GstCaps

GstCaps — Structure describing sets of media formats

Synopsis


#include <gst/gst.h>


#define     GST_CAPS_FLAGS_ANY
#define     GST_CAPS_ANY
#define     GST_CAPS_NONE
#define     GST_STATIC_CAPS_ANY
#define     GST_STATIC_CAPS_NONE
#define     GST_CAPS_IS_SIMPLE              (caps)
#define     gst_caps_is_simple              (caps)
#define     GST_DEBUG_CAPS                  (string, caps)
#define     GST_STATIC_CAPS                 (string)
struct      GstCaps;
struct      GstStaticCaps;
GstCaps*    gst_caps_new_empty              (void);
GstCaps*    gst_caps_new_any                (void);
GstCaps*    gst_caps_new_simple             (const char *media_type,
                                             const char *fieldname,
                                             ...);
GstCaps*    gst_caps_new_full               (GstStructure *struct1,
                                             ...);
GstCaps*    gst_caps_new_full_valist        (GstStructure *structure,
                                             va_list var_args);
GstCaps*    gst_caps_copy                   (const GstCaps *caps);
void        gst_caps_free                   (GstCaps *caps);
G_CONST_RETURN GstCaps* gst_static_caps_get (GstStaticCaps *static_caps);
void        gst_caps_append                 (GstCaps *caps1,
                                             GstCaps *caps2);
void        gst_caps_append_structure       (GstCaps *caps,
                                             GstStructure *structure);
GstCaps*    gst_caps_split_one              (GstCaps *caps);
int         gst_caps_get_size               (const GstCaps *caps);
GstStructure* gst_caps_get_structure        (const GstCaps *caps,
                                             int index);
GstCaps*    gst_caps_copy_1                 (const GstCaps *caps);
void        gst_caps_set_simple             (GstCaps *caps,
                                             char *field,
                                             ...);
void        gst_caps_set_simple_valist      (GstCaps *caps,
                                             char *field,
                                             va_list varargs);
gboolean    gst_caps_is_any                 (const GstCaps *caps);
gboolean    gst_caps_is_empty               (const GstCaps *caps);
gboolean    gst_caps_is_chained             (const GstCaps *caps);
gboolean    gst_caps_is_fixed               (const GstCaps *caps);
gboolean    gst_caps_is_equal               (const GstCaps *caps1,
                                             const GstCaps *caps2);
gboolean    gst_caps_is_equal_fixed         (const GstCaps *caps1,
                                             const GstCaps *caps2);
gboolean    gst_caps_is_always_compatible   (const GstCaps *caps1,
                                             const GstCaps *caps2);
gboolean    gst_caps_is_subset              (const GstCaps *subset,
                                             const GstCaps *superset);
GstCaps*    gst_caps_intersect              (const GstCaps *caps1,
                                             const GstCaps *caps2);
GstCaps*    gst_caps_union                  (const GstCaps *caps1,
                                             const GstCaps *caps2);
GstCaps*    gst_caps_normalize              (const GstCaps *caps);
GstCaps*    gst_caps_simplify               (const GstCaps *caps);
gboolean    gst_caps_do_simplify            (GstCaps *caps);
xmlNodePtr  gst_caps_save_thyself           (const GstCaps *caps,
                                             xmlNodePtr parent);
GstCaps*    gst_caps_load_thyself           (xmlNodePtr parent);
void        gst_caps_replace                (GstCaps **caps,
                                             GstCaps *newcaps);
gchar*      gst_caps_to_string              (const GstCaps *caps);
GstCaps*    gst_caps_from_string            (const gchar *string);
gboolean    gst_caps_structure_fixate_field_nearest_int
                                            (GstStructure *structure,
                                             const char *field_name,
                                             int target);
gboolean    gst_caps_structure_fixate_field_nearest_double
                                            (GstStructure *structure,
                                             const char *field_name,
                                             double target);
GstCaps*    gst_caps_subtract               (const GstCaps *minuend,
                                             const GstCaps *subtrahend);


Description

Details

GST_CAPS_FLAGS_ANY

#define GST_CAPS_FLAGS_ANY	  (1 << 0)

Flags that this caps has no specific content, but can contain anything.


GST_CAPS_ANY

#define GST_CAPS_ANY              gst_caps_new_any()

Means that the element/pad can output 'anything'. Useful for elements that output unknown media, such as filesrc.


GST_CAPS_NONE

#define GST_CAPS_NONE             gst_caps_new_empty()

The opposite of GST_CAPS_ANY: it means that the pad/element outputs an undefined media type that can not be detected.


