ffmpeg incorrectly warns about "non-monotonous" timestamp

[mhjacobson]

Under certain circumstances, ffmpeg emits a warning like this:

[mp4 @ 0x80ee68c00] Non-monotonous DTS in output stream 0:1; previous: 226069, current: 223761; changing to 226070. This may result in incorrect timestamps in the output file.

The correct word is "non-monotonic"; "monotonous" means "not changing in pitch" or, idiomatically, "boring".

The nonstandard terminology dates back to this commit: <​https://github.com/FFmpeg/FFmpeg/commit/76d23f40314fc1dcd74a3d470b17782cc0ee5a3a>.

[Balling]

DTS must increase every tick. It cannot stay the same (this warning will trigger then too), while monotonic can mean >=.

It also often writes

[null @ 00000203a2e72b00] Application provided invalid, non monotonically increasing dts to muxer in stream 1: 14190336 >= 14190336

[Balling]

​https://patchwork.ffmpeg.org/project/ffmpeg/patch/20230829205749.60630-1-leo.izen@gmail.com/

Will fix this.

[Balling]

Fixed in 60be62d29388fdc681540dff387e0304e610bf39.

[mhjacobson]

Thank you!