XvQueryEncodings − return list of encodings for an adaptor
#include <X11/extensions/Xvlib.h>
int
XvQueryEncodings(Display *dpy, XvPortID
port,
unsigned int *p_num_encodings,
XvEncodingInfo **pp_encoding_info);
|
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.
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.
[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.
[XvBadPort]
Generated if the requested port does not exist.
XvFreeEncodingInfo(3)