[alsa-devel] laptop multichannel ethernet OR PCMCIA sound cards

flaxma at nal.gov.au flaxma at nal.gov.au
Thu Jul 2 00:18:16 CEST 2009

HI, yes

A little more background ... we are implementing research algorithms for
hearing aids ... so ... we have many mic inputs and stereo output ...

we want a digital interface to the laptop.

Need 6 analog inputs
Need 2 analog outputs

Need minimal latency both in and out as it is a collect/process/output

Sample rates anything between 22050 Hz and 48 kHz is good at this point.

At the moment we can get about 3 ms with an off the shelf firewire/usb card
 @ 48 kHz, however when we load the CPU with DSP algorithms, we sometimes
need to bump up the frame size and thus the latency goes up ...
We are running a realtime patched kernel.

I have found that there is about 2/3 of the latency in hardware buffers.

So we are still open to better USB/Firewire hardware, however would prefer
more bandwidth and hopefully less latency to the device. This is why I
asked about ethernet and possible PCMCIA.


> Matt Flax wrote:
>> We are after an ultra low latency connection to a multichannel in/out
>> sound card for a laptop. We want a portable system and don't want to
>> network to a different computer to achieve this goal.
>> As we are after ultra low latency, we are interested in both PCMCIA and
>> ethernet (gigabit) solutions.
>> Is anyone aware of any such ultra low latency hardware ?
> Can you define what you require.
> Do you want analog or digital audio I/O?
> Do you need low latency in, out or both?
> What samplerates do you need?
> What latency would be acceptable (say how many milliseconds or
> microseconds).
> regards
> Eliot

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