GstCaps

GstCaps

gst_caps_new_any

GstCaps *
gst_caps_new_any ()

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

gst_caps_new_empty

GstCaps *
gst_caps_new_empty ()

Creates a new GstCaps that is empty. That is, the returned GstCaps contains no media formats. The GstCaps is guaranteed to be writable.

gst_caps_new_empty_simple

GstCaps *
gst_caps_new_empty_simple (const char* media_type)

Creates a new GstCaps that contains one GstStructure with name media_type.

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.

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.

gst_caps_new_id_str_empty_simple

GstCaps *
gst_caps_new_id_str_empty_simple (const GstIdStr * media_type)

Creates a new GstCaps that contains one GstStructure with name media_type.

Since : 1.26

gst_caps_new_id_str_simple

GstCaps *
gst_caps_new_id_str_simple (const GstIdStr * media_type,
                            const GstIdStr * 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.

Since : 1.26

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.

gst_caps_new_static_str_empty_simple

GstCaps *
gst_caps_new_static_str_empty_simple (const char* media_type)

Creates a new GstCaps that contains one GstStructure with name media_type.

media_type needs to be valid for the remaining lifetime of the process, e.g. has to be a static string.

Since : 1.26

gst_caps_new_static_str_simple

GstCaps *
gst_caps_new_static_str_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, fieldname and all other fieldnames need to be valid for the remaining lifetime of the process, e.g. have to be static strings.

Since : 1.26

gst_caps_append

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.

gst_caps_append_structure

gst_caps_append_structure (GstCaps * caps,
                           GstStructure * structure)

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

gst_caps_append_structure_full

gst_caps_append_structure_full (GstCaps * caps,
                                GstStructure * structure,
                                GstCapsFeatures * features)

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

Since : 1.2

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

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.

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.

Since : 1.16

gst_caps_filter_and_map_in_place

gst_caps_filter_and_map_in_place (GstCaps * caps,
                                  GstCapsFilterMapFunc func,
                                  gpointer user_data)

Calls the provided function once for each structure and caps feature in the GstCaps. In contrast to gst_caps_foreach, the function may modify the structure and features. In contrast to gst_caps_map_in_place, the structure and features are removed from the caps if FALSE is returned from the function. The caps must be mutable.

Since : 1.6

gst_caps_fixate

GstCaps *
gst_caps_fixate (GstCaps * caps)

Modifies the given caps into a representation with only fixed values. First the caps will be truncated and then the first structure will be fixated with gst_structure_fixate.

This function takes ownership of caps and will call gst_caps_make_writable on it so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref.

Note that it is not guaranteed that the returned caps have exactly one structure. If caps are empty caps then the returned caps will be the empty too and contain no structure at all.

Calling this function with ANY caps is not allowed.

gst_caps_foreach

gboolean
gst_caps_foreach (const GstCaps * caps,
                  GstCapsForeachFunc func,
                  gpointer user_data)

Calls the provided function once for each structure and caps feature in the GstCaps. The function must not modify the fields. Also see gst_caps_map_in_place and gst_caps_filter_and_map_in_place.

Since : 1.6

gst_caps_get_features

GstCapsFeatures *
gst_caps_get_features (const GstCaps * caps,
                       guint index)

Finds the features in caps at index, and returns it.

WARNING: This function takes a const GstCaps *, but returns a non-const GstCapsFeatures *. This is for programming convenience -- the caller should be aware that features 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 features returned in the usual way, e.g. with functions like gst_caps_features_add.

Since : 1.2

gst_caps_get_size

guint
gst_caps_get_size (const GstCaps * caps)

Gets the number of structures contained in caps.

gst_caps_get_structure

GstStructure *
gst_caps_get_structure (const GstCaps * caps,
                        guint index)

Finds the structure in caps at 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.

gst_caps_id_str_set_simple

gst_caps_id_str_set_simple (GstCaps * caps,
                            const GstIdStr * field,
                            ... ...)

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

Since : 1.26

gst_caps_id_str_set_simple_valist

gst_caps_id_str_set_simple_valist (GstCaps * caps,
                                   const GstIdStr * field,
                                   va_list varargs)

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

Since : 1.26

gst_caps_id_str_set_value

gst_caps_id_str_set_value (GstCaps * caps,
                           const GstIdStr * 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.

Since : 1.26

gst_caps_intersect

GstCaps *
gst_caps_intersect (GstCaps * caps1,
                    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.

gst_caps_intersect_full

GstCaps *
gst_caps_intersect_full (GstCaps * caps1,
                         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.

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.

gst_caps_is_any

gboolean
gst_caps_is_any (const GstCaps * caps)

Determines if caps represents any media format.

gst_caps_is_empty

gboolean
gst_caps_is_empty (const GstCaps * caps)

Determines if caps represents no media formats.

