11 Replies Latest reply on Jun 25, 2020 5:47 PM by jroback

    Audio problems with RTAV in video conferences

    jroback Novice

      We're really struggling to get a good experience out of Horizon view for video conferences.  (Horizon 7.x  on Windows 10 VMs, using PCOIP across the Internet with Windows Horizon Clients). 


      We've got RTAV going with PCOIP (not extending mic or camera via USB)  and that is making the video work reasonably well, but where we're really struggling is the audio.  We did use group policy setting "Configure the PCoIP session audio bandwidth limit" to increase audio receive quality as mentioned in KB 2045764.  And we found that going into the microphone properties for the RTAV device on the VM, we are able to increase the microphone sample rate to 16K, which helped a lot.  So we though we were all set.... but then realized the microphone resets to 8K on each reconnection.    We then found KB article 78402 which points out that by design for backwards compatibility, which really kind of killed my excitement.


      The KB is kind of frustrating because the "expected behavior" explanation implies this isn't a big deal and won't change.   But this isn't just a question of the audio not sounding great… what we're finding is that the echo cancellation in video call software isn't working right with the 8K microphone stream, and so everyone on the calls is hearing echos and clicks from the RTAV participants.  These issues decreases dramatically when we turn it up to 16K.


      Unfortunately, setting the rate change requires many clicks in Windows, and so isn't something we can ask end users to do for every call, so if we can't automate it, we can't use it. I've done some tracing with process monitor, etc, to try to track down what is changing when we manually move this to 16K, but it seems buried deep in the registry under instance specific GUIDS, and not something we can easily automate.


      Does anyone know if VMware plans to allow us to control this with Group Policy at some point?  Or has anyone found a way to automate this?   I've even though about hitting windows API's via powershell, but that seems like a black hole too.


      For now we've had to resort to suggesting users do their video conferences outside of Horizon, which I really hate to do because it becomes a slippery slope back to them wanting a full client locally.

        • 1. Re: Audio problems with RTAV in video conferences
          bjohn Hot Shot

          Sorry to hijack this thread, but wondering if you seen this. We have issues with RTAV, where the microphone suddenly stops working. What happens is that all of the sudden there is no output from the microphone. I can still hear thru the headset, but what I’m speaking is not heard by others.

          I have to disconnect/reconnect the session and disconnect/reconnect the headset for it to work again.

          • 2. Re: Audio problems with RTAV in video conferences
            JoshJames Lurker

            I have the same issue.  The echo makes RTAV unusable with Google Meet.  It does seem to be less of an issue with application based Zoom.  What conference tool(s) are you testing with?    I don't have HTML5 redirection set up, not sure if it will help...

            • 3. Re: Audio problems with RTAV in video conferences
              jroback Novice

              We're seeing this with Lifesize, as this is our platform of choice, but I would think it would occur on any platform that is using RTAV for audio.   Microphone will always revert to 8K sample rate on login per kb.vmware.com/s/article/78402


              What's frustrating is that VMware has forced the default on this to 8K, and Microsoft appears to have purposely blocked any attempt to change the default by anything except the gui,  But even if we have the user change it by GUI, Vmware resets it on the next logon.   Microsoft has blocked  Powershell and API commands from changing this so that the end user gets to decide this setting.    So we're stuck with having to live with 8K or instruct users to change this themselves for each login, neither of which is a great answer.


              I can understand VMware wanting to maintain backward compatibility per the technote, but if they could just give us a registry entry to override this, they could immediately improve the audio experience of people using VDI for video conferences.  If you look through Reddit, you'll see that the geneeral consensus of IT folks having to support video conferences through VDI is "Don't".   They're directing users to run their sessions outside of VDI, which leads folks down a road that's hard to get back from.


              Something I've wondered about is using RTAV for video and forcing microphone and speaker output to use the non RTAV driver... but this seems like it would be setting things up for bad sync issues.


              Would be very interested to hear if others have found the magic solution for making video conferences work well in Horizon.

