[FFmpeg-user] SMPTE when converting to JPEGs

[Moritz Barsnick]

On Tue, Oct 24, 2017 at 10:22:20 +0200, Wolfgang Hugemann wrote:
> > Is there a formalised way to embed timecode in JPEGs?
> > Does the OP mean "burned in?"
> 
> Sorry for using the wrong words; I meant "burned in", i.e. written onto 
> each frame / JPEG. (As you can tell from my name, I am not a native 
> speaker.)

You didn't answer Carl Eugen's very important question: Did you use
ffmpeg to convert the camera's AVI to JPEG frames? What command did you
use?

If the AVI says 30 fps, and it is as you assume that the frame rate is
different (or variable), and you used ffmpeg's default options, then
ffmpeg will have created a constant frame rate sequence of images,
duplicating or dropping frames as needed. It's possible though to
instruct ffmpeg to create one output image for every input frame
(regardsless of its timestamp or frame rate), but I want to understand
exactly what you did first. ;-)

Please show us your full command line and the complete, uncut console
output.

> My question is however where exactly ffmpeg's timecode stems from. It 
> doesn't seem to be a simple frame count (?).

Which timecode to you mean? What did you do with ffmpeg? ffmpeg doesn't
insert timecodes into JPEGs it creates (AFAIK).

> The Exif timestamp's accuracy is only integer seconds.

ffmpeg doesn't write EXIF. Unless I'm totally mistaken, the timestamps
are lost when creating image sequences.

> codec library (Lavc57.38.100 in my case) into the JPEG comment. I have 
> no idea whether you can change this behaviour.

>From looking at the code, I though that this is hardcoded. A simple
test shows, though, that I can copy a JPEG comment from an input file
to an output file. *Sigh* I'm too stupid to understand that. Once we
figure it out, we can add it to the documentation. (But you won't be
able to put the timestamp into the comment.)

Cheers,
Moritz