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GStreamer 0.10 Core Reference Manual | ![]() |
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#include <gst/gst.h> #define GST_VALUE_HOLDS_FOURCC (x) #define GST_MAKE_FOURCC (a,b,c,d) #define GST_STR_FOURCC (f) #define GST_FOURCC_FORMAT #define GST_FOURCC_ARGS (fourcc) #define GST_TYPE_FOURCC void gst_value_set_fourcc (GValue *value, guint32 fourcc); guint32 gst_value_get_fourcc (const GValue *value); #define GST_VALUE_HOLDS_INT_RANGE (x) #define GST_TYPE_INT_RANGE void gst_value_set_int_range (GValue *value, gint start, gint end); gint gst_value_get_int_range_min (const GValue *value); gint gst_value_get_int_range_max (const GValue *value); #define GST_VALUE_HOLDS_DOUBLE_RANGE (x) #define GST_TYPE_DOUBLE_RANGE void gst_value_set_double_range (GValue *value, gdouble start, gdouble end); gdouble gst_value_get_double_range_min (const GValue *value); gdouble gst_value_get_double_range_max (const GValue *value); #define GST_VALUE_HOLDS_LIST (x) #define GST_TYPE_LIST #define GST_VALUE_HOLDS_ARRAY (x) #define GST_TYPE_ARRAY void gst_value_list_append_value (GValue *value, const GValue *append_value); void gst_value_list_prepend_value (GValue *value, const GValue *prepend_value); void gst_value_list_concat (GValue *dest, const GValue *value1, const GValue *value2); guint gst_value_list_get_size (const GValue *value); const GValue* gst_value_list_get_value (const GValue *value, guint index); #define GST_VALUE_HOLDS_FRACTION (x) #define GST_TYPE_FRACTION void gst_value_set_fraction (GValue *value, gint numerator, gint denominator); gint gst_value_get_fraction_numerator (const GValue *value); gint gst_value_get_fraction_denominator (const GValue *value); gboolean gst_value_fraction_multiply (GValue *product, const GValue *factor1, const GValue *factor2); gboolean gst_value_fraction_subtract (GValue *dest, const GValue *minuend, const GValue *subtrahend); #define GST_VALUE_HOLDS_FRACTION_RANGE (x) #define GST_TYPE_FRACTION_RANGE void gst_value_set_fraction_range (GValue *value, const GValue *start, const GValue *end); const GValue* gst_value_get_fraction_range_min (const GValue *value); const GValue* gst_value_get_fraction_range_max (const GValue *value); void gst_value_set_fraction_range_full (GValue *value, gint numerator_start, gint denominator_start, gint numerator_end, gint denominator_end); #define GST_VALUE_HOLDS_DATE (x) #define GST_TYPE_DATE void gst_value_set_date (GValue *value, const GDate *date); const GDate* gst_value_get_date (const GValue *value); #define GST_VALUE_HOLDS_CAPS (x) void gst_value_set_caps (GValue *value, const GstCaps *caps); const GstCaps* gst_value_get_caps (const GValue *value); #define GST_VALUE_HOLDS_STRUCTURE (x) void gst_value_set_structure (GValue *value, const GstStructure *structure); const GstStructure* gst_value_get_structure (const GValue *value); #define GST_VALUE_HOLDS_MINI_OBJECT (value) #define GST_VALUE_HOLDS_BUFFER (x) #define gst_value_get_buffer (v) #define gst_value_set_buffer (v,b) #define gst_value_take_buffer (v,b) #define GST_VALUE_LESS_THAN #define GST_VALUE_EQUAL #define GST_VALUE_GREATER_THAN #define GST_VALUE_UNORDERED gint (*GstValueCompareFunc) (const GValue *value1, const GValue *value2); gchar* (*GstValueSerializeFunc) (const GValue *value1); gboolean (*GstValueDeserializeFunc) (GValue *dest, const gchar *s); gboolean (*GstValueUnionFunc) (GValue *dest, const GValue *value1, const GValue *value2); gboolean (*GstValueIntersectFunc) (GValue *dest, const GValue *value1, const GValue *value2); gboolean (*GstValueSubtractFunc) (GValue *dest, const GValue *minuend, const GValue *subtrahend); GstValueTable; gboolean gst_value_is_fixed (const GValue *value); void gst_value_register (const GstValueTable *table); void gst_value_init_and_copy (GValue *dest, const GValue *src); gchar* gst_value_serialize (const GValue *value); gboolean gst_value_deserialize (GValue *dest, const gchar *src); gint gst_value_compare (const GValue *value1, const GValue *value2); gboolean gst_value_can_compare (const GValue *value1, const GValue *value2); gboolean gst_value_union (GValue *dest, const GValue *value1, const GValue *value2); gboolean gst_value_can_union (const GValue *value1, const GValue *value2); void gst_value_register_union_func (GType type1, GType type2, GstValueUnionFunc func); gboolean gst_value_subtract (GValue *dest, const GValue *minuend, const GValue *subtrahend); gboolean gst_value_can_subtract (const GValue *minuend, const GValue *subtrahend); void gst_value_register_subtract_func (GType minuend_type, GType subtrahend_type, GstValueSubtractFunc func); gboolean gst_value_intersect (GValue *dest, const GValue *value1, const GValue *value2); gboolean gst_value_can_intersect (const GValue *value1, const GValue *value2); void gst_value_register_intersect_func (GType type1, GType type2, GstValueIntersectFunc func); void gst_value_array_append_value (GValue *value, const GValue *append_value); guint gst_value_array_get_size (const GValue *value); const GValue* gst_value_array_get_value (const GValue *value, guint index); void gst_value_array_prepend_value (GValue *value, const GValue *prepend_value);
GValue implementations specific to GStreamer.
Note that operations on the same GstValue (or GValue) from multiple threads may lead to undefined behaviour.
Last reviewed on 2008-03-11 (0.10.18)
#define GST_VALUE_HOLDS_FOURCC(x) (G_VALUE_HOLDS((x), gst_fourcc_get_type ()))
Checks if the given GValue contains a GST_TYPE_FOURCC value.
x : |
the GValue to check |
#define GST_MAKE_FOURCC(a,b,c,d) ((guint32)((a)|(b)<<8|(c)<<16|(d)<<24))
Transform four characters into a guint32 fourcc value with host endianness.
guint32 fourcc = GST_MAKE_FOURCC ('M', 'J', 'P', 'G');
a : |
the first character |
b : |
the second character |
c : |
the third character |
d : |
the fourth character |
#define GST_STR_FOURCC(f) ((guint32)(((f)[0])|((f)[1]<<8)|((f)[2]<<16)|((f)[3]<<24)))
Transform an input string into a guint32 fourcc value with host endianness. Caller is responsible for ensuring the input string consists of at least four characters.
guint32 fourcc = GST_STR_FOURCC ("MJPG");
f : |
a string with at least four characters |
#define GST_FOURCC_FORMAT "c%c%c%c"
Can be used together with GST_FOURCC_ARGS to properly output a
guint32 fourcc value in a printf()
-style text message.
printf ("fourcc: %" GST_FOURCC_FORMAT "\n", GST_FOURCC_ARGS (fcc));
#define GST_FOURCC_ARGS(fourcc)
Can be used together with GST_FOURCC_FORMAT to properly output a
guint32 fourcc value in a printf()
-style text message.
fourcc : |
a guint32 fourcc value to output |
#define GST_TYPE_FOURCC gst_fourcc_get_type ()
a GValue type that represents 4 byte identifier (e.g. used for codecs)
Returns : | the GType of GstFourcc |
void gst_value_set_fourcc (GValue *value, guint32 fourcc);
Sets value
to fourcc
.
value : |
a GValue initialized to GST_TYPE_FOURCC |
fourcc : |
the guint32 fourcc to set |
guint32 gst_value_get_fourcc (const GValue *value);
Gets the guint32 fourcc contained in value
.
value : |
a GValue initialized to GST_TYPE_FOURCC |
Returns : | the guint32 fourcc contained in value .
|
#define GST_VALUE_HOLDS_INT_RANGE(x) (G_VALUE_HOLDS((x), gst_int_range_get_type ()))
Checks if the given GValue contains a GST_TYPE_INT_RANGE value.
x : |
the GValue to check |
#define GST_TYPE_INT_RANGE gst_int_range_get_type ()
a GValue type that represents an integer range
Returns : | the GType of GstIntRange |
void gst_value_set_int_range (GValue *value, gint start, gint end);
Sets value
to the range specified by start
and end
.
