GStreamer Core Reference Manual
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GstEvent

Name

GstEvent -- Event definitions.

Synopsis


#include <gst/gst.h>


enum        GstEventType;
#define     GST_EVENT_TYPE                  (event)
#define     GST_EVENT_SRC                   (event)
#define     GST_EVENT_TIMESTAMP             (event)
enum        GstSeekType;
enum        GstSeekAccuracy;
#define     GST_EVENT_SEEK_TYPE             (event)
#define     GST_EVENT_SEEK_FORMAT           (event)
#define     GST_EVENT_SEEK_METHOD           (event)
#define     GST_EVENT_SEEK_FLAGS            (event)
#define     GST_EVENT_SEEK_OFFSET           (event)
#define     GST_EVENT_SEEK_ACCURACY         (event)
#define     GST_SEEK_FLAGS_MASK
#define     GST_SEEK_FLAGS_SHIFT
#define     GST_SEEK_FORMAT_MASK
#define     GST_SEEK_FORMAT_SHIFT
#define     GST_SEEK_METHOD_MASK
#define     GST_SEEK_METHOD_SHIFT
#define     GST_EVENT_DISCONT_NEW_MEDIA     (event)
#define     GST_EVENT_DISCONT_OFFSET        (event,i)
#define     GST_EVENT_DISCONT_OFFSET_LEN    (event)
struct      GstEvent;
GstEvent*   gst_event_new                   (GstEventType type);
GstEvent*   gst_event_copy                  (GstEvent *event);
void        gst_event_free                  (GstEvent *event);
GstEvent*   gst_event_new_seek              (GstSeekType type,
                                             gint64 offset);
GstEvent*   gst_event_new_discontinuous     (gboolean new_media,
                                             GstFormat format1,
                                             ...);
gboolean    gst_event_discont_get_value     (GstEvent *event,
                                             GstFormat format,
                                             gint64 *value);
#define     gst_event_new_filler            ()
#define     gst_event_new_flush             ()

Description

The event classes are used to construct and query events.

Events are usually created with gst_event_new() which takes the event type as an argument. properties specific to the event can be set afterwards with the provided macros. The event is freed with gst_event_free().

gst_event_new_seek() is a usually used to create a seek event and it takes the needed parameters for a seek event.

gst_event_new_flush() creates a new flush event.

Details

enum GstEventType

typedef enum {
  GST_EVENT_UNKNOWN,
  GST_EVENT_EOS,
  GST_EVENT_FLUSH,
  GST_EVENT_EMPTY,
  GST_EVENT_DISCONTINUOUS,
  GST_EVENT_NEW_MEDIA,
  GST_EVENT_QOS,
  GST_EVENT_SEEK,
  GST_EVENT_FILLER,
  GST_EVENT_SIZE
} GstEventType;

The different major types of events.

GST_EVENT_UNKNOWNunknown event.
GST_EVENT_EOSan end-of-stream event.
GST_EVENT_FLUSHa flush event.
GST_EVENT_EMPTYan empty event.
GST_EVENT_DISCONTINUOUSa discontinuous event to indicate the stream has a discontinuity.
GST_EVENT_NEW_MEDIAa new media stream is started
GST_EVENT_QOSa quality of service event
GST_EVENT_SEEKa seek event.
GST_EVENT_FILLERa dummy element that should be ignored by plugins
GST_EVENT_SIZE 

GST_EVENT_TYPE()

#define GST_EVENT_TYPE(event)		(GST_EVENT(event)->type)

Get the event type.

event :The event to query.

GST_EVENT_SRC()

#define GST_EVENT_SRC(event)		(GST_EVENT(event)->src)

The source object that generated this event

event :The event to query

GST_EVENT_TIMESTAMP()

#define GST_EVENT_TIMESTAMP(event)	(GST_EVENT(event)->timestamp)

Get the timestamp of the event.

event :The event to query.

enum GstSeekType

typedef enum {
  GST_SEEK_METHOD_CUR		= (1 << GST_SEEK_METHOD_SHIFT),
  GST_SEEK_METHOD_SET		= (2 << GST_SEEK_METHOD_SHIFT),
  GST_SEEK_METHOD_END		= (3 << GST_SEEK_METHOD_SHIFT),

  GST_SEEK_FLAG_FLUSH		= (1 << (GST_SEEK_FLAGS_SHIFT + 0)),
  GST_SEEK_FLAG_ACCURATE	= (1 << (GST_SEEK_FLAGS_SHIFT + 1)),
  GST_SEEK_FLAG_KEY_UNIT	= (1 << (GST_SEEK_FLAGS_SHIFT + 2))
} GstSeekType;

The different types of seek events.

GST_SEEK_METHOD_CURSeek to an relative position
GST_SEEK_METHOD_SETSeek to an absolute position
GST_SEEK_METHOD_ENDSeek relative to the end of the stream
GST_SEEK_FLAG_FLUSHFlush any pending data while seeking
GST_SEEK_FLAG_ACCURATESeek as accuratly as possible
GST_SEEK_FLAG_KEY_UNITSeek to a nearby key unit

enum GstSeekAccuracy

typedef enum {
  GST_SEEK_CERTAIN,
  GST_SEEK_FUZZY
} GstSeekAccuracy;

The seekaccuracy gives more information of how the seek was performed, if the seek was accurate or fuzzy.

