Table of Contents


Xv - X Window System video extension


The Xv extension provides support for video adaptors attached to an X display. It takes the approach that a display may have one or more video adaptors, each of which has one or more ports through which independent video streams pass.

An adaptor may be able to display video in a drawable, capture video from a drawable, or both. It translates between video encoding (NTSC, PAL, SECAM, etc...) and drawable format (depth and visual-id pair). An adaptor may support multiple video encodings and/or multiple drawable formats.

Clients use Xv(3X) to gain access and manage sharing of a display's video resources. Typically, a client will use XvQueryExtension(3X) to determine the status of the extension, XvQueryAdaptors(3X) to get a description of what video adaptors exist, and XvQueryEncodings(3X) to get a description of what video encodings an adaptor supports.

Once a client has determined what video resources are available, it is free to put video into a drawable or get video from a drawable, according the capabilities supported. Clients can select to receive events when video activity changes in a drawable and when port attributes have changed.

Summary of Library Functions

The following is a summary of Xv library functions:

XvGetPortAttribute(3X) - return current port attribute value

XvGetStill(3X) - capture a single frame of video from a drawable

XvGetVideo(3X) - capture video from a drawable

XvGrabPort(3X) - lock port for exclusive use by client

XvPortNotify(3X) - event generated when port attributes change

XvPutStill(3X) - write a single frame of video to a drawable

XvPutVideo(3X) - write video into a drawable

XvQueryAdaptors(3X) - return adaptor information for a screen

XvQueryBestSize(3X) - determine the optimum drawable region size

XvQueryEncodings(3X) - return list of encodings for an adaptor

XvQueryExtension(3X) - return version and revision of extension

XvSelectPortNotify(3X) - enable or disable XvPortNotify events

XvSelectVideoNotify(3X) - enable or disable XvVideoNotify events

XvSetPortAttribute(3X) - set an attribute for a port

XvStopVideo(3X) - stop active video

XvUngrabPort(3X) - release a grabbed port

XvVideoNotify(3X) - event generated for video processing

Each of these functions is described in its own Xv man page.

Table of Contents