GstEvent

GstEvent — Structure describing events that are passed up and down a pipeline

Synopsis


#include <gst/gst.h>


                    GstEvent;
enum                GstEventType;
#define             GST_EVENT_TRACE_NAME
#define             GST_EVENT_TYPE                      (event)
#define             GST_EVENT_TYPE_NAME                 (event)
#define             GST_EVENT_TYPE_BOTH
#define             GST_EVENT_TIMESTAMP                 (event)
#define             GST_EVENT_SRC                       (event)
#define             GST_EVENT_IS_DOWNSTREAM             (ev)
#define             GST_EVENT_IS_SERIALIZED             (ev)
#define             GST_EVENT_IS_UPSTREAM               (ev)
enum                GstSeekType;
enum                GstSeekFlags;
enum                GstEventTypeFlags;
#define             GST_EVENT_MAKE_TYPE                 (num,flags)
#define             gst_event_copy                      (ev)
const GstStructure* gst_event_get_structure             (GstEvent *event);
GstEvent*           gst_event_new_buffer_size           (GstFormat format,
                                                         gint64 minsize,
                                                         gint64 maxsize,
                                                         gboolean async);
GstEvent*           gst_event_new_custom                (GstEventType type,
                                                         GstStructure *structure);
GstEvent*           gst_event_new_eos                   (void);
GstEvent*           gst_event_new_flush_start           (void);
GstEvent*           gst_event_new_flush_stop            (void);
GstEvent*           gst_event_new_latency               (GstClockTime latency);
GstEvent*           gst_event_new_navigation            (GstStructure *structure);
GstEvent*           gst_event_new_new_segment           (gboolean update,
                                                         gdouble rate,
                                                         GstFormat format,
                                                         gint64 start,
                                                         gint64 stop,
                                                         gint64 position);
GstEvent*           gst_event_new_new_segment_full      (gboolean update,
                                                         gdouble rate,
                                                         gdouble applied_rate,
                                                         GstFormat format,
                                                         gint64 start,
                                                         gint64 stop,
                                                         gint64 position);
GstEvent*           gst_event_new_qos                   (gdouble proportion,
                                                         GstClockTimeDiff diff,
                                                         GstClockTime timestamp);
GstEvent*           gst_event_new_seek                  (gdouble rate,
                                                         GstFormat format,
                                                         GstSeekFlags flags,
                                                         GstSeekType start_type,
                                                         gint64 start,
                                                         GstSeekType stop_type,
                                                         gint64 stop);
GstEvent*           gst_event_new_tag                   (GstTagList *taglist);
void                gst_event_parse_buffer_size         (GstEvent *event,
                                                         GstFormat *format,
                                                         gint64 *minsize,
                                                         gint64 *maxsize,
                                                         gboolean *async);
void                gst_event_parse_latency             (GstEvent *event,
                                                         GstClockTime *latency);
void                gst_event_parse_new_segment         (GstEvent *event,
                                                         gboolean *update,
                                                         gdouble *rate,
                                                         GstFormat *format,
                                                         gint64 *start,
                                                         gint64 *stop,
                                                         gint64 *position);
void                gst_event_parse_new_segment_full    (GstEvent *event,
                                                         gboolean *update,
                                                         gdouble *rate,
                                                         gdouble *applied_rate,
                                                         GstFormat *format,
                                                         gint64 *start,
                                                         gint64 *stop,
                                                         gint64 *position);
void                gst_event_parse_qos                 (GstEvent *event,
                                                         gdouble *proportion,
                                                         GstClockTimeDiff *diff,
                                                         GstClockTime *timestamp);
void                gst_event_parse_seek                (GstEvent *event,
                                                         gdouble *rate,
                                                         GstFormat *format,
                                                         GstSeekFlags *flags,
                                                         GstSeekType *start_type,
                                                         gint64 *start,
                                                         GstSeekType *stop_type,
                                                         gint64 *stop);
void                gst_event_parse_tag                 (GstEvent *event,
                                                         GstTagList **taglist);
GstEvent*           gst_event_ref                       (GstEvent *event);
#define             gst_event_unref                     (ev)
#define             gst_event_replace                   (old_event,new_event)
GstEventTypeFlags   gst_event_type_get_flags            (GstEventType type);
const gchar*        gst_event_type_get_name             (GstEventType type);
GQuark              gst_event_type_to_quark             (GstEventType type);


Description

The event class provides factory methods to construct and functions query (parse) events.

