Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!uunet!mcsun!corton!enst!ulysse!wayne
From: laroche@wayne (Jean Laroche )
Newsgroups: comp.sys.next
Subject: Re: Could system play & record simultaneously ?
Message-ID: <137@ulysse.enst.fr>
Date: 24 Jun 91 16:03:45 GMT
References: <1991Jun24.101635.14514@hardy.u.washington.edu>
Sender: news@ulysse.enst.fr
Lines: 36

In article <1991Jun24.101635.14514@hardy.u.washington.edu>  
jjb@hardy.u.washington.edu (Jim Black) writes:
> Someone wrote on this newsgroup recently that he knew that "the DSP 
> couldn't play and record at the same time".  Is this true?  
> 
> I'm not asking whether the SoundPlayer (for instance) will support
> playing and recording at the same time.  
> 
> Rather, is there anything about the DSP itself that would prevent recording 
> a stereo 44.1KHz signal - while playing another one through the stereo outs?  
> (Assuming, of course, that there's enough disk bandwidth available to read 
> one sound while writing a new one.)
> 
> It seems to me that the DSP has plenty of power to handle two stereo jobs in 
> realtime (eg, it can play 2x2 44.1KHz tracks via rtmix), but I dunno...
> 
> 
> --
> Jim Black  (jjb@u.washington.edu)


Yes, you can record a sound from the DSP SSI port and play another one on the  
stereo outs. You just need to set-up two different stream, one from the DSP to  
the memory, the other one from the memory to the DACs. In fact, it makes it  
possible to create delays of over 2 minutes, using the main memory: While you  
record on the memory, you play chunks that you recorded a while ago on some  
other part of the memory. OK, it's not very useful, but it's fun, it works  
great, in real time, for 44100 stereo! You just need Analog/Digital converters  
to plug into your DSP port (something like Metaresearch's Digital Ears, or  
Singular Solution's A/D64X) I have the source code, if anybody is interested.

The one thing you can't do, though, is to play a sound at the very same time  
you're recording it. That is, you can't listen to what you're currently  
recording. That's a driver problem, not a DSP problem. 

Jean Laroche, Paris