Although a phase shift isn't possible an upmix might give you a reasonable result. For instance in Peace a basic upmix switch is available which does this under the hood:
The last 2 lines are for 7.1 upmix. A more complex version of this can be made which is more conform Dolby Pro Logic II. The commands can be build up in the Configuration Editor or entered directly into config.txt.
The only phase shifting I'm aware of in Equalizer APO can be done with the all-pass filter but this is on a given frequency.
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Hi,
are you still interested in shifting the phase of signals?
I think you could use a discrete FIR approximation of the hilbert transformation to shift the phase of the signals by 90 degree: https://en.wikipedia.org/wiki/Hilbert_transform#Discrete_Hilbert_transform
If you have a wav-file with the impulse response of the discrete hilbert transformation you can use the 'Convolution' command of EqApo to change the phase of the signals.
I could also build the wav file with the neede impulse response for you if you do not know how to generate it.
Best Regards
Alex
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I am indeed still interested, and I found out about the hilbert transform myself. I am still chewing on the mathematics of it.
From what I read, it should also be possible to do with 6 all pass filters and 1 delay stage, but the math for calculating the filter coefficients is beyond me.
I am working on it though, thanks for your tip.
Best regards, Erik
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Those work in the frequency domain, with different algorithms for looking at the magnitudes from the stereo signal, in each freq. bin, and creating 5.1 output channels from that.
"We" think these sound as good or better than the comercial solutions out there.
Can covert stereo to surround via drag and drop or live on the fly as you play files.
Cheers
Z
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Thanks for making Equalizer APO.
I am using it on top of the Dirac Live virtual sound card to do bass management. The program works flawlessly for that.
I am now wondering if I can use Equalizer APO for upmixing of stereo content to 5.1.
Wikipedia describes the Dolby PL-2 upmix matrix at this location:
https://en.wikipedia.org/wiki/Matrix_decoder#Dolby_Pro_Logic_II_matrix_.285:2:5.29
I am clear on how to calculate the square roots, but not the phase shifts. Is this possibe? How can I add phase shift with Equalizer APO?
Although a phase shift isn't possible an upmix might give you a reasonable result. For instance in Peace a basic upmix switch is available which does this under the hood:
The last 2 lines are for 7.1 upmix. A more complex version of this can be made which is more conform Dolby Pro Logic II. The commands can be build up in the Configuration Editor or entered directly into config.txt.
The only phase shifting I'm aware of in Equalizer APO can be done with the all-pass filter but this is on a given frequency.
Hi,
are you still interested in shifting the phase of signals?
I think you could use a discrete FIR approximation of the hilbert transformation to shift the phase of the signals by 90 degree:
https://en.wikipedia.org/wiki/Hilbert_transform#Discrete_Hilbert_transform
If you have a wav-file with the impulse response of the discrete hilbert transformation you can use the 'Convolution' command of EqApo to change the phase of the signals.
I could also build the wav file with the neede impulse response for you if you do not know how to generate it.
Best Regards
Alex
Hello Alexander,
I am indeed still interested, and I found out about the hilbert transform myself. I am still chewing on the mathematics of it.
From what I read, it should also be possible to do with 6 all pass filters and 1 delay stage, but the math for calculating the filter coefficients is beyond me.
I am working on it though, thanks for your tip.
Best regards, Erik
Hello Erik,
could you please provide a link to the source that describes calculation of all-pass filters + delay to realize Hilbert tranform?
Thanks in advance!
Sorry to bomb in here with somewhat off topic info but having spent years and years on stereo to surround you might want to check here:
http://www.surroundbyus.com/sbu/viewforum.php?f=8
for free (ok donationware) tools.
Those work in the frequency domain, with different algorithms for looking at the magnitudes from the stereo signal, in each freq. bin, and creating 5.1 output channels from that.
"We" think these sound as good or better than the comercial solutions out there.
Can covert stereo to surround via drag and drop or live on the fly as you play files.
Cheers
Z