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Date: Tue, 26 May 2026 20:39:16 +0900
To: cygwin AT cygwin DOT com
Subject: Re: "Invalid DTS" warnings only in Cygwin version of ffmpeg
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From: Takashi Yano via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>
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On Tue, 26 May 2026 08:57:46 +0900
Takashi Yano wrote:
> On Mon, 25 May 2026 00:47:21 +0000
> destal takul wrote:
> > Nearly every file muxed using MKVToolnix, when remuxed using the Cygwin version of ffmpeg with '-c copy', will result in "Invalid DTS: XX PTS: XX, replacing by guess" and "Non-monotonic DTS; previous: XX, current: XX; changing to XX. This may result in incorrect timestamps in the output file." warnings, while the Linux and native Windows builds (by gyan.dev) of the exact same ffmpeg version do not generate such warnings when remuxing the exact same input file. This seems to be stemming from some math library difference that results in incorrect parsing of timestamps in the Cygwin version.
> 
> Thanks for the report. I was able to reproduce the issue.
> Let me take a closer look.

I have found the cause. The cygwin ffmpeg package is based on the
Fedora ffmpeg-free package, and the issue also occurs in Fedora's
ffmeg-free package. In other words, the issue originates from
Fedora. I have added a workaround for this problem.

Please wait for 8.1.1-3, in which the issue will be fixed.

-- 
Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>

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