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 B561E42FA1 for ; Sat, 16 Jul 2022 14:24:03 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 7E89E68B914; Sat, 16 Jul 2022 17:24:01 +0300 (EEST) Received: from mail8.parnet.fi (mail8.parnet.fi [77.234.108.134]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id B5EF668B67D for ; Sat, 16 Jul 2022 17:23:54 +0300 (EEST) Received: from mail9.parnet.fi (mail9.parnet.fi [77.234.108.21]) by mail8.parnet.fi with ESMTP id 26GENrSA028819-26GENrSB028819 for ; Sat, 16 Jul 2022 17:23:53 +0300 Received: from foo.martin.st (host-97-187.parnet.fi [77.234.97.187]) by mail9.parnet.fi (Postfix) with ESMTPS id EB6B6A150B for ; Sat, 16 Jul 2022 17:23:53 +0300 (EEST) Date: Sat, 16 Jul 2022 17:23:53 +0300 (EEST) From: =?ISO-8859-15?Q?Martin_Storsj=F6?= To: FFmpeg development discussions and patches In-Reply-To: <20220716132010.GJ2088045@pb2> Message-ID: References: <20220713204854.3114817-1-martin@martin.st> <20220713204854.3114817-5-martin@martin.st> <8E07A574-9F34-48B1-98BC-95A5B676A458@amazon.com> <3a7cff5-7691-e8cd-55c6-28f7f63cda27@martin.st> <20220715211948.GF2088045@pb2> <37f78b5-e37b-b71d-f8b6-236e47b3b9c@martin.st> <20220716112336.GH2088045@pb2> <20220716132010.GJ2088045@pb2> MIME-Version: 1.0 X-FE-Policy-ID: 3:14:2:SYSTEM X-Content-Filtered-By: Mailman/MimeDel 2.1.29 Subject: Re: [FFmpeg-devel] [PATCH 5/5] aarch64: me_cmp: Don't do uaddlv once per iteration 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-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On Sat, 16 Jul 2022, Michael Niedermayer wrote: > On Sat, Jul 16, 2022 at 03:30:23PM +0300, Martin Storsj=F6 wrote: >> On Sat, 16 Jul 2022, Michael Niedermayer wrote: >> >>> On Sat, Jul 16, 2022 at 12:25:37AM +0300, Martin Storsj=F6 wrote: >>>> On Fri, 15 Jul 2022, Michael Niedermayer wrote: >>>> >>>>> On Fri, Jul 15, 2022 at 10:56:03PM +0300, Martin Storsj=F6 wrote: >>>>>> On Fri, 15 Jul 2022, Swinney, Jonathan wrote: >>>>>> >>>>>>> If the max height is just 16, then this should be fine. I assumed t= hat h >>>>>>> could have a much higher value (>1024), but if that is not the case, >>>>>>> then this is a useful optimization. >>>>>> >>>>>> At least according to the me_cmp.h header, which says: >>>>>> >>>>>> /* Motion estimation: >>>>>> * h is limited to { width / 2, width, 2 * width }, >>>>>> * but never larger than 16 and never smaller than 2. >>>>>> * Although currently h < 4 is not used as functions with >>>>>> * width < 8 are neither used nor implemented. */ >>>>> >>>>> These rules where written with support for encoding of all >>>>> standard formats in mind at the time that was written. >>>>> today it may make sense to extend these rules to cover the >>>>> things which where created since then >>>> >>>> Right, but if that suddenly changes, such a change also must expect th= at it >>>> might need updates to all assembly implementations that implement that >>>> interface currently. Right now, both the defacto case (any callers in = the >>>> codebase) and the explicit documentation says that it can't be called = with >>>> parameters outside of that range. >>> >>> What i meant was that newly added functions should be more flexible than >>> these old rules. That is 2 sets of rules >>> 1. What a caller ATM can do and expect to work (thats whats written the= re) >>> 2. What an implementor of new functions should make sure is supported >> >> With 2., do you mean if adding a new function into the same struct, or if >> implementing the existing pix_abs[0][..] functions? > > i would say both > > >> >> If you mean new implementations of the existing function interface, you = say >> they "should be more flexible". How flexible must they be? Is it ok to >> assume h<=3D256 for the w=3D16 functions? > > i think thats fine Ok, I'll go ahead and push this then. >> >> Gradually increasing the requirements for existing function interfaces l= ike >> you suggest is really problematic. > > why ? > iam really just saying > "when you add new code, dont base it on old limitations" For this case, I just quoted what the header said, which seemed = authoritative to me - but it's fine for me with a wider spec too, up to = h=3D256. But saying arbitrarily "any height" really inhibits what you can d= o = in asm. Also if I shouldn't reference that limitation in the header, please = update/reword it, as it's actively misleading for anyone working on = this right now. And in general, we can design for an intended use case and calculate = whether it should work or not - but as long as it's not tested, those = cases will often have hidden bugs - see e.g. patch 1/5 in this series. // Martin _______________________________________________ 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".