tre@sdcarl.UUCP (Tom Erbe) (12/11/85)
In article <977@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: > > 3a. The Amiga supports a series of dedicated DMA channels that DO NOT > INTERFERE with the CPU speed for 4 sound channels that utilize a > wavetable (up to max available of the internal 512k ram) and associated > volume and pitch tables, which effectively constitute a 4 channel > 8-bit digital sampling synthesizer a-la Ensonique Mirage but with > 4 channels instead of however many the Mirage has. > >But for me, I bought an Amiga, the least expensive system that could do what >*I* needed in a machine, because the 520ST couldn't do those things at all >(imaging at 640x400, NTSC video compatibility, and digital sampling of >sound). > >Keith Doyle ># {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd ># cadovax!keithd@ucla-locus.arpa How does the Amiga sample sound?? I have heard this many, many times, yet no- one has ever mentioned an ADC in the machine, only an 8-bit DAC. (By the way, does this DAC have the proper anti-aliasing filters?) -- thomas r. erbe {ucbvax,ihnp4,akgua,hplabs,sdcsvax}!sdcarl!tre
keithd@cadovax.UUCP (Keith Doyle) (12/13/85)
In article <267@sdcarl.UUCP> tre@sdcarl.UUCP (Tom Erbe) writes: > >How does the Amiga sample sound?? I have heard this many, many times, yet no- >one has ever mentioned an ADC in the machine, only an 8-bit DAC. (By the way, >does this DAC have the proper anti-aliasing filters?) > > thomas r. erbe The Amiga can't sample an input sound given the basic machine, however it has the ability to playback sampled sounds once you figure how to get the sampled data into the machine. Right now, I have to use a s-100 machine that does know how to sample to do this. I expect it won't be too long before it can be done directly with the Amiga once a simple ADC board is available for it. Offhand, I don't know about what kind of output filtering the Amiga has, though it certainly sounds better than the raw 8-bit DAC output I'm using with my s-100 system. Keith Doyle # {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd # cadovax!keithd@ucla-locus.arpa
mjg@ecsvax.UUCP (Michael Gingell) (12/13/85)
> > How does the Amiga sample sound?? I have heard this many, many times, yet no- > one has ever mentioned an ADC in the machine, only an 8-bit DAC. (By the way, > does this DAC have the proper anti-aliasing filters?) > > thomas r. erbe The Amiga does not have any built in analog to digital converter for digitizing sound. It only has digital to analog converters - two to give stereo capability, each is 8 bit linear with a 4 bit (I think) scaling volume control. There are proper anti aliasing filters which cut off starting at around 7 kHz. Sound samples stored in memory can be played through the D/As using DMA completely transparent to and without slowing down the 68000. The Amigas bus operates at 14.4 MHz half of which is used by the 68000 (i.e. at 7.2 MHz) and half by the coprocessors which do DMA for video, disk I.O, sound etc. If things get really busy then the video coproccessors can steal extra time and slow down the 68K. As far as I know digitizing sound must be done by an external device. Hope this helps. Mike Gingell, ....decvax!mcnc!ecsvax!mjg > {ucbvax,ihnp4,akgua,hplabs,sdcsvax}!sdcarl!tre
sam@amiga.UUCP (Samuel C. Dicker) (12/14/85)
>>But for me, I bought an Amiga, the least expensive system that could do what >>*I* needed in a machine, because the 520ST couldn't do those things at all >>(imaging at 640x400, NTSC video compatibility, and digital sampling of >>sound). >> >>Keith Doyle >How does the Amiga sample sound?? I have heard this many, many times, yet no- >one has ever mentioned an ADC in the machine, only an 8-bit DAC. (By the way, >does this DAC have the proper anti-aliasing filters?) >-- > thomas r. erbe I hope Mr. Doyle didn't buy an Amiga JUST for digital sampling of sound. Although the Amiga can play pre-recorded or synthesized sound samples it does not have built-in user sampling. The Amiga has a 6-pole (36 decibel per octave) low pass filter for each stereo channel. I am the resident sound software person at Commodore/Amiga and I'll be happy to answer any questions about producing sound with the Amiga. {hplabs,decwr}!pyramid!amiga!sam
keithd@cadovax.UUCP (Keith Doyle) (12/18/85)
In article <399@amiga.amiga.UUCP> sam@snidely.UUCP (Samuel C. Dicker) writes: >I hope Mr. Doyle didn't buy an Amiga JUST for digital sampling of sound. >Although the Amiga can play pre-recorded or synthesized sound samples it >does not have built-in user sampling. No, but it was a factor. By the way, I *was* aware that it couldn't input sample sound but can output before I bought the Amiga. Sorry if my original article gave mis-impressions there. I kinda felt being able to play the samples back is a good 80% of the job. After all, you can get by only sampling the input at a fixed rate if you absolutely have to, and don't have to do input so often that it even has to be done by every machine, but you need lots of controls and parameters etc. for the output side usually. (if you want to play Beethovens 9th in dog barks that is). Keith Doyle # {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd # cadovax!keithd@ucla-locus.arpa