org.freedesktop.gstreamer.elements

Class AppSrc

java.lang.Object

org.freedesktop.gstreamer.glib.NativeObject

org.freedesktop.gstreamer.glib.RefCountedObject

org.freedesktop.gstreamer.glib.GObject

org.freedesktop.gstreamer.GstObject

org.freedesktop.gstreamer.Element

org.freedesktop.gstreamer.elements.BaseSrc

org.freedesktop.gstreamer.elements.AppSrc

All Implemented Interfaces:

AutoCloseable

public class AppSrc
extends BaseSrc

A source Element that provides an easy way for applications to insert data into a GStreamer pipeline.

See upstream documentation at https://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gst-plugins-base-libs/html/gst-plugins-base-libs-appsrc.html

Before operating appsrc, the Caps property must be set to fixed caps describing the format of the data that will be pushed with appsrc. An exception to this is when pushing buffers with unknown caps, in which case no caps should be set. This is typically true of file-like sources that push raw byte buffers. If you don't want to explicitly set the caps, you can use gst_app_src_push_sample (not yet mapped). This method gets the caps associated with the sample and sets them on the appsrc replacing any previously set caps (if different from sample's caps).

The main way of handing data to the appsrc element is by calling the pushBuffer(Buffer) method or by emitting the push-buffer action signal. This will put the buffer onto a queue from which appsrc will read from in its streaming thread. It is important to note that data transport will not happen from the thread that performed the push-buffer call.

The "max-bytes" property controls how much data can be queued in appsrc before appsrc considers the queue full. A filled internal queue will always signal the "enough-data" signal, which signals the application that it should stop pushing data into appsrc. The "block" property will cause appsrc to block the push-buffer method until free data becomes available again.

When the internal queue is running out of data, the "need-data" signal is emitted, which signals the application that it should start pushing more data into appsrc.

In addition to the "need-data" and "enough-data" signals, appsrc can emit the "seek-data" signal when the "stream-mode" property is set to "seekable" or "random-access". The signal argument will contain the new desired position in the stream expressed in the unit set with the "format" property. After receiving the seek-data signal, the application should push-buffers from the new position.

These signals allow the application to operate the appsrc in two different ways:

The push mode, in which the application repeatedly calls the push-buffer/push-sample method with a new buffer/sample. Optionally, the queue size in the appsrc can be controlled with the enough-data and need-data signals by respectively stopping/starting the push-buffer/push-sample calls. This is a typical mode of operation for the stream-type "stream" and "seekable". Use this mode when implementing various network protocols or hardware devices.

The pull mode, in which the need-data signal triggers the next push-buffer call. This mode is typically used in the "random-access" stream-type. Use this mode for file access or other randomly accessable sources. In this mode, a buffer of exactly the amount of bytes given by the need-data signal should be pushed into appsrc.

In all modes, the size property on appsrc should contain the total stream size in bytes. Setting this property is mandatory in the random-access mode. For the stream and seekable modes, setting this property is optional but recommended.

When the application has finished pushing data into appsrc, it should call endOfStream() or emit the end-of-stream action signal. After this call, no more buffers can be pushed into appsrc until a flushing seek occurs or the state of the appsrc has gone through READY.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AppSrc.ENOUGH_DATA Signal that the source has enough data.
static interface	AppSrc.NEED_DATA Signal that the source needs more data.
static interface	AppSrc.SEEK_DATA Seek to the given offset, expressed in terms of the Format set on the AppSrc.
static class	AppSrc.StreamType The stream type.

Nested classes/interfaces inherited from class org.freedesktop.gstreamer.Element

Element.NO_MORE_PADS, Element.PAD_ADDED, Element.PAD_REMOVED

Nested classes/interfaces inherited from class org.freedesktop.gstreamer.glib.GObject

GObject.GCallback, GObject.GInterface

Nested classes/interfaces inherited from class org.freedesktop.gstreamer.glib.NativeObject

NativeObject.Initializer, NativeObject.TypeProvider, NativeObject.TypeRegistration<T extends NativeObject>

Field Summary

Fields

Modifier and Type	Field and Description
static String	GST_NAME
static String	GTYPE_NAME

Constructor Summary

Constructors

Constructor and Description
AppSrc(String name)

Method Summary

Modifier and Type	Method and Description
void	connect(AppSrc.ENOUGH_DATA listener) Adds a listener for the enough-data signal
void	connect(AppSrc.NEED_DATA listener) Adds a listener for the need-data signal
void	connect(AppSrc.SEEK_DATA listener) Adds a listener for the seek-data signal
void	disconnect(AppSrc.ENOUGH_DATA listener) Removes a listener for the enough-data signal
void	disconnect(AppSrc.NEED_DATA listener) Removes a listener for the need-data signal
void	disconnect(AppSrc.SEEK_DATA listener) Removes a listener for the seek-data signal
FlowReturn	endOfStream() Indicates to the appsrc element that the last buffer queued in the element is the last buffer of the stream.
Caps	getCaps() Get the configured Caps on the AppSrc.
long[]	getLatency() Get the latency.
long	getMaxBytes() Get the maximum number of bytes that can be queued.
long	getSize() Get the size of the stream in bytes.
AppSrc.StreamType	getStreamType() Get the stream type set on the appsrc.
FlowReturn	pushBuffer(Buffer buffer) Adds a buffer to the queue of buffers that the appsrc element will push to its source pad.
void	setCaps(Caps caps) Set the capabilities on the appsrc element.
void	setLatency(long min, long max) Configure the min and max latency in src .
void	setMaxBytes(long max) Set the maximum amount of bytes that can be queued in appsrc .
void	setSize(long size) Set the size of the stream in bytes.
void	setStreamType(AppSrc.StreamType type) Set the stream type on appsrc .

