Setting and limiting call quality

Many factors can affect the video call quality as seen by individual participants on a call. Some of these factors are external to Pexip Infinity, such as the call protocols used by the endpoints participating in the conference, the compute and camera resources available to the endpoint, and constraints introduced by the network or call control systems. However, other factors that influence quality can be controlled within Pexip Infinity, typically at the platform level but with the ability to override those global settings for specific conferences.

Video call quality typically depends upon the resolution (for sharpness, and often expressed in terms of SD, HD or Full HD) and the frame rate (for smoothness). High resolutions and frame rates require more bandwidth than lower resolutions and frame rates, although the exact requirements vary according to the codec and compression algorithms being used.

The choice of resolution, frame rate and codec also impacts the amount of compute resource required by a Conferencing Node to host a conference, and hence the overall capacity of each Conferencing Node in terms of the number of concurrent participants and conferences it can host.

It is important to note that endpoints ultimately decide what bandwidth and resolution they send to Pexip Infinity, while Pexip Infinity is responsible for deciding what gets sent to the endpoints.

Maximum call quality

While the actual quality of the call as seen by individual participants depends upon the factors discussed above, you can configure within Pexip Infinity a Maximum call quality that limits what a Conferencing Node will send to — and request from — each participant in the conference.

The Maximum call quality options are SD, HD or Full HD and the associated resulting maximum resolution and frame rate for video are shown below:

Maximum call quality (video resolution) Maximum resolution Maximum frame rate (fps)
SD (448p) 768 x 448 30
HD (720p) 1280 x 720 30
Full HD (1080p) 1920 x 1200 30

By default, Pexip Infinity conferences have a maximum call quality of HD. You can configure this at the global platform level and, if required, override it for each individual service (VMR, Call Routing Rule and so on). For example, you could use the default option of "HD" for most of your services by default, but enable Full HD on some specific services.

Note that this is the maximum quality that Pexip Infinity will send to conference participants. The configured Maximum outbound call bandwidth for a service can cause Pexip Infinity to select a lower quality than the configured Maximum call quality (see Managing and restricting call bandwidth for more information).

Impact on resource usage

The Maximum call quality setting also controls how much compute resource is allocated and reserved by a Conferencing Node for each participant that joins the conference. This is measured within Pexip Infinity in relation to the amount of resources required by a standard HD connection.

In general, when compared to a single high definition HD 720p call:

  • a Full HD 1080p call uses twice the resource
  • an SD standard definition call uses half the resource
  • an audio-only call uses one sixteenth of the resource.

However, note that:

  • A WebRTC call using the VP8 codec uses the same amount of resource as H.264, and the VP9 codec uses around 25% more resource. Therefore:

    • VP9 at 720p uses the equivalent of 1.25 HD resources
    • VP9 at 1080p uses the equivalent of 2.5 HD resources
    • the maximum number of calls a given Conferencing Node can support will be fewer for VP9 calls, for example a node that supports 39 H.264/VP8 SD calls will support 31 VP9 SD calls.

    Note that within the same conference some participants may use VP9 (if they are connected to a Conferencing Node using the AVX2 or later instruction set) while other participants may use VP8 (if they are connected to a Conferencing Node on older hardware).

  • Conferences or gateway calls that use the Adaptive Composition layout, and Teams conferences that use the Teams-like layout, consume additional Conferencing Node resources. The actual amount of additional resource depends on many factors, but as a guide, it uses an additional 1 HD of resource per conference, for up to 3 other video participants, plus approximately another 0.5 HD for each additional (4th, 5th etc.) video participant that is on stage. This is regardless of the call quality / resolution of the conference itself and each individual participant's connection (codec, bandwidth and so on).
  • H.323 audio-only calls are treated the same as video calls for resource usage purposes.
  • Connections to a Media Playback Service use 1.2 times as much resource as a connection to a VMR.
  • When transferring a participant, the transferee can temporarily take two sets of resources while in the process of being transferred. This should not normally last more than a few seconds.

Thus, setting the maximum call quality to a "high" value such as Full HD will result in more resources being reserved than selecting a "low" value such as SD, and the more resources that are used or reserved means a lower capacity in terms of overall concurrent connections (also referred to as ports) for each Conferencing Node.

For more information, see Capacity planning and Hardware resource allocation rules.

Considerations for using Full HD (1080p) for main video in calls

Enabling Full HD (1080p) capabilities allows any endpoint capable of Full HD to send and receive its main video at 1080p to those conferences. However, as discussed above, enabling Full HD has implications on bandwidth and capacity across your deployment, specifically:

  • Full HD calls require approximately double the Conferencing Node resources and double the bandwidth of an HD call.
  • 1 Full HD of capacity will be reserved for backplanes between Conferencing Nodes.

Note that 1080p is automatically used for sharing high-resolution content with HD-capable endpoints if there is sufficient available bandwidth i.e. presentation content may still be sent at 1080p even if Full HD is not allowed for main video.

Setting the maximum call quality for participants in a conference

To set the maximum call quality for all calls across your entire deployment:

  1. Go to Platform > Global settings.
  2. In the Service configuration section, select the required Maximum call quality:

    • SD: each participant is limited to SD quality.
    • HD: each participant is limited to HD (720p) quality.
    • Full HD (1080p): allows any endpoint capable of Full HD to send and receive its main video at 1080p.
  3. Select Save.

To override the global default and set the maximum call quality for an individual service or Call Routing Rule:

  1. Go to the relevant service or rule:

    • Services > Virtual Meeting Rooms
    • Services > Virtual Auditoriums
    • Services > Virtual Receptions
    • Services > Scheduled conferences
    • Services > Call routing
  2. Either select the name of the service or rule you want to edit, or click Add.
  3. In the Advanced options section, or the Call media settings section for routing rules, select the required Maximum call quality:

    • Use global setting: use the global maximum call quality setting.
    • SD: each participant is limited to SD quality.
    • HD: each participant is limited to HD (720p) quality.
    • Full HD (1080p): allows any endpoint capable of Full HD to send and receive its main video at 1080p.
  4. Select Save.

Changes to the maximum call quality take effect for any new conferences initiated after the change has been made.