the GType of a structure
Calls the provided function once for each field in the #GstStructure. In contrast to gst_structure_foreach(), the function may modify the fields. In contrast to gst_structure_map_in_place(), the field is removed from the structure if %FALSE is returned from the function. The structure must be mutable.
a function to call for each field
Fixate all values in structure using gst_value_fixate().
structure will be modified in-place and should be writable.
Fixates a #GstStructure by changing the given field with its fixated value.
a field in structure
Fixates a #GstStructure by changing the given field_name field to the given
target boolean if that field is not fixed yet.
a field in structure
the target value of the fixation
Fixates a #GstStructure by changing the given field to the nearest
double to target that is a subset of the existing field.
a field in structure
the target value of the fixation
Fixates a #GstStructure by changing the given field to the nearest
fraction to target_numerator/``target_denominator that is a subset
of the existing field.
a field in structure
The numerator of the target value of the fixation
The denominator of the target value of the fixation
Fixates a #GstStructure by changing the given field to the nearest
integer to target that is a subset of the existing field.
a field in structure
the target value of the fixation
Fixates a #GstStructure by changing the given field_name field to the given
target string if that field is not fixed yet.
a field in structure
the target value of the fixation
Calls the provided function once for each field in the #GstStructure. The function must not modify the fields. Also see gst_structure_map_in_place() and gst_structure_filter_and_map_in_place().
a function to call for each field
Frees a #GstStructure and all its fields and values. The structure must not have a parent when this function is called.
This is useful in language bindings where unknown #GValue types are not
supported. This function will convert the %GST_TYPE_ARRAY into a newly
allocated #GValueArray and return it through array. Be aware that this is
slower then getting the #GValue directly.
the name of a field
Sets the boolean pointed to by value corresponding to the value of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
the name of a field
Sets the clock time pointed to by value corresponding to the clock time
of the given field. Caller is responsible for making sure the field exists
and has the correct type.
the name of a field
Sets the date pointed to by value corresponding to the date of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
On success value will point to a newly-allocated copy of the date which
should be freed with g_date_free() when no longer needed (note: this is
inconsistent with e.g. gst_structure_get_string() which doesn't return a
copy of the string).
the name of a field
Sets the datetime pointed to by value corresponding to the datetime of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
On success value will point to a reference of the datetime which
should be unreffed with gst_date_time_unref() when no longer needed
(note: this is inconsistent with e.g. gst_structure_get_string()
which doesn't return a copy of the string).
the name of a field
Sets the double pointed to by value corresponding to the value of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
the name of a field
Sets the int pointed to by value corresponding to the value of the
given field. Caller is responsible for making sure the field exists,
has the correct type and that the enumtype is correct.
the name of a field
the enum type of a field
Finds the field with the given name, and returns the type of the value it contains. If the field is not found, G_TYPE_INVALID is returned.
the name of the field
Read the GstFlagSet flags and mask out of the structure into the provided pointers.
the name of a field
Sets the integers pointed to by value_numerator and value_denominator
corresponding to the value of the given field. Caller is responsible
for making sure the field exists and has the correct type.
the name of a field
Sets the int pointed to by value corresponding to the value of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
the name of a field
Sets the #gint64 pointed to by value corresponding to the value of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
the name of a field
This is useful in language bindings where unknown #GValue types are not
supported. This function will convert the %GST_TYPE_LIST into a newly
allocated GValueArray and return it through array. Be aware that this is
slower then getting the #GValue directly.
the name of a field
Get the name of structure as a string.
Get the name of structure as a GQuark.
Finds the field corresponding to fieldname, and returns the string
contained in the field's value. Caller is responsible for making
sure the field exists and has the correct type.
The string should not be modified, and remains valid until the next call to a gst_structure_*() function with the given structure.
the name of a field
Sets the uint pointed to by value corresponding to the value of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
the name of a field
Sets the #guint64 pointed to by value corresponding to the value of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
the name of a field
Get the value of the field with name fieldname.
the name of the field to get
Check if structure contains a field named fieldname.
the name of a field
Check if structure contains a field named fieldname and with GType type.
the name of a field
the type of a value
Checks if the structure has the given name
structure name to check for
Get the value of the field with GQuark field.
the #GQuark of the field to get
Check if structure contains a field named field.
#GQuark of the field name
Check if structure contains a field named field and with GType type.
#GQuark of the field name
the type of a value
Sets the field with the given GQuark field to value. If the field
does not exist, it is created. If the field exists, the previous
value is replaced and freed.
a #GQuark representing a field
the new value of the field
Sets the field with the given GQuark field to value. If the field
does not exist, it is created. If the field exists, the previous
value is replaced and freed.
a #GQuark representing a field
the new value of the field
Calls the provided function once for each field in the #GstStructure. In contrast to gst_structure_foreach(), the function may modify but not delete the fields. The structure must be mutable.
a function to call for each field
Get the number of fields in the structure.
Get the name of the given field number, counting from 0 onwards.
the index to get the name of
Removes all fields in a GstStructure.
Removes the field with the given name. If the field with the given name does not exist, the structure is unchanged.
the name of the field to remove
Converts structure to a human-readable string representation.
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.
