gstreamer/gst/gstevent.c
Tim-Philipp Müller 75e17f0002 event: add construct and parse API for the new STREAM CONFIG event
codec data and stream headers don't belong into caps, since they
are not negotiated. We signal them using the STREAM CONFIG event
instead.
2012-01-27 17:42:07 +00:00

1550 lines
48 KiB
C

/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wim.taymans@chello.be>
* 2005 Wim Taymans <wim@fluendo.com>
*
* gstevent.c: GstEvent subsystem
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* SECTION:gstevent
* @short_description: Structure describing events that are passed up and down
* a pipeline
* @see_also: #GstPad, #GstElement
*
* The event class provides factory methods to construct events for sending
* and functions to query (parse) received 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. It is valid to pass %NULL for unwanted details.
*
* 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 specify seeking time and mode.
* <example>
* <title>performing a seek on a pipeline</title>
* <programlisting>
* 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");
* ...
* </programlisting>
* </example>
*
* Last reviewed on 2006-09-6 (0.10.10)
*/
#include "gst_private.h"
#include <string.h> /* memcpy */
#include "gstinfo.h"
#include "gstevent.h"
#include "gstenumtypes.h"
#include "gstutils.h"
#include "gstquark.h"
#include "gstvalue.h"
GType _gst_event_type = 0;
typedef struct
{
GstEvent event;
GstStructure *structure;
} GstEventImpl;
#define GST_EVENT_STRUCTURE(e) (((GstEventImpl *)(e))->structure)
typedef struct
{
const gint type;
const gchar *name;
GQuark quark;
} GstEventQuarks;
static GstEventQuarks event_quarks[] = {
{GST_EVENT_UNKNOWN, "unknown", 0},
{GST_EVENT_FLUSH_START, "flush-start", 0},
{GST_EVENT_FLUSH_STOP, "flush-stop", 0},
{GST_EVENT_STREAM_START, "stream-start", 0},
{GST_EVENT_CAPS, "caps", 0},
{GST_EVENT_STREAM_CONFIG, "stream-config", 0},
{GST_EVENT_SEGMENT, "segment", 0},
{GST_EVENT_TAG, "tag", 0},
{GST_EVENT_BUFFERSIZE, "buffersize", 0},
{GST_EVENT_SINK_MESSAGE, "sink-message", 0},
{GST_EVENT_EOS, "eos", 0},
{GST_EVENT_SEGMENT_DONE, "segment-done", 0},
{GST_EVENT_GAP, "gap", 0},
{GST_EVENT_QOS, "qos", 0},
{GST_EVENT_SEEK, "seek", 0},
{GST_EVENT_NAVIGATION, "navigation", 0},
{GST_EVENT_LATENCY, "latency", 0},
{GST_EVENT_STEP, "step", 0},
{GST_EVENT_RECONFIGURE, "reconfigure", 0},
{GST_EVENT_CUSTOM_UPSTREAM, "custom-upstream", 0},
{GST_EVENT_CUSTOM_DOWNSTREAM, "custom-downstream", 0},
{GST_EVENT_CUSTOM_DOWNSTREAM_OOB, "custom-downstream-oob", 0},
{GST_EVENT_CUSTOM_DOWNSTREAM_STICKY, "custom-downstream-sticky", 0},
{GST_EVENT_CUSTOM_BOTH, "custom-both", 0},
{GST_EVENT_CUSTOM_BOTH_OOB, "custom-both-oob", 0},
{0, NULL, 0}
};
GST_DEFINE_MINI_OBJECT_TYPE (GstEvent, gst_event);
void
_priv_gst_event_initialize (void)
{
gint i;
_gst_event_type = gst_event_get_type ();
g_type_class_ref (gst_seek_flags_get_type ());
g_type_class_ref (gst_seek_type_get_type ());
for (i = 0; event_quarks[i].name; i++) {
event_quarks[i].quark = g_quark_from_static_string (event_quarks[i].name);
}
}
/**
* gst_event_type_get_name:
* @type: the event type
*
* Get a printable name for the given event type. Do not modify or free.
*
* Returns: a reference to the static name of the event.
*/
const gchar *
gst_event_type_get_name (GstEventType type)
{
gint i;
for (i = 0; event_quarks[i].name; i++) {
if (type == event_quarks[i].type)
return event_quarks[i].name;
}
return "unknown";
}
/**
* gst_event_type_to_quark:
* @type: the event type
*
* Get the unique quark for the given event type.
*
* Returns: the quark associated with the event type
*/
GQuark
gst_event_type_to_quark (GstEventType type)
{
gint i;
for (i = 0; event_quarks[i].name; i++) {
if (type == event_quarks[i].type)
return event_quarks[i].quark;
}
return 0;
}
/**
* gst_event_type_get_flags:
* @type: a #GstEventType
*
* Gets the #GstEventTypeFlags associated with @type.
*
* Returns: a #GstEventTypeFlags.
