Name
XvQueryEncodings - return list of encodings for an adaptor
Syntax
#include
XvQueryEncodings(Display *dpy, XvPortID port,
unsigned int *p_num_encodings,
XvEncodingInfo **pp_encoding_info);
Arguments
-
_d_p_y
Specifies the connection to the X server.
-
-
_X_v_P_o_r_t_I_D
Specifies the port whose adaptor is to be queried for its
-
list of encodings.
-
_p___n_u_m___e_n_c_o_d_i_n_g_s
A pointer to where the number of encodings supported
-
by the adaptor is written.
-
_p_p___e_n_c_o_d_i_n_g___i_n_f_o
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;
-
_e_n_c_o_d_i_n_g___i_d
Specifies the encoding-id of the encoding. The encoding-id is used to
-
identify an encoding when a port's encoding attribute is changed.
-
_n_a_m_e
A pointer to a formatted string that identifies the encoding. The string
-
has the format "_t_i_m_i_n_g_-_s_i_g_n_a_l_t_y_p_e". For example "ntsc-composite".
-
_w_i_d_t_h_,_h_e_i_g_h_t
The width and height, in pixels, of the decoded video image.
-
-
_r_a_t_e
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 _n_u_m_e_r_a_t_o_r and _d_e_n_o_m_i_n_a_t_o_r 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.
Returned 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)