H.264 Codec

The capability to support HD video conferencing resolutions and multiple video streams within the Gallery View is driven by Microsoft switching from the proprietary RTVideo codec to the more commonly used H.264 video codec.

The H.264 codec used by Lync 2013 supports Scalable Video Coding (SVC), which allows the server to provide unique streams to endpoints depending on their capabilities. For example, based on the same source stream, the A/V MCU can deliver a lower-resolution stream to a small tablet, deliver a medium-quality stream to a desktop, and still provide a 1080p stream to a room system.

The shift also enables clients to leverage GPU hardware for encoding and decoding, which means the processor requirements for client workstations have also been reduced. Instead of requiring a quad-core processor to send HD video, clients now need only a dual-core processor to send HD and a single-core processor to receive HD video. This helps reduce strain on the A/V MCU, which had previously required a significant amount of processor resources to mix and distribute a single RTVideo stream to endpoints. H.264 can also deliver HD video streams at lower bandwidth levels than RTVideo required, so organizations can support more HD video calls.