FFMPEG Concat Dropping Frames

Question

I'm using FFMPEG to do the following two things:

• create an mp4 given a set of images
• compile mp4s to create a longer video (mp4)

To create mp4s from images, I use the following command:

ffmpeg -r 5 -i 'img%03d.jpg' output.mp4

As far as I know, this creates a video with a framerate of 5fps.

But when I try to compile mp4s, it seems like frames within each mp4 are being dropped.

To create the compiled footage, I create a text file that points to all the mp4s that should be included in the compilation, eg

file 'set1/output.mp4'
file 'set2/output.mp4'
file 'set3/output.mp4'
file 'set4/output.mp4'
file 'set5/output.mp4'
file 'set6/output.mp4'
file 'set7/output.mp4'

Then I run the following command:

ffmpeg -f concat -i input.txt -codec copy compilation.mp4

The resulting video seems to drop 2-3 frames from each of the output videos.

How do I ensure that the compiled video doesn't drop any frames?

(For reference, I used the following tutorial: https://trac.ffmpeg.org/wiki/Concatenate )

Answer 1

I was able to find a work-around using the following tutorial:

FFmpeg making video from images placed in different folders

Rather than compiling mp4s, I could point to all the image assets that should be compiled into the final video file.

I created a text file that looked like this:

file 'set1/img%03d.jpg'
file 'set2/img%03d.jpg'
file 'set3/img%03d.jpg'
file 'set4/img%03d.jpg'
file 'set5/img%03d.jpg'
file 'set6/img%03d.jpg'
file 'set7/img%03d.jpg'

Where each set folder contains images with the naming convention img001.jpg, img002.jpg, etc.

Then I can compile all the images into a final video using the following command:

ffmpeg -f concat -r 5 -i input.txt compilation.mp4