XvQueryEncodings (3)
NAME
XvQueryEncodings - return list of encodings for an adaptorSYNOPSIS
#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.