Events are usually created with gst_event_new_*() which takes event-type specific parameters as arguments. To send an event application will usually use gst_element_send_event() and elements will use gst_pad_send_event() or gst_pad_push_event(). The event should be unreffed with gst_event_unref() if it has not been sent.

Events that have been received can be parsed with their respective gst_event_parse_*() functions.

Events are passed between elements in parallel to the data stream. Some events are serialized with buffers, others are not. Some events only travel downstream, others only upstream. Some events can travel both upstream and downstream.

The events are used to signal special conditions in the datastream such as EOS (end of stream) or the start of a new stream-segment. Events are also used to flush the pipeline of any pending data.

Most of the event API is used inside plugins. Applications usually only construct and use seek events. To do that gst_event_new_seek() is used to create a seek event. It takes the needed parameters to specity seeking time and mode.

Example 8. performing a seek on a pipeline

  GstEvent *event;
  gboolean result;
  ...
  // construct a seek event to play the media from second 2 to 5, flush
  // the pipeline to decrease latency.
  event = gst_event_new_seek (1.0, 
     GST_FORMAT_TIME, 
     GST_SEEK_FLAG_FLUSH,
     GST_SEEK_TYPE_SET, 2 * GST_SECOND,
     GST_SEEK_TYPE_SET, 5 * GST_SECOND);
  ...
  result = gst_element_send_event (pipeline, event);
  if (!result)
    g_warning ("seek failed");
  ...
  


Last reviewed on 2006-09-6 (0.10.10)

Details

GstEvent

typedef struct {
  GstMiniObject mini_object;

  GstEventType  type;
  guint64	timestamp;
  GstObject	*src;

  GstStructure	*structure;
} GstEvent;

A GstEvent.

GstMiniObject mini_object; the parent structure
GstEventType type; the GstEventType of the event
guint64 timestamp; the timestamp of the event
GstObject *src; the src of the event
GstStructure *structure; the GstStructure containing the event info.

enum GstEventType

typedef enum {
  GST_EVENT_UNKNOWN		  = GST_EVENT_MAKE_TYPE (0, 0),
  /* bidirectional events */
  GST_EVENT_FLUSH_START		  = GST_EVENT_MAKE_TYPE (1, FLAG(BOTH)),
  GST_EVENT_FLUSH_STOP		  = GST_EVENT_MAKE_TYPE (2, FLAG(BOTH) | FLAG(SERIALIZED)),
  /* downstream serialized events */
  GST_EVENT_EOS			  = GST_EVENT_MAKE_TYPE (5, FLAG(DOWNSTREAM) | FLAG(SERIALIZED)),
  GST_EVENT_NEWSEGMENT		  = GST_EVENT_MAKE_TYPE (6, FLAG(DOWNSTREAM) | FLAG(SERIALIZED)),
  GST_EVENT_TAG			  = GST_EVENT_MAKE_TYPE (7, FLAG(DOWNSTREAM) | FLAG(SERIALIZED)),
  GST_EVENT_BUFFERSIZE		  = GST_EVENT_MAKE_TYPE (8, FLAG(DOWNSTREAM) | FLAG(SERIALIZED)),
  /* upstream events */
  GST_EVENT_QOS			  = GST_EVENT_MAKE_TYPE (15, FLAG(UPSTREAM)),
  GST_EVENT_SEEK		  = GST_EVENT_MAKE_TYPE (16, FLAG(UPSTREAM)),
  GST_EVENT_NAVIGATION		  = GST_EVENT_MAKE_TYPE (17, FLAG(UPSTREAM)),
  GST_EVENT_LATENCY		  = GST_EVENT_MAKE_TYPE (18, FLAG(UPSTREAM)),

  /* custom events start here */
  GST_EVENT_CUSTOM_UPSTREAM	  = GST_EVENT_MAKE_TYPE (32, FLAG(UPSTREAM)),
  GST_EVENT_CUSTOM_DOWNSTREAM	  = GST_EVENT_MAKE_TYPE (32, FLAG(DOWNSTREAM) | FLAG(SERIALIZED)),
  GST_EVENT_CUSTOM_DOWNSTREAM_OOB = GST_EVENT_MAKE_TYPE (32, FLAG(DOWNSTREAM)),
  GST_EVENT_CUSTOM_BOTH		  = GST_EVENT_MAKE_TYPE (32, FLAG(BOTH) | FLAG(SERIALIZED)),
  GST_EVENT_CUSTOM_BOTH_OOB	  = GST_EVENT_MAKE_TYPE (32, FLAG(BOTH))
} GstEventType;

GstEventType lists the standard event types that can be sent in a pipeline.

