Comment by niftich

Typically it's a dedicated hardware block on the die of a larger chip, like AMD's UVD [1] and VCE [2] inside their GPU/APUs, or Nvidia's PureVideo [3] and NVENC [4]. Sometimes the line is even blurrier, like the Broadcom SOC in the Raspberry Pi, where various more general-purpose processors can work together to decode [5].

Then you have APIs that try to disassemble all the typical stages of video codec processing that applications can call and GPU drivers can implement, which serve as a bridge between hardware-assisted decode and application code. These are APIs like DXVA or one of the several in use with Linux [6].

[1] https://en.wikipedia.org/wiki/Unified_Video_Decoder [2] https://en.wikipedia.org/wiki/Video_Coding_Engine [3] https://en.wikipedia.org/wiki/Nvidia_PureVideo [4] https://en.wikipedia.org/wiki/Nvidia_NVENC [5] https://github.com/hermanhermitage/videocoreiv [6] https://wiki.archlinux.org/index.php/Hardware_video_accelera...