RTV Support Released for Polycom Solutions
As of today Polycom has officially released native support for Microsoft’s Real-Time Video (RTV) media codec in HDX Telepresence endpoints and RMX Conferencing bridges. The HDX also supports Microsoft’s implementation of the Centralized Conferencing Control Protocol (CCCP or C3P) which is an XML-based protocol extension to SIP/SDP.
It is important to understand that the capabilities described in the following sections are natively integrated into each product and there are no signaling gateways or media transcoders required for any of these features.
As discussed in a previous article the HDX now supports all RTV video resolutions for both peer-to-peer Lync video calls as well as multiparty video conferences hosted on the Lync AVMCU. Previously peer video calling was supported with a limited video resolution of H.263 CIF, which both the HDX and Lync native understood. With RTV there are three different resolutions available for peer-to-peer video sessions: CIF, VGA, and HD (720p), while video conferences hosted on the Lync AVMCU are limited to CIF or VGA. As always, a quad-core processor is required on the Lync client’s workstation in order to support both sending and receiving of 720p high definition video for two-party calls.
But for multiparty conferencing the Lync AVMCU only utilizes RTV, it does not support H.263 CIF like the clients do. And for signaling the AVMCU handles both ad-hoc and scheduled conferences by leveraging CCCP in the SDP messages within the SIP protocol. So only native Microsoft Lync clients could join a Lync conference (Lync, Lync Phone Edition, Attendee client, MOC, etc) as only they understand both RTV and CCCP used by the Lync AVMCU.
Now that the HDX can handle both RTV and CCCP then it is possible to join a Lync conference in the same ways that normal Lync clients can join, by either be dragged into a conference or by using Click-to-Conference from standard Online Meeting invitations.
This screenshot shows a peer-to-peer call between ah HD-capable Lync client and an HDX 8000 running 3.0.1 software with RTV enabled. The HDX call statistics report that both inbound and outbound streams are RTV 720p, with G.722 used for the audio.
Since there is very little motion in this video the actual Video Rate Used value is towards the bottom end of the bandwidth needed for RTV-HD sessions. The following table lists the supported bandwidth ranges for each resolution available in the RTV codec for reference:
|RTV||Resolution||FPS||Min. Bandwidth||Max. Bandwidth|
|CIF||352×288||15||50 Kbps||250 Kbps|
|VGA||640×480||30||350 Kbps||600 Kbps|
|HD (720p)||1280×720||30||800 Kbps||1500 Kbps|
On-the-fly conferences which are escalated up from peer-to-peer conversations can incorporate an HDX at any time. A Lync-registered HDX can be dragged into a Lync peer video call or a Lync-to-HDX call successfully be escalated to a conference by adding a third party of any supported client type.
The screenshot below shows a two-party Lync video call which was turned into a conference by inviting a federated Lync user registered on an HDX. (Notice that now the video resolution is limited to VGA since HD is not supported on the Lync AVMCU.)
Joining Scheduled Conferences
The process of using the Online Meeting add-in for Lync/Outlook to invite other users is no different when an HDX is involved. Simply invite the Lync user to the meeting and if that user is signed-in on an HDX then it can join using the same native process.
By viewing the Exchange-integrated calendar on the HDX menu the newly scheduled meeting appears as a video-enabled meeting as indicated by the green camera icon. Simply selecting the Join Now button launches the call.
The Lync Online Meeting invitation details are used to build the proper SIP URI by using the meet FQDN, the organizer’s SIP username, and the meeting focus ID.
Once the call is imitated the HDX web management interface can be used to see the actual SIP URI used to connect to the Lync AVMCU.:
This screenshot below shows RTV CIF in use by default when the video window is still snapped-in to the conversation window. The current resolution in inbound and outbound streams can be viewed in the advanced Channel Status details for an individual participant.
Once the window is popped-out and resized to over roughly 480×360 pixels then the codec will switch to using VGA resolution. This resolution change is not obvious at first as it uses the same aspect ratio, but it is noticeable on the Lync client by the video quality improving to about 3 times the pixel depth.
If the window is then resized larger than about 960×540 pixels, or is maximized to full screen, then 720p HD will be used. This switch is easily seen as the aspect ratio changes to 16:9 and is even further cleaned up as video quality is now 3 times the pixel depth of VGA, and nearly 10x better looking than CIF.
The Lync client will use the same resolution for sending video as it asks to receive from the RMX, so when viewing the video in a smaller window other parties in the conference will see that client’s video at the same resolution. Alternatively switching to receive HD will also send HD quality video to the far-end.
With the support for higher quality VGA and HD resolutions now any content transmitted as video becomes more clear and easier to read. As The Lync client can only support a single video stream the RMX treats Lync users as legacy video endpoints in terms of content management. Content pushed using H.239 based simultaneous video channels will be converted into a single video stream by the RMX, as shown below. The video steam received by the Lync client dedicates the majority of screen real estate to the content while minimizing the ‘people’ video panels.
Although only Lync is referenced in this article all of the functionality above is available and supported for Office Communications Server 2007 R2 environments as well, with one exception: CCCP. In both OCS releases Microsoft chose to use different versions of ICE between the Front End server (ICE v6) and the Edge server (ICE v19), where as Lync Server 2010 uses ICE v19 throughout the entire product line. As the Polycom implementation of CCCP is only compatible with the current ICE v19 used in Lync server then an HDX will not be able to join conferences hosted on an OCS AVMCU, only conferences hosted on the Lync AVMCU.