Hello all!

I am building a test platform that needs to record voice at 8khz sample
rate. This application is used in telephony networks. I am using the
ASIO API to get the voice samples from a sound card.

I tried using the Sound Blaster Audigy and X-Fi sound cards, but those
boards do not support sampling of voice at 8Khz when using ASIO (I
guess lower sample rates are obsolete nowadays..). I also tried using
the ASIO4ALL driver which works at 8khz, but this introduces too much
latency (delay).

Anyone knows if there is a PCI or PCMCIA sound card out there that
supports native 8Khz rate sampling over ASIO?

Thanks very much, any help greatly appreciated.

Christian

In article .com,
wrote:
Hello all!

I am building a test platform that needs to record voice at 8khz sample
rate. This application is used in telephony networks. I am using the
ASIO API to get the voice samples from a sound card.

I tried using the Sound Blaster Audigy and X-Fi sound cards, but those
boards do not support sampling of voice at 8Khz when using ASIO (I
guess lower sample rates are obsolete nowadays..). I also tried using
the ASIO4ALL driver which works at 8khz, but this introduces too much
latency (delay).

Anyone knows if there is a PCI or PCMCIA sound card out there that
supports native 8Khz rate sampling over ASIO?

I assume you also need 8-bit non-linear encoding as well?

The easiest thing to do is record at a high rate, then downsample.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Yes downsampling is an option. But this inserts delays, especially in
my situation where I want to record and output the signal in realtime.
But I'm willing to try. :-)

Do you have access to any source code or pseudo-code that can resample
(for realtime applications??) using an integral factor (48khz to 8khz
is a 1 to 6 ratio).

Thanks for the info.

Christian

Christian Pare wrote:
Yes downsampling is an option. But this inserts delays, especially in
my situation where I want to record and output the signal in realtime.
But I'm willing to try. :-)

Well, you used to be able to buy cards with telco codecs in them.... not
really typical soundcards, though.

Do you have access to any source code or pseudo-code that can resample
(for realtime applications??) using an integral factor (48khz to 8khz
is a 1 to 6 ratio).

Well, the question is whether you also have to deal with nonlinear encoding.
That's more of a nightmare than the simple downsampling (which you can
deal with by low-pass filtering and then decimating, since you have an
easy integral division to do).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

You might try the Bitworks card. Specifically for telco audio. Talk to
John Gledhill there. Very smart guy.

http://www.bitworks.org/