xvqueryencodings(3) - Linux man page
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.
- The XvRational structure is used to specify a fractional number. It has the following structure:
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.