Adaptive Bitrate (ABR) streaming is a delivery technology designed to provide consistent, high-quality viewing in situations where bandwidth may fluctuate, and where viewers may be on a wide range of devices.
ABR streaming addresses these issues by encoding content into multiple variants, each potentially a different bit rate, frame size and/or frame rate. These variants are combined into a single package that represents the original content. ABR players switch between variants depending upon the device and available bandwidth, to ensure consistent high-quality playback.
For example, a single ABR package might include six variants, each encoded at progressively higher bit rates. The player will adaptively switch between low bit rates and high bit rates, depending upon the connectivity of the device.
How it works?
During playback, video and audio are delivered via HTTP in small segments, typically between 3 and 10 seconds in length. Each content package includes multiple variants, and each variant may include many segments. The player is provided with a package manifest file outlining which variants are available and the location of the segments for each variant.
The video player requests and downloads a segment from a variant. While the segment is played, the connection speed is monitored, and the player may opt to switch variants, either increasing or decreasing the video bit rate based upon the connection speed. Players may also choose variants with different frame sizes or frame rates to optimize the visual experience for the device. This adaptive behavior is what ensures consistent playback regardless of connection speed or device.
By Piotr Kreglicki
Read more at telestreamblog.telestream.net