Name

XvQueryEncodings - return list of encodings for an adaptor

Syntax

#include

XXvvQQuueerryyEEnnccooddiinnggss((_d_p_y_, _p_o_r_t_, _p___n_u_m___e_n_c_o_d_i_n_g_s_, _p_p___e_n_c_o_d_i_n_g___i_n_f_o_)

rreeggiisstteerr DDiissppllaayy _*_d_p_y;
XXvvPPoorrttIIDD _p_o_r_t;
uunnssiiggnneedd lloonngg _*_p___n_u_m___e_n_c_o_d_i_n_g_s;
XXvvEEnnccooddiinnggIInnffoo _*_*_p_p___e_n_c_o_d_i_n_g___i_n_f_o;

Arguments

_*_d_p_y 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.
_p_o_r_t 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(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)