A base class for getrange based source elements. More...

#include <gstreamermm/basesrc.h>

Inheritance diagram for Gst::BaseSrc:

[legend]

Public Member Functions
	BaseSrc (BaseSrc&& src) noexcept

BaseSrc&	operator= (BaseSrc&& src) noexcept

	~BaseSrc () noexcept override

GstBaseSrc*	gobj ()
	Provides access to the underlying C GObject. More...

const GstBaseSrc*	gobj () const
	Provides access to the underlying C GObject. More...

GstBaseSrc*	gobj_copy ()
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

FlowReturn	wait_playing ()
	If the Gst::BaseSrcClass.create() method performs its own synchronisation against the clock it must unblock when going from PLAYING to the PAUSED state and call this method before continuing to produce the remaining data. More...

bool	is_live () const
	Check if an element is in live mode. More...

void	set_live (bool live)
	If the element listens to a live source, live should be set to `true`. More...

void	set_format (Format format)
	Sets the default format of the source. More...

bool	query_latency (bool& live, Gst::ClockTime& min_latency, Gst::ClockTime& max_latency) const
	Query the source for the latency parameters. More...

guint	get_blocksize () const
	Get the number of bytes that src will push out with each buffer. More...

void	set_blocksize (guint blocksize)
	Set the number of bytes that src will push out with each buffer. More...

bool	get_do_timestamp () const
	Query if src timestamps outgoing buffers based on the current running_time. More...

void	set_do_timestamp (bool timestamp)
	Configure src to automatically timestamp outgoing buffers based on the current running_time of the pipeline. More...

bool	new_seamless_segment (gint64 start, gint64 stop, gint64 position)
	Prepare a new seamless segment for emission downstream. More...

bool	set_caps (const Glib::RefPtr< Gst::Caps >& caps)
	Set new caps on the basesrc source pad. More...

Gst::FlowReturn	start_wait ()
	Wait until the start operation completes. More...

void	set_dynamic_size (bool dynamic_size)
	If not dynamic_size, size is only updated when needed, such as when trying to read past current tracked size. More...

void	set_async (bool async)
	Configure async behaviour in src, no state change will block. More...

bool	is_async () const
	Get the current async behaviour of src. More...

void	start_complete (Gst::FlowReturn ret)
	Complete an asynchronous start operation. More...

void	set_automatic_eos (bool automatic_eos)
	If automatic_eos is `true`, src will automatically go EOS if a buffer after the total size is returned. More...

Glib::RefPtr< Gst::Allocator >	get_allocator (Gst::AllocationParams& params)
	Returns the memory allocator used by the base class and its params. More...

Glib::RefPtr< Gst::Pad >	get_src_pad ()
	Gets the source Gst::Pad object of the element. More...

Glib::RefPtr< const Gst::Pad >	get_src_pad () const

Glib::PropertyProxy< gulong >	property_blocksize ()
	Size in bytes to read per buffer (-1 = default). More...

Glib::PropertyProxy_ReadOnly< gulong >	property_blocksize () const
	Size in bytes to read per buffer (-1 = default). More...

Glib::PropertyProxy< bool >	property_do_timestamp ()
	Apply current stream time to buffers. More...

Glib::PropertyProxy_ReadOnly< bool >	property_do_timestamp () const
	Apply current stream time to buffers. More...

Glib::PropertyProxy< int >	property_num_buffers ()
	Number of buffers to output before sending EOS (-1 = unlimited). More...

Glib::PropertyProxy_ReadOnly< int >	property_num_buffers () const
	Number of buffers to output before sending EOS (-1 = unlimited). More...

Glib::PropertyProxy< bool >	property_typefind ()
	Run typefind before negotiating. More...

Glib::PropertyProxy_ReadOnly< bool >	property_typefind () const
	Run typefind before negotiating. More...

virtual Glib::RefPtr< Gst::Caps >	get_caps_vfunc (const Glib::RefPtr< Gst::Caps >& caps) const
	Called to get the caps to report. More...

virtual bool	set_caps_vfunc (const Glib::RefPtr< Gst::Caps >& caps)
	Notify subclass of changed output caps. More...

virtual bool	negotiate_vfunc ()
	Negotiated the caps with the peer. More...

virtual bool	stop_vfunc ()
	Stop processing. More...

virtual bool	start_vfunc ()
	Start processing. More...

virtual void	get_times_vfunc (const Glib::RefPtr< Gst::Buffer >& buffer, Gst::ClockTime&start, Gst::ClockTime&end) const
	Given a buffer, return the start and stop time when it should be pushed out. More...

virtual bool	get_size_vfunc (guint64&size) const
	Return the total size of the resource, in the configured format. More...

virtual bool	is_seekable_vfunc () const
	Check if the source can seek. More...

virtual bool	unlock_vfunc ()
	Unlock any pending access to the resource. More...

virtual bool	event_vfunc (const Glib::RefPtr< Gst::Event >& event)
	Override this to implement custom event handling. More...

virtual FlowReturn	create_vfunc (guint64 offset, guint size, Glib::RefPtr< Gst::Buffer >& buffer)

virtual bool	do_seek_vfunc (Gst::Segment& segment)
	Perform seeking on the resource to the indicated segment. More...

virtual bool	base_src_query_vfunc (const Glib::RefPtr< Gst::Query >&query)
	Handle a requested query. More...

virtual Glib::RefPtr< Gst::Caps >	fixate_vfunc (const Glib::RefPtr< Gst::Caps >& caps)
	Called during negotiation if caps need fixating. More...

virtual bool	unlock_stop_vfunc ()
	Clear the previous unlock request. More...

virtual bool	prepare_seek_segment_vfunc (const Glib::RefPtr< Gst::Event >&seek, Gst::Segment& segment)
	Prepare the Gst::Segment that will be passed to the do_seek_vfunc() vmethod for executing a seek request. More...

virtual bool	decide_allocation_vfunc (const Glib::RefPtr< Gst::Query >&query)
	Configure the allocation query. More...

