GstCaps

GstCaps — Structure describing sets of media formats

Synopsis

#include <gst/gst.h>

struct              GstCaps;
struct              GstStaticCaps;
enum                GstCapsIntersectMode;
enum                GstCapsFlags;
#define             GST_CAPS_ANY
#define             GST_CAPS_NONE
#define             GST_CAPS_REFCOUNT                   (caps)
#define             GST_CAPS_REFCOUNT_VALUE             (caps)
#define             GST_STATIC_CAPS_ANY
#define             GST_STATIC_CAPS_NONE
#define             GST_CAPS_IS_SIMPLE                  (caps)
#define             GST_DEBUG_CAPS                      (string,
                                                         caps)
#define             GST_STATIC_CAPS                     (string)
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);
GstCaps *           gst_caps_copy_nth                   (const GstCaps *caps,
                                                         guint nth);
GstCaps *           gst_static_caps_get                 (GstStaticCaps *static_caps);
void                gst_caps_append                     (GstCaps *caps1,
                                                         GstCaps *caps2);
void                gst_caps_merge                      (GstCaps *caps1,
                                                         GstCaps *caps2);
void                gst_caps_append_structure           (GstCaps *caps,
                                                         GstStructure *structure);
void                gst_caps_remove_structure           (GstCaps *caps,
                                                         guint idx);
GstStructure *      gst_caps_steal_structure            (GstCaps *caps,
                                                         guint index);
void                gst_caps_merge_structure            (GstCaps *caps,
                                                         GstStructure *structure);
guint               gst_caps_get_size                   (const GstCaps *caps);
GstStructure *      gst_caps_get_structure              (const GstCaps *caps,
                                                         guint index);
void                gst_caps_set_value                  (GstCaps *caps,
                                                         const char *field,
                                                         const GValue *value);
void                gst_caps_set_simple                 (GstCaps *caps,
                                                         const char *field,
                                                         ...);
void                gst_caps_set_simple_valist          (GstCaps *caps,
                                                         const 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_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);
gboolean            gst_caps_is_subset_structure        (const GstCaps *caps,
                                                         const GstStructure *structure);
gboolean            gst_caps_can_intersect              (const GstCaps *caps1,
                                                         const GstCaps *caps2);
GstCaps *           gst_caps_intersect                  (const GstCaps *caps1,
                                                         const GstCaps *caps2);
GstCaps *           gst_caps_intersect_full             (const GstCaps *caps1,
                                                         const GstCaps *caps2,
                                                         GstCapsIntersectMode mode);
GstCaps *           gst_caps_union                      (const GstCaps *caps1,
                                                         const GstCaps *caps2);
GstCaps *           gst_caps_normalize                  (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);
GstCaps *           gst_caps_subtract                   (const GstCaps *minuend,
                                                         const GstCaps *subtrahend);
GstCaps *           gst_caps_make_writable              (GstCaps *caps);
GstCaps *           gst_caps_ref                        (GstCaps *caps);
void                gst_caps_truncate                   (GstCaps *caps);
void                gst_caps_unref                      (GstCaps *caps);

Description

Caps (capabilities) are lighweight refcounted objects describing media types. They are composed of an array of GstStructure.

Caps are exposed on GstPadTemplate to describe all possible types a given pad can handle. They are also stored in the GstRegistry along with a description of the GstElement.

Caps are exposed on the element pads using the gst_pad_get_caps() pad function. This function describes the possible types that the pad can handle or produce at runtime.

Caps are also attached to buffers to describe to content of the data pointed to by the buffer with gst_buffer_set_caps(). Caps attached to a GstBuffer allow for format negotiation upstream and downstream.

A GstCaps can be constructed with the following code fragment:

Example 7. Creating caps

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GstCaps *caps;
caps = gst_caps_new_simple ("video/x-raw-yuv",
     "format", GST_TYPE_FOURCC, GST_MAKE_FOURCC ('I', '4', '2', '0'),
     "framerate", GST_TYPE_FRACTION, 25, 1,
     "pixel-aspect-ratio", GST_TYPE_FRACTION, 1, 1,
     "width", G_TYPE_INT, 320,
     "height", G_TYPE_INT, 240,
     NULL);


A GstCaps is fixed when it has no properties with ranges or lists. Use gst_caps_is_fixed() to test for fixed caps. Only fixed caps can be set on a GstPad or GstBuffer.

