EXIF timestamps are finish time rather than start time

[dpocock]

The filename appears to be based on the start time but the EXIF data appears to be the finish time.

For a 14 second recording:

$ exiftool -list 2025-08-16-11-07-14.m4a | grep 2025| grep -v ^File
Create Date                     : 2025:08:16 09:07:28
Modify Date                     : 2025:08:16 09:07:28
Track Create Date               : 2025:08:16 09:07:28
Track Modify Date               : 2025:08:16 09:07:28
Media Create Date               : 2025:08:16 09:07:28
Media Modify Date               : 2025:08:16 09:07:28

The filename is based on the real starting time 11:07:14

The EXIF metadata tags are all the stop time 11:07:28

There is an archived copy of the EXIF2.2 spec (PDF) online.

They suggest, on page 94

etim Records the time of Exif audio file creation. This is defined as the time the recording of audio data was started.

Similar comments on pages 116, 118, 120.