Gst::FlowReturn	alloc_vfunc (guint64 offset, guint size, Glib::RefPtr< Gst::Buffer >& buffer)
	Ask the subclass to allocate a buffer with for offset and size. More...

virtual Gst::FlowReturn	fill_vfunc (guint64 offset, guint size, const Glib::RefPtr< Gst::Buffer >& buffer)
	Ask the subclass to fill the buffer with data for offset and size. More...

Public Member Functions inherited from Gst::Element
	Element (Element&& src) noexcept

Element&	operator= (Element&& src) noexcept

	~Element () noexcept override

GstElement*	gobj ()
	Provides access to the underlying C GObject. More...

const GstElement*	gobj () const
	Provides access to the underlying C GObject. More...

GstElement*	gobj_copy ()
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

Glib::RefPtr< Gst::Element >	link (const Glib::RefPtr< Gst::Element >& dest)
	Links this source element to the dest element. More...

bool	add_pad (const Glib::RefPtr< Gst::Pad >& pad)
	Adds a pad (link point) to element. More...

void	create_all_pads ()
	Creates a pad for each pad template that is always available. More...

Glib::RefPtr< Gst::Pad >	create_compatible_pad (const Glib::RefPtr< const Gst::Pad >& pad, const Glib::RefPtr< const Gst::Caps >& caps)
	Looks for an unlinked pad to which the given pad can link. More...

Glib::RefPtr< Gst::PadTemplate >	get_compatible_pad_template (const Glib::RefPtr< const Gst::PadTemplate >& compattempl)
	Retrieves a pad template from element that is compatible with compattempl. More...

Glib::RefPtr< const Gst::PadTemplate >	get_compatible_pad_template (const Glib::RefPtr< const Gst::PadTemplate >& compattempl) const
	Retrieves a pad template from element that is compatible with compattempl. More...

Glib::RefPtr< Gst::Pad >	get_request_pad (const Glib::ustring& name)
	Retrieves a pad from the element by name (e.g. "src_\\%d"). More...

Glib::RefPtr< Gst::Pad >	request_pad (const Glib::RefPtr< Gst::PadTemplate >& templ, const Glib::ustring& name, const Glib::RefPtr< const Gst::Caps >& caps)
	Retrieves a request pad from the element according to the provided template. More...

Glib::RefPtr< Gst::Pad >	request_pad (const Glib::RefPtr< Gst::PadTemplate >& templ, const Glib::ustring& name)
	A request_pad() convenience overload. More...

Glib::RefPtr< Gst::Pad >	request_pad (const Glib::RefPtr< Gst::PadTemplate >& templ, const Glib::RefPtr< const Gst::Caps >& caps)
	A request_pad() convenience overload. More...

Glib::RefPtr< Gst::Pad >	request_pad (const Glib::RefPtr< Gst::PadTemplate >& templ)
	A request_pad() convenience overload. More...

Glib::RefPtr< Gst::Pad >	get_static_pad (const Glib::ustring& name)
	Retrieves a pad from element by name. More...

Glib::RefPtr< const Gst::Pad >	get_static_pad (const Glib::ustring& name) const
	Retrieves a pad from element by name. More...

void	no_more_pads ()
	Use this function to signal that the element does not expect any more pads to show up in the current pipeline. More...

void	release_request_pad (const Glib::RefPtr< Gst::Pad >& pad)
	Makes the element free the previously requested pad as obtained with get_request_pad(). More...

bool	remove_pad (const Glib::RefPtr< Gst::Pad >& pad)
	Removes pad from element. More...

Gst::Iterator< Gst::Pad >	iterate_pads ()
	Retrieves an iterator of element's pads. More...

Gst::Iterator< const Gst::Pad >	iterate_pads () const
	Retrieves an iterator of element's pads. More...

Gst::Iterator< Gst::Pad >	iterate_sink_pads ()
	Retrieves an iterator of element's sink pads. More...

Gst::Iterator< const Gst::Pad >	iterate_sink_pads () const
	Retrieves an iterator of element's sink pads. More...

Gst::Iterator< Gst::Pad >	iterate_src_pads ()
	Retrieves an iterator of element's source pads. More...

Gst::Iterator< const Gst::Pad >	iterate_src_pads () const
	Retrieves an iterator of element's source pads. More...

void	unlink (const Glib::RefPtr< Gst::Element >& dest)
	Unlinks all source pads of the source element with all sink pads of the sink element to which they are linked. More...

void	set_context (const Glib::RefPtr< Gst::Context >& context)
	Sets the context of the element. More...

bool	link_pads (const Glib::ustring& srcpadname, const Glib::RefPtr< Gst::Element >& dest, const Glib::ustring& destpadname)
	Links the two named pads of the source and destination elements. More...

void	unlink_pads (const Glib::ustring& srcpadname, const Glib::RefPtr< Gst::Element >& dest, const Glib::ustring& destpadname)
	Unlinks the two named pads of the source and destination elements. More...

bool	link_pads (const Glib::ustring& srcpadname, const Glib::RefPtr< Gst::Element >& dest, const Glib::ustring& destpadname, const Glib::RefPtr< Gst::Caps >& filter)
	Links the two named pads of the source and destination elements. More...

bool	link_pads (const Glib::ustring& srcpadname, const Glib::RefPtr< Gst::Element >& dest, const Glib::ustring& destpadname, PadLinkCheck flags)
	Links the two named pads of the source and destination elements. More...

