Package org.freedesktop.gstreamer.base

Class BaseTransform

java.lang.Object

io.github.jwharm.javagi.base.ProxyInstance

org.gnome.gobject.TypeInstance

org.gnome.gobject.GObject

org.gnome.gobject.InitiallyUnowned

org.freedesktop.gstreamer.gst.GstObject

org.freedesktop.gstreamer.gst.Element

org.freedesktop.gstreamer.base.BaseTransform

All Implemented Interfaces:

Proxy

Direct Known Subclasses:

AudioFilter, BaseTransform.BaseTransformImpl, VideoFilter

@Generated("io.github.jwharm.JavaGI")
public abstract class BaseTransform
extends Element

This base class is for filter elements that process data. Elements that are suitable for implementation using GstBaseTransform are ones where the size and caps of the output is known entirely from the input caps and buffer sizes. These include elements that directly transform one buffer into another, modify the contents of a buffer in-place, as well as elements that collate multiple input buffers into one output buffer, or that expand one input buffer into multiple output buffers. See below for more concrete use cases.

It provides for:

• one sinkpad and one srcpad
• Possible formats on sink and source pad implemented with custom transform_caps function. By default uses same format on sink and source.

• Handles state changes
• Does flushing
• Push mode
• Pull mode if the sub-class transform can operate on arbitrary data

Use Cases
Passthrough mode

• Element has no interest in modifying the buffer. It may want to inspect it, in which case the element should have a transform_ip function. If there is no transform_ip function in passthrough mode, the buffer is pushed intact.

• The GstBaseTransformClass.passthrough_on_same_caps variable will automatically set/unset passthrough based on whether the element negotiates the same caps on both pads.

• GstBaseTransformClass.passthrough_on_same_caps on an element that doesn't implement a transform_caps function is useful for elements that only inspect data (such as level)

• Example elements

• Level
• Videoscale, audioconvert, videoconvert, audioresample in certain modes.

Modifications in-place - input buffer and output buffer are the same thing.

• The element must implement a transform_ip function.
• Output buffer size must <= input buffer size
• If the always_in_place flag is set, non-writable buffers will be copied and passed to the transform_ip function, otherwise a new buffer will be created and the transform function called.

• Incoming writable buffers will be passed to the transform_ip function immediately.
• only implementing transform_ip and not transform implies always_in_place = true

• Example elements:
• Volume
• Audioconvert in certain modes (signed/unsigned conversion)
• videoconvert in certain modes (endianness swapping)

Modifications only to the caps/metadata of a buffer

• The element does not require writable data, but non-writable buffers should be subbuffered so that the meta-information can be replaced.

• Elements wishing to operate in this mode should replace the prepare_output_buffer method to create subbuffers of the input buffer and set always_in_place to true

• Example elements
• Capsfilter when setting caps on outgoing buffers that have none.
• identity when it is going to re-timestamp buffers by datarate.

Normal mode

• always_in_place flag is not set, or there is no transform_ip function
• Element will receive an input buffer and output buffer to operate on.
• Output buffer is allocated by calling the prepare_output_buffer function.
• Example elements:
• Videoscale, videoconvert, audioconvert when doing scaling/conversions

Special output buffer allocations

• Elements which need to do special allocation of their output buffers beyond allocating output buffers via the negotiated allocator or buffer pool should implement the prepare_output_buffer method.

• Example elements:
• efence

Sub-class settable flags on GstBaseTransform

• passthrough

• Implies that in the current configuration, the sub-class is not interested in modifying the buffers.
• Elements which are always in passthrough mode whenever the same caps has been negotiated on both pads can set the class variable passthrough_on_same_caps to have this behaviour automatically.

• always_in_place
• Determines whether a non-writable buffer will be copied before passing to the transform_ip function.

• Implied true if no transform function is implemented.
• Implied false if ONLY transform function is implemented.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BaseTransform.BaseTransformClass	Subclasses can override any of the available virtual methods or not, as needed.
static class	BaseTransform.BaseTransformImpl	The BaseTransformImpl type represents a native instance of the abstract BaseTransform class.
static class	BaseTransform.Builder<B extends BaseTransform.Builder<B>>	Inner class implementing a builder pattern to construct a GObject with properties.

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

Element.ElementClass, Element.ElementImpl, Element.NoMorePadsCallback, Element.PadAddedCallback, Element.PadRemovedCallback

Nested classes/interfaces inherited from class org.freedesktop.gstreamer.gst.GstObject

GstObject.DeepNotifyCallback, GstObject.ObjectClass, GstObject.ObjectImpl

Nested classes/interfaces inherited from class org.gnome.gobject.InitiallyUnowned

InitiallyUnowned.InitiallyUnownedClass

Nested classes/interfaces inherited from class org.gnome.gobject.GObject

GObject.NotifyCallback

Constructor Summary

Constructors

Constructor	Description
BaseTransform(MemorySegment address)	Create a BaseTransform proxy instance for the provided memory address.

