| XvQueryEncodings(3) | Library Functions Manual | XvQueryEncodings(3) | 
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)