.TH XvQueryEncodings __libmansuffix__ __vendorversion__ "libXv Functions"
.SH NAME
XvQueryEncodings \- return list of encodings for an adaptor
.\"
.SH SYNOPSIS
.B #include <X11/extensions/Xvlib.h>
.sp
.nf
.BI "int XvQueryEncodings(Display *" dpy ", XvPortID " port ","
.BI "                     unsigned int *" p_num_encodings ","
.BI "                     XvEncodingInfo **" pp_encoding_info ");"
.fi
.SH ARGUMENTS
.\"
.IP \fIdpy\fR 8
Specifies the connection to the X server.
.IP \fIXvPortID\fR 8
Specifies the port whose adaptor is to be queried for its
list of encodings.
.IP \fIp_num_encodings\fR 8
A pointer to where the number of encodings supported
by the adaptor is written.
.IP \fIpp_encoding_info\fR 8
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 8
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 8
A pointer to a formatted string that identifies the encoding.  The string
has the format "\fItiming\fR-\fIsignaltype\fR".  For example "ntsc-composite".
.IP \fIwidth,height\fR 8
The width and height, in pixels, of the decoded video image.
.IP \fIrate\fR 8
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
.BR XvQueryEncodings (__libmansuffix__)
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 RETURN VALUES
.IP [Success] 8
Returned if
.BR XvQueryEncodings (__libmansuffix__)
completed successfully.
.IP [XvBadExtension] 8
Returned if the Xv extension is unavailable.
.IP [XvBadAlloc] 8
Returned if
.BR XvQueryEncodings (__libmansuffix__)
failed to allocate memory to process the request.
.SH DIAGNOSTICS
.IP [XvBadPort] 8
Generated if the requested port does not exist.
.\"
.SH SEE ALSO
.\"
.BR XvFreeEncodingInfo (__libmansuffix__)