[opus] Phase perservation in Opus

[Bent Bisballe Nyeng]

Hi list

I'm writing some unit tests for a piece of software using the opus 
library for audio encoding before transfering though RTP.
In order to test my RTP implementation I thought I would transfer an 
encoded 440Hz sinus, and then do a diff of the received/decoded signal.
However, my strategy seems to fail completely since the recreated sinus 
looks nothing like the one in the decoded signal.

So my question is; is the phase not likely to be preserved during opus 
encoding/decoding or did I simply make an error in my test code?

I am aware that the diff should not be binary equivalent to the input 
signal, but my thought is to do an error calculation and accept the test 
if under a certain threshold.

Kind regards
Bent Bisballe Nyeng