GstBase.Aggregator

g GObject.InitiallyUnowned GObject.InitiallyUnowned Gst.Object Gst.Object GObject.InitiallyUnowned->Gst.Object GObject.Object GObject.Object GObject.Object->GObject.InitiallyUnowned Gst.Element Gst.Element GstBase.Aggregator GstBase.Aggregator Gst.Element->GstBase.Aggregator Gst.Object->Gst.Element

Subclasses:

None

Methods

Inherited:

Gst.Element (81), Gst.Object (27), GObject.Object (37)

Structs:

Gst.ElementClass (10), GObject.ObjectClass (5)

finish_buffer (buffer)

finish_buffer_list (bufferlist)

get_allocator ()

get_buffer_pool ()

get_force_live ()

get_ignore_inactive_pads ()

get_latency ()

negotiate ()

peek_next_sample (pad)

selected_samples (pts, dts, duration, info)

set_force_live (force_live)

set_ignore_inactive_pads (ignore)

set_latency (min_latency, max_latency)

set_src_caps (caps)

simple_get_next_time ()

update_segment (segment)

Virtual Methods

Inherited:

Gst.Element (16), Gst.Object (1), GObject.Object (7)

do_aggregate (timeout)

do_clip (aggregator_pad, buf)

do_decide_allocation (query)

do_finish_buffer (buffer)

do_finish_buffer_list (bufferlist)

do_fixate_src_caps (caps)

do_flush ()

do_get_next_time ()

do_negotiate ()

do_negotiated_src_caps (caps)

do_peek_next_sample (aggregator_pad)

do_propose_allocation (pad, decide_query, query)

do_sink_event (aggregator_pad, event)

do_sink_event_pre_queue (aggregator_pad, event)

do_sink_query (aggregator_pad, query)

do_sink_query_pre_queue (aggregator_pad, query)

do_src_activate (mode, active)

do_src_event (event)

do_src_query (query)

do_start ()

do_stop ()

do_update_src_caps (caps)

Properties

Inherited:

Gst.Object (2)

Name

Type

Flags

Short Description

emit-signals

bool

r/w

Send signals

latency

int

r/w

Additional latency in live mode to allow upstream to take longer to produce buffers for the current position (in nanoseconds)

min-upstream-latency

int

r/w

When sources with a higher latency are expected to be plugged in dynamically after the aggregator has started playing, this allows overriding the minimum latency reported by the initial source(s). This is only taken into account when larger than the actually reported minimum latency. (nanoseconds)

start-time

int

r/w

Start time to use if start-time-selection=set

start-time-selection

GstBase.AggregatorStartTimeSelection

r/w

Decides which start time is output

Signals

Inherited:

Gst.Element (3), Gst.Object (1), GObject.Object (1)

Name

Short Description

samples-selected

Signals that the GstBase.Aggregator subclass has selected the next set of input samples it will aggregate.

Fields

Inherited:

Gst.Element (3), Gst.Object (1), GObject.Object (1)

Name

Type

Access

Description

parent

Gst.Element

r

srcpad

Gst.Pad

r

the aggregator’s source pad

Class Details

class GstBase.Aggregator(**kwargs)
Bases:

Gst.Element

Abstract:

Yes

Structure:

GstBase.AggregatorClass

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

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

New in version 1.14.

finish_buffer(buffer)
Parameters:

buffer (Gst.Buffer) – the Gst.Buffer to push.

Return type:

Gst.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.

finish_buffer_list(bufferlist)
Parameters:

bufferlist (Gst.BufferList) – the Gst.BufferList to push.

Return type:

Gst.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.

New in version 1.18.

get_allocator()
Returns:

allocator:

the Gst.Allocator used

params:

the Gst.AllocationParams of allocator

Return type:

(allocator: Gst.Allocator or None, params: Gst.AllocationParams)

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

Unref the allocator after use it.

get_buffer_pool()
Returns:

the instance of the Gst.BufferPool used by trans; free it after use it

Return type:

Gst.BufferPool or None

get_force_live()
Returns:

whether live status was forced on self.

Return type:

bool

Subclasses may use the return value to inform whether they should return Gst.FlowReturn.EOS from their aggregate implementation.

New in version 1.22.

get_ignore_inactive_pads()
Returns:

whether inactive pads will not be waited on

Return type:

bool

New in version 1.20.

get_latency()
Returns:

The latency or Gst.CLOCK_TIME_NONE if the element does not sync

Return type:

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()
Returns:

True if the negotiation succeeded, else False.

Return type:

bool

Negotiates src pad caps with downstream elements. Unmarks Gst.PadFlags.NEED_RECONFIGURE in any case. But marks it again if #GstAggregatorClass::negotiate fails.

New in version 1.18.

peek_next_sample(pad)
Parameters:

pad (GstBase.AggregatorPad) –

Returns:

The sample that is about to be aggregated. It may hold a Gst.Buffer or a Gst.BufferList. The contents of its info structure is subclass-dependent, and documented on a subclass basis. The buffers held by the sample are not writable.

Return type:

Gst.Sample or 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 GstBase.Aggregator ::samples-selected handler, and can be used to precisely control aggregating parameters for a given set of input samples.

New in version 1.18.

selected_samples(pts, dts, duration, info)
Parameters:
  • pts (int) – The presentation timestamp of the next output buffer

  • dts (int) – The decoding timestamp of the next output buffer

  • duration (int) – The duration of the next output buffer

  • info (Gst.Structure or None) – a Gst.Structure containing additional information

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

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

New in version 1.18.

set_force_live(force_live)
Parameters:

force_live (bool) –

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

New in version 1.22.

set_ignore_inactive_pads(ignore)
Parameters:

ignore (bool) – whether inactive pads should not be waited on

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.

