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Path: utzoo!watmath!clyde!bonnie!akgua!gatech!seismo!rochester!srs!matt
From: matt@srs.UUCP (Matt Goheen)
Newsgroups: net.micro.mac
Subject: Re: Make my Mac talk with no POPs
Message-ID: <187@srs.UUCP>
Date: Tue, 10-Dec-85 11:19:37 EST
Article-I.D.: srs.187
Posted: Tue Dec 10 11:19:37 1985
Date-Received: Fri, 13-Dec-85 07:45:03 EST
References: <185@srs.UUCP> <4261@topaz.RUTGERS.EDU>
Distribution: net
Organization: S.R. Systems, Rochester NY
Lines: 43

> See Macintosh Technical Note #19: How to Produce Continuous Sound Without
> "Clicking".  Soon to be available at a site near you.....

    I've had a few people respond with pointers to the mysterious
Technical Note #19, however, I have not been able to get ahold of it
(USENET is my ONLY net contact to the Mac world).  Furthermore, I
don't think it is exactly what I'm looking for.  Perhaps I should
try to make my problem a bit clearer.

    I am trying to play SHORT pieces of a long waveform.  I get the
POP when ever I play (write) any record that is NOT a multiple of 1K.
I don't have the IM manuals here, but the sequence is something like
this:

	1) Set up the FFrec with the ratio (for the DA rate) and the
	   mode (FFMode - free form mode).  Follow these values with
	   the actual sound data.
	2) Set up the ParamBlkRec for the PBWrite call (I'm not using
	   the sound routines because I started working on this before
	   Aztec C supported them, I suppose I could change now but
	   seeing as the sound routines for Aztec just call PBWrite,
	   I don't see that it's really necessary).  This means
	   making ioBuffer point to the FFrec and setting ioReqCount
	   to the number of values to play (write).

    In case anyone needs more info, I am using a data rate of about
13 samples/ms.  My current fix is to round the record length to the
nearest 1K interval (up), save the extra data in a temporary buffer,
zero to the end of the 1K block, play the damn thing and finally,
copy the saved stuff back.  If anyone wants a code fragment to solve
this just ask (I'd put in now if I had it here, it is kind of involved).

    If ioReqCount is not a multiple of 1K, you get a nasty POP at the
end of the sound.  I am NOT producing CONTINUOUS sound, only a short
burst.  Uggh.

    Well, that better explains it at least...thanks to those who tried
to help...


					    Matt Goheen
					    S.R. Systems
				...!{seismo,allegra}!rochester!srs!matt