Various methods exist to work with the media types such as subtracting or intersecting.

Last reviewed on 2007-02-13 (0.10.10)

Details

struct GstCaps

struct GstCaps {
  GType type;

  /* refcounting */
  gint           refcount;

  GstCapsFlags flags;
};

Object describing media types.

GType type;

GType of the caps

gint refcount;

the atomic refcount value

GstCapsFlags flags;

extra flags for the caps, read only.

struct GstStaticCaps

struct GstStaticCaps {
  GstCaps caps;
  const char *string;
};

Datastructure to initialize GstCaps from a string description usually used in conjunction with GST_STATIC_CAPS() and gst_static_caps_get() to instantiate a GstCaps.

GstCaps caps;

the cached GstCaps

const char *string;

a string describing a caps

enum GstCapsIntersectMode

typedef enum {
  GST_CAPS_INTERSECT_ZIG_ZAG            =  0,
  GST_CAPS_INTERSECT_FIRST              =  1
} GstCapsIntersectMode;

Modes of caps intersection

GST_CAPS_INTERSECT_ZIG_ZAG tries to preserve overall order of both caps by iterating on the caps' structures as the following matrix shows:

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caps1
      +-------------
      | 1  2  4  7
caps2 | 3  5  8 10
      | 6  9 11 12

Used when there is no explicit precedence of one caps over the other. e.g. tee's sink pad getcaps function, it will probe its src pad peers' for their caps and intersect them with this mode.

GST_CAPS_INTERSECT_FIRST is useful when an element wants to preserve another element's caps priority order when intersecting with its own caps. Example: If caps1 is [A, B, C] and caps2 is [E, B, D, A], the result would be [A, B], maintaining the first caps priority on the intersection.

GST_CAPS_INTERSECT_ZIG_ZAG

Zig-zags over both caps.

GST_CAPS_INTERSECT_FIRST

Keeps the first caps order.

Since 0.10.33


enum GstCapsFlags

typedef enum {
  GST_CAPS_FLAGS_NONE = 0,
  GST_CAPS_FLAGS_ANY = (1 << 0)
} GstCapsFlags;

Extra flags for a caps.

GST_CAPS_FLAGS_NONE

no extra flags (Since 0.10.36)

GST_CAPS_FLAGS_ANY

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_CAPS_REFCOUNT()

#define GST_CAPS_REFCOUNT(caps)                 ((GST_CAPS(caps))->refcount)

Get access to the reference count field of the caps

caps :

a GstCaps

GST_CAPS_REFCOUNT_VALUE()

#define GST_CAPS_REFCOUNT_VALUE(caps)           (g_atomic_int_get (&(GST_CAPS(caps))->refcount))

Get the reference count value of the caps.

caps :

a GstCaps

GST_STATIC_CAPS_ANY

#define GST_STATIC_CAPS_ANY       GST_STATIC_CAPS("ANY")

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


GST_STATIC_CAPS_NONE

#define GST_STATIC_CAPS_NONE      GST_STATIC_CAPS("NONE")

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


GST_CAPS_IS_SIMPLE()

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

Convenience macro that checks if the number of structures in the given caps is exactly one.

caps :

the GstCaps instance to check

GST_DEBUG_CAPS()

#define             GST_DEBUG_CAPS(string, caps)

Warning

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

Convenience macro for printing out the contents of caps with GST_DEBUG().

string :

a string that should be prepended to the caps data.

caps :

the GstCaps instance to print

GST_STATIC_CAPS()

#define             GST_STATIC_CAPS(string)

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

string :

the string describing the caps

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. Caller is responsible for unreffing the returned caps.