*/
GstEventTypeFlags
gst_event_type_get_flags (GstEventType type)
{
GstEventTypeFlags ret;
ret = type & ((1 << GST_EVENT_NUM_SHIFT) - 1);
return ret;
}
static void
_gst_event_free (GstEvent * event)
{
GstStructure *s;
g_return_if_fail (event != NULL);
g_return_if_fail (GST_IS_EVENT (event));
GST_CAT_LOG (GST_CAT_EVENT, "freeing event %p type %s", event,
GST_EVENT_TYPE_NAME (event));
s = GST_EVENT_STRUCTURE (event);
if (s) {
gst_structure_set_parent_refcount (s, NULL);
gst_structure_free (s);
}
g_slice_free1 (GST_MINI_OBJECT_SIZE (event), event);
}
static void gst_event_init (GstEventImpl * event, gsize size,
GstEventType type);
static GstEvent *
_gst_event_copy (GstEvent * event)
{
GstEventImpl *copy;
GstStructure *s;
copy = g_slice_new0 (GstEventImpl);
gst_event_init (copy, sizeof (GstEventImpl), GST_EVENT_TYPE (event));
GST_EVENT_TIMESTAMP (copy) = GST_EVENT_TIMESTAMP (event);
GST_EVENT_SEQNUM (copy) = GST_EVENT_SEQNUM (event);
s = GST_EVENT_STRUCTURE (event);
if (s) {
GST_EVENT_STRUCTURE (copy) = gst_structure_copy (s);
gst_structure_set_parent_refcount (GST_EVENT_STRUCTURE (copy),
&copy->event.mini_object.refcount);
}
return GST_EVENT_CAST (copy);
}
static void
gst_event_init (GstEventImpl * event, gsize size, GstEventType type)
{
gst_mini_object_init (GST_MINI_OBJECT_CAST (event), _gst_event_type, size);
event->event.mini_object.copy = (GstMiniObjectCopyFunction) _gst_event_copy;
event->event.mini_object.free = (GstMiniObjectFreeFunction) _gst_event_free;
GST_EVENT_TYPE (event) = type;
GST_EVENT_TIMESTAMP (event) = GST_CLOCK_TIME_NONE;
GST_EVENT_SEQNUM (event) = gst_util_seqnum_next ();
}
static GstEvent *
gst_event_new (GstEventType type)
{
GstEventImpl *event;
event = g_slice_new0 (GstEventImpl);
GST_CAT_DEBUG (GST_CAT_EVENT, "creating new event %p %s %d", event,
gst_event_type_get_name (type), type);
gst_event_init (event, sizeof (GstEventImpl), type);
return GST_EVENT_CAST (event);
}
/**
* gst_event_new_custom:
* @type: The type of the new event
* @structure: (transfer full): the structure for the event. The event will
* take ownership of the 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.
*
* Returns: (transfer full): the new custom event.
*/
GstEvent *
gst_event_new_custom (GstEventType type, GstStructure * structure)
{
GstEvent *event;
/* structure must not have a parent */
event = gst_event_new (type);
if (structure) {
if (!gst_structure_set_parent_refcount (structure,
&event->mini_object.refcount))
goto had_parent;
GST_EVENT_STRUCTURE (event) = structure;
}
return event;
/* ERRORS */
had_parent:
{
gst_event_unref (event);
g_warning ("structure is already owned by another object");
return NULL;
}
}
/**
* gst_event_get_structure:
* @event: The #GstEvent.
*
* Access the structure of the event.
*
* 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.
*/
const GstStructure *
gst_event_get_structure (GstEvent * event)
{
g_return_val_if_fail (GST_IS_EVENT (event), NULL);
return GST_EVENT_STRUCTURE (event);
}
/**
* gst_event_writable_structure:
* @event: The #GstEvent.
*
* Get a writable version of the structure.
*
* 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.
* This function checks if @event is writable and will never return NULL.
*
* MT safe.
*/
GstStructure *
gst_event_writable_structure (GstEvent * event)
{
GstStructure *structure;
g_return_val_if_fail (GST_IS_EVENT (event), NULL);
g_return_val_if_fail (gst_event_is_writable (event), NULL);
structure = GST_EVENT_STRUCTURE (event);
if (structure == NULL) {
structure =
gst_structure_new_id_empty (gst_event_type_to_quark (GST_EVENT_TYPE
(event)));
gst_structure_set_parent_refcount (structure, &event->mini_object.refcount);
GST_EVENT_STRUCTURE (event) = structure;
}
return structure;
}
/**
* gst_event_has_name:
* @event: The #GstEvent.
* @name: name to check
*
* Checks if @event has the given @name. This function is usually used to
* check the name of a custom event.
*
* Returns: %TRUE if @name matches the name of the event structure.
*
* Since: 0.10.20
*/
gboolean
gst_event_has_name (GstEvent * event, const gchar * name)
{
g_return_val_if_fail (GST_IS_EVENT (event), FALSE);
if (GST_EVENT_STRUCTURE (event) == NULL)
return FALSE;
return gst_structure_has_name (GST_EVENT_STRUCTURE (event), name);
}
/**
* gst_event_get_seqnum:
* @event: A #GstEvent.
*
* Retrieve the sequence number of a event.
*
* Events have ever-incrementing sequence numbers, which may also be set
* explicitly via gst_event_set_seqnum(). Sequence numbers are typically used to
* indicate that a event corresponds to some other set of events or messages,
* for example an EOS event corresponding to a SEEK event. It is considered good
* practice to make this correspondence when possible, though it is not
* required.