The custom event types can be used for private messages between elements that can't be expressed using normal GStreamer buffer passing semantics. Custom events carry an arbitrary GstStructure. Specific custom events are distinguished by the name of the structure.

GST_EVENT_UNKNOWN unknown event.
GST_EVENT_FLUSH_START Start a flush operation
GST_EVENT_FLUSH_STOP Stop a flush operation
GST_EVENT_EOS End-Of-Stream. No more data is to be expected to follow without a NEWSEGMENT event.
GST_EVENT_NEWSEGMENT A new media segment follows in the dataflow.
GST_EVENT_TAG A new set of metadata tags has been found in the stream.
GST_EVENT_BUFFERSIZE Notification of buffering requirements
GST_EVENT_QOS A quality message. Used to indicate to upstream elements that the downstream elements are being starved of or flooded with data.
GST_EVENT_SEEK A request for a new playback position and rate.
GST_EVENT_NAVIGATION Navigation events are usually used for communicating user requests, such as mouse or keyboard movements, to upstream elements.
GST_EVENT_LATENCY Notification of new latency adjustment. Since: 0.10.12
GST_EVENT_CUSTOM_UPSTREAM Upstream custom event
GST_EVENT_CUSTOM_DOWNSTREAM Downstream custom event that travels in the data flow.
GST_EVENT_CUSTOM_DOWNSTREAM_OOB Custom out-of-band downstream event.
GST_EVENT_CUSTOM_BOTH Custom upstream or downstream event. In-band when travelling downstream.
GST_EVENT_CUSTOM_BOTH_OOB Custom upstream or downstream out-of-band event.

GST_EVENT_TRACE_NAME

#define GST_EVENT_TRACE_NAME	"GstEvent"

The name used for memory allocation tracing


GST_EVENT_TYPE()

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

Get the GstEventType of the event.

event : the event to query

GST_EVENT_TYPE_NAME()

#define GST_EVENT_TYPE_NAME(event)	(gst_event_type_get_name(GST_EVENT_TYPE(event)))

Get a constant string representation of the GstEventType of the event.

event : the event to query

GST_EVENT_TYPE_BOTH

#define             GST_EVENT_TYPE_BOTH

The same thing as GST_EVENT_TYPE_UPSTREAM | GST_EVENT_TYPE_DOWNSTREAM.


GST_EVENT_TIMESTAMP()

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

Get the GstClockTime timestamp of the event. This is the time when the event was created.

event : the event to query

GST_EVENT_SRC()

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

The source GstObject that generated this event.

event : the event to query

GST_EVENT_IS_DOWNSTREAM()

#define GST_EVENT_IS_DOWNSTREAM(ev)	!!(GST_EVENT_TYPE (ev) & GST_EVENT_TYPE_DOWNSTREAM)

Check if an event can travel downstream.

ev : the event to query

GST_EVENT_IS_SERIALIZED()

#define GST_EVENT_IS_SERIALIZED(ev)	!!(GST_EVENT_TYPE (ev) & GST_EVENT_TYPE_SERIALIZED)

Check if an event is serialized with the data stream.

ev : the event to query

GST_EVENT_IS_UPSTREAM()

#define GST_EVENT_IS_UPSTREAM(ev)	!!(GST_EVENT_TYPE (ev) & GST_EVENT_TYPE_UPSTREAM)

Check if an event can travel upstream.

ev : the event to query

enum GstSeekType

typedef enum {
  /* one of these */
  GST_SEEK_TYPE_NONE		= 0,
  GST_SEEK_TYPE_CUR		= 1,
  GST_SEEK_TYPE_SET		= 2,
  GST_SEEK_TYPE_END		= 3
} GstSeekType;

The different types of seek events. When constructing a seek event with gst_event_new_seek(), a format, a seek method and optional flags are to be provided. The seek event is then inserted into the graph with gst_pad_send_event() or gst_element_send_event().

