On 11/01/13 17:42, shal@xxxxxxx wrote:
----- Mail original -----
De: "Hans Wilmers" <hanswil@xxxxxxxxxx>
À: linux-audio-user@xxxxxxxxxxxxxxxxxxxx
Envoyé: Jeudi 10 Janvier 2013 23:23:56
Objet: Re: Sound Devices USBPre2, UAC2 status
On 01/10/2013 10:30 PM, shal@xxxxxxx wrote:
De: "Hans Wilmers" <hanswil@xxxxxxxxxx>
No luck with this either - fastest one I get is 48000. This
corresponds
to the output of lsusb, which does not list samplerates over 48000
for
this device.
I have tried different kernel, 3.2 to 3.7.1, vanilla or ubuntu
kernel.
The lsusb does not means that you are limited to 48000.
The lsusb provides the "devices descriptor" and a devices
descriptors has one or more "configuration descriptor". The kernel
chooses one of the "configuration descriptor".
In your device descriptor (provided directly by the device) there
is two possibles configuration descriptons (the
bNumConfigurations=2). The first one corresponds to the UAC1 mode
in high-speed (this is my one configuration) and so limited to
48000. The second one is the UAC2 mode (the expected mode).
Perhaps the kernel choose the fist good one, so UAC1 .
Can you send the result of cat /proc/asound/USBPre2/stream0 ?
Yes, see below.
/ Hans
--------------- /proc/asound/USBPre2/stream0 -------------
Sound Devices USBPre2 at usb-0000:00:1a.0-1.2, high speed : USB Audio
Playback:
Status: Stop
Interface 1
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 6 OUT (ASYNC)
Rates: 8000, 16000, 24000, 32000, 44100, 48000
Data packet interval: 1000 us
Interface 1
Altset 2
Format: S24_3LE
Channels: 2
Endpoint: 6 OUT (ASYNC)
Rates: 8000, 16000, 24000, 32000, 44100, 48000
Data packet interval: 1000 us
Hi Hans,
So , effectively you are limited to 48000.
I supposed that the linux kernel chooses this first valid configuration descriptor.
This behavior can be modified in the kernel with adding a quirk in the code.
If my usbPre2 has the good device descripton, I can devlop and test this patch.
But my devices does not offer the UAC2 configuration descriptor.
I have write a post on the Sound Devices Forum. Perhaps I will have help to understand why my device has this strange behavior and correct it.
In this case, I think I can patch the kernel to have the UAC2 mode...
Olivier
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that would be amazing! I just joined the forum to raise their awereness
but I can't post yet it seems!
I submitted a bugreport to alsa's bugtracker aloong time ago where there
have been some additional discussion and someone actually have written
somekind of patch, I never got it to work tho.. but the tracker is down
now it seems.... I also started some threads on the alsa mailing list,
both users and dev.
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