[FFmpeg-user] drawtext timecode drop frame 23.967

[Moritz Barsnick]

On Wed, Dec 14, 2016 at 16:41:21 +0000, Nathaniel Finney wrote:
> It seems the drawtext filter timecode option doesn't allow using 23.967:
> ....  timecode='00\:00\:00\;00':rate=24000/1001: ...
> 
> [Parsed_drawtext_4 @ 0x7ff2c74010c0] Drop frame is only allowed with
> 30000/1001 or 60000/1001 FPS
> 
> I'm not sure why this is, 23.967 is a common NTSC frame rate, any ideas on
> this?

SMPTE frame (drop) counting is not defined for 23.967:
http://www.hpaonline.com/wp-content/uploads/2015/02/Dalet_Telestream_W1130-hpa2015.pdf

This code of ffmpeg's av_timecode_adjust_ntsc_framenum2(), which is
used there:
https://github.com/FFmpeg/FFmpeg/blob/b46dcd5209a77254345ae098b83a872634c5591b/libavutil/timecode.c#L34
does consequently not implement 23.967.

You're provoking drop-frame notation by using the semi-colon ';' (or
dot '.') instead of the colon ':', I believe.

Moritz