Real time video call best practice guidelines

How much bandwidth is required for a real time video call?

The amount of bandwidth required for a real time video call depends on the required resolution, frame rate and target bit rate as shown here.

What affects real time video/audio quality?

Three factors influence the video/audio quality:

1. Limitations on the device and what it will support.

• Physical resolution of the camera, Graphics Processing Power, CPU, and resource contention by other application features and other applications running in the background.
• An iPad Air has the processing power to support higher resolutions, an iPad 2 does not.
• iPad2 also as an example have known WiFi performance characteristics at various iOS version levels.
• Network Conditions

• QoS
• Available Bandwidth
• WiFi Spectrum Saturation
• Contention and Packet Loss
• Latency
• The resilience of the codec to the network conditions

• The Live Assist solution supports NACK/PLI and adaptive bit rate control for the video stream which greatly improves resilience to packet loss and changes in bandwidth availability allowing for a higher quality video experience even in less than ideal network conditions.
• However, even this has limitations and logic needs to be employed to address higher thresholds of network problems.

Production Video Quality cannot be achieved without;

• addressing the configuration of the network to support a quality video experience.
• analyzing resource consumption of client devices to ensure enough resources are available to achieve a positive end-user experience. Other background applications can easily effect resource availability.

Network Requirements

There needs to be sufficient bandwidth available to support the required resolution, frame rate and target bit-rate - see here for details.

In addition, the following constraints exist for an acceptable user experience:

• Packet loss:
• Video – no more than 20% loss
• Audio – no more than 10% loss
• Latency
• Latency won’t affect the quality but will affect the user experience if it is too high. We recommend no more than 100ms latency between the endpoint and Media Broker.
• Jitter
• Should be no more than 50ms