value : |
a GValue initialized to GST_TYPE_INT_RANGE |
start : |
the start of the range |
end : |
the end of the range |
gint gst_value_get_int_range_min (const GValue *value);
Gets the minimum of the range specified by value
.
value : |
a GValue initialized to GST_TYPE_INT_RANGE |
Returns : | the minimum of the range |
gint gst_value_get_int_range_max (const GValue *value);
Gets the maximum of the range specified by value
.
value : |
a GValue initialized to GST_TYPE_INT_RANGE |
Returns : | the maxumum of the range |
#define GST_VALUE_HOLDS_DOUBLE_RANGE(x) (G_VALUE_HOLDS((x), gst_double_range_get_type ()))
Checks if the given GValue contains a GST_TYPE_DOUBLE_RANGE value.
x : |
the GValue to check |
#define GST_TYPE_DOUBLE_RANGE gst_double_range_get_type ()
a GValue type that represents a floating point range with double precission
Returns : | the GType of GstIntRange |
void gst_value_set_double_range (GValue *value, gdouble start, gdouble end);
Sets value
to the range specified by start
and end
.
value : |
a GValue initialized to GST_TYPE_DOUBLE_RANGE |
start : |
the start of the range |
end : |
the end of the range |
gdouble gst_value_get_double_range_min (const GValue *value);
Gets the minimum of the range specified by value
.
value : |
a GValue initialized to GST_TYPE_DOUBLE_RANGE |
Returns : | the minimum of the range |
gdouble gst_value_get_double_range_max (const GValue *value);
Gets the maximum of the range specified by value
.
value : |
a GValue initialized to GST_TYPE_DOUBLE_RANGE |
Returns : | the maxumum of the range |
#define GST_VALUE_HOLDS_LIST(x) (G_VALUE_HOLDS((x), gst_value_list_get_type ()))
Checks if the given GValue contains a GST_TYPE_LIST value.
x : |
the GValue to check |
#define GST_TYPE_LIST gst_value_list_get_type ()
a GValue type that represents an unordered list of GValue values. This is used for example to express a list of possible values for a field in a caps structure, like a list of possible sample rates, of which only one will be chosen in the end. This means that all values in the list are meaningful on their own.
Returns : | the GType of GstValueList (which is not explicitly typed) |
#define GST_VALUE_HOLDS_ARRAY(x) (G_VALUE_HOLDS((x), gst_value_array_get_type ()))
Checks if the given GValue contains a GST_TYPE_ARRAY value.
x : |
the GValue to check |
#define GST_TYPE_ARRAY gst_value_array_get_type ()
a GValue type that represents an ordered list of GValue values. This is used to express a set of values that is meaningful only in their specific combination and order of values. Each value on its own is not particularly meaningful, only the ordered array in its entirety is meaningful. This is used for example to express channel layouts for multichannel audio where each channel needs to be mapped to a position in the room.
Returns : | the GType of GstArrayList (which is not explicitly typed) |
void gst_value_list_append_value (GValue *value, const GValue *append_value);
Appends append_value
to the GstValueList in value
.
value : |
a GValue of type GST_TYPE_LIST |
append_value : |
the value to append |
void gst_value_list_prepend_value (GValue *value, const GValue *prepend_value);
Prepends prepend_value
to the GstValueList in value
.
value : |
a GValue of type GST_TYPE_LIST |
prepend_value : |
the value to prepend |
void gst_value_list_concat (GValue *dest, const GValue *value1, const GValue *value2);
Concatenates copies of value1
and value2
into a list. Values that are not
of type GST_TYPE_LIST are treated as if they were lists of length 1.
dest
will be initialized to the type GST_TYPE_LIST.
dest : |
an uninitialized GValue to take the result |
value1 : |
a GValue |
value2 : |
a GValue |
guint gst_value_list_get_size (const GValue *value);
Gets the number of values contained in value
.
value : |
a GValue of type GST_TYPE_LIST |
Returns : | the number of values |
const GValue* gst_value_list_get_value (const GValue *value, guint index);
Gets the value that is a member of the list contained in value
and
has the index index
.
value : |
a GValue of type GST_TYPE_LIST |
index : |
index of value to get from the list |
Returns : | the value at the given index |
#define GST_VALUE_HOLDS_FRACTION(x) (G_VALUE_HOLDS((x), gst_fraction_get_type ()))
Checks if the given GValue contains a GST_TYPE_FRACTION value.
x : |
the GValue to check |
#define GST_TYPE_FRACTION gst_fraction_get_type ()
a GValue type that represents a fraction of an integer numerator over an integer denominator
Returns : | the GType of GstFraction (which is not explicitly typed) |
void gst_value_set_fraction (GValue *value, gint numerator, gint denominator);
Sets value
to the fraction specified by numerator
over denominator
.
