Hi,

At 2007-11-22 21:48:40, Jacob Meuser wrote:
> It's been reported that 8kHz sampling rates cause an "evil"
> sound with snapper(4). 8kHz is the audio(4) default, so, just
> about any operation with these devices causes the "evil" sound.

I have experienced that too with snapper(4). I also recall that some
users mentioned audio stability problems after playing a lot of files with
tumbler(4), this may be the cause of such problems (if they were using
the /dev/audio device with its 8 kHz default rate).

> disabling 8kHz in sys/arch/macppc/dev/i2s.c avoids the "evil" sound.
> however, this disables 8kHz sampling rates in all i2s based audio
> devices, and I'd rather not do that if not necessary.

According to the datasheets of these codecs, these are the supported rates:
snapper: 32 kHz, 44.1 kHz, 48 kHz
tumbler: 32 kHz, 44.1 kHz, 48 kHz, 96 kHz
daca: 8 kHz, 11.025 kHz, 12 kHz, 16 kHz, 22.05 kHz, 24 kHz, 32 kHz,
44.1 kHz, 48 kHz

'snapper' and 'tumbler' do not require any special configuration to set the
sampling rate. However, 'daca' might need to be informed of the band of the
rate setting via the I2C register SR_REG (subaddress 0x01). These are
the values:

000 32-48 kHz
001 26-32 kHz
010 20-26 kHz
011 14-20 kHz
100 10-14 kHz
101 8-10 kHz

The current daca(4) driver does not configure this register, and the
default setting
is the 32-48 kHz band.
There is also an autoselect mode, but this appears to be for MPEG streams.

-Marco