XvQueryEncodings(3X)

Name

       XvQueryEncodings - 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.

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.

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 Also

       XvFreeEncodingInfo(3X)

X.Org                            Version 6.8.2            XvQueryEncodings(3X)