GST_SEEK_TYPE_NONE no change in position is required
GST_SEEK_TYPE_CUR change relative to current position
GST_SEEK_TYPE_SET absolute position is requested
GST_SEEK_TYPE_END relative position to duration is requested

enum GstSeekFlags

typedef enum {
  GST_SEEK_FLAG_NONE		= 0,
  GST_SEEK_FLAG_FLUSH		= (1 << 0),
  GST_SEEK_FLAG_ACCURATE	= (1 << 1),
  GST_SEEK_FLAG_KEY_UNIT	= (1 << 2),
  GST_SEEK_FLAG_SEGMENT		= (1 << 3)
} GstSeekFlags;

Flags to be used with gst_element_seek() or gst_event_new_seek(). All flags can be used together.

A non flushing seek might take some time to perform as the currently playing data in the pipeline will not be cleared.

An accurate seek might be slower for formats that don't have any indexes or timestamp markers in the stream. Specifying this flag might require a complete scan of the file in those cases.

When performing a segment seek: after the playback of the segment completes, no EOS will be emmited by the element that performed the seek, but a GST_MESSAGE_SEGMENT_DONE message will be posted on the bus by the element. When this message is posted, it is possible to send a new seek event to continue playback. With this seek method it is possible to perform seemless looping or simple linear editing.

GST_SEEK_FLAG_NONE no flag
GST_SEEK_FLAG_FLUSH flush pipeline
GST_SEEK_FLAG_ACCURATE accurate position is requested, this might be considerably slower for some formats.
GST_SEEK_FLAG_KEY_UNIT seek to the nearest keyframe. This might be faster but less accurate.
GST_SEEK_FLAG_SEGMENT perform a segment seek.

enum GstEventTypeFlags

typedef enum {
  GST_EVENT_TYPE_UPSTREAM	= 1 << 0,
  GST_EVENT_TYPE_DOWNSTREAM	= 1 << 1,
  GST_EVENT_TYPE_SERIALIZED	= 1 << 2
} GstEventTypeFlags;

GstEventTypeFlags indicate the aspects of the different GstEventType values. You can get the type flags of a GstEventType with the gst_event_type_get_flags() function.

GST_EVENT_TYPE_UPSTREAM Set if the event can travel upstream.
GST_EVENT_TYPE_DOWNSTREAM Set if the event can travel downstream.
GST_EVENT_TYPE_SERIALIZED Set if the event should be serialized with data flow.

GST_EVENT_MAKE_TYPE()

#define             GST_EVENT_MAKE_TYPE(num,flags)

when making custom event types, use this macro with the num and the given flags

num : the event number to create
flags : the event flags

gst_event_copy()

#define         gst_event_copy(ev)		GST_EVENT_CAST (gst_mini_object_copy (GST_MINI_OBJECT (ev)))

Copy the event using the event specific copy function.

ev : The event to copy

gst_event_get_structure ()

const GstStructure* gst_event_get_structure             (GstEvent *event);

Access the structure of the event.

event : The GstEvent.
Returns : The structure of the event. The structure is still owned by the event, which means that you should not free it and that the pointer becomes invalid when you free the event. MT safe.

gst_event_new_buffer_size ()

GstEvent*           gst_event_new_buffer_size           (GstFormat format,
                                                         gint64 minsize,
                                                         gint64 maxsize,
                                                         gboolean async);

Create a new buffersize event. The event is sent downstream and notifies elements that they should provide a buffer of the specified dimensions.

When the async flag is set, a thread boundary is prefered.

format : buffer format
minsize : minimum buffer size
maxsize : maximum buffer size
async : thread behavior
Returns : a new GstEvent

gst_event_new_custom ()

GstEvent*           gst_event_new_custom                (GstEventType type,
                                                         GstStructure *structure);

Create a new custom-typed event. This can be used for anything not handled by other event-specific functions to pass an event to another element.

Make sure to allocate an event type with the GST_EVENT_MAKE_TYPE macro, assigning a free number and filling in the correct direction and serialization flags.

New custom events can also be created by subclassing the event type if needed.

type : The type of the new event
structure : The structure for the event. The event will take ownership of the structure.
Returns : The new custom event.

gst_event_new_eos ()

GstEvent*           gst_event_new_eos                   (void);

Create a new EOS event. The eos event can only travel downstream synchronized with the buffer flow. Elements that receive the EOS event on a pad can return GST_FLOW_UNEXPECTED as a GstFlowReturn when data after the EOS event arrives.

