FIR filter | Convolution
 

I'm looking to add real-time custom filtering as a Plug-In to ProTools 5 for WinNT. I have a table of FIR filter coefficients. Does anyone know of a Plug-In that will do this?

I know convolution with the filter coefficients (in .wav format) would accomplish the same thing. What is the difference between vocoding and convolving? Will a vocoder practically accomplish convolution? There seem to be some relatively expensive vocoding plus bundles. Any good and cheap?

john

Re: FIR filter | Convolution
 

They're not really the same thing. Phase vocoding is an analysis/resynthesis technique which uses FFT to analyze a sound and then resynthesize it with sin waves while also applying modifications such as time compression/expansion and pitch transposition.

Convolution, on the other hand, is the "dynamic spectral intersection" of two sounds. It's a way to sort of 'filter' two sounds with each other's frequncy content.

As for plug's that do convolution, I'm not sure. But you can do it with SoundHack, Sound Forge (from what I understand), and the new reverb box from Sony that is basically just a convolution box.

ph!lter

Re: FIR filter | Convolution
 

<BLOCKQUOTE><font size="1" face="Arial,Helvetica,sans-serif">quote:<HR>Originally posted by philter:
They're not really the same thing. Phase vocoding is an analysis/resynthesis technique which uses FFT to analyze a sound and then resynthesize it with sin waves while also applying modifications such as time compression/expansion and pitch transposition.

Convolution, on the other hand, is the "dynamic spectral intersection" of two sounds. It's a way to sort of 'filter' two sounds with each other's frequncy content.

As for plug's that do convolution, I'm not sure. But you can do it with SoundHack, Sound Forge (from what I understand), and the new reverb box from Sony that is basically just a convolution box.

ph!lter<HR></BLOCKQUOTE>

Thanks for the info-- i would've hated to jump into vocoding only to find out it wouldn't convolve!

I have been using Sound Forge for processing a file, but with huge sound files and many filters to process, i'm running out of space. if i could process in realtime AND in a multi-track app, however, i could run several files though the same filter, one file through several filters, and preview them all without taking up space. this would make comparisons of filters and files infinitely easier!

john

Re: FIR filter | Convolution
 

Since convolution is so processor intensive, I don't think anyone has done it in real time yet (in a consumer format).

As I mentioned before the only realtime convolution I know of is the stand alone Sony unit which uses it for reverb.

Also, the phase vocoding I was talking about is not the same thing as say, the Prosoniq Orange Vocoder, for example, in case I was unclear about that.

I give it another 1-2 years before we have RT convo plugs. We will have it though and it's gonna be dope http://www.digidesign.com/ubb/images/icons/smile.gif