Xref: utzoo comp.sys.amiga.audio:417 comp.sys.amiga.programmer:1735 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!uwm.edu!csd4.csd.uwm.edu!trantow From: trantow@csd4.csd.uwm.edu (Jerry J Trantow) Newsgroups: comp.sys.amiga.audio,comp.sys.amiga.programmer Subject: Re: 14-bit audio possible with the Amiga Message-ID: <10480@uwm.edu> Date: 24 Mar 91 19:32:56 GMT References: Sender: news@uwm.edu Followup-To: comp.sys.amiga.audio Organization: University of Wisconsin - Milwaukee Lines: 31 In article mykes@sega0.SF-Bay.ORG (Mike Schwartz) writes: >Since the Amiga audio hardware has an 8-bit DAC plus 6 bits of volume >for each audio voice, it should be trivial to play 14-bit samples. Using >Audio interrupts, you can feed audio data and volume right to the DACs >(it would use a lot of CPU on a 68000). Using another feature of the >hardware, you can have the output of one channel modulate the volume of >another. So it looks like you can use DMA to do 2 channels of 14-bit >sound. > >Any feedback? I have done a little bit of work on this.(using the DMA volume modulation) The first approach that I tried was believing that the product of the two channels would be the output. I divided each 14 bit sample into two factors (volume <=64) * (-128<=waveform<=127) and got miserable results. I don't think the two DACs change at the same time and you get a glitch when the volume changes much. ( I have not verified this on a scope.) My other attempt was to use an envelope which has the property of changing the volume gradually. This would reduce the volume change glitch, and would allow the volume to be sampled at a slower rate. I am VERY interested in what others have found. (BTW, audiotools has a demo of volume modulation.) _____________________________________________________________________________ Jerry J. Trantow | A basic premise is an absolute that permits no 8967 N. Pelham Parkway | co-operation with its antithesis and Milwaukee, Wi 53217-1954 | tolerates no tolerance. (414) 228-4689 | Ayn Rand _____________________________________________________________________________