The fraction gets reduced to the smallest numerator and denominator,
and if necessary the sign is moved to the numerator.
value : |
a GValue initialized to GST_TYPE_FRACTION |
numerator : |
the numerator of the fraction |
denominator : |
the denominator of the fraction |
gint gst_value_get_fraction_numerator (const GValue *value);
Gets the numerator of the fraction specified by value
.
value : |
a GValue initialized to GST_TYPE_FRACTION |
Returns : | the numerator of the fraction. |
gint gst_value_get_fraction_denominator (const GValue *value);
Gets the denominator of the fraction specified by value
.
value : |
a GValue initialized to GST_TYPE_FRACTION |
Returns : | the denominator of the fraction. |
gboolean gst_value_fraction_multiply (GValue *product, const GValue *factor1, const GValue *factor2);
Multiplies the two GValues containing a GstFraction and sets product
to the product of the two fractions.
product : |
a GValue initialized to GST_TYPE_FRACTION |
factor1 : |
a GValue initialized to GST_TYPE_FRACTION |
factor2 : |
a GValue initialized to GST_TYPE_FRACTION |
Returns : | FALSE in case of an error (like integer overflow), TRUE otherwise. |
gboolean gst_value_fraction_subtract (GValue *dest, const GValue *minuend, const GValue *subtrahend);
Subtracts the subtrahend
from the minuend
and sets dest
to the result.
dest : |
a GValue initialized to GST_TYPE_FRACTION |
minuend : |
a GValue initialized to GST_TYPE_FRACTION |
subtrahend : |
a GValue initialized to GST_TYPE_FRACTION |
Returns : | FALSE in case of an error (like integer overflow), TRUE otherwise. |
#define GST_VALUE_HOLDS_FRACTION_RANGE(x) (G_VALUE_HOLDS((x), gst_fraction_range_get_type ()))
Checks if the given GValue contains a GST_TYPE_FRACTION_RANGE value.
x : |
the GValue to check |
#define GST_TYPE_FRACTION_RANGE gst_fraction_range_get_type ()
a GValue type that represents a GstFraction range
Returns : | the GType of GstFractionRange |
void gst_value_set_fraction_range (GValue *value, const GValue *start, const GValue *end);
Sets value
to the range specified by start
and end
.
value : |
a GValue initialized to GST_TYPE_FRACTION_RANGE |
start : |
the start of the range (a GST_TYPE_FRACTION GValue) |
end : |
the end of the range (a GST_TYPE_FRACTION GValue) |
const GValue* gst_value_get_fraction_range_min (const GValue *value);
Gets the minimum of the range specified by value
.
value : |
a GValue initialized to GST_TYPE_FRACTION_RANGE |
Returns : | the minimum of the range |
const GValue* gst_value_get_fraction_range_max (const GValue *value);
Gets the maximum of the range specified by value
.
value : |
a GValue initialized to GST_TYPE_FRACTION_RANGE |
Returns : | the maximum of the range |
void gst_value_set_fraction_range_full (GValue *value, gint numerator_start, gint denominator_start, gint numerator_end, gint denominator_end);
Sets value
to the range specified by numerator_start
/denominator_start
and numerator_end
/denominator_end
.
value : |
a GValue initialized to GST_TYPE_FRACTION_RANGE |
numerator_start : |
the numerator start of the range |
denominator_start : |
the denominator start of the range |
numerator_end : |
the numerator end of the range |
denominator_end : |
the denominator end of the range |
#define GST_VALUE_HOLDS_DATE(x) (G_VALUE_HOLDS((x), gst_date_get_type ()))
Checks if the given GValue contains a GST_TYPE_DATE value.
x : |
the GValue to check |
#define GST_TYPE_DATE gst_date_get_type ()
a boxed GValue type for GDate that represents a date.
