FFMPEG: m4a to mp3 conversion using multiple cores

audioconversionffmpegmp3video

I use the following command to convert m4a format to mp3

ffmpeg -i audio.m4a -acodec libmp3lame audio.mp3

I've 32 x86 cores, however libmp3lame processes in a single thread. I know libmp3lame does not support multithreading, thus I'm open to other alternates that can be executed in ubuntu CLI.

If audio.m4a is 2hours long video, that usually takes > 3minutes and speed appears to be 45x to 50x.

My primary goal is to convert multiple youtube videos in mp3 format within seconds.

Update 1:

Since I'm using 32 cores CPU, when there's only one video conversion it utilizes just one core. So in that cases how to use multiple cores, to get output faster. I want to achieve the maximum from the CPU. Also if FFmpeg is not the answer, is there any other way.

Best Answer

GNU Parallel sounds exactly like what you are looking for.

Here is an example of how you could use GNU Parallel (assuming you already have a directory with all your *.m4a files named videos) using your original commands:

find /path/to/videos -name "*.m4a" | parallel 'ffmpeg -i {} -acodec libmp3lame {.}.mp3'

Two things to explain:

1: The output of the find command (i.e. the list of .m4a files to convert) will be piped into the parallel command, which will in turn (by default) execute as many jobs as there are cores. In essence it is splitting the output from the find command, and distributing it across the different jobs to work on.

2: Per the GNU Parallel Tutorial, {} is where your arguments will go, {.} will substitute in your arguments and remove the terminal extension (in this case the .m4a), and your output will be the original file name but with .mp3 extension.

NOTE: This example will write all your converted files to where your original files are. If this is an issue, then merely pass a directory to store the converted files in the argument string containing the ffmpeg command:

find /path/to/videos -name "*.m4a" | parallel 'ffmpeg -i {} -acodec libmp3lame /path/to/converted/vids/{.}.mp3'
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