*
* Note that events and messages share the same sequence number incrementor;
* two events or messages will never have the same sequence number unless
* that correspondence was made explicitly.
*
* Returns: The event's sequence number.
*
* MT safe.
*
* Since: 0.10.22
*/
guint32
gst_event_get_seqnum (GstEvent * event)
{
g_return_val_if_fail (GST_IS_EVENT (event), -1);
return GST_EVENT_SEQNUM (event);
}
/**
* gst_event_set_seqnum:
* @event: A #GstEvent.
* @seqnum: A sequence number.
*
* Set the sequence number of a event.
*
* This function might be called by the creator of a event to indicate that the
* event relates to other events or messages. See gst_event_get_seqnum() for
* more information.
*
* MT safe.
*
* Since: 0.10.22
*/
void
gst_event_set_seqnum (GstEvent * event, guint32 seqnum)
{
g_return_if_fail (GST_IS_EVENT (event));
GST_EVENT_SEQNUM (event) = seqnum;
}
/* FIXME 0.11: It would be nice to have flush events
* that don't reset the running time in the sinks
*/
/**
* gst_event_new_flush_start:
*
* 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: (transfer full): a new flush start event.
*/
GstEvent *
gst_event_new_flush_start (void)
{
return gst_event_new (GST_EVENT_FLUSH_START);
}
/**
* gst_event_new_flush_stop:
* @reset_time: if time should be reset
*
* Allocate a new flush stop event. The flush stop event can be sent
* upstream and downstream and travels serialized 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: (transfer full): a new flush stop event.
*/
GstEvent *
gst_event_new_flush_stop (gboolean reset_time)
{
GstEvent *event;
GST_CAT_INFO (GST_CAT_EVENT, "creating flush stop %d", reset_time);
event = gst_event_new_custom (GST_EVENT_FLUSH_STOP,
gst_structure_new_id (GST_QUARK (EVENT_FLUSH_STOP),
GST_QUARK (RESET_TIME), G_TYPE_BOOLEAN, reset_time, NULL));
return event;
}
/**
* gst_event_parse_flush_stop:
* @event: The event to parse
* @reset_time: (out): if time should be reset
*
* Parse the FLUSH_STOP event and retrieve the @reset_time member.
*/
void
gst_event_parse_flush_stop (GstEvent * event, gboolean * reset_time)
{
GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_STOP);
structure = GST_EVENT_STRUCTURE (event);
if (G_LIKELY (reset_time))
*reset_time =
g_value_get_boolean (gst_structure_id_get_value (structure,
GST_QUARK (RESET_TIME)));
}
/**
* gst_event_new_eos:
*
* 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.
*
* The EOS event itself will not cause any state transitions of the pipeline.
*
* Returns: (transfer full): the new EOS event.
*/
GstEvent *
gst_event_new_eos (void)
{
return gst_event_new (GST_EVENT_EOS);
}
/**
* gst_event_new_caps:
* @caps: (transfer none): a #GstCaps
*
* Create a new CAPS event for @caps. The caps event can only travel downstream
* synchronized with the buffer flow and contains the format of the buffers
* that will follow after the event.
*
* Returns: (transfer full): the new CAPS event.
*/
GstEvent *
gst_event_new_caps (GstCaps * caps)
{
GstEvent *event;
g_return_val_if_fail (caps != NULL, NULL);
g_return_val_if_fail (gst_caps_is_fixed (caps), NULL);
GST_CAT_INFO (GST_CAT_EVENT, "creating caps event %" GST_PTR_FORMAT, caps);
event = gst_event_new_custom (GST_EVENT_CAPS,
gst_structure_new_id (GST_QUARK (EVENT_CAPS),
GST_QUARK (CAPS), GST_TYPE_CAPS, caps, NULL));
return event;
}
/**
* gst_event_parse_caps:
* @event: The event to parse
* @caps: (out): A pointer to the caps
*
* Get the caps from @event. The caps remains valid as long as @event remains
* valid.
*/
void
gst_event_parse_caps (GstEvent * event, GstCaps ** caps)
{
GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_CAPS);
structure = GST_EVENT_STRUCTURE (event);
if (G_LIKELY (caps))
*caps =
g_value_get_boxed (gst_structure_id_get_value (structure,
GST_QUARK (CAPS)));
}
/**
* gst_event_new_stream_config:
* @flags: the stream config flags
*
* Create a new STREAM CONFIG event. The stream config event travels
* downstream synchronized with the buffer flow and contains stream
* configuration information for the stream, such as stream-headers
* or codec-data. It is optional and should be sent after the CAPS
* event.
*
* Returns: (transfer full): the new STREAM CONFIG event.
*/
GstEvent *
gst_event_new_stream_config (GstStreamConfigFlags flags)
{
GstEvent *event;
GST_CAT_INFO (GST_CAT_EVENT, "creating stream info event, flags=0x%x", flags);
event = gst_event_new_custom (GST_EVENT_STREAM_CONFIG,
gst_structure_new_id (GST_QUARK (EVENT_STREAM_CONFIG),
GST_QUARK (FLAGS), GST_TYPE_STREAM_CONFIG_FLAGS, flags, NULL));
return event;
}
/**
* gst_event_parse_stream_config:
* @event: The event to parse
* @flags: (out): a pointer to a variable to store the stream config flags
*
* Get the stream config flags from @event.