Returns : | the GType of GstDate |
void gst_value_set_date (GValue *value, const GDate *date);
Sets the contents of value
to coorespond to date
. The actual
GDate structure is copied before it is used.
value : |
a GValue initialized to GST_TYPE_DATE |
date : |
the date to set the value to |
const GDate* gst_value_get_date (const GValue *value);
Gets the contents of value
.
value : |
a GValue initialized to GST_TYPE_DATE |
Returns : | the contents of value
|
#define GST_VALUE_HOLDS_CAPS(x) (G_VALUE_HOLDS((x), GST_TYPE_CAPS))
Checks if the given GValue contains a GST_TYPE_CAPS value.
x : |
the GValue to check |
void gst_value_set_caps (GValue *value, const GstCaps *caps);
Sets the contents of value
to caps
. The actual
GstCaps structure is copied before it is used.
value : |
a GValue initialized to GST_TYPE_CAPS |
caps : |
the caps to set the value to |
const GstCaps* gst_value_get_caps (const GValue *value);
Gets the contents of value
.
value : |
a GValue initialized to GST_TYPE_CAPS |
Returns : | the contents of value
|
#define GST_VALUE_HOLDS_STRUCTURE(x) (G_VALUE_HOLDS((x), GST_TYPE_STRUCTURE))
Checks if the given GValue contains a GST_TYPE_STRUCTURE value.
x : |
the GValue to check |
Since 0.10.15
void gst_value_set_structure (GValue *value, const GstStructure *structure);
Sets the contents of value
to structure
. The actual
value : |
a GValue initialized to GST_TYPE_STRUCTURE |
structure : |
the structure to set the value to |
Since 0.10.15
const GstStructure* gst_value_get_structure (const GValue *value);
Gets the contents of value
.
value : |
a GValue initialized to GST_TYPE_STRUCTURE |
Returns : | the contents of value
|
Since 0.10.15
#define GST_VALUE_HOLDS_MINI_OBJECT(value) (G_VALUE_HOLDS(value, GST_TYPE_MINI_OBJECT))
Checks if the given GValue contains a GST_TYPE_MINI_OBJECT value.
value : |
the GValue to check |
#define GST_VALUE_HOLDS_BUFFER(x) (G_VALUE_HOLDS((x), GST_TYPE_BUFFER))
Checks if the given GValue contains a GST_TYPE_BUFFER value.
x : |
the GValue to check |
#define gst_value_get_buffer(v) GST_BUFFER_CAST (gst_value_get_mini_object(v))
Receives a GstBuffer as the value of v
. Does not return a reference to
the buffer, so the pointer is only valid for as long as the caller owns
a reference to v
.
v : |
a GstValue to qeury |
#define gst_value_set_buffer(v,b) gst_value_set_mini_object(v, GST_MINI_OBJECT_CAST(b))
Sets b
as the value of v
. Caller retains reference to buffer.
v : |
a GstValue to receive the data |
b : |
a GstBuffer to assign to the GstValue |
#define gst_value_take_buffer(v,b) gst_value_take_mini_object(v, GST_MINI_OBJECT_CAST(b))
Sets b
as the value of v
. Caller gives away reference to buffer.
v : |
a GstValue to receive the data |
b : |
a GstBuffer to assign to the GstValue |
#define GST_VALUE_LESS_THAN (-1)
Indicates that the first value provided to a comparison function
(gst_value_compare()
) is lesser than the second one.
#define GST_VALUE_EQUAL 0
Indicates that the first value provided to a comparison function
(gst_value_compare()
) is equal to the second one.
#define GST_VALUE_GREATER_THAN 1
Indicates that the first value provided to a comparison function
(gst_value_compare()
) is greater than the second one.
#define GST_VALUE_UNORDERED 2
Indicates that the comparison function (gst_value_compare()
) can not
determine a order for the two provided values.
gint (*GstValueCompareFunc) (const GValue *value1, const GValue *value2);
Used together with gst_value_compare()
to compare GValues.
value1 : |
first value for comparission |
value2 : |
second value for comparission |
Returns : | one of GST_VALUE_LESS_THAN, GST_VALUE_EQUAL, GST_VALUE_GREATER_THAN or GST_VALUE_UNORDERED |
gchar* (*GstValueSerializeFunc) (const GValue *value1);
Used by gst_value_serialize()
to obtain a non-binary form of the GValue.
