Class Aggregator

java.lang.Object
org.javagi.base.ProxyInstance
org.gnome.gobject.TypeInstance
org.gnome.gobject.GObject
org.gnome.gobject.InitiallyUnowned
org.freedesktop.gstreamer.gst.GstObject
org.freedesktop.gstreamer.gst.Element
org.freedesktop.gstreamer.base.Aggregator
All Implemented Interfaces:
Proxy
Direct Known Subclasses:
Aggregator.Aggregator$Impl, AudioAggregator, VideoAggregator
@Generated("org.javagi.JavaGI") public abstract class Aggregator extends Element

Manages a set of pads with the purpose of aggregating their buffers. Control is given to the subclass when all pads have data.

  • Base class for mixers and muxers. Subclasses should at least implement the GstAggregatorClass::aggregate virtual method.

  • Installs a GstPadChainFunction, a GstPadEventFullFunction and a GstPadQueryFunction to queue all serialized data packets per sink pad. Subclasses should not overwrite those, but instead implement GstAggregatorClass::sink_event and GstAggregatorClass::sink_query as needed.

  • When data is queued on all pads, the aggregate vmethod is called.

  • One can peek at the data on any given GstAggregatorPad with the gst_aggregator_pad_peek_buffer() method, and remove it from the pad with the gst_aggregator_pad_pop_buffer () method. When a buffer has been taken with pop_buffer (), a new buffer can be queued on that pad.

  • When gst_aggregator_pad_peek_buffer() or gst_aggregator_pad_has_buffer() are called, a reference is taken to the returned buffer, which stays valid until either:

    • gst_aggregator_pad_pop_buffer() is called, in which case the caller is guaranteed that the buffer they receive is the same as the peeked buffer.
    • gst_aggregator_pad_drop_buffer() is called, in which case the caller is guaranteed that the dropped buffer is the one that was peeked.
    • the subclass implementation of GstAggregatorClass.aggregate returns.

    Subsequent calls to gst_aggregator_pad_peek_buffer() or gst_aggregator_pad_has_buffer() return / check the same buffer that was returned / checked, until one of the conditions listed above is met.

    Subclasses are only allowed to call these methods from the aggregate thread.

  • If the subclass wishes to push a buffer downstream in its aggregate implementation, it should do so through the gst_aggregator_finish_buffer() method. This method will take care of sending and ordering mandatory events such as stream start, caps and segment. Buffer lists can also be pushed out with gst_aggregator_finish_buffer_list().

  • Same goes for EOS events, which should not be pushed directly by the subclass, it should instead return GST_FLOW_EOS in its aggregate implementation.

  • Note that the aggregator logic regarding gap event handling is to turn these into gap buffers with matching PTS and duration. It will also flag these buffers with GST_BUFFER_FLAG_GAP and GST_BUFFER_FLAG_DROPPABLE to ease their identification and subsequent processing. In addition, if the gap event was flagged with GST_GAP_FLAG_MISSING_DATA, a custom meta is added to the resulting gap buffer (GstAggregatorMissingDataMeta).

  • Subclasses must use (a subclass of) GstAggregatorPad for both their sink and source pads. See gst_element_class_add_static_pad_template_with_gtype().

This class used to live in gst-plugins-bad and was moved to core.

Since:
1.14

  • Constructor Details

    • Aggregator

      public Aggregator(MemorySegment address)
      Create a Aggregator instance for the provided memory address.
      Parameters:
      address - the memory address of the native object

    • Aggregator

      public Aggregator()
      Create a new Aggregator.

  • Method Details

    • getType

      public static @Nullable Type getType()
      Get the GType of the Aggregator class.
      Returns:
      the GType

    • getMemoryLayout

      public static MemoryLayout getMemoryLayout()
      The memory layout of the native struct.
      Returns:
      the memory layout

    • asParent

      protected Aggregator asParent()
      Return this instance as if it were its parent type. Comparable to the Java super keyword, but ensures the parent typeclass is also used in native code.
      Overrides:
      asParent in class Element
      Returns:
      the instance as if it were its parent type

    • finishBuffer

      public FlowReturn finishBuffer(Buffer buffer)
      This method will push the provided output buffer downstream. If needed, mandatory events such as stream-start, caps, and segment events will be sent before pushing the buffer.
      Parameters:
      buffer - the GstBuffer to push.

    • finishBufferList

      public FlowReturn finishBufferList(BufferList bufferlist)
      This method will push the provided output buffer list downstream. If needed, mandatory events such as stream-start, caps, and segment events will be sent before pushing the buffer.
      Parameters:
      bufferlist - the GstBufferList to push.
      Since:
      1.18

    • getAllocator

      public void getAllocator(@Nullable Out<Allocator> allocator, @Nullable AllocationParams params)

      Lets GstAggregator sub-classes get the memory allocator acquired by the base class and its params.