Returns :

the new GstCaps. [transfer full]

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. [transfer full]

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(). Caller is responsible for unreffing the returned caps.

media_type :

the media type of the structure

fieldname :

first field to set

... :

additional arguments

Returns :

the new GstCaps. [transfer full]

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. [transfer full]

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. [transfer full]

gst_caps_copy ()

GstCaps *           gst_caps_copy                       (const GstCaps *caps);

Creates a new GstCaps as a copy of the old caps. The new caps will have a refcount of 1, owned by the caller. The structures are copied as well.

Note that this function is the semantic equivalent of a gst_caps_ref() followed by a gst_caps_make_writable(). If you only want to hold on to a reference to the data, you should use gst_caps_ref().

When you are finished with the caps, call gst_caps_unref() on it.

caps :

the GstCaps to copy

Returns :

the new GstCaps. [transfer full]

gst_caps_copy_nth ()

GstCaps *           gst_caps_copy_nth                   (const GstCaps *caps,
                                                         guint nth);

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

caps :

the GstCaps to copy

nth :

the nth structure to copy

Returns :

the new GstCaps. [transfer full]

gst_static_caps_get ()

GstCaps *           gst_static_caps_get                 (GstStaticCaps *static_caps);

Converts a GstStaticCaps to a GstCaps.

static_caps :

the GstStaticCaps to convert

Returns :

a pointer to the GstCaps. Unref after usage. Since the core holds an additional ref to the returned caps, use gst_caps_make_writable() on the returned caps to modify it. [transfer full]

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. If either caps is ANY, the resulting caps will be ANY.

caps1 :

the GstCaps that will be appended to

caps2 :

the GstCaps to append. [transfer full]

gst_caps_merge ()

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

Appends the structures contained in caps2 to caps1 if they are not yet expressed by caps1. The structures in caps2 are not copied -- they are transferred to caps1, and then caps2 is freed. If either caps is ANY, the resulting caps will be ANY.

caps1 :

the GstCaps that will take the new entries

caps2 :

the GstCaps to merge in. [transfer full]

Since 0.10.10


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. [transfer full]

gst_caps_remove_structure ()

void                gst_caps_remove_structure           (GstCaps *caps,
                                                         guint idx);

removes the stucture with the given index from the list of structures contained in caps.

caps :

the GstCaps to remove from

idx :

Index of the structure to remove

gst_caps_steal_structure ()

GstStructure *      gst_caps_steal_structure            (GstCaps *caps,
                                                         guint index);

Retrieves the stucture with the given index from the list of structures contained in caps. The caller becomes the owner of the returned structure.

caps :

the GstCaps to retrieve from

index :

Index of the structure to retrieve

Returns :

a pointer to the GstStructure corresponding to index. [transfer full]

Since 0.10.30


gst_caps_merge_structure ()

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

Appends structure to caps if its not already expressed by caps. The structure is not copied; caps becomes the owner of structure.

caps :

the GstCaps that will the new structure

structure :

the GstStructure to merge. [transfer full]

gst_caps_get_size ()

guint               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,
                                                         guint 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. However, if you know the caps are writable, either because you have just copied them or made them writable with gst_caps_make_writable(), you may modify the structure returned in the usual way, e.g. with functions like gst_structure_set().

You do not need to free or unref the structure returned, it belongs to the GstCaps.

caps :

a GstCaps

index :

the index of the structure

Returns :

a pointer to the GstStructure corresponding to index. [transfer none]

gst_caps_set_value ()

void                gst_caps_set_value                  (GstCaps *caps,
                                                         const char *field,
                                                         const GValue *value);

Sets the given field on all structures of caps to the given value. This is a convenience function for calling gst_structure_set_value() on all structures of caps.

caps :

a writable caps

field :

name of the field to set

value :

value to set the field to

Since 0.10.26


gst_caps_set_simple ()

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

Sets fields in a GstCaps. The arguments must be passed in the same manner as gst_structure_set(), and be NULL-terminated.

Note

Prior to GStreamer version 0.10.26, this function failed when caps was not simple. If your code needs to work with those versions of GStreamer, you may only call this function when GST_CAPS_IS_SIMPLE() is TRUE for caps.

