Extracting audio from a 3gp video file recorded on an Android phone (this was tested on a video file recorded on Google Nexus One running Gingerbread).
First find out what audio format is present in the file:
ffmpeg -i VID_20110518_184415.3gp . . Stream #0.0(eng): Audio: aac, 16000 Hz, mono, s16, 96 kb/s
Turns out, the audio encoded as .aac. Here’s what can be done next:
1. Don’t transcode the audio just extract the audio track as it is:
ffmpeg -i VID_20110518_184415.3gp -vn -acodec copy clarinet.aac
2. Extract audio and transcode it to mp3 at 64kbps:
ffmpeg -i VID_20110518_184415.3gp -vn -acodec libmp3lame -ab 64k clarinet.mp3
3. Extract audio and transcode it to ogg at medium quality:
ffmpeg -i VID_20110518_184415.3gp -vn -acodec libvorbis -aq 50 clarinet.ogg
This can be handy if you want to embed the file using the new HTML5 audio tag. e.g.
<audio controls> <source src="clarinet.ogg"/> <source src="clarinet.mp3"/> </audio>
With a lot of help from: http://howto-pages.org/ffmpeg/