Hello guys, I'm new here. The company that i work for is developing a LV2 host pedal board (http://portalmod.com/en/index.html) and my job now is to find if I can improve in anyway our usb driver (which is the kernel's snd-usb driver). I know the code is already optimized but I was hoping that, since we only use one specific sound card and we won't need a generic driver, I could change something in the code to optimize it latency wise. I have only a brief knowledge on the USB protocol and even less on writing drivers, so I'm here first to ask if it's possible to improve latency by changing the driver's code and, if possible, if you guys could give me some directions on how to do it.
Thanks in advance,
Lucas
Lucas Takejame wrote:
I was hoping that, since we only use one specific sound card and we won't need a generic driver, I could change something in the code to optimize it latency wise.
USB packets are transferred in frames (or microframes). The driver already allows to use a buffer with only two frames; you cannot go below this hardware limit.
Regards, Clemens
Hi Lucas,
I wonder if I've misunderstood what you're trying to accomplish...
On 12/11/2013 08:59 AM, Lucas Takejame wrote:
snd-usb driver). I know the code is already optimized but I was hoping that, since we only use one specific sound card and we won't need a generic driver, I could change something in the code to optimize it latency wise. I
Are you creating a product that *is* a USB sound card and you want to write a driver for it?
...or do you have some pre-existing USB sound card (and driver) that this product is using and you're trying to set up a low-latency audio workstation that uses it?
-gabe
The product is the pedal board actually (which has the same hardware as a computer, but with the necessary changes to work out in a gig, like a hardcase and audio dedicated OS), we designed the sound card. I was only wondering if there was anything that I could change considering that we have a fixed mother board ( Intel DN2800MT ) and sound card ( works with a TUSB3200A and AK5386 ADC, AK4382A DAC, if that helps hehe), i don't know how much the driver being generic interfere in the performance, that is my doubt.
Thanks for the responses,
Lucas
2013/12/12 Gabriel M. Beddingfield gabrbedd@gmail.com
Hi Lucas,
I wonder if I've misunderstood what you're trying to accomplish...
On 12/11/2013 08:59 AM, Lucas Takejame wrote:
snd-usb driver). I know the code is already optimized but I was hoping that, since we only use one specific sound card and we won't need a generic driver, I could change something in the code to optimize it latency wise. I
Are you creating a product that *is* a USB sound card and you want to write a driver for it?
...or do you have some pre-existing USB sound card (and driver) that this product is using and you're trying to set up a low-latency audio workstation that uses it?
-gabe
On Fri, December 13, 2013 3:24 am, Lucas Takejame wrote:
The product is the pedal board actually (which has the same hardware as a computer, but with the necessary changes to work out in a gig, like a hardcase and audio dedicated OS), we designed the sound card. I was only wondering if there was anything that I could change considering that we have a fixed mother board ( Intel DN2800MT ) and sound card ( works with a TUSB3200A and AK5386 ADC, AK4382A DAC, if that helps hehe), i don't know how much the driver being generic interfere in the performance, that is my doubt.
A well built standards compliant USB audio device will be able to handle 64 frames/period with the generic driver.
Have you run any benchmarks?
What is the lowest period size you can use with jack without getting dropouts?
There may be some additional steps to configure your system for low latency. In that case it is probably more appropriate to discuss on JACK mailing list or back on LAD :-)
Thanks for the responses,
Lucas
2013/12/12 Gabriel M. Beddingfield gabrbedd@gmail.com
Hi Lucas,
I wonder if I've misunderstood what you're trying to accomplish...
On 12/11/2013 08:59 AM, Lucas Takejame wrote:
snd-usb driver). I know the code is already optimized but I was hoping that, since we only use one specific sound card and we won't need a generic driver, I could change something in the code to optimize it latency wise. I
Are you creating a product that *is* a USB sound card and you want to write a driver for it?
...or do you have some pre-existing USB sound card (and driver) that this product is using and you're trying to set up a low-latency audio workstation that uses it?
-gabe
-- Lucas Conejero Takejame Engenharia Elétrica - ênfase em computação Escola Politécnica - USP _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
-- Patrick Shirkey Boost Hardware Ltd
-
Clemens Ladisch -
Gabriel M. Beddingfield -
Lucas Takejame -
Patrick Shirkey