Plug'n Script - down mixer with Dolby Prologic?

[carlos3]

Has anybody scripted simple down mixer with Dolby Prologic capabilities?
I'm very interested in, but I don't have enough knowledge to script it myself.
Maybe I'll try it. Do you give me some advice?

I would follow this procedure:

Lt = L + C*1/sqrt(2) + (Ls+Rs)
Rt = R + C*1/sqrt(2) - (Ls+Rs)

Is there some trick to compensate loudness?
I would add some mix level parameter to adjust level of input channels...

Thank you!

[carlos3]

I just programmed basic version of down mix and it is working quite good!

gain variables are updated from updateInputParameters function.

Code: Select all

void processSample(array<double>& ioSample)
{  
    double left=ioSample[0];
    double center=ioSample[1];
    double right=ioSample[2];
	double ls=ioSample[3];
	double rs=ioSample[4];

	double left_total = total_gain * (gain_left * left + gain_center * center - (gain_ls * ls + gain_rs * rs));
	double right_total = total_gain * (gain_right * right + gain_center * center + (gain_ls * ls + gain_rs * rs));

	ioSample[0] = left_total;
	ioSample[1] = 0;
	ioSample[2] = right_total;
	ioSample[3] = 0;
	ioSample[4] = 0;
}

Is there a way to drop unused channels, so Protools (which I use) will report only stereo track instead of 5.1?
Anyway, this is Prologic with mono surround channel only, Prologic II use stereo surround, I'll try to work it out too...

[Blue Cat Audio]

That's an interesting topic!

The only way to be able to output stereo only would be to define another configuration with 6 inputs and 2 outputs, but this would lead to way too many configurations if we do it for all combinations, which would unfortunately clutter the plug-in menu... Have you tried using busses to extract the stereo channels from the 5.1 stereo submix?

[carlos3]

That is definitely a solution! I will try that...