[SOLVED] Need help with script: Mix video and audio files with ffmpeg

H5X00R · 04-09-2013, 02:03 AM

Hi,

I need scripting help. I have 3 video files and 3 audio files.

I want to use ffmpeg to mix the videos with its corresponded audio. Below is the list. This is just an example:

audio-1.wav
audio-2.wav
audio-3.wav
video-1.mp4
video-2.mp4
video-3.mp4

Here is my script thus far

Code:

#!/bin/bash 

for i in *.mp4
do
for j in *.wav
do
echo ffmpeg -i "$j" -i "$i" -vcodec copy tmp/"$i"
done
done

Here is the output from the script

Quote:

ffmpeg -i audio-1.wav -i video-1.mp4 -vcodec copy tmp/video-1.mp4
ffmpeg -i audio-2.wav -i video-1.mp4 -vcodec copy tmp/video-1.mp4
ffmpeg -i audio-3.wav -i video-1.mp4 -vcodec copy tmp/video-1.mp4
ffmpeg -i audio-1.wav -i video-2.mp4 -vcodec copy tmp/video-2.mp4
ffmpeg -i audio-2.wav -i video-2.mp4 -vcodec copy tmp/video-2.mp4
ffmpeg -i audio-3.wav -i video-2.mp4 -vcodec copy tmp/video-2.mp4
ffmpeg -i audio-1.wav -i video-3.mp4 -vcodec copy tmp/video-3.mp4
ffmpeg -i audio-2.wav -i video-3.mp4 -vcodec copy tmp/video-3.mp4
ffmpeg -i audio-3.wav -i video-3.mp4 -vcodec copy tmp/video-3.mp4

I want the script to do this

Quote:

ffmpeg -i audio-1.wav -i video-1.mp4 -vcodec copy tmp/video-1.mp4
ffmpeg -i audio-2.wav -i video-2.mp4 -vcodec copy tmp/video-2.mp4
ffmpeg -i audio-3.wav -i video-3.mp4 -vcodec copy tmp/video-3.mp4

I appreciate any suggestions or a better approach for my solution. Thanks

David the H. · 04-09-2013, 05:56 PM

If you're using bash or another shell with array support, you can use paired arrays instead.

Code:

vidarray=( *.mp4 )
audarray=( *.wav )

for i in "${!vidarray[@]}"; do
    echo ffmpeg -i "${vidarray[i]}" -i "${audarray[i]}" -vcodec copy "./tmp/${vidarray[i]}"
done

This assumes that the shell will sort the two lists of files identically, of course. If you have many files, you should ensure that the filenames are zero-padded*, or set the arrays manually.

(*I recommend always zero-padding numbers in your filenames; it makes handling them like this so much easier. Try to avoid using spaces or other shell-reserved characters too.)

H5X00R · 04-09-2013, 06:58 PM

Thanks David for the code,

I did solved my solution last night after experimenting for 30 minutes. I appreciate it.

Here is the code I used:

Code:

#!/bin/bash 
list=(*.wav)
x=0
for i in *.mp4
do
echo ffmpeg -i "${list[$x]}" -i "$i" -vcodec copy tmp/"$i"
(( x++ ))
done

But your version has less lines and in shell scripting the less coding the better.

+1

David the H. · 04-09-2013, 07:22 PM

Yeah, that'll work too. It's really the same as mine except that it uses only one array, replacing the other with a direct globbing loop.

A quick suggestion, though:

Code:

"${list[x++]}"

Regular array [index] fields operate in an arithmetic context, meaning you can do everything in them that you can do inside ((..)). You don't need '$' in front of variables (except in complex cases), and you can do the post-incrementing there instead of afterwards. Just be sure not to add the increment operator until the last instance that uses the current value!

Setting x=0 first isn't really necessary either. Uninitialized variables are treated as having a default value of zero when expanded in arithmetic contexts.

arithmetic expressions

H5X00R · 04-09-2013, 08:01 PM

Quote:

"${list[x++]}"

Thanks for the tip