NAME

       XvQueryEncodings - return list of encodings for an adaptor

SYNOPSIS

       #include <X11/extensions/Xvlib.h>

       int XvQueryEncodings(Display *dpy, XvPortID port,
                            unsigned int *p_num_encodings,
                            XvEncodingInfo **pp_encoding_info);

ARGUMENTS

       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.

DESCRIPTION

       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.

RETURN VALUES

       [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.

DIAGNOSTICS

       [XvBadPort]
               Generated if the requested port does not exist.

SEE ALSO

       XvFreeEncodingInfo(3)