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 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.
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 process
the request.
Diagnostics
[XvBadPort]
Generated if the requested port does not exist.
See Also
XvFreeEncodingInfo(3)
