Whisper – New Voice Solution for OpenSim

Today, vComm Solutions of Switzerland released Whisper, a high quality voice solution for OpenSim based on the popular Mumble open source VoIP client. The key feature of this solution is that it enables avatar lip sync and speaker indication to work correctly, in addition to providing very stable, high quality voice.

The code will be released as open source soon but in the meantime the client is being provided as a Windows download that can be tested against a demo OSGrid region, kindly provided by Snoopy Pfeffer of Dreamland Metaverse.

Recently there has been a huge amount of interest in OpenSim, as an Open Source and low cost alternative to the kind of virtual world environments provided by Second Life.

The server side of OpenSim is an open source framework for creating virtual environments, but crucially it supports the protocols used by the Second Life viewer, and the many third party viewers based on it, as well as supporting much of the same scripting functionality in the 3D environments.

This has allowed low cost grids and stand-alone 3D regions to spring up as an attractive alternative to Second Life for educators and businesses wanting to explore 3D environments for collaboration. However, voice has been one of the few areas in which OpenSim suffered in comparison with Second Life.

The voice-over-IP that is integrated in Second Life provides high quality spatial sound and is hooked into the viewer to give indication of who is speaking, body animations and a crude form of mouth movement or lip sync during speech. The voice solution in Second Life relies upon Vivox, and the client portion is managed by the SLVoice executable, separate to the main Second Life viewer process. SLVoice and the viewer then communicate with each other to provide the various speech related features.

Ideally, OpenSim servers would simply provide Vivox-based voice, but Vivox typically requires tens of thousands of licenses to be purchased, which is of no use to the majority of OpenSim deployments. There has been talk of a small scale type of licensing for Vivox but nothing has so far come of it as far as I know. Additionally, an open source virtual world server ideally should have an open source voice component to go with it!

Mumble is an open source voice chat application for groups popular for online gaming, capable of providing high quality spatial audio via it’s server component — Murmur. The Whisper solution from vComm was the idea of Volker Gaessler, founder of vComm, and works by replacing the SLVoice executable with a Mumble client that looks exactly the same to the viewer process. This new SLVoice executable then communicates with an instance of Murmur associated with the OpenSim region.

If you need to use the same viewer with Second Life or with an OpenSim region that requires the original SLVoice, a script is provided to switch the old executable back. Management of the voice server is via an OpenSim region module that handles registering voice parcels and users, communicating with Murmur via the ICE remote procedure call mechanism.

(Image courtesy KnowSense.)

So how does Whisper perform in practice? At Flying Island we’ve been trialling Whisper in OpenSim as part of our Roobaab collaboration product, and we’ve been very impressed.

Currently the sound is not spatial and is auto-leveled, so wherever you are on the land parcel you will hear your colleagues with the same volume. For typical meeting scenarios, this is actually fine — we are able to drop straight into meetings and begin talking with no need to adjust sound volumes, none of the eternal fiddling with settings that seemed to plague most SL voice meetings.

The quality is superb, and we’ve had no real issues. I can say that for our use case Whisper has really made a huge difference and I have no hesitation in using it with clients, integrated into Roobaab.

vComm plans to continue development to add the option of spatial sound, private voice calls in addition to the current parcel-wide voice, and compatibility with the modified voice element in Linden Lab’s Viewer 2. There are also plans to automate the switch from Mumble-based voice to Vivox or Freeswitch.

Right now you can try Whisper for yourself using instructions here and logging into the OSGrid sim “Mumble Sandbox” — you’ll need an account on OSGrid of course, which is free if you don’t already have one.

This is a big step forward for OpenSim adoption — congratulations to Volker and Snoopy and everyone involved.

This article is reprinted with permission from the KnowSense company blog.

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