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Webcam / USB headset redirection problems on Raspberry Pi


Both Citrix Workspace App and VMware Horizon Client have ARM ports that are functionally very limited in comparison with their x86/x86_64 Linux ports.  ThinLinX does not have access to the source code of either client, and therefore cannot do anything about this - we must work with what we are given.

In particular, the ARM port of Citrix's RTME (Real Time Media Engine) extension is not available - at least, not publicly - and the ARM port of Horizon Client lacks a number of extensions that have not yet been ported to ARM, in particular the RTAV (Real Time Audio Video) extension which performs much the same function for Horizon Client as RTME does for Workspace App.

What that means in practice is that both webcams and USB audio devices (particularly microphones) perform either sub-optimally or not at all on the Raspberry Pi platform.  It's theoretically possible to redirect such devices using low-level USB redirection, but this is very inefficient compared with the high-level virtual channel redirections that would be provided by RTME/RTAV.  Horizon Client is very unreliable when attempting to redirect USB audio devices, and is likely to cause temporary session lock-ups.  Similarly, some webcams may be unable to cope with the latencies of USB-over-IP redirection and may be effectively inoperable when used in this way.

For Citrix Workspace App, what happens by default is probably the best that you can hope for on the Raspberry Pi platform.  For Horizon Client, you could try editing /etc/vmware/config and setting viewusb.AllowAudioIn and viewusb.AllowAudioOut to "TRUE", but this may cause problems such as temporary lock-ups when accessing audio properties and playback failures, and may not work at all until the client is rebooted.

If you encounter problems, please complain to the relevant vendor (Citrix or VMware), demanding RTME (Citrix) or RTAV (VMware) for Linux ARM.  If they receive enough complaints, they may eventually do something about it.

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Article details
Article ID: 19
Category: Workarounds for Old Versions
Date added: 2019-05-29 03:25:11
Views: 1617

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