Raspberry PI 2B/3 and USB audio
Brian Scott
bscott at bunyatech.com.au
Wed Nov 28 00:47:10 UTC 2018
On 27/11/18 6:38 pm, Hans Petter Selasky wrote:
> On 11/26/18 8:47 PM, Herbert J. Skuhra wrote:
>> Well, this USB sound card works perfectly fine on my desktop PC
>> running FreeBSD (amd64).
>
> Hi,
>
> There is a problem in the DWC OTG USB controller driver that it cannot
> handle the big data payload 24-bit 48KHz sampling requires.
> Unfortunately your device has only one sample size selection.
>
> If you buy a USB sound device marked as "HIGH SPEED USB" it should
> work. Yours is "spd=FULL".
>
> --HPS
Just an additional data point,
This one also sounds like junk but is high speed:
ugen0.6: <Generic USB Audio> at usbus0, cfg=0 md=HOST spd=HIGH
(480Mbps) pwr=ON (100mA)
bLength = 0x0012
bDescriptorType = 0x0001
bcdUSB = 0x0200
bDeviceClass = 0x0000 <Probed by interface class>
bDeviceSubClass = 0x0000
bDeviceProtocol = 0x0000
bMaxPacketSize0 = 0x0040
idVendor = 0x0bda
idProduct = 0x4040
bcdDevice = 0x0000
iManufacturer = 0x0003 <Generic>
iProduct = 0x0001 <USB Audio>
iSerialNumber = 0x0002 <201405280001>
bNumConfigurations = 0x0001
But I notice that it handles both 48000 and 8000 according to the sound
driver.
cat /dev/sndstat
FreeBSD Audio Driver (64bit 2009061500/aarch64)
Installed devices:
pcm0: <USB audio> at ? kld snd_uaudio (1p:1v/1r:1v) default
snddev flags=0x2e2<AUTOVCHAN,BUSY,MPSAFE,REGISTERED,VPC>
[pcm0:play:dsp0.p0]: spd 48000, fmt 0x00200010, flags
0x00002100, 0x00000004
interrupts 0, underruns 0, feed 0, ready 0
[b:3072/1536/2|bs:4096/2048/2]
channel flags=0x2100<BUSY,HAS_VCHAN>
{userland} -> feeder_mixer(0x00200010) -> {hardware}
pcm0:play:dsp0.p0[pcm0:virtual:dsp0.vp0]: spd 8000, fmt
0x00100008, flags 0x10000000, 0x00000000
interrupts 0, underruns 0, feed 0, ready 0 [b:0/0/0|bs:0/0/0]
channel flags=0x10000000<VIRTUAL>
{userland} -> feeder_root(0x00000000) -> {hardware}
[pcm0:record:dsp0.r0]: spd 48000,fmt 0x00200010/0x00210000,
flags 0x00002100, 0x00000007
interrupts 0, overruns 0, feed 0, hfree 4608, sfree 4096
[b:4608/2304/2|bs:4096/2048/2]
channel flags=0x2100<BUSY,HAS_VCHAN>
{hardware} -> feeder_root(0x00210000) ->
feeder_format(0x00210000 -> 0x00200010) -> feeder_mixer(0x00200010)
-> {userland}
pcm0:record:dsp0.r0[pcm0:virtual:dsp0.vr0]: spd 8000, fmt
0x00100008, flags 0x10000000, 0x00000000
interrupts 0, overruns 0, feed 0, hfree 0, sfree 0
[b:0/0/0|bs:0/0/0]
channel flags=0x10000000<VIRTUAL>
{hardware} -> feeder_root(0x00000000) -> {userland}
No devices installed from userspace.
Output sounds like rubbish with both 8000 speed stuff sent directly to
/dev/dsp using cat and higher quality stuff sent via sox play.
It could also just be a junk piece of hardware from my local electronics
shop.
Cheers,
Brian
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