GST_EVENT_SEEK_TYPE()

#define GST_EVENT_SEEK_TYPE(event)		(GST_EVENT(event)->event_data.seek.type)

Get the seektype of the GST_EVENT_SEEK.

event :The event to query.

GST_EVENT_SEEK_FORMAT()

#define GST_EVENT_SEEK_FORMAT(event)		(GST_EVENT_SEEK_TYPE(event) & GST_SEEK_FORMAT_MASK)

The format of the seek value

event :The event operate on

GST_EVENT_SEEK_METHOD()

#define GST_EVENT_SEEK_METHOD(event)		(GST_EVENT_SEEK_TYPE(event) & GST_SEEK_METHOD_MASK)

The seek method to use as one of GstSeekType

event :The event operate on

GST_EVENT_SEEK_FLAGS()

#define GST_EVENT_SEEK_FLAGS(event)		(GST_EVENT_SEEK_TYPE(event) & GST_SEEK_FLAGS_MASK)

The optional seek flags

event :The event operate on

GST_EVENT_SEEK_OFFSET()

#define GST_EVENT_SEEK_OFFSET(event)		(GST_EVENT(event)->event_data.seek.offset)

Get the offset of the seek event.

event :The event to query.

GST_EVENT_SEEK_ACCURACY()

#define GST_EVENT_SEEK_ACCURACY(event)		(GST_EVENT(event)->event_data.seek.accuracy)

Indicates how accurate the event was performed.

event :The event to query

GST_SEEK_FLAGS_MASK

#define GST_SEEK_FLAGS_MASK	0xfff00000

GST_SEEK_FLAGS_SHIFT

#define GST_SEEK_FLAGS_SHIFT	20

GST_SEEK_FORMAT_MASK

#define GST_SEEK_FORMAT_MASK	0x0000ffff

GST_SEEK_FORMAT_SHIFT

#define GST_SEEK_FORMAT_SHIFT	0

GST_SEEK_METHOD_MASK

#define GST_SEEK_METHOD_MASK	0x000f0000

GST_SEEK_METHOD_SHIFT

#define GST_SEEK_METHOD_SHIFT	16

GST_EVENT_DISCONT_NEW_MEDIA()

#define GST_EVENT_DISCONT_NEW_MEDIA(event)	(GST_EVENT(event)->event_data.discont.new_media)

Flag that indicates the discont event was because of a new media type.

event :The event to operate on

GST_EVENT_DISCONT_OFFSET()

#define GST_EVENT_DISCONT_OFFSET(event,i)	(GST_EVENT(event)->event_data.discont.offsets[i])

The offset of the discont event. A discont evetn can hold up to 8 different format/value pairs.

event :The event to query
i :The offset/value pair.

GST_EVENT_DISCONT_OFFSET_LEN()

#define GST_EVENT_DISCONT_OFFSET_LEN(event)	(GST_EVENT(event)->event_data.discont.noffsets)

Get the number of offset/value pairs this event has.

event :The event to query.

struct GstEvent

struct GstEvent {
  GstData data;

  GstEventType  type;
  guint64	timestamp;
  GstObject	*src;

  union {
    struct {
      GstSeekType 	type;
      gint64      	offset;
      GstSeekAccuracy 	accuracy;
    } seek;
    struct {
      GstFormatValue 	offsets[8];
      gint      	noffsets;
      gboolean		new_media;
    } discont;
    struct {
      GstFormat 	format;
      gint64      	value;
    } size;
  } event_data;
};

The event data structure.

GstData dataThe parent data type.
GstEventType typeThe event type.
guint64 timestampThe event timestamp.
GstObject *srcThe object that generated the event

gst_event_new ()

GstEvent*   gst_event_new                   (GstEventType type);

Allocate a new event of the given type.

type : The type of the new event
Returns : A new event.

gst_event_copy ()

GstEvent*   gst_event_copy                  (GstEvent *event);

Copy the event

event : The event to copy
Returns : A copy of the event.

gst_event_free ()

void        gst_event_free                  (GstEvent *event);

Free the given element.

event : The event to free

gst_event_new_seek ()

GstEvent*   gst_event_new_seek              (GstSeekType type,
                                             gint64 offset);

Allocate a new seek event with the given parameters.

type : The type of the seek event
offset : The offset of the seek
Returns : A new seek event.

gst_event_new_discontinuous ()

GstEvent*   gst_event_new_discontinuous     (gboolean new_media,
                                             GstFormat format1,
                                             ...);

Allocate a new discontinuous event with the geven format/value pairs.

new_media : A flag indicating a new media type starts
format1 : The format of the discont value
... : more discont values and formats
Returns : A new discontinuous event.

gst_event_discont_get_value ()

gboolean    gst_event_discont_get_value     (GstEvent *event,
                                             GstFormat format,
                                             gint64 *value);

Get the value for the given format in the dicont event.

event : The event to query
format : The format of the discont value
value : A pointer to the value
Returns : TRUE if the discont event caries the specified format/value pair.

gst_event_new_filler()

#define		gst_event_new_filler()		gst_event_new(GST_EVENT_FILLER)

Create a new dummy event that should be ignored

gst_event_new_flush()

#define		gst_event_new_flush()		gst_event_new(GST_EVENT_FLUSH)

Create a new flush event.

See Also

GstPad



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