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.TH XvQueryEncodings 3X __vendorversion__
.\" $XFree86$
.SH Name
XvQueryEncodings \- return list of encodings for an adaptor
.\"
.SH Syntax
.B #include <X11/extensions/Xvlib.h>
.sp 1l
\fBXvQueryEncodings(\fIdpy, port, p_num_encodings, pp_encoding_info)\fR
.sp 1l
\fBregister Display \fI*dpy\fR;
.br
\fBXvPortID \fIport\fR;
.br
\fBunsigned long \fI*p_num_encodings\fR;
.br
\fBXvEncodingInfo \fI**pp_encoding_info\fR;
.\"
.SH Arguments
.IP \fI*dpy\fR 15
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.
.IP \fIport\fR 15
Specifies the port whose adaptor is to be queried for its
list of encodings.
.IP \fIp_num_encodings\fR 15
A pointer to where the number of encodings supported
by the adaptor is written.
.IP \fIpp_encoding_info\fR 15
A pointer to where the list of returned
encoding information is returned.
XvEncodingInfo has the following structure:
.EX
typedef struct {
XvEncodingID encoding_id;
char *name;
unsigned long width;
unsigned long height;
XvRational rate;
unsigned long num_encodings;
} XvEncodingInfo;
.EE
.IP \fIencoding_id\fR 15
Specifies the encoding-id of the encoding. The encoding-id is used to
identify an encoding when a port's encoding attribute is changed.
.IP \fIname\fR 15
A pointer to a formatted string that identifies the encoding. The string
has the format "\fItiming-signaltype\fR". For example "ntsc-composite".
.IP \fIwidth,height\fR 15
The width and height, in pixels, of the decoded video image.
.IP \fIrate\fR 15
The field rate of the decoded video.
.PP
The XvRational structure is used to specify a fractional number.
It has the following structure:
.EX
typedef struct {
int numerator;
int denominator;
} XvRational;
.EE
The \fInumerator\fP and \fIdenominator\fP fields specify the
appropriate parts of a fractional number.
.\"
.SH Description
XvQueryEncodings(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.
.SH Returned Values
.IP [Success] 8
Returned if XvQueryEncodings(3X) completed successfully.
.IP [XvBadExtension] 8
Returned if the Xv extension is unavailable.
.IP [XvBadAlloc] 8
Returned if XvQueryEncodings(3X) failed to allocate memory to process
the request.
.SH Diagnostics
.IP [XvBadPort] 8
Generated if the requested port does not exist.
.\"
.SH See Also
.\"
XvFreeEncodingInfo(3X)
.br
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