Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mailrus!umich!caen.engin.umich.edu!mingin!news
From: billkatt@mondo.engin.umich.edu (billkatt)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Need help with the new sound manager!
Message-ID: <1990Mar11.174934.19476@caen.engin.umich.edu>
Date: 11 Mar 90 17:49:00 GMT
References: <900004@hpvcfs1.HP.COM>
Sender: news@caen.engin.umich.edu (USENET News System)
Reply-To: billkatt@mondo.engin.umich.edu (billkatt)
Organization: Computer Aided Engineering Network (CAEN), University of Michigan
Lines: 41

In article <900004@hpvcfs1.HP.COM> stevem@hpvcfs1.HP.COM (Steve Miller) writes:
>
>OK boys and girls, I'm about at my wits end on the subject of playing 'snd '
>resources on the Mac.  I'm trying to use snd's in a simple game where the
>sounds are played asynchronously while arcade style animation is occuring.
>I'm using Think Pascal 2.01 under system 6.02 (finder 6.1) and my code is
>structured like this:
>
[sorry, code deleted]
>
>What happens is that the sounds start out playing fine.  After the first 3 to 6
>instances of the sound, it will stop playing them.  Occasionally they will
>start up again for 1 or 2 instances before permanently failing to play.
>
>Then the system will crash with an address error or with an
>"internal error 4023" inside SndDisposeChannel at the end of the game:
>
>error := SndDisposeChannel(channel_ptr,TRUE);
>
>
>If the sounds are played sychronously then everything is OK.  I've tried many
>variations on the above scheme with exactly the same results (not flushing
>the commands, letting the system allocate the channel pointer, etc...)  Since
>I already found one bug in volume 5 of Inside Mac pertaining to the new
>sound manager's use of Async. sound, I feel there might be something else I'm
>missing.
>
Well, digitized sounds are [type 1, type 2 insert correct one here] sounds,
and they not only have a "BufferCmd" in their structure to play the sound, but
they also have a c ommand to add the sampled sounds synthesizer to the channel
so it can play it.  Each time you do a SndPlay it installs another copy of
the sampled sound synthesizer in the channel.

there are three ways to fix this:

1. dispose the channel and allocate another one before you play the sound.
2. remove the synthesizer from the SND resource and install one yourself (once)
3. Use a "SndDoCommand" with a BufferCmd to play just the sampled sound but not
   execute the synthesizer install.

-Steve