when i extract an audio from video using ffmpeg, It appear an error

Question

I need the audio from video. So i find the ffmpeg. When i use

ffmpeg -i test.mp4 -acodec copy -vn test.mp3

It get the following error:

Invalid audio stream. Exactly one MP3 audio stream is required. could not write header for output file #0 (incorrect codec parameters ) invalid argument

How can this be solved?

Answer 1

If you need only to get the audio to MP3, you can simply use:

ffmpeg -i test.mp4 test.mp3