Methods inherited from class org.freedesktop.gstreamer.Element

addPad, connect, connect, connect, disconnect, disconnect, disconnect, getBaseTime, getBus, getClock, getContext, getFactory, getPads, getRequestPad, getSinkPads, getSrcPads, getStartTime, getState, getState, getState, getState, getStaticPad, isPlaying, link, linkFiltered, linkMany, linkPads, linkPadsFiltered, makeRawElement, pause, play, postMessage, query, queryDuration, queryPosition, ready, releaseRequestPad, removePad, seek, seekSimple, sendEvent, setBaseTime, setContext, setLockedState, setStartTime, setState, stop, syncStateWithParent, unlink, unlinkMany, unlinkPads

Methods inherited from class org.freedesktop.gstreamer.GstObject

addControlBinding, getAsString, getControlBinding, getName, getParent, hasActiveControlBindings, removeControlBinding, setAsString, setControlBindingDisabled, setControlBindingsDisabled, setName, suggestNextSync, syncValues, toString

Methods inherited from class org.freedesktop.gstreamer.glib.GObject

addCallback, connect, connect, disconnect, dispose, emit, emit, get, getPropertyDefaultValue, getPropertyMaximumValue, getPropertyMinimumValue, getRefCount, getTypeName, invalidate, listPropertyNames, removeCallback, set

Methods inherited from class org.freedesktop.gstreamer.glib.NativeObject

close, disown, equals, getPointer, getRawPointer, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

GST_NAME

public static final String GST_NAME

See Also:

Constant Field Values

GTYPE_NAME

public static final String GTYPE_NAME

See Also:

Constant Field Values

Constructor Detail

AppSrc

public AppSrc(String name)

Method Detail

setCaps

public void setCaps(Caps caps)

Set the capabilities on the appsrc element. This function takes a copy of the caps structure. After calling this method, the source will only produce caps that match caps . caps must be fixed and the caps on the buffers must match the caps or left NULL.

Overrides:

setCaps in class Element

Parameters:

caps - the new Caps to set.

getCaps

public Caps getCaps()

Get the configured Caps on the AppSrc.

Returns:

the caps

setSize

public void setSize(long size)

Set the size of the stream in bytes. A value of -1 means that the size is not known.

Parameters:

size - the size to set, or -1 if not known

getSize

public long getSize()

Get the size of the stream in bytes. A value of -1 means that the size is not known.

Returns:

the size of the stream, or -1 if not specified

setStreamType

public void setStreamType(AppSrc.StreamType type)

Set the stream type on appsrc . For seekable streams, the "seek" signal must be connected to.

Parameters:

type - stream type

getStreamType

public AppSrc.StreamType getStreamType()

Get the stream type set on the appsrc.

Returns:

stream type

setMaxBytes

public void setMaxBytes(long max)

Set the maximum amount of bytes that can be queued in appsrc . After the maximum amount of bytes are queued, appsrc will emit the "enough-data" signal.

Parameters:

max - number of bytes to queue

getMaxBytes

public long getMaxBytes()

Get the maximum number of bytes that can be queued.

Returns:

maximum number of bytes

setLatency

public void setLatency(long min,
                       long max)

Configure the min and max latency in src . If min is set to -1, the default latency calculations for pseudo-live sources will be used.

Parameters:

min - the minimum latency

max - the maximum latency

getLatency

public long[] getLatency()

Get the latency. The returned value is a long array of length two, with min latency at index 0 and max latency at index 1.

Returns:

values as long[]{min, max}

pushBuffer

public FlowReturn pushBuffer(Buffer buffer)

Adds a buffer to the queue of buffers that the appsrc element will push to its source pad. This function takes ownership of the buffer.

When the block property is TRUE, this function can block until free space becomes available in the queue.

Parameters:

buffer - a Buffer to push

Returns:

GST_FLOW_OK when the buffer was successfully queued. GST_FLOW_FLUSHING when appsrc is not PAUSED or PLAYING. GST_FLOW_EOS when EOS occurred.

endOfStream

public FlowReturn endOfStream()

Indicates to the appsrc element that the last buffer queued in the element is the last buffer of the stream.

Returns:

GST_FLOW_OK when the EOS was successfuly queued. GST_FLOW_FLUSHING when appsrc is not PAUSED or PLAYING.

connect

public void connect(AppSrc.ENOUGH_DATA listener)

Adds a listener for the enough-data signal

Parameters:

listener - Listener to be called this when appsrc fills its queue.

disconnect

public void disconnect(AppSrc.ENOUGH_DATA listener)

Removes a listener for the enough-data signal

Parameters:

listener - The listener that was previously added.

connect

public void connect(AppSrc.NEED_DATA listener)

Adds a listener for the need-data signal

Parameters:

listener - Listener to be called when appsrc needs data.

disconnect

public void disconnect(AppSrc.NEED_DATA listener)

Removes a listener for the need-data signal

Parameters:

listener - The listener that was previously added.

connect

public void connect(AppSrc.SEEK_DATA listener)

Adds a listener for the seek-data signal

Parameters:

listener - listener to be called when a seek is requested

disconnect

public void disconnect(AppSrc.SEEK_DATA listener)

Removes a listener for the seek-data signal

Parameters:

listener - The listener that was previously added.