In November 2022 the Video Services Forum (VSF) published TR-06-4 Part 1, Reliable Internet Stream Transport (RIST) Source Adaptation. The purpose of RIST is to provide a common industry specification for low-latency, reliable video contribution over the Internet, so that broadcasters are not locked into proprietary solutions. Source Adaptation adds the ability for the content sender to dynamically adapt to network conditions. In its simplest form, a live encoder can change its bit rate based on the instantaneous available bandwidth. In a multi-link situation, the sender can also dynamically change the way the content is split between the links. Such techniques are not new and have been in use for years, especially for cell bonding solutions. However, these are all proprietary systems. VSF TR-06-4 Part 1 opens it for multi-vendor interoperability, while allowing individual implementers to innovate. This presentation includes a technical description of TR-06-4 Part 1, as well as preliminary field data from tests performed over the Internet. The tests indicate that the Specification works well in practice and is a viable open alternative for proprietary systems. Moreover, since RIST is based on RTP, it ensures backward interoperability with existing systems.
