AppSrc

The appsrc element can be used by applications to insert data into a GStreamer pipeline. Unlike most GStreamer elements, appsrc provides external API functions.

appsrc can be used by linking with the libgstapp library to access the methods directly or by using the appsrc action signals.

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. 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 gst_app_src_push_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 gst_app_src_end_of_stream() 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.

class AppSrc : BaseSrc , URIHandlerIF {}

Constructors

this
this(GstAppSrc* gstAppSrc, bool ownedRef)

Sets our main struct and passes it to the parent class.

Members

Functions

addOnEndOfStream
gulong addOnEndOfStream(GstFlowReturn delegate(AppSrc) dlg, ConnectFlags connectFlags)

Notify @appsrc that no more buffer are available.

addOnEnoughData
gulong addOnEnoughData(void delegate(AppSrc) dlg, ConnectFlags connectFlags)

Signal that the source has enough data. It is recommended that the application stops calling push-buffer until the need-data signal is emitted again to avoid excessive buffer queueing.

addOnNeedData
gulong addOnNeedData(void delegate(uint, AppSrc) dlg, ConnectFlags connectFlags)

Signal that the source needs more data. In the callback or from another thread you should call push-buffer or end-of-stream.

addOnPushBuffer
gulong addOnPushBuffer(GstFlowReturn delegate(Buffer, AppSrc) dlg, ConnectFlags connectFlags)

Adds a buffer to the queue of buffers that the appsrc element will push to its source pad. This function does not take ownership of the buffer so the buffer needs to be unreffed after calling this function.

addOnPushBufferList
gulong addOnPushBufferList(GstFlowReturn delegate(BufferList, AppSrc) dlg, ConnectFlags connectFlags)

Adds a buffer list to the queue of buffers and buffer lists that the appsrc element will push to its source pad. This function does not take ownership of the buffer list so the buffer list needs to be unreffed after calling this function.

addOnPushSample
gulong addOnPushSample(GstFlowReturn delegate(Sample, AppSrc) dlg, ConnectFlags connectFlags)

Extract a buffer from the provided sample and adds the extracted buffer to the queue of buffers that the appsrc element will push to its source pad. This function set the appsrc caps based on the caps in the sample and reset the caps if they change. Only the caps and the buffer of the provided sample are used and not for example the segment in the sample. This function does not take ownership of the sample so the sample needs to be unreffed after calling this function.

addOnSeekData
gulong addOnSeekData(bool delegate(ulong, AppSrc) dlg, ConnectFlags connectFlags)

Seek to the given offset. The next push-buffer should produce buffers from the new @offset. This callback is only called for seekable stream types.

appSrcSetCaps
void appSrcSetCaps(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.

endOfStream
GstFlowReturn endOfStream()

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

getAppSrcStruct
GstAppSrc* getAppSrcStruct(bool transferOwnership)

Get the main Gtk struct

getCaps
Caps getCaps()

Get the configured caps on @appsrc.

getCurrentLevelBytes
ulong getCurrentLevelBytes()

Get the number of currently queued bytes inside @appsrc.

getDuration
GstClockTime getDuration()

Get the duration of the stream in nanoseconds. A value of GST_CLOCK_TIME_NONE means that the duration is not known.

getEmitSignals
bool getEmitSignals()

Check if appsrc will emit the "new-preroll" and "new-buffer" signals.

getLatency
void getLatency(ulong min, ulong max)

Retrieve the min and max latencies in @min and @max respectively.

getMaxBytes
ulong getMaxBytes()

Get the maximum amount of bytes that can be queued in @appsrc.

getSize
long getSize()

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

getStreamType
GstAppStreamType getStreamType()

Get the stream type. Control the stream type of @appsrc with gst_app_src_set_stream_type().

getStruct
void* getStruct()

the main Gtk struct as a void*

pushBuffer
GstFlowReturn 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.

pushBufferList
GstFlowReturn pushBufferList(BufferList bufferList)

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

pushSample
GstFlowReturn pushSample(Sample sample)

Extract a buffer from the provided sample and adds it to the queue of buffers that the appsrc element will push to its source pad. Any previous caps that were set on appsrc will be replaced by the caps associated with the sample if not equal.

setCallbacks
void setCallbacks(GstAppSrcCallbacks* callbacks, void* userData, GDestroyNotify notify)

Set callbacks which will be executed when data is needed, enough data has been collected or when a seek should be performed. This is an alternative to using the signals, it has lower overhead and is thus less expensive, but also less flexible.

setDuration
void setDuration(GstClockTime duration)

Set the duration of the stream in nanoseconds. A value of GST_CLOCK_TIME_NONE means that the duration is not known.

setEmitSignals
void setEmitSignals(bool emit)

Make appsrc emit the "new-preroll" and "new-buffer" signals. This option is by default disabled because signal emission is expensive and unneeded when the application prefers to operate in pull mode.

