X-Video Motion Compensation (XvMC), is an extension of the X video extension (Xv) for the

X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wit ...

. The XvMC

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standa ...

allows video programs to offload portions of the

video decoding A video decoder is an electronic circuit, often contained within a single integrated circuit chip, that converts base-band analog video signals to digital video. Video decoders commonly allow programmable control over video characteristics such ...

process to the

GPU A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, mobil ...

video-hardware. In theory this process should also reduce bus bandwidth requirements. Currently, the supported portions to be offloaded by XvMC onto the GPU are motion compensation (mo comp) and inverse discrete cosine transform (iDCT) for

MPEG-2 MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic video coding format, coding of moving pictures and associated audio information". It describes a combination of Lossy compression, lossy video compression and ...

video. XvMC also supports offloading decoding of mo comp, iDCT, and

VLD french: Libéraux et démocrates flamands ouverts , abbreviation = Open Vld , logo = , leader1_title = President , leader1_name = Egbert Lachaert , foundation = 1992 (VLD)2007 (Open Vld) , predecessor = P ...

("Variable-Length Decoding", more commonly known as "slice level acceleration") for not only

but also

MPEG-4 ASP MPEG-4 Part 2, MPEG-4 Visual (formally ISO/ IEC 14496-2) is a video compression format developed by the Moving Picture Experts Group (MPEG). It belongs to the MPEG-4 ISO/IEC standards. It uses block-wise motion compensation and a discrete cosine ...

video on VIA Unichrome (S3 Graphics Chrome Series) hardware. XvMC was the first UNIX equivalent of the Microsoft Windows DirectX Video Acceleration (DxVA) API. Popular software applications known to take advantage of XvMC include

MPlayer MPlayer is a free and open-source media player software application. It is available for Linux, OS X and Microsoft Windows. Versions for OS/2, Syllable, AmigaOS, MorphOS and AROS Research Operating System are also available. A port for DOS usi ...

MythTV MythTV is a free and open-source home entertainment application with a simplified "10-foot user interface" design for the living room TV. It turns a computer with the necessary hardware into a network streaming digital video recorder, a digital ...

, and

xine xine is a multimedia playback engine for Unix-like operating systems released under the GNU General Public License. xine is built around a shared library (xine-lib) that supports different frontend player applications. xine uses libraries ...

Device drivers

Each hardware video

capable of XvMC video acceleration requires a

X11 The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wi ...

software

device driver In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and ot ...

to enable these features.

Hardware manufacturers

Nvidia

There are currently three X11 Nvidia drivers available: a 2D-only

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

but obfuscated driver maintained by Nvidia called nv, a

proprietary {{Short pages monitor