*/
void
gst_event_parse_stream_config (GstEvent * event, GstStreamConfigFlags * flags)
{
GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
structure = GST_EVENT_STRUCTURE (event);
if (G_LIKELY (flags != NULL)) {
*flags =
g_value_get_enum (gst_structure_id_get_value (structure,
GST_QUARK (FLAGS)));
}
}
/**
* gst_event_set_stream_config_codec_data:
* @event: a stream config event
* @buf: a #GstBuffer with codec data
*
* Set codec data on the stream info event to signal out of bound setup data
* to downstream elements. Unlike stream headers, codec data contains data
* that is required to interpret the data stream, but is not valid as-is
* inside the data stream and thus can't just be prepended to or inserted
* into the data stream.
*/
void
gst_event_set_stream_config_codec_data (GstEvent * event, GstBuffer * buf)
{
GstStructure *s;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
g_return_if_fail (GST_IS_BUFFER (buf) && gst_buffer_get_size (buf) > 0);
s = GST_EVENT_STRUCTURE (event);
gst_structure_id_set (s, GST_QUARK (CODEC_DATA), GST_TYPE_BUFFER, buf, NULL);
}
/**
* gst_event_set_stream_config_codec_data:
* @event: a stream config event
* @buf: (transfer none): location where to store the #GstBuffer with codec data
*
* Extracts the codec data buffer from the stream info event. Will store
* %NULL in @buf if the event contains no codec data. The buffer returned
* will remain valid as long as @event remains valid. The caller should
* acquire a referenceto to @buf if needed.
*/
void
gst_event_parse_stream_config_codec_data (GstEvent * event, GstBuffer ** buf)
{
const GValue *val;
GstStructure *s;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
g_return_if_fail (buf != NULL);
s = GST_EVENT_STRUCTURE (event);
val = gst_structure_id_get_value (s, GST_QUARK (CODEC_DATA));
if (val != NULL)
*buf = g_value_get_boxed (val);
else
*buf = NULL;
}
/**
* gst_event_add_stream_config_header:
* @event: a stream config event
* @buf: a #GstBuffer with stream header data
*
* Adds a stream header to the stream info event to signal stream headers to
* to downstream elements such as multifilesink, tcpserversink etc. Stream
* headers can be and should usually be prepended to the data stream at any
* point in the stream (which requires a streamable format), e.g. to a new
* client connecting, or when starting a new file segment. stream header
* buffers will all be used together in the order they were added to the
* stream config event. Stream headers are sent as buffers at the beginning
* of the data flow in addition to the stream config event. Elements that
* care about stream headers need to make sure that they don't insert or
* interpret these header buffers twice if they interpret them.
*/
void
gst_event_add_stream_config_header (GstEvent * event, GstBuffer * buf)
{
GstStructure *s;
GValue buf_val = { 0, };
GValue *val;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
g_return_if_fail (GST_IS_BUFFER (buf) && gst_buffer_get_size (buf) > 0);
g_value_init (&buf_val, GST_TYPE_BUFFER);
g_value_set_boxed (&buf_val, buf);
s = GST_EVENT_STRUCTURE (event);
val = (GValue *) gst_structure_id_get_value (s, GST_QUARK (STREAM_HEADERS));
if (val == NULL) {
GValue new_array = { 0, };
g_value_init (&new_array, GST_TYPE_ARRAY);
gst_value_array_append_value (&new_array, &buf_val);
gst_structure_id_take_value (s, GST_QUARK (STREAM_HEADERS), &new_array);
} else {
gst_value_array_append_value (val, &buf_val);
}
g_value_unset (&buf_val);
}
/**
* gst_event_get_n_stream_config_headers:
* @event: a stream config event
*
* Extract the number of stream header buffers.
*
* Returns: the number of stream header buffers attached to the stream info
* @event.
*/
guint
gst_event_get_n_stream_config_headers (GstEvent * event)
{
const GValue *val;
GstStructure *s;
guint num = 0;
g_return_val_if_fail (GST_IS_EVENT (event), 0);
g_return_val_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG, 0);
s = GST_EVENT_STRUCTURE (event);
val = gst_structure_id_get_value (s, GST_QUARK (STREAM_HEADERS));
if (val != NULL)
num = gst_value_array_get_size (val);
return num;
}
/**
* gst_event_parse_nth_stream_config_header:
* @event: a stream config event
* @index: number of the stream header to retrieve
* @buf: location where to store the n-th stream header #GstBuffer
*
* Retrieves the n-th stream header buffer attached to the stream config
* event and stores it in @buf. Will store %NULL in @buf if there is no such
* stream header.
