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Date:      Wed, 07 Jul 1999 04:32:19 -0700
From:      Chris Doherty <cdoherty@nttmcl.com>
To:        freebsd-multimedia@freebsd.org
Subject:   SB Vibra16: more joy and rapture
Message-ID:  <3.0.6.32.19990707043219.007cae90@alicia.nttmcl.com>

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hi--

so I've gotten the card up and running, playing sound, recording and
playing back sound for the most part (it's choppy and slow, but I also
haven't looked into fixing it, so it's nothing to complain about yet).

the first fun thing I found out is that while you can open it O_RDWR
without an error, it doesn't work. :-)

the next thing is a little more bothersome. for most of the ioctl() calls,
it alters the 3rd argument, so that if you set the sample rate too high, it
returns the highest possible rate in the 3rd argument. according to the OSS
docs, if you try to set the card to an unsupported sound format (e.g.
AFMT_S16_LE), it will/might return either something funky, or a supported
format you can use. if it was successful, the 3rd argument should be left
alone.

here's what's happening: I called SNDCTL_DSP_GETFMTS and discovered that it
allegedly supports AFMT_S16_LE. so I do the following (Ioctl() is just a
wrapper function):

int format = AFMT_S16_LE;
Ioctl( fd, SNDCTL_DSP_SETFMT, &format );

at which point format == 0. disturbed, I then did

Ioctl( fd, AFMT_QUERY, &format );

thinking I might get the current format; and ioctl() failed!

is this a characteristic of SB cards? can I safely assume if ioctl()
returns ok from SNDCTL_DSP_SETFMT, that the format has been set? if
AFMT_QUERY doesn't work, I have no way of knowing if any of the other
options work (AFMT_U8 didn't, really, or it did but the quality was
insufferable). and SNDCTL_DSP_GETFMTS may have been lying as well.

the card tested positive for AFMT_WEIRD; is this what that means? :-)

Chris


---------------
I don't speak for NTT MCL. I'm an intern.

Chris Doherty
cdoherty@nttmcl.com


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