              • 4. Re: Audio problems with RTAV in video conferences
                ofox Enthusiast
                VMware Employees

                It's hard to tell w/o further debug or looking into logs.

                • 5. Re: Audio problems with RTAV in video conferences
                  ofox Enthusiast
                  VMware Employees

                  Thanks for the issue report.


                  The KB is right that the default sample rate is 8KHz and changing it to 16K would not persist across sessions. Since MSFT only allows to change it via deivce UI setting manually, at the moment we're not aware of an automation way to change it programatically. So far we do not experience any echo issue with many popular UC apps(incl. but not limited to Zoom, Webex, SfB etc.) tested in our lab. And Lifesize is new to us, we'd like to give it a try if we could get hold of a free trial version. Currently we're not certain about what role the sample rate plays in the echo issue you're reporting. In a long run we'll consider whether and research how we could support a configuration for switching among sample rates.


                  Thanks, and feel free to let us know should you have any feedback.

                  2 people found this helpful
                  • 6. Re: Audio problems with RTAV in video conferences
                    bcoserinf Novice


                    we face the same issue with Blast and RTAV and it's not new. We don't understand why we can't change the audio sampling rate as we want. We have already reported this problem in this thread in 2016. It's the mean reason why we had stick with pcoip protocol until this year since Blast permit audio at 16KHz and we have problem with pcoip and video in Zoom. 16Khz audio is OK but not match Pcoip yet.


                    With agent 7.8 we were able to force the audio at 16KHz between each login but the agent 7.12 seems to change the way audio RTAV is handle and now we return back to 8KHz between each session.


                    Furthermore, the Blast RTAV don't permit 16KHz audio if the video resolution is set too high. We did a lot of testing and the maximum video resolution we can reach with 16Khz audio is 352X288... If we push more than this the audio step back to 8000Khz despite the user select 16Khz in the audio driver.


                    Blast Extreme works pretty well but the audio quality was a problem since the begining. It's a big drawback in conference application, more than a poor video quality. Again, why just let administrators decide what is best for their use case? We have the choice with video so why not audio?



                    1 person found this helpful
                    • 7. Re: Audio problems with RTAV in video conferences
                      danielkrause Enthusiast


                      we are using Webex and Microsoft Teams.


                      With RTAV we have the same issues.


                      I am absolutely not happy with the quality of the Sound in VDI, espacially about the packet loss rate. The customers today are used to perfect sound quality and good images quality and cannot understand, that a smartphone can deliver that and a vdi not in the same quality.


                      Webex and MS Teams / Jabber providing VDI Hybrid programms, that stream from the thinclient the signal to the VDI Session.

                      So this would be a good solution.

                      Saidly we have PCoIP Zero Clients, so we cannot use it.

                      • 8. Re: Audio problems with RTAV in video conferences
                        jroback Novice



                        Thanks so much for offering to look into this further!  I can certainly get you set up with a demonstration account on LifeSize to test things out.   I'll send you a direct message here with my contact information.


                        Thanks again,


                        • 9. Re: Audio problems with RTAV in video conferences
                          serinfbco Novice

                          We've been searching a way to change the mic quality (8khz to 16khz)

                          I've made a script that forces to 16khz. It writes back the hexdata where it stores the 8khz to 16khz part (by comparing with regshot)


                          Vmware Blast - Script to change microphone audio quality to 16khz - Workaround


                          Hope it helps someone, it works for us, the users don't report back about losing mic input or quality.

                          You should test it before the prod

                          1 person found this helpful
                          • 10. Re: Audio problems with RTAV in video conferences
                            jroback Novice

                            Thanks so much for sharing this!   Will give it a try!


                            • 11. Re: Audio problems with RTAV in video conferences
                              jroback Novice

                              One additional thing I've been thinking about is taking the audio inputs and outputs and routing them outside of the RTAV connection by directly selecting either the teradici audio device or a USB headset directly.   I am concerned about getting lip-sync issues between audio and video if we go this route, however.  But haven't had time to try this yet.