Glib::RefPtr< Gst::Element >	link (const Glib::RefPtr< Gst::Element >& dest, const Glib::RefPtr< Gst::Caps >& filter)
	Links src to dest using the given caps as filtercaps. More...

void	set_base_time (ClockTime time)
	Set the base time of an element. More...

ClockTime	get_base_time () const
	Returns the base time of the element. More...

void	set_start_time (Gst::ClockTime time)
	Set the start time of an element. More...

Gst::ClockTime	get_start_time () const
	Returns the start time of the element. More...

void	set_bus (const Glib::RefPtr< Gst::Bus >& bus)
	Sets the bus of the element. More...

Glib::RefPtr< Gst::Bus >	get_bus ()
	Returns the bus of the element. More...

Glib::RefPtr< const Gst::Bus >	get_bus () const
	Returns the bus of the element. More...

Glib::RefPtr< Gst::ElementFactory >	get_factory ()
	Retrieves the factory that was used to create this element. More...

Glib::RefPtr< const Gst::ElementFactory >	get_factory () const
	Retrieves the factory that was used to create this element. More...

bool	set_clock (const Glib::RefPtr< Gst::Clock >& clock)
	Sets the clock for the element. More...

Glib::RefPtr< Gst::Clock >	get_clock ()
	Gets the currently configured clock of the element. More...

Glib::RefPtr< const Gst::Clock >	get_clock () const
	Gets the currently configured clock of the element. More...

Glib::RefPtr< Gst::Clock >	provide_clock ()
	Get the clock provided by the given element. More...

Glib::RefPtr< const Gst::Clock >	provide_clock () const
	Get the clock provided by the given element. More...

StateChangeReturn	set_state (State state)
	Sets the state of the element. More...

StateChangeReturn	get_state (State& state, State& pending, ClockTime timeout) const
	Gets the state of the element. More...

bool	set_locked_state (gboolean locked_state)
	Locks the state of an element, so state changes of the parent don't affect this element anymore. More...

bool	is_locked_state () const
	Checks if the state of an element is locked. More...

void	abort_state ()
	Abort the state change of the element. More...

StateChangeReturn	continue_state (StateChangeReturn ret)
	Commit the state change of the element and proceed to the next pending state if any. More...

void	lost_state ()
	Brings the element to the lost state. More...

bool	sync_state_with_parent ()
	Tries to change the state of the element to the same as its parent. More...

StateChangeReturn	change_state (StateChange transition)
	Perform transition on element. More...

void	post_message (int code, int line, MessageType type=Gst::MESSAGE_INFO, const Glib::QueryQuark& domain=get_core_error_quark(), const Glib::ustring& text=Glib::ustring(), const Glib::ustring& debug=Glib::ustring(), const Glib::ustring& file=Glib::ustring(), const Glib::ustring& function=Glib::ustring())
	Post an error, warning or info message on the bus from inside an element. More...

bool	post_message (Glib::RefPtr< Gst::Message >&& message)
	Post a message on the element's Gst::Bus. More...

bool	query (const Glib::RefPtr< Gst::Query >& query) const
	Performs a query on the given element. More...

bool	query_convert (Gst::Format src_format, gint64 src_val, Format dest_format, gint64& dest_val) const
	Queries an element to convert src_val in src_format to dest_format. More...

bool	query_position (Gst::Format format, gint64& cur) const
	Queries an element (usually top-level pipeline or playbin element) for the stream position in nanoseconds. More...

bool	query_position (Gst::Format format) const
	A query_position() convenience overload. More...

bool	query_duration (Gst::Format format, gint64& duration) const
	Queries an element (usually top-level pipeline or playbin element) for the total stream duration in nanoseconds. More...

bool	query_duration (Gst::Format format) const
	A query_duration() convenience overload. More...

bool	seek (Format format, SeekFlags seek_flags, gint64 seek_pos)
	Simple API to perform a seek on the given element, meaning it just seeks to the given position relative to the start of the stream. More...

bool	seek (double rate, Format format, SeekFlags flags, SeekType cur_type, gint64 cur, SeekType stop_type, gint64 stop)
	Sends a seek event to an element. More...

bool	send_event (Glib::RefPtr< Gst::Event >&& event)
	Sends an event to an element. More...

bool	send_event (const Glib::RefPtr< Gst::Event >& event)
	A send_event() convenience overload. Allows to re-use event parameter after function call. More...

Glib::RefPtr< Gst::Context >	get_context (const Glib::ustring& context_type)
	Gets the context with context_type set on the element or `nullptr`. More...

Glib::RefPtr< Gst::Context >	get_context_unlocked (const Glib::ustring& context_type)
	Gets the context with context_type set on the element or `nullptr`. More...

std::vector< Glib::RefPtr< Gst::Context > >	get_contexts ()
	Gets the contexts set on the element. More...