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.

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.

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.

gst_caps_is_strictly_equal

gboolean
gst_caps_is_strictly_equal (const GstCaps * caps1,
                            const GstCaps * caps2)

Checks if the given caps are exactly the same set of caps.

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.

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.

gst_caps_is_subset_structure_full

gboolean
gst_caps_is_subset_structure_full (const GstCaps * caps,
                                   const GstStructure * structure,
                                   const GstCapsFeatures * features)

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

Since : 1.2

gst_caps_map_in_place

gboolean
gst_caps_map_in_place (GstCaps * caps,
                       GstCapsMapFunc func,
                       gpointer user_data)

Calls the provided function once for each structure and caps feature in the GstCaps. In contrast to gst_caps_foreach, the function may modify but not delete the structures and features. The caps must be mutable.

Since : 1.6

gst_caps_merge

GstCaps *
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 a writable copy of caps1, and then caps2 is freed. If either caps is ANY, the resulting caps will be ANY.

gst_caps_merge_structure

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

Appends structure to caps if it is not already expressed by caps.

gst_caps_merge_structure_full

GstCaps *
gst_caps_merge_structure_full (GstCaps * caps,
                               GstStructure * structure,
                               GstCapsFeatures * features)

Appends structure with features to caps if its not already expressed by caps.

Since : 1.2

gst_caps_normalize

GstCaps *
gst_caps_normalize (GstCaps * caps)

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

This function takes ownership of caps and will call gst_caps_make_writable on it so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref.

gst_caps_ref

GstCaps *
gst_caps_ref (GstCaps * caps)

Adds 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.

gst_caps_remove_structure

gst_caps_remove_structure (GstCaps * caps,
                           guint idx)

Removes the structure with the given index from the list of structures contained in caps.

gst_caps_serialize

gchar *
gst_caps_serialize (const GstCaps * caps,
                    GstSerializeFlags flags)

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

This prints the caps in human readable form.

This version of the caps serialization function introduces support for nested structures and caps but the resulting strings won't be parsable with GStreamer prior to 1.20 unless GST_SERIALIZE_FLAG_BACKWARD_COMPAT is passed as flag.

Since : 1.20

gst_caps_set_features

gst_caps_set_features (GstCaps * caps,
                       guint index,
                       GstCapsFeatures * features)

Sets the features for the structure at index.

Since : 1.2

gst_caps_set_features_simple

gst_caps_set_features_simple (GstCaps * caps,
                              GstCapsFeatures * features)

Sets the features for all the structures of caps.

Since : 1.16

gst_caps_set_simple

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.

gst_caps_set_simple_static_str

gst_caps_set_simple_static_str (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.

field and all other field names need to be valid for the remaining lifetime of the process, e.g. have to be static strings.

Since : 1.26

gst_caps_set_simple_static_str_valist

gst_caps_set_simple_static_str_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.

field and all other field names need to be valid for the remaining lifetime of the process, e.g. have to be static strings.

Since : 1.26

gst_caps_set_simple_valist

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.

gst_caps_set_value

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.

gst_caps_set_value_static_str

gst_caps_set_value_static_str (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.

field needs to be valid for the remaining lifetime of the process, e.g. has to be a static string.

Since : 1.26

gst_caps_simplify

GstCaps *
gst_caps_simplify (GstCaps * caps)

Converts the given caps 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.

This function takes ownership of caps and will call gst_caps_make_writable on it if necessary, so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref.

This method does not preserve the original order of caps.

gst_caps_steal_structure

GstStructure *
gst_caps_steal_structure (GstCaps * caps,
                          guint index)

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

gst_caps_subtract

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

Subtracts the subtrahend from the minuend.

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

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:

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

This prints the caps in human readable form.

The implementation of serialization up to 1.20 would lead to unexpected results when there were nested GstCaps / GstStructure deeper than one level.

gst_caps_truncate

GstCaps *
gst_caps_truncate (GstCaps * caps)

Discards all but the first structure from caps. Useful when fixating.

This function takes ownership of caps and will call gst_caps_make_writable on it if necessary, so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref.

Note that it is not guaranteed that the returned caps have exactly one structure. If caps is any or empty caps then the returned caps will be the same and contain no structure at all.

gst_caps_unref

gst_caps_unref (GstCaps * caps)

Unrefs a GstCaps and frees all its structures and the structures' values when the refcount reaches 0.

gst_caps_from_string

GstCaps *
gst_caps_from_string (const gchar * string)

Converts caps from a string representation.