GST_STATIC_CAPS_ANY

#define GST_STATIC_CAPS_ANY       GST_STATIC_CAPS("ANY")

Creates a static caps that matches anything. This can be used in pad templates.

Returns :a new GstCaps instance

GST_STATIC_CAPS_NONE

#define GST_STATIC_CAPS_NONE      GST_STATIC_CAPS("NONE")

Creates a static caps that matches nothing. This can be used in pad templates.

Returns :a new GstCaps instance

GST_CAPS_IS_SIMPLE()

#define GST_CAPS_IS_SIMPLE(caps) (gst_caps_get_size(caps) == 1)

Convinience macro that checks if the number of structures in the gives caps is exactly one.

caps :the GstCaps instance to check

gst_caps_is_simple()

#define gst_caps_is_simple(caps) GST_CAPS_IS_SIMPLE(caps)

caps :

GST_DEBUG_CAPS()

#define     GST_DEBUG_CAPS(string, caps)

Warning

GST_DEBUG_CAPS is deprecated and should not be used in newly-written code.

Convinience macro for prining out the contents of caps with GST_DEBUG().

string :a string the should be prepend to the caps data.
caps :the caps to print

GST_STATIC_CAPS()

#define     GST_STATIC_CAPS(string)

Creates a static caps from an input string. This can be used in pad templates.

string :the string describing the caps.
Returns :a new GstCaps instance

struct GstCaps

struct GstCaps {

  GType type;

  guint16 flags;
  GPtrArray *structs;

  gpointer _gst_reserved[GST_PADDING];
};


struct GstStaticCaps

struct GstStaticCaps {

  GstCaps caps;
  const char *string;
  gpointer _gst_reserved[GST_PADDING];
};


gst_caps_new_empty ()

GstCaps*    gst_caps_new_empty              (void);

Creates a new GstCaps that is empty. That is, the returned GstCaps contains no media formats.

Returns : the new GstCaps

gst_caps_new_any ()

GstCaps*    gst_caps_new_any                (void);

Creates a new GstCaps that indicates that it is compatible with any media format.

Returns : the new GstCaps

gst_caps_new_simple ()

GstCaps*    gst_caps_new_simple             (const char *media_type,
                                             const char *fieldname,
                                             ...);

Creates a new GstCaps that contains one GstStructure. The structure is defined by the arguments, which have the same format as @gst_structure_new().

media_type : the media type of the structure
fieldname : first field to set
... : additional arguments
Returns : the new GstCaps

gst_caps_new_full ()

GstCaps*    gst_caps_new_full               (GstStructure *struct1,
                                             ...);

Creates a new GstCaps and adds all the structures listed as arguments. The list must be NULL-terminated. The structures are not copied; the returned GstCaps owns the structures.

struct1 : the first structure to add
... : additional structures to add
Returns : the new GstCaps

gst_caps_new_full_valist ()

GstCaps*    gst_caps_new_full_valist        (GstStructure *structure,
                                             va_list var_args);

Creates a new GstCaps and adds all the structures listed as arguments. The list must be NULL-terminated. The structures are not copied; the returned GstCaps owns the structures.

structure : the first structure to add
var_args : additional structures to add
Returns : the new GstCaps

gst_caps_copy ()

GstCaps*    gst_caps_copy                   (const GstCaps *caps);

Deeply copies a GstCaps, including all structures and all the structures' values.

caps : the GstCaps to copy
Returns : the new GstCaps

gst_caps_free ()

void        gst_caps_free                   (GstCaps *caps);

Frees a GstCaps and all its structures and the structures' values.

caps : the GstCaps to free

gst_static_caps_get ()

G_CONST_RETURN GstCaps* gst_static_caps_get (GstStaticCaps *static_caps);

Converts a GstStaticCaps to a GstCaps.

static_caps : the GstStaticCaps to convert
Returns : the new GstCaps

gst_caps_append ()

void        gst_caps_append                 (GstCaps *caps1,
                                             GstCaps *caps2);

Appends the structures contained in caps2 to caps1. The structures in caps2 are not copied -- they are transferred to caps1, and then caps2 is freed.

caps1 : the GstCaps that will be appended to
caps2 : the GstCaps to append

gst_caps_append_structure ()

void        gst_caps_append_structure       (GstCaps *caps,
                                             GstStructure *structure);

Appends structure to caps. The structure is not copied; caps becomes the owner of structure.

caps : the GstCaps that will be appended to
structure : the GstStructure to append

gst_caps_split_one ()

GstCaps*    gst_caps_split_one              (GstCaps *caps);

Warning

gst_caps_split_one is deprecated and should not be used in newly-written code.