Glib::SignalProxy< void >	signal_no_more_pads ()

Glib::SignalProxy< void, const Glib::RefPtr< Gst::Pad >&>	signal_pad_added ()

Glib::SignalProxy< void, const Glib::RefPtr< Gst::Pad >&>	signal_pad_removed ()

virtual void	release_pad_vfunc (const Glib::RefPtr< Gst::Pad >& pad)
	Called when a request pad is to be released. More...

virtual Glib::RefPtr< Gst::Pad >	request_new_pad_vfunc (Glib::RefPtr< Gst::PadTemplate > templ, const Glib::ustring& name, const Glib::RefPtr< const Gst::Caps >& caps)
	Called when a new pad is requested. More...

virtual StateChangeReturn	get_state_vfunc (State& state, State& pending, ClockTime timeout) const
	Get the state of the element. More...

virtual StateChangeReturn	set_state_vfunc (State state)
	Set a new state on the element. More...

virtual StateChangeReturn	change_state_vfunc (StateChange transition)
	Called by set_state to perform an incremental state change. More...

virtual void	state_changed_vfunc (Gst::State oldstate, Gst::State newstate, Gst::State pending)
	Called immediately after a new state was set. More...

virtual void	set_bus_vfunc (const Glib::RefPtr< Gst::Bus >& bus)
	Set a Gst::Bus on the element. More...

virtual Glib::RefPtr< Gst::Clock >	provide_clock_vfunc ()
	Gets the Gst::Clock provided by the element. More...

virtual bool	set_clock_vfunc (const Glib::RefPtr< Gst::Clock >& clock)
	Set the Gst::Clock on the element. More...

virtual bool	send_event_vfunc (const Glib::RefPtr< Gst::Event >& event)
	Send a Gst::Event to the element. More...

virtual bool	query_vfunc (const Glib::RefPtr< Gst::Query >&query) const
	Perform a Gst::Query on the element. More...

virtual void	set_context_vfunc (const Glib::RefPtr< Gst::Context >& context)
	Set a Gst::Context on the element. More...

virtual bool	post_message_vfunc (const Glib::RefPtr< Gst::Message >& message)
	Called when a message is posted on the element. More...

Glib::RefPtr< Gst::PadTemplate >	get_pad_template (const Glib::ustring& factory_name) const

template<typename T >
Glib::RefPtr< Gst::Element >	property (const Glib::ustring& name, const T& value)
	Sets specified property. More...

Public Member Functions inherited from Gst::Object
	Object (Object&& src) noexcept

Object&	operator= (Object&& src) noexcept

	~Object () noexcept override

GstObject*	gobj ()
	Provides access to the underlying C GObject. More...

const GstObject*	gobj () const
	Provides access to the underlying C GObject. More...

GstObject*	gobj_copy ()
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

bool	is_element () const

bool	is_element_factory () const

bool	is_pad () const

bool	is_pad_template () const

bool	is_bin () const

guint32	get_flags () const
	Returns the entire set of flags for the object. More...

bool	set_name (const Glib::ustring& name)
	Sets the name of object, or gives object a guaranteed unique name (if name is `nullptr`). More...

Glib::ustring	get_name () const
	Returns a copy of the name of object. More...

bool	set_parent (const Glib::RefPtr< Gst::Object >& parent)
	Sets the parent of object to parent. More...

Glib::RefPtr< Gst::Object >	get_parent ()
	Returns the parent of object. More...

Glib::RefPtr< const Gst::Object >	get_parent () const
	Returns the parent of object. More...

void	unparent ()
	Clear the parent of object, removing the associated reference. More...

void	set_control_rate (Gst::ClockTime control_rate)
	Change the control-rate for this object. More...

Gst::ClockTime	get_control_rate () const
	Obtain the control-rate for this object. More...

Gst::ClockTime	suggest_next_sync () const
	Returns a suggestion for timestamps where buffers should be split to get best controller results. More...

bool	sync_values (Gst::ClockTime timestamp)
	Sets the properties of the object, according to the Gst::ControlSources that (maybe) handle them and for the given timestamp. More...

void	set_control_bindings_disabled (bool disabled)
	This function is used to disable all controlled properties of the object for some time, i.e. sync_values() will do nothing. More...

bool	has_asctive_control_bindings () const
	Check if the object has an active controlled properties. More...

bool	has_ancestor (const Glib::RefPtr< const Gst::Object >& ancestor) const
	Check if object has an ancestor ancestor somewhere up in the hierarchy. More...

bool	has_as_ancestor (const Glib::RefPtr< Gst::Object >& ancestor) const
	Check if object has an ancestor ancestor somewhere up in the hierarchy. More...

bool	has_as_parent (const Glib::RefPtr< Gst::Object >& parent) const
	Check if parent is the parent of object. More...

Glib::ustring	get_path_string ()
	Generates a string describing the path of object in the object hierarchy. More...

Glib::PropertyProxy< Glib::ustring >	property_name ()
	The name of the object. More...

Glib::PropertyProxy_ReadOnly< Glib::ustring >	property_name () const
	The name of the object. More...

Glib::PropertyProxy< Glib::RefPtr< Gst::Object > >	property_parent ()
	The parent of the object. More...

Glib::PropertyProxy_ReadOnly< Glib::RefPtr< Gst::Object > >	property_parent () const
	The parent of the object. More...

Glib::SignalProxy< void, const Glib::RefPtr< Gst::Object >&, GParamSpec*>	signal_deep_notify ()

int	get_refcount () const

Static Public Member Functions
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system. More...

Static Public Member Functions inherited from Gst::Element
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system. More...

Static Public Member Functions inherited from Gst::Object
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system. More...

static bool	check_uniqueness (const Glib::ListHandle< const Gst::Object >& list, const Glib::ustring& name)
	Checks to see if there is any object named name in list. More...

