GWBasic / soft_matrix

Upmixes stereo to surround sound
MIT License
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aliasing #97

Open arily opened 3 weeks ago

arily commented 3 weeks ago

Hi, I have noticed that the upmixed result contains aliasing noises.

Here's the original stereo audio (44.1khz oversampled to 88.2 to demonstrate)

image

matrix result: (4.0 quad)

image

as you can see both above f/2 and below is not as clean as the original signal.

I noticed adjusting fft window size changes the color of the aliases.

I also tried using f64 and lower amplitude to leave headrooms, prevent clipping, but these methods only reduces the noise, not eliminating it.