[FFmpeg-devel] [PATCH] avformat/mov: remove hack breaking creation time parsing

[Bernd Dürrer]

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