XvMC
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X-Video Motion Compensation, often abbreviated as XvMC, is an extension of the X video extension for the X Window System. It allows video programs to offload portions of the MPEG2 decoding process to the GPU hardware. The portions offloaded are Motion Compensation and iDCT (Inverse Discrete Cosine Transform).
XvMC can pass IDCT decoding, and motion-compensation decoding to the video card, offloading that workload to the GPU, which is better suited to this kind of decoding than modern general-purpose CPUs. Even on most modern CPUs, the use of XvMC is required to decode 1080i HDTV in real time. Applications which are known to take advantage of XvMC are MPlayer, MythTV, and xine.
XvMC is the Linux equivalent of the Microsoft Windows DxVA API (DirectX Video Acceleration). MacOS also includes MPEG2 acceleration capabilities, but Apple has chosen[citation needed] not to expose those APIs for use outside their DVD Player application.
Motion Compensation is an algorithmic technique employed in the encoding of video data, for example in the generation of MPEG-2 files.
