ffmpeg flash frames last still image in concat sequence

Question

I want to concat several pictures into a video. Each picture must have its own duration. I use the most recent windows build for ffmpeg (20170204) and the guide from http://trac.ffmpeg.org/wiki/Slideshow/

Here is my text file:

file path/to/001.png
duration 5
file path/to/002.png
duration 6

I try using the following command:

ffmpeg.exe -f concat -safe 0 -i path/to/input.txt output.mp4

In the resulting video, the first pictures hangs for 5 seconds but the second picture only hangs for 0 seconds (I only see a glimpse of it). What am I doing wrong?

Answer 1

Based on the discussion at the bug tracker, this should be a workaround:

file path/to/001.png
duration 5
file path/to/002.png
duration 5.96
file path/to/002.png

and

ffmpeg.exe -f concat -safe 0 -i path/to/input.txt -vsync vfr output.mp4

The idea is to duplicate the entry of the last image. If you need the duration to be precise, then decrease the duration of the now 2nd-last entry by 1/fps seconds. For 25 fps video, that's 0.04s. If you don't do this, the output duration will be 0.04s longer.