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,
                                                         const char *field,
                                                         va_list varargs);

Sets fields in a GstCaps. The arguments must be passed in the same manner as gst_structure_set(), and be NULL-terminated.

Note

Prior to GStreamer version 0.10.26, this function failed when caps was not simple. If your code needs to work with those versions of GStreamer, you may only call this function when GST_CAPS_IS_SIMPLE() is TRUE for caps.

caps :

the GstCaps to set

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_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.

This function deals correctly with passing NULL for any of the caps.

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);

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_is_subset_structure ()

gboolean            gst_caps_is_subset_structure        (const GstCaps *caps,
                                                         const GstStructure *structure);

Checks if structure is a subset of caps. See gst_caps_is_subset() for more information.

caps :

a GstCaps

structure :

a potential GstStructure subset of caps

Returns :

TRUE if structure is a subset of caps

Since 0.10.36


gst_caps_can_intersect ()

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

Tries intersecting caps1 and caps2 and reports whether the result would not be empty

caps1 :

a GstCaps to intersect

caps2 :

a GstCaps to intersect

Returns :

TRUE if intersection would be not empty

Since 0.10.25


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. Defaults to GST_CAPS_INTERSECT_ZIG_ZAG mode.

caps1 :

a GstCaps to intersect

caps2 :

a GstCaps to intersect

Returns :

the new GstCaps

gst_caps_intersect_full ()

GstCaps *           gst_caps_intersect_full             (const GstCaps *caps1,
                                                         const GstCaps *caps2,
                                                         GstCapsIntersectMode mode);

Creates a new GstCaps that contains all the formats that are common to both caps1 and caps2, the order is defined by the GstCapsIntersectMode used.

caps1 :

a GstCaps to intersect

caps2 :

a GstCaps to intersect

mode :

The intersection algorithm/mode to use

Returns :

the new GstCaps

Since 0.10.33


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_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. Unrefs the GstCaps in the location pointed to by caps, if applicable, then modifies caps to point to newcaps. An additional ref on newcaps is taken.

This function does not take any locks so you might want to lock the object owning caps pointer.

caps :

a pointer to GstCaps. [inout][transfer full]

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().

For debugging purposes its easier to do something like this:

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GST_LOG ("caps are %" GST_PTR_FORMAT, caps);

This prints the caps in human readble form.

caps :

a GstCaps

Returns :

a newly allocated string representing caps. [transfer full]

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. [transfer full]

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 subtract from

subtrahend :

GstCaps to subtract

Returns :

the resulting caps

gst_caps_make_writable ()

GstCaps *           gst_caps_make_writable              (GstCaps *caps);

Returns a writable copy of caps.

If there is only one reference count on caps, the caller must be the owner, and so this function will return the caps object unchanged. If on the other hand there is more than one reference on the object, a new caps object will be returned. The caller's reference on caps will be removed, and instead the caller will own a reference to the returned object.

In short, this function unrefs the caps in the argument and refs the caps that it returns. Don't access the argument after calling this function. See also: gst_caps_ref().

caps :

the GstCaps to make writable. [transfer full]

Returns :

the same GstCaps object. [transfer full]

gst_caps_ref ()

GstCaps *           gst_caps_ref                        (GstCaps *caps);

Add a reference to a GstCaps object.

From this point on, until the caller calls gst_caps_unref() or gst_caps_make_writable(), it is guaranteed that the caps object will not change. This means its structures won't change, etc. To use a GstCaps object, you must always have a refcount on it -- either the one made implicitly by e.g. gst_caps_new_simple(), or via taking one explicitly with this function.

caps :

the GstCaps to reference

Returns :

the same GstCaps object. [transfer full]

gst_caps_truncate ()

void                gst_caps_truncate                   (GstCaps *caps);

Destructively discard all but the first structure from caps. Useful when fixating. caps must be writable.

caps :

the GstCaps to truncate

gst_caps_unref ()

void                gst_caps_unref                      (GstCaps *caps);

Unref a GstCaps and free all its structures and the structures' values when the refcount reaches 0.

caps :

the GstCaps to unref. [transfer full]

See Also

GstStructure