> De: "Hans Wilmers"
> À:
linux-audio-user@lists.linuxaudio.org
> Envoyé: Jeudi 10 Janvier 2013 13:23:57
> Objet: Re: [LAU] Sound Devices USBPre2, UAC2 status
>
> On 01/07/2013 08:25 PM,
shal@free.fr wrote:
> >
> > ----- Mail original -----
> >> De: "alexander"
> >> À:
linux-audio-user@lists.linuxaudio.org
> >> Envoyé: Lundi 7 Janvier 2013 18:27:42
> >> Objet: Re: [LAU] 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