Predicted phase not in range [-pi .. pi], but in range [-1 .. 1] about istftnet-pytorch HOT 2 OPEN

This is insanely weird. I have tried to train it by multiplying the phase by torch.pi, but it fails to converge, while using the range from -1 to 1 works very well and I could obtain human-level quality on LJSpeech when combined with AdaIN and Snake activation functions for StyleTTS 2. I have no explanation for why this is happening. It makes no sense to me. If anyone has come up with a reason please let us know.

from istftnet-pytorch.

This is a good point and I have looked into it on my own implementation of iSTFTNet which initially output [-pi:+pi] and then I skipped it to produce the output phase [-1 : +1]. In my case using Pi didn't make the synthesis sound better, in fact I noticed a small degradation compared to using [-1:+1] but that could have been a random luck with training. This was very puzzling. I have even went as far as making a trainable scaler so the network would learn the optimal value, which in my case stabilized at [-2.5:+2.5] but again, it was hard to hear there is an improvement. I should stress again this was tested on different but similar implementation. I don't know how this applies to Rishikesh's excellent implementation.

from istftnet-pytorch.