value1 : |
a GValue |
Returns : | the string representation of the value |
gboolean (*GstValueDeserializeFunc) (GValue *dest, const gchar *s);
Used by gst_value_deserialize()
to parse a non-binary form into the GValue.
dest : |
a GValue |
s : |
a string |
Returns : | TRUE for success
|
gboolean (*GstValueUnionFunc) (GValue *dest, const GValue *value1, const GValue *value2);
Used by gst_value_union()
to perform unification for a specific GValue
type. Register a new implementation with gst_value_register_union_func()
.
dest : |
a GValue for the result |
value1 : |
a GValue operand |
value2 : |
a GValue operand |
Returns : | TRUE if a union was successful
|
gboolean (*GstValueIntersectFunc) (GValue *dest, const GValue *value1, const GValue *value2);
Used by gst_value_intersect()
to perform intersection for a specific GValue
type. If the intersection is non-empty, the result is
placed in dest
and TRUE is returned. If the intersection is
empty, dest
is unmodified and FALSE is returned.
Register a new implementation with gst_value_register_intersection_func()
.
dest : |
a GValue for the result |
value1 : |
a GValue operand |
value2 : |
a GValue operand |
Returns : | TRUE if the values can intersect
|
gboolean (*GstValueSubtractFunc) (GValue *dest, const GValue *minuend, const GValue *subtrahend);
Used by gst_value_subtract()
to perform subtraction for a specific GValue
type. Register a new implementation with gst_value_register_subtract_func()
.
dest : |
a GValue for the result |
minuend : |
a GValue operand |
subtrahend : |
a GValue operand |
Returns : | TRUE if the subtraction is not empty
|
typedef struct { GType type; GstValueCompareFunc compare; GstValueSerializeFunc serialize; GstValueDeserializeFunc deserialize; } GstValueTable;
VTable for the GValue type
.
GType type ; |
a GType |
GstValueCompareFunc compare ; |
a GstValueCompareFunc |
GstValueSerializeFunc serialize ; |
a GstValueSerializeFunc |
GstValueDeserializeFunc deserialize ; |
a GstValueDeserializeFunc |
gboolean gst_value_is_fixed (const GValue *value);
Tests if the given GValue, if available in a GstStructure (or any other container) contains a "fixed" (which means: one value) or an "unfixed" (which means: multiple possible values, such as data lists or data ranges) value.
value : |
the GValue to check |
Returns : | true if the value is "fixed". |
void gst_value_register (const GstValueTable *table);
Registers functions to perform calculations on GValues of a given type. Each type can only be added once.
table : |
structure containing functions to register |
void gst_value_init_and_copy (GValue *dest, const GValue *src);
Initialises the target value to be of the same type as source and then copies the contents from source to target.
dest : |
the target value |
src : |
the source value |
gchar* gst_value_serialize (const GValue *value);
tries to transform the given value
into a string representation that allows
getting back this string later on using gst_value_deserialize()
.
value : |
a GValue to serialize |
Returns : | the serialization for value or NULL if none exists
|
gboolean gst_value_deserialize (GValue *dest, const gchar *src);
Tries to deserialize a string into the type specified by the given GValue. If the operation succeeds, TRUE is returned, FALSE otherwise.
dest : |
GValue to fill with contents of deserialization |
src : |
string to deserialize |
Returns : | TRUE on success |
gint gst_value_compare (const GValue *value1, const GValue *value2);
Compares value1
and value2
. If value1
and value2
cannot be
compared, the function returns GST_VALUE_UNORDERED. Otherwise,
if value1
is greater than value2
, GST_VALUE_GREATER_THAN is returned.
If value1
is less than value2
, GST_VALUE_LESS_THAN is returned.
If the values are equal, GST_VALUE_EQUAL is returned.
value1 : |
a value to compare |
value2 : |
another value to compare |
Returns : | A GstValueCompareType value |
gboolean gst_value_can_compare (const GValue *value1, const GValue *value2);
Determines if value1
and value2
can be compared.
value1 : |
a value to compare |
value2 : |
another value to compare |
Returns : | TRUE if the values can be compared |
gboolean gst_value_union (GValue *dest, const GValue *value1, const GValue *value2);
Creates a GValue corresponding to the union of value1
and value2
.
dest : |
the destination value |
value1 : |
a value to union |
value2 : |
another value to union |
Returns : | always returns TRUE
|
gboolean gst_value_can_union (const GValue *value1, const GValue *value2);
Determines if value1
and value2
can be non-trivially unioned.
