MAN page from Mandriva 2008 libxv1-devel-1.0.3-1mdv2008.0.i586.rpm

XvQueryEncodings

Section: C Library Functions (3)
Updated: libXv 1.0.3
Index

Name

XvQueryEncodings - return list of encodings for an adaptor

Syntax

#include <X11/extensions/Xvlib.h>

XvQueryEncodings(dpy, port, p_num_encodings, pp_encoding_info)

register Display *dpy;
XvPortID port;
unsigned long *p_num_encodings;
XvEncodingInfo **pp_encoding_info;

Arguments

*dpy

Specifies the connection to the X server.

port

Specifies the port whose adaptor is to be queried for itslist of encodings.

p_num_encodings

A pointer to where the number of encodings supportedby the adaptor is written.

pp_encoding_info

A pointer to where the list of returnedencoding information is returned.XvEncodingInfo has the following structure:

    typedef struct {
      XvEncodingID encoding_id;
      char *name;
      unsigned long width;
      unsigned long height;
      XvRational rate;
      unsigned long num_encodings;
    } XvEncodingInfo;

encoding_id

Specifies the encoding-id of the encoding. The encoding-id is used toidentify an encoding when a port's encoding attribute is changed.

name

A pointer to a formatted string that identifies the encoding. The stringhas the format "timing-signaltype". For example "ntsc-composite".

width,height

The width and height, in pixels, of the decoded video image.

rate

The field rate of the decoded video.

The XvRational structure is used to specify a fractional number.It has the following structure:

    typedef struct {
      int numerator;
      int denominator;
    } XvRational;

The numerator and denominator fields specify the appropriate parts of a fractional number.

Description

XvQueryEncodings(3) returns encoding information about an adaptor. Eachencoding is described by the XvEncodingInfo structure described above. The encodings are identified by an encoding-id, which can be used to set or getthe encoding attribute of a port.

Returned Values

[Success]: Returned if XvQueryEncodings(3) completed successfully.
[XvBadExtension]: Returned if the Xv extension is unavailable.
[XvBadAlloc]: Returned if XvQueryEncodings(3) failed to allocate memory to processthe request.

Diagnostics

[XvBadPort]: Generated if the requested port does not exist.

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