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GStreamer 0.10 Library Reference Manual | |
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#include <libs/controller/gstcontrolsource.h>
GstControlSource;
GstControlSourceClass;
gboolean (*GstControlSourceBind) (GstControlSource *self,
GParamSpec *pspec);
gboolean (*GstControlSourceGetValue) (GstControlSource *self,
GstClockTime timestamp,
GValue *value);
gboolean (*GstControlSourceGetValueArray) (GstControlSource *self,
GstClockTime timestamp,
GstValueArray *value_array);
GstTimedValue;
GstValueArray;
gboolean gst_control_source_bind (GstControlSource *self,
GParamSpec *pspec);
gboolean gst_control_source_get_value (GstControlSource *self,
GstClockTime timestamp,
GValue *value);
gboolean gst_control_source_get_value_array (GstControlSource *self,
GstClockTime timestamp,
GstValueArray *value_array);
The GstControlSource is a base class for control value sources that could be used by GstController to get timestamp-value pairs.
A GstControlSource is used by first getting an instance, binding it to a GParamSpec (for example by using gst_controller_set_control_source()) and then by having it used by the GstController or calling gst_control_source_get_value() or gst_control_source_get_value_array().
For implementing a new GstControlSource one has to implement a GstControlSourceBind method, which will depending on the GParamSpec set up the control source for use and sets the GstControlSourceGetValue and GstControlSourceGetValueArray functions. These are then used by gst_control_source_get_value() or gst_control_source_get_value_array() to get values for specific timestamps.
typedef struct {
GstControlSourceGetValue get_value; /* Returns the value for a property at a given timestamp */
GstControlSourceGetValueArray get_value_array; /* Returns values for a property in a given timespan */
} GstControlSource;
The instance structure of GstControlSource.
| GstControlSourceGetValue get_value; | Function for returning a value for a given timestamp |
| GstControlSourceGetValueArray get_value_array; | Function for returning a GstValueArray for a given timestamp |
typedef struct {
GObjectClass parent_class;
GstControlSourceBind bind; /* Binds the GstControlSource to a specific GParamSpec */
} GstControlSourceClass;
The class structure of GstControlSource.
| GObjectClass parent_class; | Parent class |
| GstControlSourceBind bind; | Class method for binding the GstControlSource to a specific GParamSpec |
gboolean (*GstControlSourceBind) (GstControlSource *self, GParamSpec *pspec);
Function for binding a GstControlSource to a GParamSpec.
| self : | the GstControlSource instance |
| pspec : | GParamSpec that should be bound to |
| Returns : | TRUE if the property could be bound to the GstControlSource, FALSE otherwise. |
gboolean (*GstControlSourceGetValue) (GstControlSource *self, GstClockTime timestamp, GValue *value);
Function for returning a value for a given timestamp.
| self : | the GstControlSource instance |
| timestamp : | timestamp for which a value should be calculated |
| value : | a GValue which will be set to the result. It must be initialized to the correct type. |
| Returns : | TRUE if the value was successfully calculated. |
gboolean (*GstControlSourceGetValueArray) (GstControlSource *self, GstClockTime timestamp, GstValueArray *value_array);
Function for returning a GstValueArray for a given timestamp.
| self : | the GstControlSource instance |
| timestamp : | timestamp for which a value should be calculated |
| value_array : | array to put control-values in |
| Returns : | TRUE if the values were successfully calculated. |
typedef struct {
GstClockTime timestamp; /* timestamp of the value change */
GValue value; /* the corresponding value */
} GstTimedValue;
Structure for saving a timestamp and a value.
typedef struct {
gchar *property_name;
gint nbsamples;
GstClockTime sample_interval;
gpointer *values;
} GstValueArray;
Structure to receive multiple values at once.
| gchar *property_name; | the name of the property this array belongs to |
| gint nbsamples; | number of samples requested |
| GstClockTime sample_interval; | interval between each sample |
| gpointer *values; | pointer to the array |
gboolean gst_control_source_bind (GstControlSource *self, GParamSpec *pspec);
Binds a GstControlSource to a specific property. This must be called only once for a GstControlSource.
| self : | the GstControlSource object |
| pspec : | GParamSpec for the property for which this GstControlSource should generate values. |
| Returns : | TRUE if the GstControlSource was bound correctly, FALSE otherwise. |
gboolean gst_control_source_get_value (GstControlSource *self, GstClockTime timestamp, GValue *value);
Gets the value for this GstControlSource at a given timestamp.
| self : | the GstControlSource object |
| timestamp : | the time for which the value should be returned |
| value : | the value |
| Returns : | FALSE if the value couldn't be returned, TRUE otherwise. |
gboolean gst_control_source_get_value_array (GstControlSource *self, GstClockTime timestamp, GstValueArray *value_array);
Gets an array of values for one element property.
All fields of value_array must be filled correctly. Especially the value_array->values array must be big enough to keep the requested amount of values.
The type of the values in the array is the same as the property's type.
| self : | the GstControlSource object |
| timestamp : | the time that should be processed |
| value_array : | array to put control-values in |
| Returns : | TRUE if the given array could be filled, FALSE otherwise |