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XvQueryEncodings(3)             libXv Functions            XvQueryEncodings(3)


XvQueryEncodings - return list of encodings for an adaptor


#include <X11/extensions/Xvlib.h> int XvQueryEncodings(Display *dpy, XvPortID port, unsigned int *p_num_encodings, XvEncodingInfo **pp_encoding_info);


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.


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.


[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.


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


XvFreeEncodingInfo(3) X Version 11 libXv 1.0.12 XvQueryEncodings(3)

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