I know that flv and mp4 files contain aac audio, while avivideo usually mp3 audio streams.What command (avconv, ffmpeg) would extract the audio without transcoding it?
Command to extract audio from video without conversion
audio;video
ffmpeg -i video.mp4 -vn -acodec copy audio.aacHeres a short explanation on what every parameter does:-i option specifies the input file.-vn option is used to skip the video part.-acodec copy will copy the audio stream keeping the original codec.