Adaptive Bitrate Streaming (ABR)
Adaptive bitrate streaming or ABR streaming, sometimes shortened to ABS, is a technique for dynamically adjusting the compression level and video quality of a stream to match bandwidth availability.
Older video streaming approaches relied on distributing a fixed bitrate video stream. If your network connection could not support that bitrate, you could not watch the video without dramatic buffering, if at all. With ABR, you can now stream video across the Internet, with both point to point streaming and OTT services to multiple devices.
For point to point streaming, ABR can mean adapting a single RTMP or SRT stream to fit the available bandwidth between two devices such as an encoder and decoder. For point to point video streaming, an encoder needs to be able to adapt the compression level of a stream in real-time, as available bandwidth is constantly changing. This is also known as network adaptive encoding or NAE.
For OTT services, ABR will usually rely on an ABR packaging protocol such as HLS or MPEG-DASH where multiple streams are defined by profiles such as low, medium, and high quality. The ABR streams are divided into chunks of video, between 1 – 15 seconds, so that individual viewing devices can dynamically pick and choose the video chunk that best fits available bandwidth at a given time. ABR streaming for OTT requires the use of an encoder or transcoder which can encode a single video source at multiple bitrates.