Re: Native Instruments USB Driver

[Jonathan Leonard <jonathan.adams.leonard@xxxxxxxxx>]

Hi Daniel!

Hi Jonathan,

On Aug 7, 2007, at 12:49 AM, Jonathan Leonard wrote:

I can get clear playback of a wav file through aplay and XMMS with the soundcard assigned as card 0, or hw:0  However accessing the headphone output on the kore controller has not been possible for me yet.

The headphone output on the Kore controller is a separate channel which you should be able to access as "hw:0,0,1".

Excellent - I'll try that!

Concerning Jack, I have only been able to connect to jackd using a buffer size of 1024.  I have tried three sample rates:  44.1, 48 and 96k; these are fine but only with 1024 frames or greater.  Depending on various other settings I may set in qjackcontrol, the cpu usage of jackd varies widely.  For example, if I select anything other than 2 ins and outs, its either 90% cpu, or the server will not connect.  With the Kore Controller, if I select what should be the proper number of channels; 2 ins and 6 outs, no connection.  After some time experimenting like this, occassionally qjackcontrol will blink out of existence entirely, which I confirm with a ps -A in the terminal.  Or, the entire OS freezes without override and a system restart is required.  Also when jack is connected at 1024 frames, there are about 10 xruns per second.

I'm not sure whether your jackd problems are acutally related to the driver at all.

Have you tried your jackd config with any other driver, maybe some onboard soundcard in your computer? Probably someone with more jackd experience can give some more substantiated information :)

Yes I have tried the same config with another soundcard.  The Echoaudio Layla20 which has worked reliably with a range of settings.

+++/alsa-kernel/usb/caiaq.c

Ln 63:

.periods_bytes_min = 4096

Is this limit cool for low latency?  Is it possible to get lower buffer sizes than 1024 frames?

My primary jack problem, and with aplay is I cannot use the NI devices at a period size less than 1024 frames.

Using aplay I cannot get beneath buffer size = 683 without this error:

aplay: set_params:969: Can't use period equal to buffer size (683 == 683)

This is somewhat echoed by calling the sw_params while a stream is playing:

$cat /proc/asound/card0/pcm??/sub?/sw_params

I found another alsa patch that was submitted to provide lower latency response here.

But of course that is a different device.

I also found a response from alsa-dev from clemens asking why that limit is there at all.

Given, we don't know jack. (har har har)  But could I solve my issue by changing this minimum in the c file and rebuilding?  Or is this a limit set from 'on high'?  Hoping for a technical explanation...

Thanks for your help and the driver!!!

jonathan adams leonard

ps:  looking forward to those matrix notes being updated and cleaned up though I hope the migration to wiki doesn't slow this down.  Personally I know there is newer info to add for RME support because my multiface II works with JAD live DVD and there is no mention of this in the matrix - only the pci cards.

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