*/
void
gst_event_parse_nth_stream_config_header (GstEvent * event, guint index,
GstBuffer ** buf)
{
const GValue *val, *buf_val;
GstStructure *s;
GstBuffer *ret = NULL;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
g_return_if_fail (buf != NULL);
s = GST_EVENT_STRUCTURE (event);
val = gst_structure_id_get_value (s, GST_QUARK (STREAM_HEADERS));
if (val != NULL) {
buf_val = gst_value_array_get_value (val, index);
if (buf_val != NULL)
ret = g_value_get_boxed (buf_val);
}
*buf = ret;
}
/**
* gst_event_new_segment:
* @segment: (transfer none): a #GstSegment
*
* Create a new SEGMENT event for @segment. The segment event can only travel
* downstream synchronized with the buffer flow and contains timing information
* and playback properties for the buffers that will follow.
*
* 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 valid range is expressed with the @start and @stop
* values.
*
* The time 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.
* @time represents the stream_time of a buffer carrying a timestamp of
* @start. @time 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:
*
* time + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)
*
* Returns: (transfer full): the new SEGMENT event.
*/
GstEvent *
gst_event_new_segment (const GstSegment * segment)
{
GstEvent *event;
g_return_val_if_fail (segment != NULL, NULL);
g_return_val_if_fail (segment->rate != 0.0, NULL);
g_return_val_if_fail (segment->applied_rate != 0.0, NULL);
g_return_val_if_fail (segment->format != GST_FORMAT_UNDEFINED, NULL);
GST_CAT_INFO (GST_CAT_EVENT, "creating segment event %" GST_SEGMENT_FORMAT,
segment);
event = gst_event_new_custom (GST_EVENT_SEGMENT,
gst_structure_new_id (GST_QUARK (EVENT_SEGMENT),
GST_QUARK (SEGMENT), GST_TYPE_SEGMENT, segment, NULL));
return event;
}
/**
* gst_event_parse_segment:
* @event: The event to parse
* @segment: (out) (transfer none): a pointer to a #GstSegment
*
* Parses a segment @event and stores the result in the given @segment location.
* @segment remains valid only until the @event is freed. Don't modify the segment
* and make a copy if you want to modify it or store it for later use.
*/
void
gst_event_parse_segment (GstEvent * event, const GstSegment ** segment)
{
GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
if (segment) {
structure = GST_EVENT_STRUCTURE (event);
*segment = g_value_get_boxed (gst_structure_id_get_value (structure,
GST_QUARK (SEGMENT)));
}
}
/**
* gst_event_copy_segment:
* @event: The event to parse
* @segment: a pointer to a #GstSegment
*
* Parses a segment @event and copies the #GstSegment into the location
* given by @segment.
*/
void
gst_event_copy_segment (GstEvent * event, GstSegment * segment)
{
const GstSegment *src;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
if (segment) {
gst_event_parse_segment (event, &src);
gst_segment_copy_into (src, segment);
}
}
/**
* gst_event_new_tag:
* @taglist: (transfer full): metadata list. The event will take ownership
* of the taglist.
*
* Generates a metadata tag event from the given @taglist.
*
* Returns: (transfer full): a new #GstEvent
*/
GstEvent *
gst_event_new_tag (GstTagList * taglist)
{
g_return_val_if_fail (taglist != NULL, NULL);
return gst_event_new_custom (GST_EVENT_TAG, (GstStructure *) taglist);
}
/**
* gst_event_parse_tag:
* @event: a tag event
* @taglist: (out) (transfer none): pointer to metadata list
*
* Parses a tag @event and stores the results in the given @taglist location.
* No reference to the taglist will be returned, it remains valid only until
* the @event is freed. Don't modify or free the taglist, make a copy if you
* want to modify it or store it for later use.
*/
void
gst_event_parse_tag (GstEvent * event, GstTagList ** taglist)
{
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_TAG);
if (taglist)
*taglist = (GstTagList *) GST_EVENT_STRUCTURE (event);
}
/* buffersize event */
/**
* gst_event_new_buffer_size:
* @format: buffer format
* @minsize: minimum buffer size
* @maxsize: maximum buffer size
* @async: thread behavior
*
* 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 preferred.
*
* Returns: (transfer full): a new #GstEvent
*/
GstEvent *
gst_event_new_buffer_size (GstFormat format, gint64 minsize,
gint64 maxsize, gboolean async)
{
GstEvent *event;
GstStructure *structure;
GST_CAT_INFO (GST_CAT_EVENT,
"creating buffersize format %s, minsize %" G_GINT64_FORMAT
", maxsize %" G_GINT64_FORMAT ", async %d", gst_format_get_name (format),
minsize, maxsize, async);
structure = gst_structure_new_id (GST_QUARK (EVENT_BUFFER_SIZE),
GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
GST_QUARK (MINSIZE), G_TYPE_INT64, minsize,
GST_QUARK (MAXSIZE), G_TYPE_INT64, maxsize,
GST_QUARK (ASYNC), G_TYPE_BOOLEAN, async, NULL);
event = gst_event_new_custom (GST_EVENT_BUFFERSIZE, structure);
return event;
}
/**
* gst_event_parse_buffer_size:
* @event: The event to query
* @format: (out): A pointer to store the format in
* @minsize: (out): A pointer to store the minsize in
* @maxsize: (out): A pointer to store the maxsize in
* @async: (out): A pointer to store the async-flag in
*
* Get the format, minsize, maxsize and async-flag in the buffersize event.
