XvQueryEncodings

Section: libXv Functions (3)
Updated: libXv 1.0.5
Index Return to Main Contents
 

NAME

XvQueryEncodings - return list of encodings for an adaptor  

SYNOPSIS

#include <X11/extensions/Xvlib.h>

int XvQueryEncodings(Display *dpy, XvPortID port,
                     unsigned int *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 its list of encodings.
p_num_encodings
A pointer to where the number of encodings supported by the adaptor is written.
pp_encoding_info
A pointer to where the list of returned encoding 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 to identify an encoding when a port's encoding attribute is changed.
name
A pointer to a formatted string that identifies the encoding. The string has 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. Each encoding is described by the XvEncodingInfo structure described above. The encodings are identified by an encoding-id, which can be used to set or get the encoding attribute of a port.  

RETURN 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 process the request.
 

DIAGNOSTICS

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

SEE ALSO

XvFreeEncodingInfo(3)