Is there any way to extract voice chat audio from TF2/Source demo recordings?

I have a bunch of demos recorded in TF2 from before the Hatless update. Any attempt to open the files in TF2 for playback causes it to toss up a few resource loading errors that I'm assuming are the result of changes in the update, and the demo never loads.

Really all I want from these files is the voice chat audio, the action on screen wasn't important. Is there any tool available that can extract that information independent from TF2 itself?

On a similar note, for files that I can open, is there a way to make TF2 output just the audio track when recording playback using the startmovie command? I don't need the vast gigabytes of tga files.

Solution 1:

While it is still in the experimental stages and only available in source code form (java), DemoReader by Asher Baker can decode and playback the voice chat audio from demos.