Aggregator#

Added in version 1.14.

class Aggregator(**properties: Any)#

Superclasses: Element, Object, InitiallyUnowned, Object

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 PadChainFunction, a PadEventFullFunction and a
PadQueryFunction 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
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 peek_buffer() or has_buffer()
are called, a reference is taken to the returned buffer, which stays valid until either:
pop_buffer() is called, in which case the caller
is guaranteed that the buffer they receive is the same as the peeked buffer.
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 peek_buffer() or: 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 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 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) AggregatorPad for both their
sink and source pads. See add_static_pad_template_with_gtype().

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

Methods#

class Aggregator

do_aggregate(self, timeout: bool) → FlowReturn#

Parameters:: timeout

do_clip(self, aggregator_pad: AggregatorPad, buf: Buffer) → Buffer#

Parameters:

aggregator_pad
buf

do_decide_allocation(self, query: Query) → bool#

Parameters:: query

do_finish_buffer(self, buffer: Buffer) → FlowReturn#

Parameters:: buffer

do_finish_buffer_list(self, bufferlist: BufferList) → FlowReturn#

Parameters:: bufferlist

do_fixate_src_caps(self, caps: Caps) → Caps#

Parameters:: caps

do_flush(self) → FlowReturn#

do_get_next_time(self) → int#

do_negotiate(self) → bool#

do_negotiated_src_caps(self, caps: Caps) → bool#

Parameters:: caps

do_peek_next_sample(self, aggregator_pad: AggregatorPad) → Sample | None#

Parameters:: aggregator_pad

do_propose_allocation(self, pad: AggregatorPad, decide_query: Query, query: Query) → bool#

Parameters:

pad
decide_query
query

do_sink_event(self, aggregator_pad: AggregatorPad, event: Event) → bool#

Parameters:

aggregator_pad
event

do_sink_event_pre_queue(self, aggregator_pad: AggregatorPad, event: Event) → FlowReturn#

Parameters:

aggregator_pad
event

do_sink_query(self, aggregator_pad: AggregatorPad, query: Query) → bool#

Parameters:

aggregator_pad
query

do_sink_query_pre_queue(self, aggregator_pad: AggregatorPad, query: Query) → bool#

Parameters:

aggregator_pad
query

do_src_activate(self, mode: PadMode, active: bool) → bool#

Parameters:

mode
active

do_src_event(self, event: Event) → bool#

Parameters:: event

do_src_query(self, query: Query) → bool#

Parameters:: query

do_start(self) → bool#

do_stop(self) → bool#

do_update_src_caps(self, caps: Caps) → Tuple[FlowReturn, Caps]#

Parameters:: caps

finish_buffer(buffer: Buffer) → FlowReturn#

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 Buffer to push.

finish_buffer_list(bufferlist: BufferList) → FlowReturn#

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.

Added in version 1.18.

Parameters:: bufferlist – the BufferList to push.

get_allocator() → Tuple[Allocator | None, AllocationParams]#

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

Unref the allocator after use it.

get_buffer_pool() → BufferPool | None#

get_force_live() → bool#: Subclasses may use the return value to inform whether they should return %GST_FLOW_EOS from their aggregate implementation.

Added in version 1.22.

get_ignore_inactive_pads() → bool#: Added in version 1.20.

get_latency() → int#

Retrieves the latency values reported by self 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.

negotiate() → bool#: Negotiates src pad caps with downstream elements. Unmarks GST_PAD_FLAG_NEED_RECONFIGURE in any case. But marks it again if GstAggregatorClass::negotiate fails.

Added in version 1.18.

peek_next_sample(pad: AggregatorPad) → Sample | None#

Use this function to determine what input buffers will be aggregated to produce the next output buffer. This should only be called from a Aggregator::samples-selected handler, and can be used to precisely control aggregating parameters for a given set of input samples.

Added in version 1.18.

Parameters:: pad

selected_samples(pts: int, dts: int, duration: int, info: Structure | None = None) → None#

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 update_segment() is used by the subclass, it MUST be called before selected_samples().

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

Added in version 1.18.

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 Structure containing additional information

set_force_live(force_live: bool) → None#

Subclasses should call this at construction time in order for self to aggregate on a timeout even when no live source is connected.

Added in version 1.22.

