XvQueryEncodings(3x)XvQueryEncodings(3x)NameXvQueryEncodings - 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 display screen on which the Xv Server is
to accept requests from Xv clients. If the display
option is not specified, Xv uses the display screen
specified by your DISPLAY environment variable. The
display option has the format hostname:number. Using
two colons (::) instead of one (:) indicates that DECnet
is to be used for transport.
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 infor‐
mation 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 encod‐
ing-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-signal‐
type". 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.
DescriptionXvQueryEncodings(3x) 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(3x) completed successfully.
[XvBadExtension]
Returned if the Xv extension is unavailable.
[XvBadAlloc]
Returned if XvQueryEncodings(3x) failed to allocate memory to
process the request.
Diagnostics
[XvBadPort]
Generated if the requested port does not exist.
See AlsoXvFreeEncodingInfo(3x)X Version 11 libXv 1.0.1 XvQueryEncodings(3x)