This function is not implemented.

caps : a GstCaps
Returns : NULL

gst_caps_get_size ()

int         gst_caps_get_size               (const GstCaps *caps);

Gets the number of structures contained in caps.

caps : a GstCaps
Returns : the number of structures that caps contains

gst_caps_get_structure ()

GstStructure* gst_caps_get_structure        (const GstCaps *caps,
                                             int index);

Finds the structure in caps that has the index index, and returns it.

WARNING: This function takes a const GstCaps *, but returns a non-const GstStructure *. This is for programming convenience -- the caller should be aware that structures inside a constant GstCaps should not be modified.

caps : a GstCaps
index : the index of the structure
Returns : a pointer to the GstStructure corresponding to index

gst_caps_copy_1 ()

GstCaps*    gst_caps_copy_1                 (const GstCaps *caps);

Warning

gst_caps_copy_1 is deprecated and should not be used in newly-written code.

Creates a new GstCaps and appends a copy of the first structure contained in caps.

caps : the GstCaps to copy
Returns : the new GstCaps

gst_caps_set_simple ()

void        gst_caps_set_simple             (GstCaps *caps,
                                             char *field,
                                             ...);

Sets fields in a simple GstCaps. A simple GstCaps is one that only has one structure. The arguments must be passed in the same manner as @gst_structure_set(), and be NULL-terminated.

caps : the GstCaps to set
field : first field to set
... : additional parameters

gst_caps_set_simple_valist ()

void        gst_caps_set_simple_valist      (GstCaps *caps,
                                             char *field,
                                             va_list varargs);

Sets fields in a simple GstCaps. A simple GstCaps is one that only has one structure. The arguments must be passed in the same manner as @gst_structure_set(), and be NULL-terminated.

caps : the GstCaps to copy
field : first field to set
varargs : additional parameters

gst_caps_is_any ()

gboolean    gst_caps_is_any                 (const GstCaps *caps);

Determines if caps represents any media format.

caps : the GstCaps to test
Returns : TRUE if caps represents any format.

gst_caps_is_empty ()

gboolean    gst_caps_is_empty               (const GstCaps *caps);

Determines if caps represents no media formats.

caps : the GstCaps to test
Returns : TRUE if caps represents no formats.

gst_caps_is_chained ()

gboolean    gst_caps_is_chained             (const GstCaps *caps);

Warning

gst_caps_is_chained is deprecated and should not be used in newly-written code.

Determines if caps contains multiple GstStructures.

This function is deprecated, and should not be used in new code. Use #gst_caps_is_simple() instead.

caps : the GstCaps to test
Returns : TRUE if caps contains more than one structure

gst_caps_is_fixed ()

gboolean    gst_caps_is_fixed               (const GstCaps *caps);

Fixed GstCaps describe exactly one format, that is, they have exactly one structure, and each field in the structure describes a fixed type. Examples of non-fixed types are GST_TYPE_INT_RANGE and GST_TYPE_LIST.

caps : the GstCaps to test
Returns : TRUE if caps is fixed

gst_caps_is_equal ()

gboolean    gst_caps_is_equal               (const GstCaps *caps1,
                                             const GstCaps *caps2);

Checks if the given caps represent the same set of caps.

Note

This function does not work reliably if optional properties for caps are included on one caps and omitted on the other.

caps1 : a GstCaps
caps2 : another GstCaps
Returns : TRUE if both caps are equal

gst_caps_is_equal_fixed ()

gboolean    gst_caps_is_equal_fixed         (const GstCaps *caps1,
                                             const GstCaps *caps2);

Warning

gst_caps_is_equal_fixed is deprecated and should not be used in newly-written code.

Tests if two GstCaps are equal. This function only works on fixed GstCaps.

caps1 : the GstCaps to test
caps2 : the GstCaps to test
Returns : TRUE if the arguments represent the same format

gst_caps_is_always_compatible ()

gboolean    gst_caps_is_always_compatible   (const GstCaps *caps1,
                                             const GstCaps *caps2);

A given GstCaps structure is always compatible with another if every media format that is in the first is also contained in the second. That is, caps1 is a subset of caps2.

caps1 : the GstCaps to test
caps2 : the GstCaps to test
Returns : TRUE if caps1 is a subset of caps2.

gst_caps_is_subset ()

gboolean    gst_caps_is_subset              (const GstCaps *subset,
                                             const GstCaps *superset);

