29 Nov
2010
29 Nov
'10
11:03 p.m.
On Monday 29 November 2010 22:03:23 Mark Rages wrote:
Hi all,
I've got an ubuntu 10.04 system and I am using the sound card built
into my motherboard.
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".
In audacity I generated a .wav file with a 24 kHz sine wave sampled at
96 kHz. It produces a flat line on the oscilloscope when I play it
back in audacity or sox. This makes me suspect that it's getting
downsampled to 48 kHz somewhere along the way. (I also tried playing
it back in alsaplayer and the result was an ugly on the 'scope. I
didn't try listening.).
I generated a 1 kHz wave which showed up loud and clear, so the audio
path is working.
(Before you ask, I'm not trying to play music for dogs, I'm trying to
generate FM stereo pilot tone.)
So, what do I need to do to get 96kHz playback working?
You need a soundcard that does 96kHz.
Intel hda is not suited for that. "High definition audio" is only suitable for
dvd and still is spec'ed for a lot of hizz and noise...
If its for a notebook your choice is somewhat limited compared to the choice
for pci/pcie capable machines. But there are several devices for low and high
prices out there that will do 96kHz and also 192kHz. Using a hda for this is
just asking for trouble and disappointment (if it even works).
Have fun,
Arnold