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.htm...):
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.