Question

3

Bash script to run FFmpeg concat on MP4 files in batches of 5

rated 0 times [ 3] [ 0] / answers: 1 / hits: 1888 / 2 Years ago, sun, february 20, 2022, 12:26:48

I like to create a Bash script to concatenate MP4 files using FFmpeg, in batches of 5 files at a time for a directory with 100 MP4 files, so that afterwards there would be 20 files like:

001_005.mp4, 006_010.mp4, and so on...

instead of just 1 file consisting of all 100 files.

Contents of mylist.txt:

file 001.mp4

file 002.mp4

file 003.mp4

file 004.mp4

file 005.mp4

............

file 099.mp4

file 100.mp4

Though I've found a command that works just fine (from this StackOverflow thread), it would create only 1 file consisting all 100 files.

#!/bin/bash



cd /home/admn/Downloads/MP4_Files;



# Create mylist.txt:

for f in *.mp4

do

    echo "file $f" >> mylist.txt

done;



# Concatenate files:

ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4;

So, how do I modify the ffmpeg command so that it concat in batches of 5 files at a time.

All the files have exact same resolution (1080p), audio, and video codecs.

OS: Ubuntu MATE 21.04

ffmpeg version: 4.3.2-0+deb11u1ubuntu1

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answered 2 Years ago scrubuz · Accepted Answer

I think the following script will work.

First try it as it is and check that it seems to do what you want

Then remove echo from the line with ffmpeg to make it do its thing.

Check that the content of the temporary files xaa' ... xat` matches the names (and content) of the output files.

#!/bin/bash



> mylist.txt

for f in *.mp4

do

 echo "file '$f'" >> mylist.txt

done



< mylist.txt sort -t ' -n -k2 | split -l 5



k=1

for j in x*

do

 inc=$(wc -l "$j" | cut -d ' ' -f 1)

 m=$(printf "%03d" $((k)))

 n=$(printf "%03d" $((k+inc-1)))

 name="${m}_${n}.mp4"

 echo ffmpeg -f concat -safe 0 -i "$j" -c copy "$name"

 k=$((k+5))

done