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

New in version 1.20.

set_latency(min_latency, max_latency)
Parameters:
  • min_latency (int) – minimum latency

  • max_latency (int) – maximum latency

Lets GstBase.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.

set_src_caps(caps)
Parameters:

caps (Gst.Caps) – The Gst.Caps to set on the src pad.

Sets the caps to be used on the src pad.

simple_get_next_time()
Returns:

The running time based on the position

Return type:

int

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

New in version 1.16.

update_segment(segment)
Parameters:

segment (Gst.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 GstBase.Aggregator.selected_samples(), if it is used at all.

New in version 1.18.

do_aggregate(timeout) virtual
Parameters:

timeout (bool) –

Return type:

Gst.FlowReturn

do_clip(aggregator_pad, buf) virtual
Parameters:
Return type:

Gst.Buffer

do_decide_allocation(query) virtual
Parameters:

query (Gst.Query) –

Return type:

bool

do_finish_buffer(buffer) virtual
Parameters:

buffer (Gst.Buffer) – the Gst.Buffer to push.

Return type:

Gst.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.

do_finish_buffer_list(bufferlist) virtual
Parameters:

bufferlist (Gst.BufferList) – the Gst.BufferList to push.

Return type:

Gst.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.

New in version 1.18.

do_fixate_src_caps(caps) virtual
Parameters:

caps (Gst.Caps) –

Return type:

Gst.Caps

do_flush() virtual
Return type:

Gst.FlowReturn

do_get_next_time() virtual
Return type:

int

do_negotiate() virtual
Returns:

True if the negotiation succeeded, else False.

Return type:

bool

Negotiates src pad caps with downstream elements. Unmarks Gst.PadFlags.NEED_RECONFIGURE in any case. But marks it again if #GstAggregatorClass::negotiate fails.

New in version 1.18.

do_negotiated_src_caps(caps) virtual
Parameters:

caps (Gst.Caps) –

Return type:

bool

do_peek_next_sample(aggregator_pad) virtual
Parameters:

aggregator_pad (GstBase.AggregatorPad) –

Returns:

The sample that is about to be aggregated. It may hold a Gst.Buffer or a Gst.BufferList. The contents of its info structure is subclass-dependent, and documented on a subclass basis. The buffers held by the sample are not writable.

Return type:

Gst.Sample or 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 GstBase.Aggregator ::samples-selected handler, and can be used to precisely control aggregating parameters for a given set of input samples.

New in version 1.18.

do_propose_allocation(pad, decide_query, query) virtual
Parameters:
Return type:

bool

do_sink_event(aggregator_pad, event) virtual
Parameters:
Return type:

bool

do_sink_event_pre_queue(aggregator_pad, event) virtual
Parameters:
Return type:

Gst.FlowReturn

do_sink_query(aggregator_pad, query) virtual
Parameters:
Return type:

bool

do_sink_query_pre_queue(aggregator_pad, query) virtual
Parameters:
Return type:

bool

do_src_activate(mode, active) virtual
Parameters:
Return type:

bool

do_src_event(event) virtual
Parameters:

event (Gst.Event) –

Return type:

bool

do_src_query(query) virtual
Parameters:

query (Gst.Query) –

Return type:

bool

do_start() virtual
Return type:

bool

do_stop() virtual
Return type:

bool

do_update_src_caps(caps) virtual
Parameters:

caps (Gst.Caps) –

Return type:

(Gst.FlowReturn, ret: Gst.Caps)

Signal Details

GstBase.Aggregator.signals.samples_selected(aggregator, segment, pts, dts, duration, info)
Signal Name:

samples-selected

Flags:

RUN_FIRST

Parameters:
  • aggregator (GstBase.Aggregator) – The object which received the signal

  • segment (Gst.Segment) – The Gst.Segment the next output buffer is part of

  • pts (int) – The presentation timestamp of the next output buffer

  • dts (int) – The decoding timestamp of the next output buffer

  • duration (int) – The duration of the next output buffer

  • info (Gst.Structure or None) – a Gst.Structure containing additional information

Signals that the GstBase.Aggregator subclass has selected the next set of input samples it will aggregate. Handlers may call GstBase.Aggregator.peek_next_sample() at that point.

New in version 1.18.

Property Details

GstBase.Aggregator.props.emit_signals
Name:

emit-signals

Type:

bool

Default Value:

False

Flags:

READABLE, WRITABLE

Enables the emission of signals such as GstBase.Aggregator ::samples-selected

New in version 1.18.

GstBase.Aggregator.props.latency
Name:

latency

Type:

int

Default Value:

0

Flags:

READABLE, WRITABLE

Additional latency in live mode to allow upstream to take longer to produce buffers for the current position (in nanoseconds)

GstBase.Aggregator.props.min_upstream_latency
Name:

min-upstream-latency

Type:

int

Default Value:

0

Flags:

READABLE, WRITABLE

Force minimum upstream latency (in nanoseconds). When sources with a higher latency are expected to be plugged in dynamically after the aggregator has started playing, this allows overriding the minimum latency reported by the initial source(s). This is only taken into account when larger than the actually reported minimum latency.

New in version 1.16.

GstBase.Aggregator.props.start_time
Name:

start-time

Type:

int

Default Value:

18446744073709551615

Flags:

READABLE, WRITABLE

Start time to use if start-time-selection=set

GstBase.Aggregator.props.start_time_selection
Name:

start-time-selection

Type:

GstBase.AggregatorStartTimeSelection

Default Value:

GstBase.AggregatorStartTimeSelection.ZERO

Flags:

READABLE, WRITABLE

Decides which start time is output