The EOS event will travel down to the sink elements in the pipeline which will then post the GST_MESSAGE_EOS on the bus after they have finished playing any buffered data.

When all sinks have posted an EOS message, an EOS message is forwarded to the application.

Returns : The new EOS event.

gst_event_new_flush_start ()

GstEvent*           gst_event_new_flush_start           (void);

Allocate a new flush start event. The flush start event can be sent upstream and downstream and travels out-of-bounds with the dataflow.

It marks pads as being flushing and will make them return GST_FLOW_WRONG_STATE when used for data flow with gst_pad_push(), gst_pad_chain(), gst_pad_alloc_buffer(), gst_pad_get_range() and gst_pad_pull_range(). Any event (except a GST_EVENT_FLUSH_STOP) received on a flushing pad will return FALSE immediately.

Elements should unlock any blocking functions and exit their streaming functions as fast as possible when this event is received.

This event is typically generated after a seek to flush out all queued data in the pipeline so that the new media is played as soon as possible.

Returns : A new flush start event.

gst_event_new_flush_stop ()

GstEvent*           gst_event_new_flush_stop            (void);

Allocate a new flush stop event. The flush stop event can be sent upstream and downstream and travels out-of-bounds with the dataflow. It is typically sent after sending a FLUSH_START event to make the pads accept data again.

Elements can process this event synchronized with the dataflow since the preceeding FLUSH_START event stopped the dataflow.

This event is typically generated to complete a seek and to resume dataflow.

Returns : A new flush stop event.

gst_event_new_latency ()

GstEvent*           gst_event_new_latency               (GstClockTime latency);

Create a new latency event. The event is sent upstream from the sinks and notifies elements that they should add an additional latency to the timestamps before synchronising against the clock.

The latency is mostly used in live sinks and is always expressed in the time format.

latency : the new latency value
Returns : a new GstEvent

Since 0.10.12


gst_event_new_navigation ()

GstEvent*           gst_event_new_navigation            (GstStructure *structure);

Create a new navigation event from the given description.

structure : description of the event
Returns : a new GstEvent

gst_event_new_new_segment ()

GstEvent*           gst_event_new_new_segment           (gboolean update,
                                                         gdouble rate,
                                                         GstFormat format,
                                                         gint64 start,
                                                         gint64 stop,
                                                         gint64 position);

Allocate a new newsegment event with the given format/values tripplets

This method calls gst_event_new_new_segment_full() passing a default value of 1.0 for applied_rate

update : is this segment an update to a previous one
rate : a new rate for playback
format : The format of the segment values
start : the start value of the segment
stop : the stop value of the segment
position : stream position
Returns : A new newsegment event.

gst_event_new_new_segment_full ()

GstEvent*           gst_event_new_new_segment_full      (gboolean update,
                                                         gdouble rate,
                                                         gdouble applied_rate,
                                                         GstFormat format,
                                                         gint64 start,
                                                         gint64 stop,
                                                         gint64 position);

Allocate a new newsegment event with the given format/values triplets.

The newsegment event marks the range of buffers to be processed. All data not within the segment range is not to be processed. This can be used intelligently by plugins to apply more efficient methods of skipping unneeded data.

The position value of the segment is used in conjunction with the start value to convert the buffer timestamps into the stream time. This is usually done in sinks to report the current stream_time. position represents the stream_time of a buffer carrying a timestamp of start. position cannot be -1.

start cannot be -1, stop can be -1. If there is a valid stop given, it must be greater or equal the start, including when the indicated playback rate is < 0.

The applied_rate value provides information about any rate adjustment that has already been made to the timestamps and content on the buffers of the stream. (rate * applied_rate) should always equal the rate that has been requested for playback. For example, if an element has an input segment with intended playback rate of 2.0 and applied_rate of 1.0, it can adjust incoming timestamps and buffer content by half and output a newsegment event with rate of 1.0 and applied_rate of 2.0

After a newsegment event, the buffer stream time is calculated with:

position + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)

update : Whether this segment is an update to a previous one
rate : A new rate for playback
applied_rate : The rate factor which has already been applied
format : The format of the segment values
start : The start value of the segment
stop : The stop value of the segment
position : stream position
Returns : A new newsegment event.

