How to extract audio from MPEG-4 file using ffmpeg [closed]

Question

How can we extract audio from video file (MPEG-4 format)?

What is convenient form of storing the extracted audio data for further analysis? (edit: In other words: is it better to use PCM format or something like WAV if I want to get audio sound level?)

From other questions about this topic I learned that ffmpeg is a right tool to do this.

Answer 1

Regarding your first question:

You can indeed do this with ffmpeg, but I can only give you the command line form. You might want to fiddle with the output format, but have a look at the man page at http://linux.die.net/man/1/ffmpeg, or the official ffmpeg (audio) documentation at https://www.ffmpeg.org/ffmpeg.html#Audio-Options

ffmpeg -i mpeg-4videofilename -vn -ac 2 -ar 44100 -ab 320k -f mp3 output.mp3

Explanation of the command line options:

• -i input file
• -vn no video
• -ac audio channel
• -ar audio sample rate
• -ab audio bitrate
• -f output format

Answer 2

You can use the following command:

ffmpeg -i input.mp4 -vn -acodec pcm_s16le -ac 2 -ar 44100 out.wav

-vn: no video

-acodec: audio codec selection.

pcm_sl6le: 2 bytes samples in little endian format

-ac: number of audio channels

-ar: audio sample rate

out.wav output wav file