*/
void
gst_event_parse_buffer_size (GstEvent * event, GstFormat * format,
gint64 * minsize, gint64 * maxsize, gboolean * async)
{
const GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_BUFFERSIZE);
structure = GST_EVENT_STRUCTURE (event);
if (format)
*format = (GstFormat)
g_value_get_enum (gst_structure_id_get_value (structure,
GST_QUARK (FORMAT)));
if (minsize)
*minsize =
g_value_get_int64 (gst_structure_id_get_value (structure,
GST_QUARK (MINSIZE)));
if (maxsize)
*maxsize =
g_value_get_int64 (gst_structure_id_get_value (structure,
GST_QUARK (MAXSIZE)));
if (async)
*async =
g_value_get_boolean (gst_structure_id_get_value (structure,
GST_QUARK (ASYNC)));
}
/**
* gst_event_new_qos:
* @type: the QoS type
* @proportion: the proportion of the qos message
* @diff: The time difference of the last Clock sync
* @timestamp: The timestamp of the buffer
*
* 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 or
* throttling. Typically sinks generate these events for each buffer
* they receive.
*
* @type indicates the reason for the QoS event. #GST_QOS_TYPE_OVERFLOW is
* used when a buffer arrived in time or when the sink cannot keep up with
* the upstream datarate. #GST_QOS_TYPE_UNDERFLOW is when the sink is not
* receiving buffers fast enough and thus has to drop late buffers.
* #GST_QOS_TYPE_THROTTLE is used when the datarate is artificially limited
* by the application, for example to reduce power consumption.
*
* @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. When throttling is
* enabled, @diff will be set to the requested throttling interval.
*
* @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. A (negative) @diff value so that @timestamp + @diff would yield a
* result smaller than 0 is not allowed.
*
* The application can use general event probes to intercept the QoS
* event and implement custom application specific QoS handling.
*
* Returns: (transfer full): a new QOS event.
*/
GstEvent *
gst_event_new_qos (GstQOSType type, gdouble proportion,
GstClockTimeDiff diff, GstClockTime timestamp)
{
GstEvent *event;
GstStructure *structure;
/* diff must be positive or timestamp + diff must be positive */
g_return_val_if_fail (diff >= 0 || -diff <= timestamp, NULL);
GST_CAT_LOG (GST_CAT_EVENT,
"creating qos type %d, proportion %lf, diff %" G_GINT64_FORMAT
", timestamp %" GST_TIME_FORMAT, type, proportion,
diff, GST_TIME_ARGS (timestamp));
structure = gst_structure_new_id (GST_QUARK (EVENT_QOS),
GST_QUARK (TYPE), GST_TYPE_QOS_TYPE, type,
GST_QUARK (PROPORTION), G_TYPE_DOUBLE, proportion,
GST_QUARK (DIFF), G_TYPE_INT64, diff,
GST_QUARK (TIMESTAMP), G_TYPE_UINT64, timestamp, NULL);
event = gst_event_new_custom (GST_EVENT_QOS, structure);
return event;
}
/**
* gst_event_parse_qos:
* @event: The event to query
* @type: (out): A pointer to store the QoS type in
* @proportion: (out): A pointer to store the proportion in
* @diff: (out): A pointer to store the diff in
* @timestamp: (out): A pointer to store the timestamp in
*
* Get the type, proportion, diff and timestamp in the qos event. See
* gst_event_new_qos() for more information about the different QoS values.
*/
void
gst_event_parse_qos (GstEvent * event, GstQOSType * type,
gdouble * proportion, GstClockTimeDiff * diff, GstClockTime * timestamp)
{
const GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_QOS);
structure = GST_EVENT_STRUCTURE (event);
if (type)
*type = (GstQOSType)
g_value_get_enum (gst_structure_id_get_value (structure,
GST_QUARK (TYPE)));
if (proportion)
*proportion =
g_value_get_double (gst_structure_id_get_value (structure,
GST_QUARK (PROPORTION)));
if (diff)
*diff =
g_value_get_int64 (gst_structure_id_get_value (structure,
GST_QUARK (DIFF)));
if (timestamp)
*timestamp =
g_value_get_uint64 (gst_structure_id_get_value (structure,
GST_QUARK (TIMESTAMP)));
}
/**
* gst_event_new_seek:
* @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
*
* 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 playback 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.
*
* Returns: (transfer full): a new seek event.