Any two values can be trivially unioned by adding both of them
to a GstValueList. However, certain types have the possibility
to be unioned in a simpler way. For example, an integer range
and an integer can be unioned if the integer is a subset of the
integer range. If there is the possibility that two values can
be unioned, this function returns TRUE.
value1 : |
a value to union |
value2 : |
another value to union |
Returns : | TRUE if there is a function allowing the two values to be unioned. |
void gst_value_register_union_func (GType type1, GType type2, GstValueUnionFunc func);
Registers a union function that can create a union between GValues
of the type type1
and type2
.
Union functions should be registered at startup before any pipelines are
started, as gst_value_register_union_func()
is not thread-safe and cannot
be used at the same time as gst_value_union()
or gst_value_can_union()
.
type1 : |
a type to union |
type2 : |
another type to union |
func : |
a function that implments creating a union between the two types |
gboolean gst_value_subtract (GValue *dest, const GValue *minuend, const GValue *subtrahend);
Subtracts subtrahend
from minuend
and stores the result in dest
.
Note that this means subtraction as in sets, not as in mathematics.
dest : |
the destination value for the result if the subtraction is not empty |
minuend : |
the value to subtract from |
subtrahend : |
the value to subtract |
Returns : | TRUE if the subtraction is not empty
|
gboolean gst_value_can_subtract (const GValue *minuend, const GValue *subtrahend);
Checks if it's possible to subtract subtrahend
from minuend
.
minuend : |
the value to subtract from |
subtrahend : |
the value to subtract |
Returns : | TRUE if a subtraction is possible |
void gst_value_register_subtract_func (GType minuend_type, GType subtrahend_type, GstValueSubtractFunc func);
Registers func
as a function capable of subtracting the values of
subtrahend_type
from values of minuend_type
.
Subtract functions should be registered at startup before any pipelines are
started, as gst_value_register_subtract_func()
is not thread-safe and
cannot be used at the same time as gst_value_subtract()
.
minuend_type : |
type of the minuend |
subtrahend_type : |
type of the subtrahend |
func : |
function to use |
gboolean gst_value_intersect (GValue *dest, const GValue *value1, const GValue *value2);
Calculates the intersection of two values. If the values have
a non-empty intersection, the value representing the intersection
is placed in dest
. If the intersection is non-empty, dest
is
not modified.
dest : |
a uninitialized GValue that will hold the calculated intersection value |
value1 : |
a value to intersect |
value2 : |
another value to intersect |
Returns : | TRUE if the intersection is non-empty |
gboolean gst_value_can_intersect (const GValue *value1, const GValue *value2);
Determines if intersecting two values will produce a valid result.
Two values will produce a valid intersection if they have the same
type, or if there is a method (registered by
gst_value_register_intersection_func()
) to calculate the intersection.
value1 : |
a value to intersect |
value2 : |
another value to intersect |
Returns : | TRUE if the values can intersect |
void gst_value_register_intersect_func (GType type1, GType type2, GstValueIntersectFunc func);
Registers a function that is called to calculate the intersection
of the values having the types type1
and type2
.
Intersect functions should be registered at startup before any pipelines are
started, as gst_value_register_intersect_func()
is not thread-safe and
cannot be used at the same time as gst_value_intersect()
or
gst_value_can_intersect()
.
type1 : |
the first type to intersect |
type2 : |
the second type to intersect |
func : |
the intersection function |
void gst_value_array_append_value (GValue *value, const GValue *append_value);
Appends append_value
to the GstValueArray in value
.
value : |
a GValue of type GST_TYPE_ARRAY |
append_value : |
the value to append |
guint gst_value_array_get_size (const GValue *value);
Gets the number of values contained in value
.
value : |
a GValue of type GST_TYPE_ARRAY |
Returns : | the number of values |
const GValue* gst_value_array_get_value (const GValue *value, guint index);
Gets the value that is a member of the array contained in value
and
has the index index
.
value : |
a GValue of type GST_TYPE_ARRAY |
index : |
index of value to get from the array |
Returns : | the value at the given index |
void gst_value_array_prepend_value (GValue *value, const GValue *prepend_value);
Prepends prepend_value
to the GstValueArray in value
.
value : |
a GValue of type GST_TYPE_ARRAY |
prepend_value : |
the value to prepend |