      Unref the allocator after use it.

      Parameters:
      allocator - the GstAllocator used
      params - the GstAllocationParams of allocator

    • getBufferPool

      public @Nullable BufferPool getBufferPool()

    • getForceLive

      public boolean getForceLive()
      Subclasses may use the return value to inform whether they should return FlowReturn.EOS from their aggregate implementation.
      Returns:
      whether live status was forced on self.
      Since:
      1.22

    • getIgnoreInactivePads

      public boolean getIgnoreInactivePads()

    • getLatency

      public ClockTime getLatency()

      Retrieves the latency values reported by this Aggregator in response to the latency query, or GST_CLOCK_TIME_NONE if there is not live source connected and the element will not wait for the clock.

      Typically only called by subclasses.

      Returns:
      The latency or GST_CLOCK_TIME_NONE if the element does not sync

    • negotiate

      public boolean negotiate()
      Negotiates src pad caps with downstream elements. Unmarks GST_PAD_FLAG_NEED_RECONFIGURE in any case. But marks it again if GstAggregatorClass::negotiate fails.
      Returns:
      true if the negotiation succeeded, else false.
      Since:
      1.18

    • peekNextSample

      public @Nullable Sample peekNextSample(AggregatorPad pad)
      Use this function to determine what input buffers will be aggregated to produce the next output buffer. This should only be called from a GstAggregator::samples-selected handler, and can be used to precisely control aggregating parameters for a given set of input samples.
      Returns:
      The sample that is about to be aggregated. It may hold a GstBuffer or a GstBufferList. The contents of its info structure is subclass-dependent, and documented on a subclass basis. The buffers held by the sample are not writable.
      Since:
      1.18

    • pushSrcEvent

      public boolean pushSrcEvent(Event event)

      This method will push the provided event downstream. If needed, mandatory events such as stream-start, caps, and segment events will be sent before pushing the event.

      This API does not allow pushing stream-start, caps, segment and EOS events. Specific API like gst_aggregator_set_src_caps() should be used for these.

      Parameters:
      event - the GstEvent to push.
      Since:
      1.26

    • selectedSamples

      public void selectedSamples(ClockTime pts, ClockTime dts, ClockTime duration, @Nullable Structure info)

      Subclasses should call this when they have prepared the buffers they will aggregate for each of their sink pads, but before using any of the properties of the pads that govern how aggregation should be performed, for example z-index for video aggregators.

      If gst_aggregator_update_segment() is used by the subclass, it MUST be called before gst_aggregator_selected_samples().

      This function MUST only be called from the GstAggregatorClass::aggregate() function.

      Parameters:
      pts - The presentation timestamp of the next output buffer
      dts - The decoding timestamp of the next output buffer
      duration - The duration of the next output buffer
      info - a GstStructure containing additional information
      Since:
      1.18

    • setForceLive

      public void setForceLive(boolean forceLive)
      Subclasses should call this at construction time in order for this Aggregator to aggregate on a timeout even when no live source is connected.
      Since:
      1.22

    • setIgnoreInactivePads

      public void setIgnoreInactivePads(boolean ignore)

      Subclasses should call this when they don't want to time out waiting for a pad that hasn't yet received any buffers in live mode.

      GstAggregator will still wait once on each newly-added pad, making sure upstream has had a fair chance to start up.

      Parameters:
      ignore - whether inactive pads should not be waited on
      Since:
      1.20

    • setLatency

      public void setLatency(ClockTime minLatency, ClockTime maxLatency)
      Lets GstAggregator sub-classes tell the baseclass what their internal latency is. Will also post a LATENCY message on the bus so the pipeline can reconfigure its global latency if the values changed.
      Parameters:
      minLatency - minimum latency
      maxLatency - maximum latency

    • setSrcCaps

      public void setSrcCaps(Caps caps)
      Sets the caps to be used on the src pad.
      Parameters:
      caps - The GstCaps to set on the src pad.

    • simpleGetNextTime

      public ClockTime simpleGetNextTime()

      This is a simple GstAggregatorClass::get_next_time implementation that just looks at the GstSegment on the srcpad of the aggregator and bases the next time on the running time there.

      This is the desired behaviour in most cases where you have a live source and you have a dead line based aggregator subclass.

      Returns:
      The running time based on the position
      Since:
      1.16

    • updateSegment

      public void updateSegment(Segment segment)

      Subclasses should use this to update the segment on their source pad, instead of directly pushing new segment events downstream.

      Subclasses MUST call this before gst_aggregator_selected_samples(), if it is used at all.

