Hello,
I am working with owner of Chord 2qute on the following problem (FYI
long discussion at
http://www.diyaudio.com/forums/pc-based/310578-chord-2qute-dop-challenge.html):
Regular 176.4/24 PCM plays OK, however 176.4/24 DoP produces random 1-2
sec sound interruptions every several tens of seconds. Tested players -
squeezelite, MPD. The soundcard has its own power supply.
I googled out several reports of simlar problem with this soundcard,
mostly on linux (did not see any problem report for OSX).
alsainfo: http://www.fyn13.dk/diy/alsa_output_chord_2qute_4.4.0-62.txt
lsusb -v : http://www.fyn13.dk/diy/chord_lsusb.txt
hw_params and stream0 files are identical for both 176.4/24 PCM and DoP:
/proc/asound/card1/pcm0p/sub0/hw_params:
access: RW_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 176400 (176400/1)
period_size: 1764
buffer_size: 7056
/proc/asound/card1/stream0:
Chord Electronics Ltd 2Qute at usb-0000:00:14.0-2, high speed : USB Audio
Playback:
Status: Running
Interface = 2
Altset = 1
Packet Size = 224
Momentary freq = 176402 Hz (0x16.0ce0)
Feedback Format = 16.16
Interface 2
Altset 1
Format: S32_LE
Channels: 2
Endpoint: 5 OUT (ASYNC)
Rates: 32000, 44100, 48000, 88200, 96000, 176400, 192000, 352800,
384000
Data packet interval: 125 us
We checked for XRUNs, none were produced during the interruption in DoP
playback.
Powerful 4-core CPU Intel Pentium 4405U @ 2.10GHz, idle > 99% of time in
DoP playback.
However, the IRQs rate of the onboard XHCI controller is 8k/s for both
PCM and DoP playback which corresponds to 1 IRQ every 125us frame. The
rate drops to almost zero when playback is stopped in the player -
clearly it is related to the soundcard. Could this perhaps be a sign of
the problem? Please is there a way to lower the rate, like the old
removed param nrpacks of the usb-audio driver?
I suspect a buggy XMOS firmware. I very much appreciate any suggestion
or help, either with fixing in software, or further diagnostics to
support potential claim to the manufacturer.
Thank you very much. With regards,
Pavel.
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