Hi,
Suggestions:
- try with regular PCM @ 176.4Khz 24 bits to rule out issues in the way
DSD is depacked from the stream
Regular 176.4/24 was tested against the DSD/DoP, it works just fine,
eventhough it produces the very same alsa params (the same data stream)
as DoP.
- look into the ASYNC endpoint handling. It could be that the host
doesn't provide enough data and the device buffer is emptied at some
point. USB doesn't clearly define in how much time the host needs to
adjust to feedback information, the implementation may have defined its
buffer depth assuming a quick correction.
Could it be different for the two streams if both have the same
period/buffer params, the same altsetting, the same stream bandwidth?
IIUC the alsa USB driver does not distinguish between regular PCM and
DoP of the same bitspeed, at least I could not find anything in the API
when the player sends already DoP-encoded PCM samples (which it does).
Would it make sense to monitor the USB (kernel) communication with
wireshark to see whether the async feedback from the soundcard differs
for PCM and DoP?
Is it OK that the controller throws IRQ every frame?
I very much appreciate your help.
With regards,
Pavel.
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