Xref: news2.mv.net comp.os.msdos.djgpp:4581
From: malcolm AT manawatu DOT gen DOT nz (Malcolm Taylor)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Sound Blaster Question.
Date: Tue, 04 Jun 1996 21:02:34 GMT
Organization: Grafik Software
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

gaghon AT nevada DOT edu (GEORGE GAGHON) wrote:

>Once and a while (every 10 times or so), the sound will change between 
>sounding OK, and static sounding, when we load something from the Hard Disk.
>It does the same thing when in Win95.  While the sound is playing from 
>DOS, I open some Notepads up and the sound starts to shift between normal 
>and not.  

>I have tested it with another Protected mode MOD player, and it does not 
>repeat the same situation.  I checked the code to make sure it was 
>initing the DMA/DSP/Interrupts correctly, and everything seems to match.

AFAIK this is caused by the swapping between the two DMA buffer halves
at the wrong time. On some SB cards this needs to be done later than
usual. Check the VAT tools that SB05_dj is derived from and you'll
find that there is a DMA_flip_flip or something flag that sets when to
change buffer. The writer left this out of SB05_dj which seems to be
the cause of the static. My card did this with SB05_dj as well, but I
never got round to testing this theory (I just wrote my own sound).

Malcolm