uaudio - distorted output

[Hans Petter Selasky]

On 02/09/18 12:47, Ert Retre via freebsd-usb wrote:
>> Hi,
>>
>> attached are the config descriptors and the device dump of two uaudio
>> devices. Both exhibit distorted audio output. It sounds a little bit
>> like clipping / not feeding enough samples fast enough...
>>
>> I played around with dev.pcm.2.bitperfect=1, dev.pcm.2.play.vchans=0,
>> dev.pcm.2.play.vchanrate and hw.snd.latency=1...10.
>>
>> At some point vchanrate doesn't work anymore, it always stays at 4.0
>> audio, even when trying to go back to 2.0. I have to usbconfig reset the
>> device.
>>
>> Sometimes (rarely) when playing around I get clear audio output, but
>> when I try to reproduce it (going back to default value for the last
>> sysctl setting and then going back again to the same setting again), the
>> audio is distorted again.
>>
>> To me it sounds like some kind of buffer is not big enough or the data
>> is not delivered fast enough to the uaudio device. But this is a
>> dual-socket system with:
>>       CPU: Intel(R) Xeon(R) CPU           E5620  @ 2.40GHz (2133.36-MHz
>> K8-class CPU)
>>       FreeBSD/SMP: Multiprocessor System Detected: 16 CPUs
>>       FreeBSD/SMP: 2 package(s) x 4 core(s) x 2 hardware threads
>> And while playing around with uaudio the system has a load of around 1,
>> so I would expect CPU/RAM is not an issue here.
> 
> Hi,
> 
> What version of FreeBSD is this?
> 
> Try to enable hw.usb.uaudio.debug=16 during playback.

Hi,

If your device is FULL speed, you cannot connect it via an external HUB 
for more than 2 channels, recording and playback simultaneously. There 
is a capacity issue (except when using XHCI) and it will cause clipping.

Can you send the full output from usbconfig?

--HPS