[FFmpeg-user] Use processed filename as draw text after tmix, in one pass?

[Steven Kan]

Planning ahead to the successor to my honeycomb time-lapse video from 2022, processed using tmix per advice from this group:

 https://ffmpeg.org//pipermail/ffmpeg-user/2022-April/054742.html

 https://www.youtube.com/watch?v=2dUGbGcGE2c

This time I’m capturing the photos with a dSLR and gphoto on a Raspberry Pi, and the dSLR does not burn in a timestamp. 

This is actually a good thing, because I don’t like how my timestamps got tmixed away last time. I’d like to apply them after tmix.

I’m saving the photos with the timestamp as the sortable filename, e.g. 

2024-03-06-11-40-11.jpg

This time I’d like to tmix 50 frames, read the filename of the 50th frame, re-arrange the text of the filename to U.S. style, e.g. "03/06/24, 11:40:11 AM", and then drawtext it onto the output. 

Can this be done in one pass? Or would I need to do a first pass to create the text fields in some companion files, e.g. 2024-03-06-11-40-11.txt, or even multiple passes to do the tmix first and then the drawtext? I’d like to avoid multiple passes of video processing to avoid generation loss, if possible.

Thanks!