Related Functions
(Note that these are not member functions.)
Glib::RefPtr< Gst::BaseSrc >	wrap (GstBaseSrc* object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Related Functions inherited from Gst::Element
Glib::RefPtr< Gst::Element >	wrap (GstElement* object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Related Functions inherited from Gst::Object
Glib::RefPtr< Gst::Object >	wrap (GstObject* object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Additional Inherited Members
Protected Member Functions inherited from Gst::Element
virtual void	on_no_more_pads ()
	This is a default handler for the signal signal_no_more_pads(). More...

virtual void	on_pad_added (const Glib::RefPtr< Gst::Pad >& new_pad)
	This is a default handler for the signal signal_pad_added(). More...

virtual void	on_pad_removed (const Glib::RefPtr< Gst::Pad >& old_pad)
	This is a default handler for the signal signal_pad_removed(). More...

Protected Member Functions inherited from Gst::Object
virtual void	on_deep_notify (const Glib::RefPtr< Gst::Object >& prop_object, GParamSpec* prop)
	This is a default handler for the signal signal_deep_notify(). More...

Detailed Description

A base class for getrange based source elements.

This is a generice base class for source elements. The following types of sources are supported:

random access sources like files,
seekable sources,
live sources.

The source can be configured to operate in any Gst::Format with the set_format() method. The currently set format determines the format of the internal Gst::Segment and any Gst::EVENT_NEWSEGMENT events. The default format for Gst::BaseSrc is Gst::FORMAT_BYTES.

Gst::BaseSrc always supports push mode scheduling. If the following conditions are met, it also supports pull mode scheduling:

The format is set to Gst::FORMAT_BYTES (default).
Gst::BaseSrc::is_seekable_vfunc() returns TRUE.

Since GStreamer 0.10.9, any Gst::BaseSrc can enable pull based scheduling at any time by overriding Gst::BaseSrc::check_get_range_vfunc() so that it returns TRUE.

If all the conditions are met for operating in pull mode, Gst::BaseSrc is automatically seekable in push mode as well. The following conditions must be met to make the element seekable in push mode when the format is not Gst::FORMAT_BYTES:

Gst::BaseSrc::is_seekable_vfunc() returns TRUE.
Gst::BaseSrc::query_vfunc() can convert all supported seek formats to the internal format as set with set_format().
Gst::BaseSrc::do_seek_vfunc() is implemented, performs the seek and returns TRUE.

When the element does not meet the requirements to operate in pull mode, the offset and length in the Gst::BaseSrc::create_vfunc() method should be ignored. It is recommended to subclass Gst::PushSrc instead, in this situation. If the element can operate in pull mode but only with specific offsets and lengths, it is allowed to generate an error when the wrong values are passed to the Gst::BaseSrc::create_vfunc() function.

Gst::BaseSrc has support for live sources. Live sources are sources that when paused discard data, such as audio or video capture devices. A typical live source also produces data at a fixed rate and thus provides a clock to publish this rate. Use set_live() to activate the live source mode.

A live source does not produce data in the PAUSED state. This means that the Gst::BaseSrc::create_vfunc() method will not be called in PAUSED but only in PLAYING. To signal the pipeline that the element will not produce data, the return value from the READY to PAUSED state will be Gst::STATE_CHANGE_NO_PREROLL.

A typical live source will timestamp the buffers it creates with the current running time of the pipeline. This is one reason why a live source can only produce data in the PLAYING state, when the clock is actually distributed and running.

Live sources that synchronize and block on the clock (an audio source, for example) can since GStreamer 0.10.12 use wait_playing() when the create_vfunc() function was interrupted by a state change to PAUSED.

The Gst::BaseSrc::get_times_vfunc() method can be used to implement pseudo-live sources. It only makes sense to implement the get_times_vfunc() function if the source is a live source. The get_times_vfunc() function should return timestamps starting from 0, as if it were a non-live source. The base class will make sure that the timestamps are transformed into the current running_time. The base source will then wait for the calculated running_time before pushing out the buffer.

For live sources, the base class will by default report a latency of 0. For pseudo live sources, the base class will by default measure the difference between the first buffer timestamp and the start time of get_times_vfunc() and will report this value as the latency. Subclasses should override the query_vfunc() function when this behaviour is not acceptable.

TODO: Edit below paragraph for C++ and include C++ example from C API (if necessary):

There is only support in Gst::BaseSrc for exactly one source pad, which should be named "src". A source implementation (subclass of Gst::BaseSrc) should install a pad template in its class_init function, like so:

// static
void SampleBaseSrc::base_init(Gst::ElementClass<SampleBaseSrc>* klass)
{
  klass->add_pad_template(Gst::PadTemplate::create(
                                "src",
                                Gst::PAD_SRC,
                                Gst::PAD_ALWAYS,
                                Gst::Caps::create_from_string("x-application/x-foo1")
  ));
  klass->set_metadata("Source name", "Source", "My source element", "The author <[email protected]>");
}

Controlled shutdown of live sources in applications

Applications that record from a live source may want to stop recording in a controlled way, so that the recording is stopped, but the data already in the pipeline is processed to the end (remember that many live sources would go on recording forever otherwise). For that to happen the application needs to make the source stop recording and send an EOS event down the pipeline. The application would then wait for an EOS message posted on the pipeline's bus to know when all data has been processed and the pipeline can safely be stopped.

Since GStreamer 0.10.16 an application may send an EOS event to a source element to make it perform the EOS logic (send EOS event downstream or post a Gst::MESSAGE_SEGMENT_DONE on the bus). This can typically be done with the Gst::Element::send_event() function on the element or its parent bin.

