Sink

Object Hierarchy:

Description:

[ CCode ( type_id = "gst_app_sink_get_type ()" ) ]
[ GIR ( name = "AppSink" ) ]
public class Sink : Sink, URIHandler

Appsink is a sink plugin that supports many different methods for making the application get a handle on the GStreamer data in a pipeline.

Unlike most GStreamer elements, Appsink provides external API functions.

appsink can be used by linking to the gstappsink.h header file to access the methods or by using the appsink action signals and properties.

The normal way of retrieving samples from appsink is by using the pull_sample and pull_preroll methods. These methods block until a sample becomes available in the sink or when the sink is shut down or reaches EOS. There are also timed variants of these methods, try_pull_sample and try_pull_preroll, which accept a timeout parameter to limit the amount of time to wait.

Appsink will internally use a queue to collect buffers from the streaming thread. If the application is not pulling samples fast enough, this queue will consume a lot of memory over time. The "max-buffers" property can be used to limit the queue size. The "drop" property controls whether the streaming thread blocks or if older buffers are dropped when the maximum queue size is reached. Note that blocking the streaming thread can negatively affect real-time performance and should be avoided.

If a blocking behaviour is not desirable, setting the "emit-signals" property to true will make appsink emit the "new-sample" and "new-preroll" signals when a sample can be pulled without blocking.

The "caps" property on appsink can be used to control the formats that appsink can receive. This property can contain non-fixed caps, the format of the pulled samples can be obtained by getting the sample caps.

If one of the pull-preroll or pull-sample methods return null, the appsink is stopped or in the EOS state. You can check for the EOS state with the "eos" property or with the is_eos method.

The eos signal can also be used to be informed when the EOS state is reached to avoid polling.

Namespace: Gst.App

Package: gstreamer-app-1.0

Content:

Properties:

public bool buffer_list { get; set; }
public Caps caps { owned get; set; }
public bool drop { get; set; }
public bool emit_signals { get; set; }
public virtual bool eos { get; }
public uint max_buffers { get; set; }
public bool wait_on_eos { get; set; }

Creation methods:

protected Sink ()

Methods:

public bool get_buffer_list_support ()
Check if this supports buffer lists.
public Caps? get_caps ()
Get the configured caps on this.
public bool get_drop ()
Check if this will drop old buffers when the maximum amount of queued buffers is reached.
public bool get_emit_signals ()
Check if appsink will emit the "new-preroll" and "new-sample" signals.
public uint get_max_buffers ()
Get the maximum amount of buffers that can be queued in this.
public bool get_wait_on_eos ()
Check if this will wait for all buffers to be consumed when an EOS is received.
public bool is_eos ()
Check if this is EOS, which is when no more samples can be pulled because an EOS event was received.
public void set_buffer_list_support (bool enable_lists)
Instruct this to enable or disable buffer list support.
public void set_caps (Caps? caps)
Set the capabilities on the appsink element.
public void set_drop (bool drop)
Instruct this to drop old buffers when the maximum amount of queued buffers is reached.
public void set_emit_signals (bool emit)
Make appsink emit the "new-preroll" and "new-sample" signals.
public void set_max_buffers (uint max)
Set the maximum amount of buffers that can be queued in this.
public void set_wait_on_eos (bool wait)
Instruct this to wait for all buffers to be consumed when an EOS is received.

Signals:

public virtual signal FlowReturn new_preroll ()
Signal that a new preroll sample is available.
public virtual signal FlowReturn new_sample ()
Signal that a new sample is available.
public signal bool new_serialized_event ()
Signal that a new downstream serialized event is available.
public signal bool propose_allocation (Query query)
Signal that a new propose_allocation query is available.
public virtual signal Sample? pull_preroll ()
Get the last preroll sample in appsink.
public virtual signal Sample? pull_sample ()
This function blocks until a sample or EOS becomes available or the appsink element is set to the READY/NULL state.
public virtual signal MiniObject? try_pull_object (uint64 timeout)
This function blocks until a sample or an event becomes available or the appsink element is set to the READY/NULL state or the timeout expires.
public virtual signal Sample? try_pull_preroll (uint64 timeout)
Get the last preroll sample in appsink.
public virtual signal Sample? try_pull_sample (uint64 timeout)
This function blocks until a sample or EOS becomes available or the appsink element is set to the READY/NULL state or the timeout expires.

Inherited Members:

All known members inherited from class Gst.Base.Sink

All known members inherited from class Gst.Element

All known members inherited from class Gst.Object

All known members inherited from class GLib.Object

All known members inherited from interface Gst.URIHandler

get_uri_type

set_uri