30 Nov
2010
30 Nov
'10
6:55 p.m.
On Tue, Nov 30, 2010 at 1:59 AM, Clemens Ladisch <clemens(a)ladisch.de> wrote:
Mark Rages wrote:
Excellent answer. Thank you.
Regards,
Mark
markrages@gmail
--
Mark Rages, Engineer
Midwest Telecine LLC
markrages(a)midwesttelecine.com
I would like to play some audio sampled at 96
kHz. But I don't appear
to have this enabled:
markrages@markrages-desktop:~$ cat /proc/asound/card*/codec#0 | grep rates
rates [0x7f]: 8000 11025 16000 22050 32000 44100 48000
rates [0x60]: 44100 48000
rates [0x7f]: 8000 11025 16000 22050 32000 44100 48000
But the same file lists "Codec: Analog Devices AD1986A". I looked up
the datasheet, and the AD1986A is able to support 96 kHz sampling with
"Double rate audio".
"Double rate audio" is a special AC'97 mode that reuses some surround
channels to transport more samples for the two front channels. (AC'97
doesn't have enough bandwidth for more channels at 96 kHz.)
HDA assumes that all DACs can run at the same sample rate. However, it
looks as if this chip is just an AC'97 core that also has a HDA frontend,
so it cannot run all DACs at 96 kHz, so it completely disallows 96 kHz
when connected to a HDA controller.
(All HDA controllers would support 96 kHz playback, but as for AC'97,
only the Intel driver has double-rate support.)