The choice of which video coding standard to use for this purpose gets even more complicated due to the high energy required to perform video transcoding, which grows substantially in compute/energy consumption with each newer video coding standard.

Moreover, some of these clients – such as large screen TVs – are using HW video decoders, limiting any upgrade of their capabilities, while others – such as mobile handsets – have both HW and SW video decoding capabilities, which are offered through their HW-assisted multi-core CPUs and GPUs. Older clients typically support only the H.264/AVC coding standard, which was first standardized in 2003, while newer standards, such as H.265/HEVC, VP9 and AV1, are supported mostly by newer clients. The requirement to support a large variety of streaming clients having different decoding capabilities results in the generation of multiple ABR ladders, with each ladder utilizing a different video coding standard. The collection of all such encoded versions is referred to as an “ABR ladder”, with each step of the ladder representing a higher quality/bitrate representation of the same video content. This technique is called Adaptive Bit Rate (ABR) streaming, which is at the core of all modern video streaming services.

Moreover, by switching among these different representations, stalling that could take place when there are changes in bandwidth is prevented. This allows streaming clients to select the version which best fits the available connection bandwidth, resulting in smooth playback. Modern Video-On-Demand (VOD) streaming services employ multiple encoded versions of the same visual content, at varying levels of quality/bitrates.

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