On 01/07/2013 08:25 PM, shal@xxxxxxx wrote:
----- Mail original -----
De: "alexander" <axeldenstore@xxxxxxxxx>
À: linux-audio-user@xxxxxxxxxxxxxxxxxxxx
Envoyé: Lundi 7 Janvier 2013 18:27:42
Objet: Re: Sound Devices USBPre2, UAC2 status
I also own this interface, recently it has started to work in uac2
mode,
I still cant raise the samplerate, but it runs.. however, It still
runs
alot better in uac1.. when in uac2 jack mysteriously shuts down for
no
appearant reason. I run archlinux, allways uptodated with vanilla
kernel.
This is when I connect it without pressing 1. eg, uac2
http://pastebin.com/BFJTwXnJ
And as with pressing 1. http://pastebin.com/ZJ1jbPUK
Hi,
In my understanding, you are not in UAC2 , you are in high-speed mode but the usb audio protocol remains UAC1.
In the kernel source in the file include/uapi/linux/usb/audio.h is defined two values:
/* bInterfaceProtocol values to denote the version of the standard used */
#define UAC_VERSION_1 0x00
#define UAC_VERSION_2 0x20
So if the card is in UAC2 , you should see bInterfaceProtocol at 32 (or 0x20)
By example, now the RME babyface is recognize as UAC2 device, you can view its "lsub -v" here : http://minilien.fr/a0m3kc
But for the usbPre2 device with ou without pressing the "1" button, we have bInterfaceProtocol = 0. So we stays in UAC1, even the speed increase to high-speed.
I was also surprised to see that the USBPre2 now works duplex without
pressing the "1" button while connecting.
This was tested on Fedora 17 with stock kernel 3.6.6-1.fc17.
Jack was set to 512 Frames/period and 3 periods/buffer, and in a 24h
recording I got no xruns.
I did not manage to choose a sample rate unlike 48000, though.
With lsusb, I can see 2 configurations for the same device, and the
second one has bInterfaceProtocol = 32 for all interfaces except HID:
http://pastebin.com/zwq0VVbM
/ Hans
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