 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20220520132352.GV396728@pb2> References: <20220518151817.21270-1-leo.izen@gmail.com> <20220518182338.GR396728@pb2> <20220518182748.GS396728@pb2> <20220520102815.GT396728@pb2> <1d00bdb9-cf77-aa08-1799-db77d2548d0c@gmail.com> MIME-Version: 1.0 In-Reply-To: <1d00bdb9-cf77-aa08-1799-db77d2548d0c@gmail.com> Subject: Re: [FFmpeg-devel] [PATCH v4] avutil/csp: create avpriv API for colorspace structs 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="===============5586725900454235099==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============5586725900454235099== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="uFO8jlCBh1yRPqfb" Content-Disposition: inline --uFO8jlCBh1yRPqfb Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, May 20, 2022 at 08:53:35AM -0300, James Almer wrote: >=20 >=20 > On 5/20/2022 7:28 AM, Michael Niedermayer wrote: > > On Wed, May 18, 2022 at 08:27:48PM +0200, Michael Niedermayer wrote: > > > On Wed, May 18, 2022 at 08:23:38PM +0200, Michael Niedermayer wrote: > > > > On Wed, May 18, 2022 at 11:18:17AM -0400, Leo Izen wrote: > > > > > This commit moves some of the functionality from avfilter/colorsp= ace > > > > > into avutil/csp and exposes it as an avpriv API so it can be used= by > > > > > libavcodec and/or libavformat. > > > > [...] > > > > > +#ifndef AVUTIL_CSP_H > > > > > +#define AVUTIL_CSP_H > > > > > + > > > > > +#include "libavutil/pixfmt.h" > > > > > + > > > > > +typedef struct AVLumaCoefficients { > > > > > + double cr, cg, cb; > > > > > +} AVLumaCoefficients; > > > > > + > > > > > +typedef struct AVPrimaryCoefficients { > > > > > + double xr, yr, xg, yg, xb, yb; > > > > > +} AVPrimaryCoefficients; > > > > > + > > > > > +typedef struct AVWhitepointCoefficients { > > > > > + double xw, yw; > > > > > +} AVWhitepointCoefficients; > > > >=20 > > > > As said, these should not be floating point. > > > > Adding a new public API and changing it later is messy, this > > > > should be changed before its made public > > >=20 > > > i now see you replaced some public by avpriv in the latest patch > > > but still i think this should be changed to fixed point or AVRational > > > first. Even as API between the libs its messy to change it later > > > it would require us to keep the double API when its changed until > > > the next major bump > >=20 > > I see some discussion related to this on the IRC log from when i was > > sleeping. Maybe it would be better to keep this on the mailing list > >=20 > > Also iam not sure my concern was clearly worded so ill sort my argument > > and concerns so its clearer below: > >=20 > > 1. exactly representing values > > if you have a 0.1 you can represent that exactly as AVRational 1/1= 0 but > > maybe shockingly a double cannot. > > Try a printf %f of 0.1 and it will do 0.100000 looks good but that= s deception > > try that with more precission %100.99f shows this: > > 0.1000000000000000055511151231257827021181583404541015625000000000= 00000000000000000000000000000000000 > > so if we want to use exactly the values from the spec, doubles wit= h a > > unit/base of 1 do not work. > > int or even doubles with a base/unit of 30000 might work exactly if > > AVRational is unpopular. 30000 instead of 10000 is for that one pe= sky 1/3 > > 1b. the exact value that 0.1 has in float/double depends on the preciss= ion > > IEEE float > > 0.1000000014901161193847656250000000000000000000000000000000000000= 00000000000000000000000000000000000 > > IEEE double > > 0.1000000000000000055511151231257827021181583404541015625000000000= 00000000000000000000000000000000000 > > long double > > 0.1000000000000000000013552527156068805425093160010874271392822265= 62500000000000000000000000000000000 > > So there will be slight differences if (intermediate) types anywhe= re arent > > exactly the same > >=20 > > 2. someone said, you need to pick a denominator when doing float -> rat= ional > > av_d2q() will pick the best denominator for you. > >=20 > > 3. avpriv_ vs av_ > > avpriv is evil, it combines the pain of ABI/API compatibility whil= e the > > public cant use it >=20 > Not making it public allows us to not commit to a fixed design *now*. > Unless there's a clear need for this to be part of the public API, i don't > think it's a good idea to do so. This change is being made because this A= PI > is afaict needed in lavc, and not by some project using lavu. >=20 > Removing/changing an avpriv symbol or struct is a matter or waiting for t= he > nearest major bump. No need for an arbitrary 2 year wait period, compat > wrappers, or anything crazy. yes but is that really easier ? sheduling changes to happen during a bump vs adding a warper+deprecating at any time with a automatic #if removing code thx [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB If you fake or manipulate statistics in a paper in physics you will never get a job again. If you fake or manipulate statistics in a paper in medicin you will get a job for life at the pharma industry. --uFO8jlCBh1yRPqfb Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEIAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCYoeWZQAKCRBhHseHBAsP qwLSAJ99Usgc4nRnOIbVdkK+/17G/IZZFQCffJz1jR4fuRxnmLFRV3uTlgV3nmg= =RLDS -----END PGP SIGNATURE----- --uFO8jlCBh1yRPqfb-- --===============5586725900454235099== 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". --===============5586725900454235099==--