The implementation of serialization up to 1.20 would lead to unexpected results when there were nested GstCaps / GstStructure deeper than one level.

gst_caps_replace

gboolean
gst_caps_replace (GstCaps ** old_caps,
                  GstCaps * new_caps)

Modifies a pointer to a GstCaps to point to a different GstCaps. The modification is done atomically (so this is useful for ensuring thread safety in some cases), and the reference counts are updated appropriately (the old caps is unreffed, the new is reffed).

Either new_caps or the GstCaps pointed to by old_caps may be NULL.

gst_caps_take

gboolean
gst_caps_take (GstCaps ** old_caps,
               GstCaps * new_caps)

Modifies a pointer to a GstCaps to point to a different GstCaps. This function is similar to gst_caps_replace except that it takes ownership of new_caps.

GstStaticCaps

gst_static_caps_cleanup

gst_static_caps_cleanup (GstStaticCaps * static_caps)

Cleans up the cached caps contained in static_caps.

gst_static_caps_get

GstCaps *
gst_static_caps_get (GstStaticCaps * static_caps)

Converts a GstStaticCaps to a GstCaps.

gst_clear_caps

gst_clear_caps (GstCaps ** caps_ptr)

Clears a reference to a GstCaps.

caps_ptr must not be NULL.

If the reference is NULL then this function does nothing. Otherwise, the reference count of the caps is decreased and the pointer is set to NULL.

Since : 1.16

GST_CAPS_CAST

#define GST_CAPS_CAST(obj)        ((GstCaps*)(obj))

GST_CAPS_FLAGS

#define GST_CAPS_FLAGS(caps)                    GST_MINI_OBJECT_FLAGS(caps)

Gets a flags word containing GstCapsFlags flags set on this caps.

GST_CAPS_FLAG_IS_SET

#define GST_CAPS_FLAG_IS_SET(caps,flag)        GST_MINI_OBJECT_FLAG_IS_SET (caps, flag)

Gives the status of a specific flag on a caps.

GST_CAPS_FLAG_SET

#define GST_CAPS_FLAG_SET(caps,flag)           GST_MINI_OBJECT_FLAG_SET (caps, flag)

Sets a caps flag on a caps.

GST_CAPS_FLAG_UNSET

#define GST_CAPS_FLAG_UNSET(caps,flag)         GST_MINI_OBJECT_FLAG_UNSET (caps, flag)

Clears a caps flag.

GST_CAPS_IS_SIMPLE

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

Checks if the number of structures in the given caps is exactly one.

GST_CAPS_REFCOUNT

#define GST_CAPS_REFCOUNT(caps)                 GST_MINI_OBJECT_REFCOUNT(caps)

Gives access to the reference count field of the caps

GST_CAPS_REFCOUNT_VALUE

#define GST_CAPS_REFCOUNT_VALUE(caps)           GST_MINI_OBJECT_REFCOUNT_VALUE(caps)

Gets the reference count value of the caps.

GST_STATIC_CAPS

#define GST_STATIC_CAPS(string) \
{ \
  /* caps */ NULL, \
  /* string */ string, \
  GST_PADDING_INIT \
}

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

gst_caps_is_writable

#define gst_caps_is_writable(caps)     gst_mini_object_is_writable (GST_MINI_OBJECT_CAST (caps))

Tests if you can safely modify caps. It is only safe to modify caps when there is only one owner of the caps - ie, the object is writable.

gst_caps_make_writable

#define gst_caps_make_writable(caps)   GST_CAPS_CAST (gst_mini_object_make_writable (GST_MINI_OBJECT_CAST (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.

GstCapsFlags

Extra flags for a caps.

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:

         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_ANY

#define GST_CAPS_ANY              _gst_caps_any

Means that the element/pad can output 'anything'. Useful for elements that output unknown media, such as filesrc. This macro returns a singleton and should not be unreffed.

GST_CAPS_NONE

#define GST_CAPS_NONE             _gst_caps_none

The opposite of GST_CAPS_ANY: it means that the pad/element outputs an undefined media type that can not be detected. This macro returns a singleton and should not be unreffed.

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.

GstCapsFilterMapFunc

gboolean
(*GstCapsFilterMapFunc) (GstCapsFeatures * features,
                         GstStructure * structure,
                         gpointer user_data)

A function that will be called in gst_caps_filter_and_map_in_place. The function may modify features and structure, and both will be removed from the caps if FALSE is returned.

GstCapsForeachFunc

gboolean
(*GstCapsForeachFunc) (GstCapsFeatures * features,
                       GstStructure * structure,
                       gpointer user_data)

A function that will be called in gst_caps_foreach. The function may not modify features or structure.

Since : 1.6

GstCapsMapFunc

gboolean
(*GstCapsMapFunc) (GstCapsFeatures * features,
                   GstStructure * structure,
                   gpointer user_data)

A function that will be called in gst_caps_map_in_place. The function may modify features and structure.