From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.ffmpeg.org (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTPS id 2C8834BFB3 for ; Mon, 28 Jul 2025 14:15:30 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTP id 91DBD68BB29; Mon, 28 Jul 2025 17:15:25 +0300 (EEST) Received: from nef.ens.fr (nef2.ens.fr [129.199.96.40]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTPS id 52AFD687D26 for ; Mon, 28 Jul 2025 17:15:19 +0300 (EEST) X-ENS-nef-client: 129.199.129.80 ( name = phare.normalesup.org ) Received: from phare.normalesup.org (phare.normalesup.org [129.199.129.80]) by nef.ens.fr (8.14.4/1.01.28121999) with ESMTP id 56SEFI5t028470 for ; Mon, 28 Jul 2025 16:15:18 +0200 Received: by phare.normalesup.org (Postfix, from userid 1001) id 57D8B2EFE6; Mon, 28 Jul 2025 16:15:18 +0200 (CEST) Date: Mon, 28 Jul 2025 16:15:18 +0200 From: Nicolas George To: FFmpeg development discussions and patches Message-ID: References: <20250723135626.1390296-1-ffmpeg@haasn.xyz> <20250723171838.GB1401694@haasn.xyz> <20250724131154.GB95314@haasn.xyz> <20250728000028.GW29660@pb2> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20250728000028.GW29660@pb2> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (nef.ens.fr [129.199.96.32]); Mon, 28 Jul 2025 16:15:18 +0200 (CEST) Subject: Re: [FFmpeg-devel] Again pre-multiplied alpha 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: Michael Niedermayer (HE12025-07-28): > About STF, it depends on who does the work. > If a FFmpeg developer does the work, then i think STF is a good idea. > OTOH It would be an inappropriate task for a new contributor (like in GSoC). Indeed, way too hard for somebody who does not already know libavfilter very well. If perchance they do but for some reason never contributed, we cannot trust that they do. > One thing thats important for this is that whoever wants to work on this > speaks with Nicolas to make sure theres agreement on the implementation. Thanks. I had started to make the negotiation modular and extensible a few years back, that is when I realized what I now say an repeat: Any work on the format negotiation of libavfilter must start wit adding test coverage. Otherwise, the work is very likely to break specific cases that were fixed along the years. We talked about it a few weeks ago, I procrastinated answering: Adding test coverage is a boring but not difficult task, it can be done by a stranger motivated by a bounty. But I personally have absolutely no idea how to make it happen with the STF. In particular, I have absolutely no idea how much to offer. > My original plan was based on arbitrary graphs and a solution that could be > proofen to be within a constant factor of the global optimum. This would > have required simplifying the graph iteratively with a random seed multiple > times IIRC. But because a single pass "just worked" i never implemented this. I do not understand what you are talking about. Right now, the negotiation process does a loop, and it often requires a few passes to converge. There are two things missing: 1. If we want to add a new orthogonal category, copy-paste it is. 2. We have no way to negotiate dependant categories. Is it audio? let us negotiate the sample format and channel layout; is it video? let us negotiate the pixel format. Making the negotiation categories modular, with callbacks instead of hard-coded function calls, would make both relatively easy, and more importantly not a maintenance nightmare. Regards, -- Nicolas George _______________________________________________ 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".