Delay not honoured when joining .jpg files into a .mp4

[rmwiseman]

To be more precise, a similar delay is used, but from what I've found, it seems to be quantised.

I converted a couple of sequences of JPEGs into movies; the first had 554 images, the second had 665.

I tried integer delays (i.e. values for the -delay switch) from 2 to 11 and found that:

• 2, 3 and 4 all ended up with a delay of exactly 0.04 seconds between frames (equivalent, I believe, to -delay 4) in both movies, based upon the number of frames and the duration ffprobe (and my movie player, though this rounds to the nearest second) reported for the movie;
• 5, 6, and 7 all ended up with a delay of exactly 0.08 seconds (which is what I'd expect from -delay 8) in both movies;
• 8, 9 and 10 all ended up with a delay of exactly 0.12 seconds (which is what I'd expect from -delay 12) in both movies; and
• 11 ended up with a delay of exactly 0.16 seconds (which is what I'd expect from -delay 16) in both movies.

Have I missed some configuration? Even if I have, I assumed the delay shouldn't be quantised like this!

Thanks in advance of any thoughts.

[snibgo]

What version of IM, on what platform? What were your exact commands?

IM will delegate the work to ffmpeg. If you add "-verbose" to the commands, I expect this will tell you the ffmpeg commands. What are they?