Since 0.10.6


gst_event_new_qos ()

GstEvent*           gst_event_new_qos                   (gdouble proportion,
                                                         GstClockTimeDiff diff,
                                                         GstClockTime timestamp);

Allocate a new qos event with the given values. The QOS event is generated in an element that wants an upstream element to either reduce or increase its rate because of high/low CPU load or other resource usage such as network performance. Typically sinks generate these events for each buffer they receive.

proportion indicates the real-time performance of the streaming in the element that generated the QoS event (usually the sink). The value is generally computed based on more long term statistics about the streams timestamps compared to the clock. A value < 1.0 indicates that the upstream element is producing data faster than real-time. A value > 1.0 indicates that the upstream element is not producing data fast enough. 1.0 is the ideal proportion value. The proportion value can safely be used to lower or increase the quality of the element.

diff is the difference against the clock in running time of the last buffer that caused the element to generate the QOS event. A negative value means that the buffer with timestamp arrived in time. A positive value indicates how late the buffer with timestamp was.

timestamp is the timestamp of the last buffer that cause the element to generate the QOS event. It is expressed in running time and thus an ever increasing value.

The upstream element can use the diff and timestamp values to decide whether to process more buffers. For possitive diff, all buffers with timestamp <= timestamp + diff will certainly arrive late in the sink as well.

The application can use general event probes to intercept the QoS event and implement custom application specific QoS handling.

proportion : the proportion of the qos message
diff : The time difference of the last Clock sync
timestamp : The timestamp of the buffer
Returns : A new QOS event.

gst_event_new_seek ()

GstEvent*           gst_event_new_seek                  (gdouble rate,
                                                         GstFormat format,
                                                         GstSeekFlags flags,
                                                         GstSeekType start_type,
                                                         gint64 start,
                                                         GstSeekType stop_type,
                                                         gint64 stop);

Allocate a new seek event with the given parameters.

The seek event configures playback of the pipeline between start to stop at the speed given in rate, also called a playback segment. The start and stop values are expressed in format.

A rate of 1.0 means normal playback rate, 2.0 means double speed. Negatives values means backwards playback. A value of 0.0 for the rate is not allowed and should be accomplished instead by PAUSING the pipeline.

A pipeline has a default playback segment configured with a start position of 0, a stop position of -1 and a rate of 1.0. The currently configured playback segment can be queried with GST_QUERY_SEGMENT.

start_type and stop_type specify how to adjust the currently configured start and stop fields in segment. Adjustments can be made relative or absolute to the last configured values. A type of GST_SEEK_TYPE_NONE means that the position should not be updated.

When the rate is positive and start has been updated, playback will start from the newly configured start position.

For negative rates, playback will start from the newly configured stop position (if any). If the stop position if updated, it must be different from -1 for negative rates.

It is not possible to seek relative to the current playback position, to do this, PAUSE the pipeline, query the current playback position with GST_QUERY_POSITION and update the playback segment current position with a GST_SEEK_TYPE_SET to the desired position.

rate : The new playback rate
format : The format of the seek values
flags : The optional seek flags
start_type : The type and flags for the new start position
start : The value of the new start position
stop_type : The type and flags for the new stop position
stop : The value of the new stop position
Returns : A new seek event.

gst_event_new_tag ()

GstEvent*           gst_event_new_tag                   (GstTagList *taglist);

Generates a metadata tag event from the given taglist.

taglist : metadata list
Returns : a new GstEvent

gst_event_parse_buffer_size ()

void                gst_event_parse_buffer_size         (GstEvent *event,
                                                         GstFormat *format,
                                                         gint64 *minsize,
                                                         gint64 *maxsize,
                                                         gboolean *async);

Get the format, minsize, maxsize and async-flag in the buffersize event.

event : The event to query
format : A pointer to store the format in
minsize : A pointer to store the minsize in
maxsize : A pointer to store the maxsize in
async : A pointer to store the async-flag in

gst_event_parse_latency ()

void                gst_event_parse_latency             (GstEvent *event,
                                                         GstClockTime *latency);

Get the latency in the latency event.

event : The event to query
latency : A pointer to store the latency in.