Free-function: g_free
The flags to use to serialize structure
This is useful in language bindings where unknown GValue types are not
supported. This function will convert a array to %GST_TYPE_ARRAY and set
the field specified by fieldname. Be aware that this is slower then using
%GST_TYPE_ARRAY in a #GValue directly.
the name of a field
a pointer to a #GValueArray
This is useful in language bindings where unknown GValue types are not
supported. This function will convert a array to %GST_TYPE_LIST and set
the field specified by fieldname. Be aware that this is slower then using
%GST_TYPE_LIST in a #GValue directly.
the name of a field
a pointer to a #GValueArray
Sets the name of the structure to the given name. The string
provided is copied before being used. It must not be empty, start with a
letter and can be followed by letters, numbers and any of "/-_.:".
the new name of the structure
Sets the parent_refcount field of #GstStructure. This field is used to determine whether a structure is mutable or not. This function should only be called by code implementing parent objects of #GstStructure, as described in the MT Refcounting section of the design documents.
a pointer to the parent's refcount
Sets the field with the given name field to value. If the field
does not exist, it is created. If the field exists, the previous
value is replaced and freed.
the name of the field to set
the new value of the field
Sets the field with the given name field to value. If the field
does not exist, it is created. If the field exists, the previous
value is replaced and freed. The function will take ownership of value.
the name of the field to set
the new value of the field
Converts structure to a human-readable string representation.
For debugging purposes its easier to do something like this: |[ GST_LOG ("structure is %" GST_PTR_FORMAT, structure);
This prints the structure in human readable form.
This function will lead to unexpected results when there are nested #GstCaps
/ #GstStructure deeper than one level, you should user
gst_structure_serialize() instead for those cases.
Free-function: g_free
Creates a #GstStructure from a string representation. If end is not %NULL, a pointer to the place inside the given string where parsing ended will be returned.
The current implementation of serialization will lead to unexpected results when there are nested #GstCaps / #GstStructure deeper than one level unless the gst_structure_serialize() function is used (without #GST_SERIALIZE_FLAG_BACKWARD_COMPAT)
Free-function: gst_structure_free
a string representation of a #GstStructure
Atomically modifies a pointer to point to a new structure.
The #GstStructure oldstr_ptr is pointing to is freed and
newstr is taken ownership over.
Either newstr and the value pointed to by oldstr_ptr may be %NULL.
It is a programming error if both newstr and the value pointed to by
oldstr_ptr refer to the same, non-%NULL structure.
pointer to a place of a #GstStructure to take
a new #GstStructure
A #GstStructure is a collection of key/value pairs. The keys are expressed as GQuarks and the values can be of any GType.
In addition to the key/value pairs, a #GstStructure also has a name. The name starts with a letter and can be filled by letters, numbers and any of "/-_.:".
#GstStructure is used by various GStreamer subsystems to store information in a flexible and extensible way. A #GstStructure does not have a refcount because it usually is part of a higher level object such as #GstCaps, #GstMessage, #GstEvent, #GstQuery. It provides a means to enforce mutability using the refcount of the parent with the gst_structure_set_parent_refcount() method.
A #GstStructure can be created with gst_structure_new_empty() or gst_structure_new(), which both take a name and an optional set of key/value pairs along with the types of the values.
Field values can be changed with gst_structure_set_value() or gst_structure_set().
Field values can be retrieved with gst_structure_get_value() or the more convenient gst_structure_get_*() functions.
Fields can be removed with gst_structure_remove_field() or gst_structure_remove_fields().
Strings in structures must be ASCII or UTF-8 encoded. Other encodings are not allowed. Strings may be %NULL however.
The serialization format
GstStructure serialization format serialize the GstStructure name, keys/GType/values in a comma separated list with the structure name as first field without value followed by separated key/value pairs in the form
key=value, for example:The values type will be inferred if not explicitly specified with the
(GTypeName)valuesyntax, for example the following struct will have one field called 'is-string' which has the string 'true' as a value:Note: without specifying
(string),field-is-string` type would have been inferred as boolean.Note: we specified
(string)as a type even ifgchararrayis the actual GType name as for convenience some well known types have been aliased or abbreviated.To avoid specifying the type, you can give some hints to the "type system". For example to specify a value as a double, you should add a decimal (ie.
1is anintwhile1.0is adouble).Note: when a structure is serialized with #gst_structure_to_string, all values are explicitly typed.
Some types have special delimiters:
{and}). For examplea-structure, array={1, 2, 3}[and]). For examplea-structure, range=[1, 6, 2]1 being the min value, 6 the maximum and 2 the step. To specify a #GST_TYPE_INT64_RANGE you need to explicitly specify it like:a-structure, a-int64-range=(gint64) [1, 5]<and>). For example `a-structure, list=<1, 2, 3>Structures are delimited either by a null character
\0or a semicolon;the latter allowing to store multiple structures in the same string (see #GstCaps).Quotes are used as "default" delimiters and can be used around any types that don't use other delimiters (for example
a-struct, i=(int)"1"). They are use to allow adding spaces or special characters (such as delimiters, semicolumns, etc..) inside strings and you can use backslashes\to escape characters inside them, for example:They also allow for nested structure, such as:
Since 1.20, nested structures and caps can be specified using brackets (
[and]), for example: