Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!pur-ee!pur-phy!murphy
From: murphy@pur-phy (William J. Murphy)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Audio questions
Message-ID: <2097@pur-phy>
Date: 4 Apr 89 02:44:06 GMT
References: <2093@pur-phy>
Reply-To: murphy@newton.physics.purdue.edu.UUCP (William J. Murphy)
Organization: Purdue Univ. Physics Dept., W. Lafayette, IN
Lines: 34

In article <2093@pur-phy> murphy@newton.physics.purdue.edu (William J. Murphy) writes:
>
>I've just finished typing in and compiling Bob Peck's program audio.c
>from Programmer's Guide to the Amiga (gee that sounds like Hitchhiker's
>Guide to the Galaxy, was that similarity intended Bob?). Anyhow, I see how
>one can control the sampling rate of the audio chip, but how do I convert that
>into real time numbers?  Let's say for example your waveform has 16 data points
>and you set the period value to be 428, what frequency would you be producing
>out of the speaker?  
>
>My guess is that it will be freq = sampling rate/(428 * 16), but what's the
>sampling rate?
Well, to answer my own questions, I dug through an RKM at the bookstore and 
found that each tic of period = 279.365 ns. Thus the formula is

      frequency = 1/(279.365e-9 * Period * Repeat_of_Data)
                = 1/(279.365e-9 * 428 * 16)    = 522.7 Hz


>
>The next question that I have may be a bug in the program.  When I played the
                                        ^^^ Or a bug in the programmer!!!
>program 12 times in a row, I received an error "cannot create a reply port".
>This makes me think that something is not returning its port to the system. 
>I checked my program, and the DeletePort(auReplyPort) and DeletePort(auLockPort
   ^^^^^^^^^^^^^^^^^^ and I just checked it again, my error for not CALLING
finishup to delete the appropriate ports.  Sorry. :-(


Bill Murphy                         "Facts!, what we demand are solid facts!
murphy@newton.physics.purdue.edu     Wait, What we demand is a total absence of
                                     solid facts." Vroomfondel, Philosopher.
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