Xref: utzoo comp.sys.amiga.audio:436 comp.sys.amiga.programmer:1801 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!decwrl!deccrl!bloom-beacon!eru!hagbard!sunic!news.funet.fi!ujocs!jlavi From: jlavi@ujocs.joensuu.fi (Jarkko Lavinen) Newsgroups: comp.sys.amiga.audio,comp.sys.amiga.programmer Subject: Re: 14-bit audio possible with the Amiga Message-ID: <1991Mar26.154013.3996@ujocs.joensuu.fi> Date: 26 Mar 91 15:40:13 GMT References: <91083.113324DXB132@psuvm.psu.edu> Organization: University of Joensuu, Finland Lines: 33 DXB132@psuvm.psu.edu writes: >It's certainly possible. It might not be "true" 14 bit, but certainly much >better than 8 bit. >The other way to do it is to set one channel's volume to 1 and another to >64 and just let the soft channel be the least significant bits of the >14 bit audio data. Mixing two channels sounds great. That way in theory we should get 14 bits linear output. However there are few things to remember... 14 bits means 84db dynamic range. I don't think Amigas audio hardware is designed for near CD quality ? Thinking about the simple circuits there are, 10 bits would sound more reasonable. Mixing may not be linear. The two channels may not have the same zero-point. This can be overcame with software, adjusting the zero level of the channel with lower volume. This also reduces the amount of bits available. At least one bit has to be sacrfied for this. A simple test might be to play in one channel square wave with amplitude 1, volume 64 and on another channel with amplitude 64, volume 1. Now delaying the latter channel by 180 degrees (so that when one channel outputs +64, another -64) SHOULD result in zero output. I bet You get nothing but zero out! Thinking about DAC having unlinearity, say, +-0.5bits. In fact one should possibly calibrate all the combinations of the two channels. The unlinearity may easily shift, resulting the performance changing during the session... But even then, If the 14 bits isn't reality, some 10 or 11 bits dynamic range would certainly be welcome! Jarkko Lavinen