Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!samsung!olivea!mintaka!bloom-picayune.mit.edu!athena.mit.edu!othomas From: othomas@athena.mit.edu (Oliver J. Thomas) Newsgroups: comp.sys.amiga.audio Subject: Re: Re:Perfectsound Message-ID: Date: 13 May 91 23:28:42 GMT References: <1991May13.022242.13462@magnus.acs.ohio-state.edu> Sender: news@athena.mit.edu (News system) Organization: Massachusetts Institute of Technology Lines: 50 In-Reply-To: mdoerner@magnus.acs.ohio-state.edu's message of Mon, 13 May 1991 02:22:42 GMT In article <1991May13.022242.13462@magnus.acs.ohio-state.edu> mdoerner@magnus.acs.ohio-state.edu (Mike R Doerner) writes: > 1.) My friend has a bass guitar. I was wondering if I could > "digitize" him with a direct rca to amiga hook up. Is it possibe to hook > him up in such a way as to have him play a note, have it digitized, and > put as direct output in "real time"??? Yep, you can do that. Check out a program called "SuperEcho" on FishDisk It will do what you want and more, like special effects (hence, the Echo in the name...) > 2.) Is it possible to take "fuzzy" & "hissy" studio recordings > and have them re-recorded as "clean" without the hissing & fuzz (in > other words, recording w/o dolby equipment & cleaning it up.) This is a little more tricky. Basically, to clean up a signal, what is usually done is filtering (digital or analog) out those frequencies where you suspect most noise to be concentrated, and, in some cases, convolving the waveform by a smoothing function to take out the "hard edges" associated with noise. That's why Dolby NR gives a somewhat muffled sound to recordings made without NR. Now, to do this filtering on the Amiga, the basic procedure would involve transforming the incoming signal into the Frequency Domain (through Fast Fourier Transforms, usually), multiply that by the appropriate filter function, and by a smoothing function, the reverse transform it to get a time signal back, which is the cleaned up audio. Sounds simple enough, and the algorithms aren't that hard, but don't expect your Amiga to do it in real time. If you just want to clean up recordings, though, real time should not be an issue. > Please respond by mail, because if these questions are common ones, > I hope that noone will get flamed at me. (I just got my amiga 2 weeks ago) ^^^^^^ If you get flamed for a question like this, the discussion group would be in sorry state indeed. Don't feel relucant to ask valid questions. The only dumb ones are those never asked (someone once said...) Hope the above explained a little of the kind of stuff involved. If you need some specifics, like pointers to references or code, feel free to send me mail. Oliver Thomas othomas@athena.mit.edu -- --------------------------------------------------------------------------- Oliver James Thomas, othomas@athena.mit.edu, Telephone: x5-9385