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_encod-
ing_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 spec-
ified by your DISPLAY environment variable.
The display option has the format host-
name: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 information is returned. XvEn-
codingInfo 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 iden-
tifies the encoding. The string has the
1
XvQueryEncodings(3X)XvQueryEncodings(3X)
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 appropri-
ate 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 suc-
cessfully.
[XvBadExtension]
Returned if the Xv extension is unavailable.
[XvBadAlloc]
Returned if XvQueryEncodings(3X) failed to allo-
cate memory to process the request.
Diagnostics
[XvBadPort]
Generated if the requested port does not exist.
See AlsoXvFreeEncodingInfo(3X)
2
