How can I demux avi? I want to demux the audio from avi files, so that the files are lossless. I tried both Yamb and Ffmpeg. Both produce files less than 1 MB (for a video of 80 MB), which are unplayable through VLC. I tried avidemux, and it says it can't export in copy mode.
Your audio is PCM, but you're trying to streamcopy to AAC, which won't work.

To extract the audio to WAV, use

ffmpeg -i DSCN5008.AVI -acodec copy -y a.wav


To transcode the audio to AAC, use

ffmpeg -i DSCN5008.AVI -acodec aac -y a.aac


Note that AAC isn't lossless. But FLAC is a lossless and compressed codec.

ffmpeg -i DSCN5008.AVI -acodec flac -y a.flac