more usb playback-capture devices on linux alsa Topic is solved

Sub forums for various specialist XMOS applications. e.g. USB audio, motor control and robotics.
RobertPE
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more usb playback-capture devices on linux alsa

Postby RobertPE » Thu Jan 09, 2020 4:36 pm

Hello to all,
i have well compiled and running a reference design called app_usb_aud_skc_u16.
Now i need more endpoints on linux alsa.
I have multichannel audio with SPDIF and i need to split the audio channel in more USB digital Audio Playback & digital audio capture endpoints.
With alsamixer i see only 2 devices one for playback and another for capture,
is it possible to have 4 devices or more with one XMOS IC?
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fabriceo
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Postby fabriceo » Sat Jan 11, 2020 8:53 am

Hi, my view is that it would require to show multiple audio interfaces and descriptors to the host, and the app_usb_aud framework is not written/prepared for this...
also the management of 2 sets of audio endpoint would need to duplicate buffer handling in both usb_buffer.xc and decouple.xc this would be a real nightmare and needing a huge amount of man days to understand how it works and duplicate this...
you have to consider splitting the data flows upfront into the host/linux...
RobertPE
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Postby RobertPE » Sun Jan 12, 2020 4:06 pm

thanks Fabriceo,
best of all is to have a reference desing already done!
Perhaps some of xmos gurus are listening....
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akp
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Postby akp » Tue Jan 14, 2020 3:29 pm

Hi. Have you tried the dmix, dsnoop and/or dshare ALSA plugins? That might give you what you want. It will take some work but less work than rewriting the XMOS IP.
RobertPE
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Postby RobertPE » Thu Jan 16, 2020 2:52 pm

Hi.
i solve with dsnoop, thanks to akp!!
Now i need to resample some spdif input but is less effort than rewriting XMOS IP
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akp
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Postby akp » Thu Jan 16, 2020 3:42 pm

Glad you got it working! Good luck with the rest of your project.

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