Since 0.10.12


gst_event_parse_new_segment ()

void                gst_event_parse_new_segment         (GstEvent *event,
                                                         gboolean *update,
                                                         gdouble *rate,
                                                         GstFormat *format,
                                                         gint64 *start,
                                                         gint64 *stop,
                                                         gint64 *position);

Get the update flag, rate, format, start, stop and position in the newsegment event. In general, gst_event_parse_new_segment_full() should be used instead of this, to also retrieve the applied_rate value of the segment. See gst_event_new_new_segment_full() for a full description of the newsegment event.

event : The event to query
update : A pointer to the update flag of the segment
rate : A pointer to the rate of the segment
format : A pointer to the format of the newsegment values
start : A pointer to store the start value in
stop : A pointer to store the stop value in
position : A pointer to store the stream time in

gst_event_parse_new_segment_full ()

void                gst_event_parse_new_segment_full    (GstEvent *event,
                                                         gboolean *update,
                                                         gdouble *rate,
                                                         gdouble *applied_rate,
                                                         GstFormat *format,
                                                         gint64 *start,
                                                         gint64 *stop,
                                                         gint64 *position);

Get the update, rate, applied_rate, format, start, stop and position in the newsegment event. See gst_event_new_new_segment_full() for a full description of the newsegment event.

event : The event to query
update : A pointer to the update flag of the segment
rate : A pointer to the rate of the segment
applied_rate : A pointer to the applied_rate of the segment
format : A pointer to the format of the newsegment values
start : A pointer to store the start value in
stop : A pointer to store the stop value in
position : A pointer to store the stream time in

Since 0.10.6


gst_event_parse_qos ()

void                gst_event_parse_qos                 (GstEvent *event,
                                                         gdouble *proportion,
                                                         GstClockTimeDiff *diff,
                                                         GstClockTime *timestamp);

Get the proportion, diff and timestamp in the qos event. See gst_event_new_qos() for more information about the different QoS values.

event : The event to query
proportion : A pointer to store the proportion in
diff : A pointer to store the diff in
timestamp : A pointer to store the timestamp in

gst_event_parse_seek ()

void                gst_event_parse_seek                (GstEvent *event,
                                                         gdouble *rate,
                                                         GstFormat *format,
                                                         GstSeekFlags *flags,
                                                         GstSeekType *start_type,
                                                         gint64 *start,
                                                         GstSeekType *stop_type,
                                                         gint64 *stop);

Parses a seek event and stores the results in the given result locations.

event : a seek event
rate : result location for the rate
format : result location for the stream format
flags : result location for the GstSeekFlags
start_type : result location for the GstSeekType of the start position
start : result location for the start postion expressed in format
stop_type : result location for the GstSeekType of the stop position
stop : result location for the stop postion expressed in format

gst_event_parse_tag ()

void                gst_event_parse_tag                 (GstEvent *event,
                                                         GstTagList **taglist);

Parses a tag event and stores the results in the given taglist location.

event : a tag event
taglist : pointer to metadata list

gst_event_ref ()

GstEvent*           gst_event_ref                       (GstEvent *event);

Increase the refcount of this event.

event : The event to refcount
Returns : event (for convenience when doing assignments)

gst_event_unref()

#define         gst_event_unref(ev)		gst_mini_object_unref (GST_MINI_OBJECT (ev))

Decrease the refcount of an event, freeing it if the refcount reaches 0.

ev : The event to refcount

gst_event_replace()

#define             gst_event_replace(old_event,new_event)

Modifies a pointer to a GstEvent to point to a different GstEvent. 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 event is unreffed, the new one is reffed).

Either new_event or the GstEvent pointed to by old_event may be NULL.

old_event : pointer to a pointer to a GstEvent to be replaced.
new_event : pointer to a GstEvent that will replace the event pointed to by old_event.

Since 0.10.3


gst_event_type_get_flags ()

GstEventTypeFlags   gst_event_type_get_flags            (GstEventType type);

Gets the GstEventTypeFlags associated with type.

type : a GstEventType
Returns : a GstEventTypeFlags.

gst_event_type_get_name ()

const gchar*        gst_event_type_get_name             (GstEventType type);

Get a printable name for the given event type. Do not modify or free.

type : the event type
Returns : a reference to the static name of the event.

gst_event_type_to_quark ()

GQuark              gst_event_type_to_quark             (GstEventType type);

Get the unique quark for the given event type.

type : the event type
Returns : the quark associated with the event type

See Also

GstPad, GstElement