*/
GstEvent *
gst_event_new_seek (gdouble rate, GstFormat format, GstSeekFlags flags,
GstSeekType start_type, gint64 start, GstSeekType stop_type, gint64 stop)
{
GstEvent *event;
GstStructure *structure;
g_return_val_if_fail (rate != 0.0, NULL);
if (format == GST_FORMAT_TIME) {
GST_CAT_INFO (GST_CAT_EVENT,
"creating seek rate %lf, format TIME, flags %d, "
"start_type %d, start %" GST_TIME_FORMAT ", "
"stop_type %d, stop %" GST_TIME_FORMAT,
rate, flags, start_type, GST_TIME_ARGS (start),
stop_type, GST_TIME_ARGS (stop));
} else {
GST_CAT_INFO (GST_CAT_EVENT,
"creating seek rate %lf, format %s, flags %d, "
"start_type %d, start %" G_GINT64_FORMAT ", "
"stop_type %d, stop %" G_GINT64_FORMAT,
rate, gst_format_get_name (format), flags, start_type, start, stop_type,
stop);
}
structure = gst_structure_new_id (GST_QUARK (EVENT_SEEK),
GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
GST_QUARK (FLAGS), GST_TYPE_SEEK_FLAGS, flags,
GST_QUARK (CUR_TYPE), GST_TYPE_SEEK_TYPE, start_type,
GST_QUARK (CUR), G_TYPE_INT64, start,
GST_QUARK (STOP_TYPE), GST_TYPE_SEEK_TYPE, stop_type,
GST_QUARK (STOP), G_TYPE_INT64, stop, NULL);
event = gst_event_new_custom (GST_EVENT_SEEK, structure);
return event;
}
/**
* gst_event_parse_seek:
* @event: a seek event
* @rate: (out): result location for the rate
* @format: (out): result location for the stream format
* @flags: (out): result location for the #GstSeekFlags
* @start_type: (out): result location for the #GstSeekType of the start position
* @start: (out): result location for the start postion expressed in @format
* @stop_type: (out): result location for the #GstSeekType of the stop position
* @stop: (out): result location for the stop postion expressed in @format
*
* Parses a seek @event and stores the results in the given result locations.
*/
void
gst_event_parse_seek (GstEvent * event, gdouble * rate,
GstFormat * format, GstSeekFlags * flags, GstSeekType * start_type,
gint64 * start, GstSeekType * stop_type, gint64 * stop)
{
const GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEEK);
structure = GST_EVENT_STRUCTURE (event);
if (rate)
*rate =
g_value_get_double (gst_structure_id_get_value (structure,
GST_QUARK (RATE)));
if (format)
*format = (GstFormat)
g_value_get_enum (gst_structure_id_get_value (structure,
GST_QUARK (FORMAT)));
if (flags)
*flags = (GstSeekFlags)
g_value_get_flags (gst_structure_id_get_value (structure,
GST_QUARK (FLAGS)));
if (start_type)
*start_type = (GstSeekType)
g_value_get_enum (gst_structure_id_get_value (structure,
GST_QUARK (CUR_TYPE)));
if (start)
*start =
g_value_get_int64 (gst_structure_id_get_value (structure,
GST_QUARK (CUR)));
if (stop_type)
*stop_type = (GstSeekType)
g_value_get_enum (gst_structure_id_get_value (structure,
GST_QUARK (STOP_TYPE)));
if (stop)
*stop =
g_value_get_int64 (gst_structure_id_get_value (structure,
GST_QUARK (STOP)));
}
/**
* gst_event_new_navigation:
* @structure: (transfer full): description of the event. The event will take
* ownership of the structure.
*
* Create a new navigation event from the given description.
*
* Returns: (transfer full): a new #GstEvent
*/
GstEvent *
gst_event_new_navigation (GstStructure * structure)
{
g_return_val_if_fail (structure != NULL, NULL);
return gst_event_new_custom (GST_EVENT_NAVIGATION, structure);
}
/**
* gst_event_new_latency:
* @latency: the new latency value
*
* 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
* running time before synchronising against the clock.
*
* The latency is mostly used in live sinks and is always expressed in
* the time format.
*
* Returns: (transfer full): a new #GstEvent
*
* Since: 0.10.12
*/
GstEvent *
gst_event_new_latency (GstClockTime latency)
{
GstEvent *event;
GstStructure *structure;
GST_CAT_INFO (GST_CAT_EVENT,
"creating latency event %" GST_TIME_FORMAT, GST_TIME_ARGS (latency));
structure = gst_structure_new_id (GST_QUARK (EVENT_LATENCY),
GST_QUARK (LATENCY), G_TYPE_UINT64, latency, NULL);
event = gst_event_new_custom (GST_EVENT_LATENCY, structure);
return event;
}
/**
* gst_event_parse_latency:
* @event: The event to query
* @latency: (out): A pointer to store the latency in.
*
* Get the latency in the latency event.
*
* Since: 0.10.12
*/
void
gst_event_parse_latency (GstEvent * event, GstClockTime * latency)
{
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_LATENCY);
if (latency)
*latency =
g_value_get_uint64 (gst_structure_id_get_value (GST_EVENT_STRUCTURE
(event), GST_QUARK (LATENCY)));
}
/**
* gst_event_new_step:
* @format: the format of @amount
* @amount: the amount of data to step
* @rate: the step rate
* @flush: flushing steps
* @intermediate: intermediate steps
*
* Create a new step event. The purpose of the step event is to instruct a sink
* to skip @amount (expressed in @format) of media. It can be used to implement
* stepping through the video frame by frame or for doing fast trick modes.
*
* A rate of <= 0.0 is not allowed. Pause the pipeline, for the effect of rate
* = 0.0 or first reverse the direction of playback using a seek event to get
* the same effect as rate < 0.0.
*
* The @flush flag will clear any pending data in the pipeline before starting
* the step operation.
*
* The @intermediate flag instructs the pipeline that this step operation is
* part of a larger step operation.