After the EOS has been sent to the element, the application should wait for an EOS message to be posted on the pipeline's bus. Once this EOS message is received, it may safely shut down the entire pipeline.

The old behaviour for controlled shutdown introduced since GStreamer 0.10.3 is still available but deprecated as it is dangerous and less flexible.

Last reviewed on 2016-05-05 (1.8.0).

Constructor & Destructor Documentation

◆ BaseSrc()

Gst::BaseSrc::BaseSrc ( BaseSrc&& src )

noexcept

◆ ~BaseSrc()

Gst::BaseSrc::~BaseSrc ( )

overridenoexcept

Member Function Documentation

◆ alloc_vfunc()

Gst::FlowReturn Gst::BaseSrc::alloc_vfunc	(	guint64	offset,
		guint	size,
		Glib::RefPtr< Gst::Buffer >&	buffer
	)

Ask the subclass to allocate a buffer with for offset and size.

The default implementation will create a new buffer from the negotiated allocator.

◆ base_src_query_vfunc()

virtual bool Gst::BaseSrc::base_src_query_vfunc ( const Glib::RefPtr< Gst::Query >& query )

virtual

Handle a requested query.

◆ create_vfunc()

virtual FlowReturn Gst::BaseSrc::create_vfunc	(	guint64	offset,
		guint	size,
		Glib::RefPtr< Gst::Buffer >&	buffer
	)

virtual

◆ decide_allocation_vfunc()

virtual bool Gst::BaseSrc::decide_allocation_vfunc ( const Glib::RefPtr< Gst::Query >& query )

virtual

Configure the allocation query.

◆ do_seek_vfunc()

virtual bool Gst::BaseSrc::do_seek_vfunc ( Gst::Segment& segment )

virtual

Perform seeking on the resource to the indicated segment.

◆ event_vfunc()

virtual bool Gst::BaseSrc::event_vfunc ( const Glib::RefPtr< Gst::Event >& event )

virtual

Override this to implement custom event handling.

◆ fill_vfunc()

virtual Gst::FlowReturn Gst::BaseSrc::fill_vfunc	(	guint64	offset,
		guint	size,
		const Glib::RefPtr< Gst::Buffer >&	buffer
	)

virtual

Ask the subclass to fill the buffer with data for offset and size.

The passed buffer is guaranteed to hold the requested amount of bytes.

◆ fixate_vfunc()

virtual Glib::RefPtr<Gst::Caps> Gst::BaseSrc::fixate_vfunc ( const Glib::RefPtr< Gst::Caps >& caps )

virtual

Called during negotiation if caps need fixating.

Implement instead of setting a fixate function on the source pad.

◆ get_allocator()

Glib::RefPtr<Gst::Allocator> Gst::BaseSrc::get_allocator ( Gst::AllocationParams& params )

Returns the memory allocator used by the base class and its params.

Parameters

params The Gst::AllocationParams of allocator.

Returns: The Gst::Allocator used.

◆ get_blocksize()

guint Gst::BaseSrc::get_blocksize ( ) const

Get the number of bytes that src will push out with each buffer.

Returns: The number of bytes pushed with each buffer.

◆ get_caps_vfunc()

virtual Glib::RefPtr<Gst::Caps> Gst::BaseSrc::get_caps_vfunc ( const Glib::RefPtr< Gst::Caps >& caps ) const

virtual

Called to get the caps to report.

◆ get_do_timestamp()

bool Gst::BaseSrc::get_do_timestamp ( ) const

Query if src timestamps outgoing buffers based on the current running_time.

Returns: true if the base class will automatically timestamp outgoing buffers.

◆ get_size_vfunc()

virtual bool Gst::BaseSrc::get_size_vfunc ( guint64 & size ) const

virtual

Return the total size of the resource, in the configured format.

◆ get_src_pad() [1/2]

Glib::RefPtr<Gst::Pad> Gst::BaseSrc::get_src_pad ( )

Gets the source Gst::Pad object of the element.

◆ get_src_pad() [2/2]

Glib::RefPtr<const Gst::Pad> Gst::BaseSrc::get_src_pad ( ) const

◆ get_times_vfunc()

virtual void Gst::BaseSrc::get_times_vfunc	(	const Glib::RefPtr< Gst::Buffer >&	buffer,
		Gst::ClockTime&	start,
		Gst::ClockTime&	end
	)		const

virtual

Given a buffer, return the start and stop time when it should be pushed out.

The base class will sync on the clock using these times.

◆ get_type()

static GType Gst::BaseSrc::get_type ( )

static

Get the GType for this class, for use with the underlying GObject type system.

◆ gobj() [1/2]

GstBaseSrc* Gst::BaseSrc::gobj ( )

inline

Provides access to the underlying C GObject.

◆ gobj() [2/2]

const GstBaseSrc* Gst::BaseSrc::gobj ( ) const

inline

Provides access to the underlying C GObject.

◆ gobj_copy()

GstBaseSrc* Gst::BaseSrc::gobj_copy ( )

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

◆ is_async()

bool Gst::BaseSrc::is_async ( ) const

Get the current async behaviour of src.

◆ is_live()

bool Gst::BaseSrc::is_live ( ) const

Check if an element is in live mode.

Returns: true if element is in live mode.

◆ is_seekable_vfunc()

virtual bool Gst::BaseSrc::is_seekable_vfunc ( ) const

virtual

Check if the source can seek.