setLatency
void setLatency(ulong min, ulong 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.

setMaxBytes
void setMaxBytes(ulong 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.

setSize
void setSize(long size)

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

setStreamType
void setStreamType(GstAppStreamType type)

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

Mixins

__anonymous
mixin URIHandlerT!(GstAppSrc)
Undocumented in source.

Static functions

getType
GType getType()

Variables

gstAppSrc
GstAppSrc* gstAppSrc;

the main Gtk struct

Inherited Members

From BaseSrc

gstBaseSrc
GstBaseSrc* gstBaseSrc;

the main Gtk struct

getBaseSrcStruct
GstBaseSrc* getBaseSrcStruct(bool transferOwnership)

Get the main Gtk struct

getStruct
void* getStruct()

the main Gtk struct as a void*

getType
GType getType()
getAllocator
void getAllocator(Allocator allocator, AllocationParams params)

Lets #GstBaseSrc sub-classes to know the memory @allocator used by the base class and its @params.

getBlocksize
uint getBlocksize()

Get the number of bytes that @src will push out with each buffer.

getBufferPool
BufferPool getBufferPool()
getDoTimestamp
bool getDoTimestamp()

Query if @src timestamps outgoing buffers based on the current running_time.

isAsync
bool isAsync()

Get the current async behaviour of @src. See also gst_base_src_set_async().

isLive
bool isLive()

Check if an element is in live mode.

newSeamlessSegment
bool newSeamlessSegment(long start, long stop, long time)

Prepare a new seamless segment for emission downstream. This function must only be called by derived sub-classes, and only from the create() function, as the stream-lock needs to be held.

queryLatency
bool queryLatency(bool live, GstClockTime minLatency, GstClockTime maxLatency)

Query the source for the latency parameters. @live will be %TRUE when @src is configured as a live source. @min_latency and @max_latency will be set to the difference between the running time and the timestamp of the first buffer.

setAsync
void setAsync(bool async)

Configure async behaviour in @src, no state change will block. The open, close, start, stop, play and pause virtual methods will be executed in a different thread and are thus allowed to perform blocking operations. Any blocking operation should be unblocked with the unlock vmethod.

setAutomaticEos
void setAutomaticEos(bool automaticEos)

If @automatic_eos is %TRUE, @src will automatically go EOS if a buffer after the total size is returned. By default this is %TRUE but sources that can't return an authoritative size and only know that they're EOS when trying to read more should set this to %FALSE.

setBlocksize
void setBlocksize(uint blocksize)

Set the number of bytes that @src will push out with each buffer. When @blocksize is set to -1, a default length will be used.

setCaps
bool setCaps(Caps caps)

Set new caps on the basesrc source pad.

setDoTimestamp
void setDoTimestamp(bool timestamp)

Configure @src to automatically timestamp outgoing buffers based on the current running_time of the pipeline. This property is mostly useful for live sources.

setDynamicSize
void setDynamicSize(bool dynamic)

If not @dynamic, size is only updated when needed, such as when trying to read past current tracked size. Otherwise, size is checked for upon each read.

setFormat
void setFormat(GstFormat format)

Sets the default format of the source. This will be the format used for sending SEGMENT events and for performing seeks.

setLive
void setLive(bool live)

If the element listens to a live source, @live should be set to %TRUE.

startComplete
void startComplete(GstFlowReturn ret)

Complete an asynchronous start operation. When the subclass overrides the start method, it should call gst_base_src_start_complete() when the start operation completes either from the same thread or from an asynchronous helper thread.

startWait
GstFlowReturn startWait()

Wait until the start operation completes.

submitBufferList
void submitBufferList(BufferList bufferList)

Subclasses can call this from their create virtual method implementation to submit a buffer list to be pushed out later. This is useful in cases where the create function wants to produce multiple buffers to be pushed out in one go in form of a #GstBufferList, which can reduce overhead drastically, especially for packetised inputs (for data streams where the packetisation/chunking is not important it is usually more efficient to return larger buffers instead).

waitPlaying
GstFlowReturn waitPlaying()

If the #GstBaseSrcClass.create() method performs its own synchronisation against the clock it must unblock when going from PLAYING to the PAUSED state and call this method before continuing to produce the remaining data.

From URIHandlerIF

getURIHandlerStruct
GstURIHandler* getURIHandlerStruct(bool transferOwnership)

Get the main Gtk struct

getStruct
void* getStruct()

the main Gtk struct as a void*

getType
GType getType()
getProtocols
string[] getProtocols()

Gets the list of protocols supported by @handler. This list may not be modified.

getUri
string getUri()

Gets the currently handled URI.

getUriType
GstURIType getUriType()

Gets the type of the given URI handler

setUri
bool setUri(string uri)

Tries to set the URI of the given handler.

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