Yeah, they use Opus and VP8, AFAIK, which are both fantastic codecs. The quality is great, although there's no echo cancelation yet, so you want to be using it with headphones.

Would you mind filing an issue about the echo on the corresponding tracker with your device details?

iOS: https://github.com/WhisperSystems/Signal-iOS/issues/new

Android: https://github.com/WhisperSystems/Signal-Android/issues/new

Sure thing, although I think the issue was gone with the latest release (but I used headphones so it might not have been). I'll retest and file.

This is great, might actually use it for calls now.