◆ negotiate_vfunc()

virtual bool Gst::BaseSrc::negotiate_vfunc ( )

virtual

Negotiated the caps with the peer.

◆ new_seamless_segment()

bool Gst::BaseSrc::new_seamless_segment	(	gint64	start,
		gint64	stop,
		gint64	position
	)

Prepare a new seamless segment for emission downstream.

This function must only be called by derived sub-classes, and only from the create() function, as the stream-lock needs to be held.

The format for the new segment will be the current format of the source, as configured with set_format()

Parameters

start	The new start value for the segment.
stop	Stop value for the new segment.
position	The new time value for the start of the new segment.

Returns: true if preparation of the seamless segment succeeded.

◆ operator=()

BaseSrc& Gst::BaseSrc::operator= ( BaseSrc&& src )

noexcept

◆ prepare_seek_segment_vfunc()

virtual bool Gst::BaseSrc::prepare_seek_segment_vfunc	(	const Glib::RefPtr< Gst::Event >&	seek,
		Gst::Segment&	segment
	)

virtual

Prepare the Gst::Segment that will be passed to the do_seek_vfunc() vmethod for executing a seek request.

Sub-classes should override this if they support seeking in formats other than the configured native format. By default, it tries to convert the seek arguments to the configured native format and prepare a segment in that format.

◆ property_blocksize() [1/2]

Glib::PropertyProxy< gulong > Gst::BaseSrc::property_blocksize ( )

Size in bytes to read per buffer (-1 = default).

Returns: A PropertyProxy that allows you to get or set the value of the property, or receive notification when the value of the property changes.

◆ property_blocksize() [2/2]

Glib::PropertyProxy_ReadOnly< gulong > Gst::BaseSrc::property_blocksize ( ) const

Size in bytes to read per buffer (-1 = default).

Returns: A PropertyProxy_ReadOnly that allows you to get the value of the property, or receive notification when the value of the property changes.

◆ property_do_timestamp() [1/2]

Glib::PropertyProxy< bool > Gst::BaseSrc::property_do_timestamp ( )

Apply current stream time to buffers.

Returns: A PropertyProxy that allows you to get or set the value of the property, or receive notification when the value of the property changes.

◆ property_do_timestamp() [2/2]

Glib::PropertyProxy_ReadOnly< bool > Gst::BaseSrc::property_do_timestamp ( ) const

Apply current stream time to buffers.

Returns: A PropertyProxy_ReadOnly that allows you to get the value of the property, or receive notification when the value of the property changes.

◆ property_num_buffers() [1/2]

Glib::PropertyProxy< int > Gst::BaseSrc::property_num_buffers ( )

Number of buffers to output before sending EOS (-1 = unlimited).

Returns: A PropertyProxy that allows you to get or set the value of the property, or receive notification when the value of the property changes.

◆ property_num_buffers() [2/2]

Glib::PropertyProxy_ReadOnly< int > Gst::BaseSrc::property_num_buffers ( ) const

Number of buffers to output before sending EOS (-1 = unlimited).

Returns: A PropertyProxy_ReadOnly that allows you to get the value of the property, or receive notification when the value of the property changes.

◆ property_typefind() [1/2]

Glib::PropertyProxy< bool > Gst::BaseSrc::property_typefind ( )

Run typefind before negotiating.

Returns: A PropertyProxy that allows you to get or set the value of the property, or receive notification when the value of the property changes.

◆ property_typefind() [2/2]

Glib::PropertyProxy_ReadOnly< bool > Gst::BaseSrc::property_typefind ( ) const

Run typefind before negotiating.

Returns: A PropertyProxy_ReadOnly that allows you to get the value of the property, or receive notification when the value of the property changes.

◆ query_latency()

bool Gst::BaseSrc::query_latency	(	bool &	live,
		Gst::ClockTime&	min_latency,
		Gst::ClockTime&	max_latency
	)		const

Query the source for the latency parameters.

live will be true when src is configured as a live source. min_latency and max_latency will be set to the difference between the running time and the timestamp of the first buffer.

This function is mostly used by subclasses.

Parameters

live	If the source is live.
min_latency	The min latency of the source.
max_latency	The max latency of the source.

Returns: true if the query succeeded.

◆ set_async()

void Gst::BaseSrc::set_async ( bool async )

Configure async behaviour in src, no state change will block.

The open, close, start, stop, play and pause virtual methods will be executed in a different thread and are thus allowed to perform blocking operations. Any blocking operation should be unblocked with the unlock vmethod.

Parameters

async New async mode.

◆ set_automatic_eos()

void Gst::BaseSrc::set_automatic_eos ( bool automatic_eos )

If automatic_eos is true, src will automatically go EOS if a buffer after the total size is returned.

By default this is true but sources that can't return an authoritative size and only know that they're EOS when trying to read more should set this to false.

Parameters

automatic_eos Automatic eos.

◆ set_blocksize()

void Gst::BaseSrc::set_blocksize ( guint blocksize )

Set the number of bytes that src will push out with each buffer.

When blocksize is set to -1, a default length will be used.

Parameters

blocksize The new blocksize in bytes.

◆ set_caps()

bool Gst::BaseSrc::set_caps ( const Glib::RefPtr< Gst::Caps >& caps )

Set new caps on the basesrc source pad.

Parameters

caps	A Gst::Caps.

Returns: true if the caps could be set.

◆ set_caps_vfunc()

virtual bool Gst::BaseSrc::set_caps_vfunc ( const Glib::RefPtr< Gst::Caps >& caps )

virtual

Notify subclass of changed output caps.

