How can I extract audio from video with ffmpeg?

Question

I tried the following command to extract audio from video:

ffmpeg -i Sample.avi -vn -ar 44100 -ac 2 -ab 192k -f mp3 Sample.mp3

but I get the following output

libavutil     50.15. 1 / 50.15. 1
libavcodec    52.72. 2 / 52.72. 2
libavformat   52.64. 2 / 52.64. 2
libavdevice   52. 2. 0 / 52. 2. 0
libavfilter    1.19. 0 /  1.19. 0
libswscale     0.11. 0 /  0.11. 0
libpostproc   51. 2. 0 / 51. 2. 0
SamplE.avi: Invalid data found when processing input

Can anyone help, please?

Answer 1

To extract the audio stream without re-encoding:

ffmpeg -i input-video.avi -vn -acodec copy output-audio.aac

• -vn is no video.
• -acodec copy says use the same audio stream that's already in there.

Read the output to see what codec it is, to set the right filename extension.