This article relies excessively on references to primary sources. Please improve this article by adding secondary or tertiary sources. Find sources: "X video extension" – news · newspapers · books · scholar · JSTOR(March 2013) (Learn how and when to remove this message)
X video extension
Original author(s)
X.Org Foundation
Stable release
2.0
/ July 25, 1991; 32 years ago (1991-07-25)
The X video extension, often abbreviated as XVideo or Xv, is a video output mechanism for the X Window System. The protocol was designed by David Carver; the specification for version 2 of the protocol was written in July 1991.[1] It is mainly used today to resize video content in the video controller hardware in order to enlarge a given video or to watch it in full screen mode. Without XVideo, X would have to do this scaling on the main CPU. That requires a considerable amount of processing power, which could slow down or degrade the video stream; video controllers are specifically designed for this kind of computation, so can do it much more cheaply. Similarly, the X video extension can have the video controller perform color space conversions, and change the contrast, brightness, and hue of a displayed video stream.
In order for this to work, three things have to come together:
The video controller has to provide the required functions.
The device driver software for the video controller and the X display server program have to implement the XVideo interface.
The video playback software has to make use of this interface.
Most modern video controllers provide the functions required for XVideo; this feature is known as hardware scaling and YUV acceleration or sometimes as 2D hardware acceleration. The XFree86 X display server has implemented XVideo since version 4.0.2. To check whether a given X display server supports XVideo, one can use the utility xdpyinfo. To check whether the video controller provides the required functions and whether the X device driver implements XVideo for any of them, one can use the xvinfo program.
Video playback programs that run under the X Window system, such as MPlayer, MythTV or xine, typically have an option to enable XVideo output. It is very advisable to switch on this option if the system GPU video-hardware and device drivers supports XVideo and more modern rendering systems such as OpenGL and VDPAU are unavailable – the speedup is very noticeable even on a fast CPU.
While the protocol itself has features for reading and writing of video streams from and to video adapters, in practice today only the functions XvPutImage and XvShmPutImage are used: the client program repeatedly prepares images and passes them on to the graphics hardware to be scaled, converted and displayed.
The Xvideoextension, often abbreviated as XVideo or Xv, is a video output mechanism for the X Window System. The protocol was designed by David Carver;...
The X Rendering Extension (Render or XRender) is an extension to the X11 core protocol to implement image compositing in the X server, to allow an efficient...
user. X's network protocol is based on X command primitives. This approach allows both 2D and (through extensions like GLX) 3D operations by an X client...
manipulation program for Unix Subaru XV, a compact SUV Xvideoextension, an extension to the X Window System Other uses: 15 (number), in Roman numerals...
Audio Video Interleave (also Audio Video Interleaved and known by its initials and filename extension AVI, usually pronounced /ˌeɪ.viːˈaɪ/) is a proprietary...
require it. X has largely kept to these principles since. The X.Org Foundation develops the reference implementation with a view to extension and improvement...
DivX is a brand of video codec products developed by DivX, LLC. There are three DivX codecs: the original MPEG-4 Part 2 DivX codec, the H.264/MPEG-4 AVC...
Media Video (WMV). The most common file extensions for ASF files are extension .WMA (audio-only files using Windows Media Audio, with MIME-type audio/x-ms-wma)...
MPlayer, DivX Plus Player, and Nero Showtime (included with Nero Multimedia Suite). The format without DRM can also be played in the webOS Video Player for...
encrypted. Files in VOB format have a .vob filename extension and are typically stored in the VIDEO_TS directory at the root of a DVD. The VOB format is...
(after changing the extension from .gvi to .avi, although this method of just renaming the file extension does not work with videos purchased with DRM...
open standard. Matroska file extensions are .mkv for video (which may include subtitles or audio), .mk3d for stereoscopic video, .mka for audio-only files...
(with file extension .mkv), or AVI container format (extension .avi). One common way to store WMV in an AVI file is to use the WMV 9 Video Compression...
macOS, originally Mac OS X, previously shortened as OS X, is an operating system developed and marketed by Apple since 2001. It is the primary operating...
completed in May 2003, and various extensions of its capabilities have been added in subsequent editions. High Efficiency Video Coding (HEVC), a.k.a. H.265 and...
related to the content of the video and/or the target of the link being placed. Hardware overlay Texture mapping Subtitle (captioning) Xvideoextension...
BIOS Extensions (VBE) is a VESA standard, currently at version 3, that defines the interface that can be used by software to access compliant video boards...
most ways, HEVC is an extension of the concepts in H.264/MPEG-4 AVC. Both work by comparing different parts of a frame of video to find areas that are...
variety of output driver protocols to display video, including VDPAU, the Xvideoextension, OpenGL, DirectX, Direct3D, Quartz Compositor, VESA, Framebuffer...
Bink Video is a proprietary file format (extensions .bik and .bk2) for video developed by Epic Games Tools (formerly RAD Game Tools), a part of Epic Games...
as the Google Chrome Extensions Gallery. Some extensions focus on providing accessibility features. Google Tone is an extension developed by Google that...