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 6AEE240333 for ; Mon, 20 Dec 2021 14:06:54 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 26F5268AE5D; Mon, 20 Dec 2021 16:06:52 +0200 (EET) Received: from canta.com.ar (mail.canta.com.ar [162.217.64.29]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id DAD0168A8E7 for ; Mon, 20 Dec 2021 16:06:45 +0200 (EET) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=canta.com.ar; s=mail; h=Content-Transfer-Encoding:Content-Type:Message-ID: Subject:To:From:Date:MIME-Version:Sender:Reply-To:Cc:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=pXDf7mYeeA5/Gatync61PyaSkDr9qYK/dAUXNdbDTcg=; b=pw4DNlH0xTN//t0xksgkdfwBSH eQBM+3I3aD367xS/hVXSF9GgffJR3yoieItT2uWxtuqBV88sWAAlDKFhzZvkWp7EFyNKAFS6pxKAP Nvr2GxMJoCbgvnpKD7Wx91x6NbCN3AVWXQCy3BN957w+F2OhOFcnoP2FUqqmdjuiS7iM=; Received: from [127.0.0.1] (helo=canta.com.ar) by canta.com.ar with esmtp (Exim 4.92.3) (envelope-from ) id 1mzJJM-0003dT-BT for ffmpeg-devel@ffmpeg.org; Mon, 20 Dec 2021 11:06:44 -0300 MIME-Version: 1.0 Date: Mon, 20 Dec 2021 11:06:44 -0300 From: =?UTF-8?Q?Daniel_Cantar=C3=ADn?= To: ffmpeg-devel@ffmpeg.org Message-ID: <678798058a84fb8a30dcfaa177431607@canta.com.ar> X-Sender: canta@canta.com.ar Subject: Re: [FFmpeg-devel] Politics 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: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: > > consider a subtitle track > consider 2 video tracks for US 30000/1001 fps and EU 25 fps > > the 6th frame in the US track is at 0.2002 sec, the 5th in the EU > track at 0.2sec > > > if these differ and you want a subtitle to either stop displaying after > the > earlier or begin displaying after the earlier reliably. Then you need a > timebase that can represent points within each such close encounter of > frame > times. > So, this isn't a subtitle problem if subtitle timings are correct. You let 0.2002 in the subtitle, players will decide the frame. You want to match the frame with the content, then you transcode the video properly. Am I losing something? Then again, we're of course not discussing players. One may say "that's not ffmpeg responsability", yet players are 90% of the time the main reason we have to do any extra work with ffmpeg. If we discuss real life scenarios, we should be discussing players. I also fail to see why would somebody want a "frame-perfect" sync between two videos with different FPS. That's absurd: there's no such thing as "frame-perfect" in such scenarios. What you would want is video timings to be honored. That is: FPS conversion to be faithful to video timings and content. I can imagine such precision dealing with frames being blurred and having to do lots of fine tuning in order to be able to perceive a single frame off in subtitles. That would be the real problematic situation, not any .0002 rounding. So, I see your example as a case of "what would the player do with that 0.2002 rounding" (in which case, we all know there would be two different subtitle files/streams with different precision for each video if it's THAT important) instead of "we need to change the timebase to something 4 decimals precise multiplier to both videos". And even if this fails and a frame is interpreted incorrectly in the player, good luck finding anyone saying anything about it: nobody cares about a single frame when it's about subtitles. People watching subtitles are simply not looking at that. This isn't speedrunning: it's translating and transcribing. People wants to understand what's going on in the screen, not debugging video frames. So, I see no "serious subtitle problem" nor anything close to "unnaceptable" here. Let's remark, as softworkz say, this are all fantasy scenarios, and the patchset doesn't show any real precision problem so far. If anyone is willing to share input files to test such possible precision problems, I'm willing to do the tests. No such files so far. _______________________________________________ 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".