Parameters:: force_live

set_ignore_inactive_pads(ignore: bool) → None#

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.

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

Added in version 1.20.

Parameters:: ignore – whether inactive pads should not be waited on

set_latency(min_latency: int, max_latency: int) → None#

Lets Aggregator 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:

min_latency – minimum latency
max_latency – maximum latency

set_src_caps(caps: Caps) → None#

Sets the caps to be used on the src pad.

Parameters:: caps – The Caps to set on the src pad.

simple_get_next_time() → int#

This is a simple GstAggregatorClass::get_next_time implementation that just looks at the Segment 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.

Added in version 1.16.

update_segment(segment: Segment) → None#

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 selected_samples(), if it is used at all.

Added in version 1.18.

Parameters:: segment

Properties#

class Aggregator

props.emit_signals: bool#: The type of the None singleton.

Added in version 1.18.

props.latency: int#: The type of the None singleton.

props.min_upstream_latency: int#: The type of the None singleton.

Added in version 1.16.

props.start_time: int#: The type of the None singleton.

props.start_time_selection: AggregatorStartTimeSelection#: The type of the None singleton.

Signals#

class Aggregator.signals

samples_selected(segment: Segment, pts: int, dts: int, duration: int, info: Structure | None = None) → None#

The type of the None singleton.

Added in version 1.18.

Parameters:

segment – The Segment the next output buffer is part of
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 Structure containing additional information

Virtual Methods#

class Aggregator

do_aggregate(timeout: bool) → FlowReturn#

The type of the None singleton.

Parameters:: timeout

do_clip(aggregator_pad: AggregatorPad, buf: Buffer) → Buffer#

The type of the None singleton.

Parameters:

aggregator_pad
buf

do_decide_allocation(query: Query) → bool#

The type of the None singleton.

Parameters:: query

do_finish_buffer(buffer: Buffer) → FlowReturn#

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 Buffer to push.

do_finish_buffer_list(bufferlist: BufferList) → FlowReturn#

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.

Added in version 1.18.

Parameters:: bufferlist – the BufferList to push.

do_fixate_src_caps(caps: Caps) → Caps#

The type of the None singleton.

Parameters:: caps

do_flush() → FlowReturn#: The type of the None singleton.

do_get_next_time() → int#: The type of the None singleton.

do_negotiate() → bool#: Negotiates src pad caps with downstream elements. Unmarks GST_PAD_FLAG_NEED_RECONFIGURE in any case. But marks it again if GstAggregatorClass::negotiate fails.

Added in version 1.18.

do_negotiated_src_caps(caps: Caps) → bool#

The type of the None singleton.

Parameters:: caps

do_peek_next_sample(aggregator_pad: AggregatorPad) → Sample | None#

Added in version 1.18.

Parameters:: aggregator_pad

do_propose_allocation(pad: AggregatorPad, decide_query: Query, query: Query) → bool#

The type of the None singleton.

Parameters:

pad
decide_query
query

do_sink_event(aggregator_pad: AggregatorPad, event: Event) → bool#

The type of the None singleton.

Parameters:

aggregator_pad
event

do_sink_event_pre_queue(aggregator_pad: AggregatorPad, event: Event) → FlowReturn#

The type of the None singleton.

Parameters:

aggregator_pad
event

do_sink_query(aggregator_pad: AggregatorPad, query: Query) → bool#

The type of the None singleton.

Parameters:

aggregator_pad
query

do_sink_query_pre_queue(aggregator_pad: AggregatorPad, query: Query) → bool#

The type of the None singleton.

Parameters:

aggregator_pad
query

do_src_activate(mode: PadMode, active: bool) → bool#

The type of the None singleton.

Parameters:

mode
active

do_src_event(event: Event) → bool#

The type of the None singleton.

Parameters:: event

do_src_query(query: Query) → bool#

The type of the None singleton.

Parameters:: query

do_start() → bool#: The type of the None singleton.

do_stop() → bool#: The type of the None singleton.

do_update_src_caps(caps: Caps) → Tuple[FlowReturn, Caps]#

The type of the None singleton.

Parameters:: caps

Fields#

class Aggregator

parent#

priv#

srcpad#: The aggregator’s source pad

Aggregator#

Methods#

Properties#

Signals#

Virtual Methods#

Fields#

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