difference between demo_phasevocoder.m and the win32 executable pvdoneright.exe

[lszhou0126]

Hi,

When I run demo_phasevocoder.m and pvdoneright.exe of the same input signal, I got two outputs with big difference. For stretch of 2, the output of pvdoneright.exe sounds good, while some music noise in the output of demo_phasevocoder.m. May I known is there any diference between them. Thanks

[nholighaus]

The demo should provide several outputs, computed by different phase vocoder algorithms. Please check that you compared against the output produced using the 'rtpghi' algorithm for phase propagation. If the problem persists, we'll look into it. While there might be miniscule differences between the implementations in PhaseReT and the executable, they should not perceptually affect the result. If anything the PhaseReT implementation is expected to have less issues. 

[lszhou0126]

I put the input and outputs at the attachment zif file. And the configure of 'flags' as follow, it says that the demo using the 'rtpghi' algorithm for phase propagation.

wav.zip

[nholighaus]

Thank you for providing details. There is definitely a noticeable difference in results. I can also reproduce your result obtained with phasecvocoder.m.

It is difficult to judge with the shifted (instead of stretched) output, but if I play the output from the executable at half speed and the twice stretched output of phasevocoder.m, my subjective impression is that the latter is closer in timbre to the input. The result from the executable has a roughness/mid-frequency noise that is not present, or at least much weaker, in the input. As a consequence, the shifted signal from the executable sounds 'richer', but I would argue that this is an artifact. I would actually prefer the phasevocoder.m output.

Nonetheless, we should figure out where the difference comes from. I will try digging out the source of the executable, but that will take some time.

[lszhou0126]

Thank you for your replay, and I'm looking forward to it.

[susnak]

The C code is now available here
https://github.com/ltfat/pvdoneright