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From: "Bernd Dürrer" <Bernd.Duerrer@gmx.de>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH] avformat/mov: remove hack breaking creation time parsing
Date: Wed, 12 Apr 2023 10:10:20 +0200
Message-ID: <trinity-58fd0ab7-fe68-45d6-9251-fcf8cafc1cff-1681287020471@3c-app-gmx-bs18> (raw)
In-Reply-To: <b97dcfa1-9746-49f7-13bd-cbc75f84a71e@passwd.hu>

On Tue, 11 Apr 2023, Marton Balint wrote:
 
>> As defined in ISO/IEC 14496-12, clause 8.2, "creation_time is an integer
>> that declares the creation time of the presentation (in seconds since
>> midnight, Jan. 1, 1904, in UTC time)". This is the date when the content
>> was created (which may have been on photographic film), and not when it
>> was encoded as a digital file.
>
> I don't think that is true, it is not clear from the specs at best. The
> creation time of the presentation can just as easily refer to the file
> itself, not the content. Feel free to reencode something with a commercial
> encoder, I would be suprised if creation time was kept.

I agree that it may be debated for what purpose the creation_time tag has been intended by the authors of the standard, and that this tag may be used inconsistently by different encoders. However, it remains a fact that ffmpeg does not support the date range defined in the standard, and that ffmpeg writes an incorrect date to the file if a date before 1970 is provided. This is a bug that should be amended.

Kind regards,

Bernd
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  reply	other threads:[~2023-04-12  8:10 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-11 11:46 Bernd Dürrer
2023-04-11 18:15 ` Marton Balint
2023-04-12  8:10   ` Bernd Dürrer [this message]
2023-04-12  8:38     ` "zhilizhao(赵志立)"
2023-04-13 10:13   ` Bernd Dürrer
  -- strict thread matches above, loose matches on Subject: below --
2023-04-08 18:37 Marton Balint
2023-04-08 21:14 ` Michael Niedermayer
2023-04-09 13:49   ` Marton Balint
2023-04-09 14:06     ` Anton Khirnov
2023-04-09 17:20     ` Michael Niedermayer
2023-04-09 17:52       ` Marton Balint
2023-04-09 21:27         ` Michael Niedermayer
2023-04-10 19:11           ` Marton Balint
2023-04-10 22:34             ` Michael Niedermayer
2023-04-10  2:44       ` "zhilizhao(赵志立)"
2023-04-10 14:31         ` Michael Niedermayer

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