◆ set_do_timestamp()

void Gst::BaseSrc::set_do_timestamp ( bool timestamp )

Configure src to automatically timestamp outgoing buffers based on the current running_time of the pipeline.

This property is mostly useful for live sources.

Parameters

timestamp Enable or disable timestamping.

◆ set_dynamic_size()

void Gst::BaseSrc::set_dynamic_size ( bool dynamic_size )

If not dynamic_size, size is only updated when needed, such as when trying to read past current tracked size.

Otherwise, size is checked for upon each read.

Parameters

dynamic_size New dynamic size mode.

◆ set_format()

void Gst::BaseSrc::set_format ( Format format )

Sets the default format of the source.

This will be the format used for sending SEGMENT events and for performing seeks.

If a format of GST_FORMAT_BYTES is set, the element will be able to operate in pull mode if the Gst::BaseSrcClass.is_seekable() returns true.

This function must only be called in states < Gst::STATE_PAUSED.

Parameters

format The format to use.

◆ set_live()

void Gst::BaseSrc::set_live ( bool live )

If the element listens to a live source, live should be set to true.

A live source will not produce data in the PAUSED state and will therefore not be able to participate in the PREROLL phase of a pipeline. To signal this fact to the application and the pipeline, the state change return value of the live source will be GST_STATE_CHANGE_NO_PREROLL.

Parameters

live	New live-mode.

◆ start_complete()

void Gst::BaseSrc::start_complete ( Gst::FlowReturn ret )

Complete an asynchronous start operation.

When the subclass overrides the start method, it should call start_complete() when the start operation completes either from the same thread or from an asynchronous helper thread.

Parameters

ret	A Gst::FlowReturn.

◆ start_vfunc()

virtual bool Gst::BaseSrc::start_vfunc ( )

virtual

Start processing.

Subclasses should open resources and prepare to produce data.

◆ start_wait()

Gst::FlowReturn Gst::BaseSrc::start_wait ( )

Wait until the start operation completes.

Returns: A Gst::FlowReturn.

◆ stop_vfunc()

virtual bool Gst::BaseSrc::stop_vfunc ( )

virtual

Stop processing.

Subclasses should use this to close resources.

◆ unlock_stop_vfunc()

virtual bool Gst::BaseSrc::unlock_stop_vfunc ( )

virtual

Clear the previous unlock request.

Subclasses should clear any state they set during unlock_vfunc(), such as clearing command queues.

◆ unlock_vfunc()

virtual bool Gst::BaseSrc::unlock_vfunc ( )

virtual

Unlock any pending access to the resource.

Subclasses should unblock any blocked function ASAP.

◆ wait_playing()

FlowReturn Gst::BaseSrc::wait_playing ( )

If the Gst::BaseSrcClass.create() method performs its own synchronisation against the clock it must unblock when going from PLAYING to the PAUSED state and call this method before continuing to produce the remaining data.

This function will block until a state change to PLAYING happens (in which case this function returns Gst::FLOW_OK) or the processing must be stopped due to a state change to READY or a FLUSH event (in which case this function returns Gst::FLOW_FLUSHING).

Returns: Gst::FLOW_OK if src is PLAYING and processing can continue. Any other return value should be returned from the create vmethod.

Friends And Related Function Documentation

◆ wrap()

Glib::RefPtr< Gst::BaseSrc > wrap	(	GstBaseSrc *	object,
		bool	take_copy = `false`
	)

Parameters

object	The C instance.
take_copy	False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns: A C++ instance that wraps this C instance.

Public Member Functions

Static Public Member Functions

Related Functions

Additional Inherited Members

Detailed Description

Controlled shutdown of live sources in applications

Constructor & Destructor Documentation

◆ BaseSrc()

◆ ~BaseSrc()

Member Function Documentation

◆ alloc_vfunc()

◆ base_src_query_vfunc()

◆ create_vfunc()

◆ decide_allocation_vfunc()

◆ do_seek_vfunc()

◆ event_vfunc()

◆ fill_vfunc()

◆ fixate_vfunc()

◆ get_allocator()

◆ get_blocksize()

◆ get_caps_vfunc()

◆ get_do_timestamp()

◆ get_size_vfunc()

◆ get_src_pad() [1/2]

◆ get_src_pad() [2/2]

◆ get_times_vfunc()

◆ get_type()

◆ gobj() [1/2]

◆ gobj() [2/2]

◆ gobj_copy()

◆ is_async()

◆ is_live()

◆ is_seekable_vfunc()

◆ negotiate_vfunc()

◆ new_seamless_segment()

◆ operator=()

◆ prepare_seek_segment_vfunc()

◆ property_blocksize() [1/2]

◆ property_blocksize() [2/2]

◆ property_do_timestamp() [1/2]

◆ property_do_timestamp() [2/2]

◆ property_num_buffers() [1/2]

◆ property_num_buffers() [2/2]

◆ property_typefind() [1/2]

◆ property_typefind() [2/2]

◆ query_latency()

◆ set_async()

◆ set_automatic_eos()

◆ set_blocksize()

◆ set_caps()

◆ set_caps_vfunc()

◆ set_do_timestamp()

◆ set_dynamic_size()

◆ set_format()

◆ set_live()

◆ start_complete()

◆ start_vfunc()

◆ start_wait()

◆ stop_vfunc()

◆ unlock_stop_vfunc()

◆ unlock_vfunc()

◆ wait_playing()

Friends And Related Function Documentation

◆ wrap()