Re: /dev/sound always records 4 bytes per sample? (3.5 auich ac97)

[Jacob Meuser <jakemsr_(_at_)_jakemsr_(_dot_)_com>]

On Thu, Feb 24, 2005 at 08:53:11AM -0500, Jeff Chilton wrote:
> Jacob Meuser wrote:
> 
> >On Wed, Feb 23, 2005 at 01:13:22PM -0500, Jeff Chilton wrote:
> > 
> >
> >>Hi all,
> >>
> >>Either I'm missing something obvious or /dev/sound doesn't work as 
> >>advertised...
> >>   
> >>
> >
> >it works right for me.  even 'dd if=/dev/audio ...' produces 16002
> >bytes/sec.
> >
> > 
> >
> That's interesting.  I thought opening /dev/audio set the device to 8kHz 
> mu-law 8-bit mono, which would yield 8000 bytes/sec.  That's what the 
> comments in /usr/src/sys/dev/audio.c suggest...

hmm, yes, you're right.  that's what the manpage says also.

running audioctl after the 'dd if=/dev/audio' command, I see

record.precision=16
record.encoding=slinear_le

even though I explicitly set it to

record.precision=8
record.encoding=mulaw

before running the dd command.

> >>record.rate=8000
> >>record.channels=2
> >>record.precision=16
> >>record.encoding=ulinear
> >>   
> >>
> >
> >what about record.source ?
> > 
> >
> 
> Don't seem to get one of those in OpenBSD 3.5.  I've got record.port=0x2 
> (line in), though.

oops, my bad.  I did mean redcord.port.

> > 
> >
> >>Does everyone always record stereo linear:16?
> >>   
> >>
> >
> >seems most software does by default.
> >
> > 
> >
> Good enough for me.  I can make my own mu-law.
> 
> >>dmesg output:
> >>
> >>OpenBSD 3.5 (GENERIC) #34: Mon Mar 29 12:24:55 MST 2004
> >>
> >>auich0 at pci0 dev 2 function 7 "SIS 7012 AC97 Audio" rev 0xa0: irq 11, 
> >>SiS7012 AC97
> >>ac97: codec id 0x414c4720 (Avance Logic ALC650)
> >>ac97: codec features 20 bit DAC, 18 bit ADC, Realtek 3D
> >>audio0 at auich0
> >>auich0: measured ac97 link rate at 48005 Hz, will use 48000 Hz
> >>
> >>   
> >>
> >
> >where's the rest?  reproducable with newer code?
> > 
> >
> 
> Actually, I rolled back to 3.5 from 3.6, where I couldn't get audioctl 
> to work at all.  Everything was "set failed: invalid request".  So I'll 
> revisit that after I free up this computer's twin brother (another 
> "Shuttle SS51G").
> 
> Thanks!

good luck!

-- 
<jakemsr_(_at_)_jakemsr_(_dot_)_com>