Checks if all caps represented by subset are also represented by superset

Note

This function does not work reliably if optional properties for caps are included on one caps and omitted on the other.

subset : a GstCaps
superset : a potentially greater GstCaps
Returns : TRUE if subset is a subset of superset

gst_caps_intersect ()

GstCaps*    gst_caps_intersect              (const GstCaps *caps1,
                                             const GstCaps *caps2);

Creates a new GstCaps that contains all the formats that are common to both caps1 and caps2.

caps1 : a GstCaps to intersect
caps2 : a GstCaps to intersect
Returns : the new GstCaps

gst_caps_union ()

GstCaps*    gst_caps_union                  (const GstCaps *caps1,
                                             const GstCaps *caps2);

Creates a new GstCaps that contains all the formats that are in either caps1 and caps2.

caps1 : a GstCaps to union
caps2 : a GstCaps to union
Returns : the new GstCaps

gst_caps_normalize ()

GstCaps*    gst_caps_normalize              (const GstCaps *caps);

Creates a new GstCaps that represents the same set of formats as caps, but contains no lists. Each list is expanded into separate GstStructures.

caps : a GstCaps to normalize
Returns : the new GstCaps

gst_caps_simplify ()

GstCaps*    gst_caps_simplify               (const GstCaps *caps);

Warning

gst_caps_simplify is deprecated and should not be used in newly-written code.

Creates a new GstCaps that represents the same set of formats as caps, but simpler. Component structures that are identical are merged. Component structures that have ranges or lists that can be merged are also merged.

caps : a GstCaps to simplify
Returns : the new GstCaps

gst_caps_do_simplify ()

gboolean    gst_caps_do_simplify            (GstCaps *caps);

Modifies the given caps inplace into a representation that represents the same set of formats, but in a simpler form. Component structures that are identical are merged. Component structures that have values that can be merged are also merged.

caps : a GstCaps to simplify
Returns : TRUE, if the caps could be simplified

gst_caps_save_thyself ()

xmlNodePtr  gst_caps_save_thyself           (const GstCaps *caps,
                                             xmlNodePtr parent);

Serializes a GstCaps to XML and adds it as a child node of parent.

caps : a GstCaps structure
parent : a XML parent node
Returns : a XML node pointer

gst_caps_load_thyself ()

GstCaps*    gst_caps_load_thyself           (xmlNodePtr parent);

Creates a GstCaps from its XML serialization.

parent : a XML node
Returns : a new GstCaps structure

gst_caps_replace ()

void        gst_caps_replace                (GstCaps **caps,
                                             GstCaps *newcaps);

Replaces *caps with newcaps. Frees the GstCaps in the location pointed to by caps, if applicable, then modifies caps to point to newcaps.

caps : a pointer to GstCaps
newcaps : a GstCaps to replace *caps

gst_caps_to_string ()

gchar*      gst_caps_to_string              (const GstCaps *caps);

Converts caps to a string representation. This string representation can be converted back to a GstCaps by gst_caps_from_string.

caps : a GstCaps
Returns : a newly allocated string representing caps.

gst_caps_from_string ()

GstCaps*    gst_caps_from_string            (const gchar *string);

Converts caps from a string representation.

string : a string to convert to GstCaps
Returns : a newly allocated GstCaps

gst_caps_structure_fixate_field_nearest_int ()

gboolean    gst_caps_structure_fixate_field_nearest_int
                                            (GstStructure *structure,
                                             const char *field_name,
                                             int target);

Fixates a GstStructure by changing the given field to the nearest integer to target that is a subset of the existing field.

structure : a GstStructure
field_name : a field in structure
target : the target value of the fixation
Returns : TRUE if the structure could be fixated

gst_caps_structure_fixate_field_nearest_double ()

gboolean    gst_caps_structure_fixate_field_nearest_double
                                            (GstStructure *structure,
                                             const char *field_name,
                                             double target);

Fixates a GstStructure by changing the given field to the nearest double to target that is a subset of the existing field.

structure : a GstStructure
field_name : a field in structure
target : the target value of the fixation
Returns : TRUE if the structure could be fixated

gst_caps_subtract ()

GstCaps*    gst_caps_subtract               (const GstCaps *minuend,
                                             const GstCaps *subtrahend);

Subtracts the subtrahend from the minuend.

Note

This function does not work reliably if optional properties for caps are included on one caps and omitted on the other.

minuend : GstCaps to substract from
subtrahend : GstCaps to substract
Returns : the resulting caps