      Since:
      1.18

    • aggregate

      protected FlowReturn aggregate(boolean timeout)
      Mandatory. Called when buffers are queued on all sinkpads. Classes should iterate the GstElement->sinkpads and peek or steal buffers from the GstAggregatorPads. If the subclass returns GST_FLOW_EOS, sending of the eos event will be taken care of. Once / if a buffer has been constructed from the aggregated buffers, the subclass should call _finish_buffer.

    • clip

      protected Buffer clip(AggregatorPad aggregatorPad, Buffer buf)
      Optional. Called when a buffer is received on a sink pad, the task of clipping it and translating it to the current segment falls on the subclass. The function should use the segment of data and the negotiated media type on the pad to perform clipping of input buffer. This function takes ownership of buf and should output a buffer or return NULL in if the buffer should be dropped.

    • createNewPad

      protected AggregatorPad createNewPad(PadTemplate templ, String reqName, Caps caps)
      Optional. Called when a new pad needs to be created. Allows subclass that don't have a single sink pad template to provide a pad based on the provided information.

    • decideAllocation

      protected boolean decideAllocation(Query query)
      Optional. Allows the subclass to influence the allocation choices. Setup the allocation parameters for allocating output buffers. The passed in query contains the result of the downstream allocation query.

    • fixateSrcCaps

      protected Caps fixateSrcCaps(Caps caps)
      Optional. Fixate and return the src pad caps provided. The function takes ownership of caps and returns a fixated version of caps. caps is not guaranteed to be writable.

    • flush

      protected FlowReturn flush()
      Optional. Called after a successful flushing seek, once all the flush stops have been received. Flush pad-specific data in GstAggregatorPad->flush.

    • getNextTime

      protected ClockTime getNextTime()
      Optional. Called when the element needs to know the running time of the next rendered buffer for live pipelines. This causes deadline based aggregation to occur. Defaults to returning GST_CLOCK_TIME_NONE causing the element to wait for buffers on all sink pads before aggregating.

    • negotiatedSrcCaps

      protected boolean negotiatedSrcCaps(Caps caps)
      Optional. Notifies subclasses what caps format has been negotiated

    • proposeAllocation

      protected boolean proposeAllocation(AggregatorPad pad, Query decideQuery, Query query)
      Optional. Allows the subclass to handle the allocation query from upstream.

    • sinkEvent

      protected boolean sinkEvent(AggregatorPad aggregatorPad, Event event)
      Optional. Called when an event is received on a sink pad, the subclass should always chain up.

    • sinkEventPreQueue

      protected FlowReturn sinkEventPreQueue(AggregatorPad aggregatorPad, Event event)
      Optional. Called when an event is received on a sink pad before queueing up serialized events. The subclass should always chain up (Since: 1.18).

    • sinkQuery

      protected boolean sinkQuery(AggregatorPad aggregatorPad, Query query)
      Optional. Called when a query is received on a sink pad, the subclass should always chain up.

    • sinkQueryPreQueue

      protected boolean sinkQueryPreQueue(AggregatorPad aggregatorPad, Query query)
      Optional. Called when a query is received on a sink pad before queueing up serialized queries. The subclass should always chain up (Since: 1.18).

    • srcActivate

      protected boolean srcActivate(PadMode mode, boolean active)
      Optional. Called when the src pad is activated, it will start/stop its pad task right after that call.

    • srcEvent

      protected boolean srcEvent(Event event)
      Optional. Called when an event is received on the src pad, the subclass should always chain up.

    • srcQuery

      protected boolean srcQuery(Query query)
      Optional. Called when a query is received on the src pad, the subclass should always chain up.

    • start

      protected boolean start()
      Optional. Called when the element goes from READY to PAUSED. The subclass should get ready to process aggregated buffers.

    • stop

      protected boolean stop()
      Optional. Called when the element goes from PAUSED to READY. The subclass should free all resources and reset its state.

    • updateSrcCaps

      protected FlowReturn updateSrcCaps(Caps caps, @Nullable Out<Caps> ret)

    • onSamplesSelected

      public SignalConnection<Aggregator.SamplesSelectedCallback> onSamplesSelected(Aggregator.SamplesSelectedCallback handler)
      Signals that the GstAggregator subclass has selected the next set of input samples it will aggregate. Handlers may call gst_aggregator_peek_next_sample() at that point.
      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      Since:
      1.18
      See Also:

    • emitSamplesSelected

      public void emitSamplesSelected(@Nullable Segment segment, long pts, long dts, long duration, @Nullable Structure info)
      Emits the "samples-selected" signal. See onSamplesSelected(Aggregator.SamplesSelectedCallback).