[FFmpeg-user] creation_time tag cannot be set before 1970-01-01 with ffmpeg

[Bernd Dürrer]

Hi,
 
I use twonky as DLNA server that provides the year from the creation_time metadata tag of MP4 files to DLNA clients. Therefore, I use ffmpeg to set creation_time to the date when the content of the MP4 video was created. This works fine for dates starting at January 1st 1970. For earlier dates (e.g. ffmpeg -i input.mp4 -map_metadata 0 -metadata creation_time="1965-01-01 12:00:00" -codec copy output.mp4), though the date is correctly displayed during the copy process, afterwards ffprobe yields a future date (in the example, ffprobe output.mp4 displays creation_time as 2036-01-01T23:59:59.000000Z). According to 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)", so dates before 1970 should be possible.

It seems to be an Unix epoch issue. Will this be amended in a future release of ffmpeg? Is anybody aware of another metadata editor that may set creation_time to dates earlier than 1970?

Kind regards,

Bernd