*
* Returns: (transfer full): a new #GstEvent
*
* Since: 0.10.24
*/
GstEvent *
gst_event_new_step (GstFormat format, guint64 amount, gdouble rate,
gboolean flush, gboolean intermediate)
{
GstEvent *event;
GstStructure *structure;
g_return_val_if_fail (rate > 0.0, NULL);
GST_CAT_INFO (GST_CAT_EVENT, "creating step event");
structure = gst_structure_new_id (GST_QUARK (EVENT_STEP),
GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
GST_QUARK (AMOUNT), G_TYPE_UINT64, amount,
GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
GST_QUARK (FLUSH), G_TYPE_BOOLEAN, flush,
GST_QUARK (INTERMEDIATE), G_TYPE_BOOLEAN, intermediate, NULL);
event = gst_event_new_custom (GST_EVENT_STEP, structure);
return event;
}
/**
* gst_event_parse_step:
* @event: The event to query
* @format: (out) (allow-none): a pointer to store the format in
* @amount: (out) (allow-none): a pointer to store the amount in
* @rate: (out) (allow-none): a pointer to store the rate in
* @flush: (out) (allow-none): a pointer to store the flush boolean in
* @intermediate: (out) (allow-none): a pointer to store the intermediate
* boolean in
*
* Parse the step event.
*
* Since: 0.10.24
*/
void
gst_event_parse_step (GstEvent * event, GstFormat * format, guint64 * amount,
gdouble * rate, gboolean * flush, gboolean * intermediate)
{
const GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STEP);
structure = GST_EVENT_STRUCTURE (event);
if (format)
*format =
(GstFormat) g_value_get_enum (gst_structure_id_get_value (structure,
GST_QUARK (FORMAT)));
if (amount)
*amount = g_value_get_uint64 (gst_structure_id_get_value (structure,
GST_QUARK (AMOUNT)));
if (rate)
*rate = g_value_get_double (gst_structure_id_get_value (structure,
GST_QUARK (RATE)));
if (flush)
*flush = g_value_get_boolean (gst_structure_id_get_value (structure,
GST_QUARK (FLUSH)));
if (intermediate)
*intermediate = g_value_get_boolean (gst_structure_id_get_value (structure,
GST_QUARK (INTERMEDIATE)));
}
/**
* gst_event_new_reconfigure:
* Create a new reconfigure event. The purpose of the reconfingure event is
* to travel upstream and make elements renegotiate their caps or reconfigure
* their buffer pools. This is useful when changing properties on elements
* or changing the topology of the pipeline.
*
* Returns: (transfer full): a new #GstEvent
*
* Since: 0.11.0
*/
GstEvent *
gst_event_new_reconfigure (void)
{
GstEvent *event;
GST_CAT_INFO (GST_CAT_EVENT, "creating reconfigure event");
event = gst_event_new_custom (GST_EVENT_RECONFIGURE, NULL);
return event;
}
/**
* gst_event_new_sink_message:
* @msg: (transfer none): the #GstMessage to be posted
*
* Create a new sink-message event. The purpose of the sink-message event is
* to instruct a sink to post the message contained in the event synchronized
* with the stream.
*
* Returns: (transfer full): a new #GstEvent
*
* Since: 0.10.26
*/
/* FIXME 0.11: take ownership of msg for consistency? */
GstEvent *
gst_event_new_sink_message (GstMessage * msg)
{
GstEvent *event;
GstStructure *structure;
g_return_val_if_fail (msg != NULL, NULL);
GST_CAT_INFO (GST_CAT_EVENT, "creating sink-message event");
structure = gst_structure_new_id (GST_QUARK (EVENT_SINK_MESSAGE),
GST_QUARK (MESSAGE), GST_TYPE_MESSAGE, msg, NULL);
event = gst_event_new_custom (GST_EVENT_SINK_MESSAGE, structure);
return event;
}
/**
* gst_event_parse_sink_message:
* @event: The event to query
* @msg: (out) (transfer full): a pointer to store the #GstMessage in.
*
* Parse the sink-message event. Unref @msg after usage.
*
* Since: 0.10.26
*/
void
gst_event_parse_sink_message (GstEvent * event, GstMessage ** msg)
{
const GstStructure *structure;
g_return_if_fail (GST_IS_EVENT (event));
g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SINK_MESSAGE);
structure = GST_EVENT_STRUCTURE (event);
if (msg)
*msg =
GST_MESSAGE (g_value_dup_boxed (gst_structure_id_get_value
(structure, GST_QUARK (MESSAGE))));
}
/**
* gst_event_new_stream_start
*
* Create a new STREAM_START event. The stream start event can only
* travel downstream synchronized with the buffer flow. It is expected
* to be the first event that is sent for a new stream.
*
* Source elements, demuxers and other elements that create new streams
* are supposed to send this event as the first event of a new stream. It
* should not be send after a flushing seek or in similar situations
* and is used to mark the beginning of a new logical stream. Elements
* combining multiple streams must ensure that this event is only forwarded
* downstream once and not for every single input stream.
*
* Returns: (transfer full): the new STREAM_START event.
*/
GstEvent *
gst_event_new_stream_start (void)
{
return gst_event_new (GST_EVENT_STREAM_START);
}