Method Summary

Modifier and Type	Method	Description
protected boolean	acceptCaps(PadDirection direction, Caps caps)	Optional.
protected BaseTransform	asParent()	Returns this instance as if it were its parent type.
protected void	beforeTransform(Buffer buffer)	Optional.
static BaseTransform.Builder<? extends BaseTransform.Builder>	builder()	A BaseTransform.Builder object constructs a BaseTransform with the specified properties.
protected boolean	copyMetadata(Buffer input, Buffer outbuf)	Optional.
protected boolean	decideAllocation(Query query)	Setup the allocation parameters for allocating output buffers.
protected boolean	filterMeta(Query query, Type api, Structure params)	Return true if the metadata API should be proposed in the upstream allocation query.
protected Caps	fixateCaps(PadDirection direction, Caps caps, Caps othercaps)
protected FlowReturn	generateOutput(Out<Buffer> outbuf)
void	getAllocator(@Nullable Out<Allocator> allocator, @Nullable AllocationParams params)	Lets GstBaseTransform sub-classes know the memory allocator used by the base class and its params.
BufferPool	getBufferPool()
static MemoryLayout	getMemoryLayout()	The memory layout of the native struct.
static Type	getType()	Get the GType of the BaseTransform class
protected boolean	getUnitSize(Caps caps, Out<Long> size)
boolean	isInPlace()	See if this BaseTransform is configured as a in_place transform.
boolean	isPassthrough()	See if this BaseTransform is configured as a passthrough transform.
boolean	isQosEnabled()	Queries if the transform will handle QoS.
protected FlowReturn	prepareOutputBuffer(Buffer input, Out<Buffer> outbuf)
protected boolean	proposeAllocation(Query decideQuery, Query query)	Propose buffer allocation parameters for upstream elements.
protected boolean	query(PadDirection direction, Query query)	Optional.
boolean	reconfigure()	Negotiates src pad caps with downstream elements if the source pad is marked as needing reconfiguring.
void	reconfigureSink()	Instructs this BaseTransform to request renegotiation upstream.
void	reconfigureSrc()	Instructs this BaseTransform to renegotiate a new downstream transform on the next buffer.
protected boolean	setCaps(Caps incaps, Caps outcaps)	Allows the subclass to be notified of the actual caps set.
void	setGapAware(boolean gapAware)	If gapAware is false (the default), output buffers will have the BufferFlags.GAP flag unset.
void	setInPlace(boolean inPlace)	Determines whether a non-writable buffer will be copied before passing to the transform_ip function.
void	setPassthrough(boolean passthrough)	Set passthrough mode for this filter by default.
void	setPreferPassthrough(boolean preferPassthrough)	If preferPassthrough is true (the default), this BaseTransform will check and prefer passthrough caps from the list of caps returned by the transform_caps vmethod.
void	setQosEnabled(boolean enabled)	Enable or disable QoS handling in the transform.
protected boolean	sinkEvent(Event event)
protected boolean	srcEvent(Event event)
protected boolean	start()	Optional.
protected boolean	stop()	Optional.
protected FlowReturn	submitInputBuffer(boolean isDiscont, Buffer input)	Function which accepts a new input buffer and pre-processes it.
protected FlowReturn	transform(Buffer inbuf, Buffer outbuf)	Required if the element does not operate in-place.
protected Caps	transformCaps(PadDirection direction, Caps caps, Caps filter)	Optional.
protected FlowReturn	transformIp(Buffer buf)	Required if the element operates in-place.
protected boolean	transformMeta(Buffer outbuf, Meta meta, Buffer inbuf)	Optional.
protected boolean	transformSize(PadDirection direction, Caps caps, long size, Caps othercaps, Out<Long> othersize)
void	updateQos(double proportion, ClockTimeDiff diff, ClockTime timestamp)	Set the QoS parameters in the transform.
boolean	updateSrcCaps(Caps updatedCaps)	Updates the srcpad caps and sends the caps downstream.

Methods inherited from class org.freedesktop.gstreamer.gst.Element

abortState, addPad, addPropertyDeepNotifyWatch, addPropertyNotifyWatch, callAsync, changeState, continueState, createAllPads, decorateStreamId, decorateStreamIdPrintf, emitNoMorePads, emitPadAdded, emitPadRemoved, foreachPad, foreachSinkPad, foreachSrcPad, getBaseTime, getBus, getClock, getCompatiblePad, getCompatiblePadTemplate, getContext, getContexts, getContextUnlocked, getCurrentClockTime, getCurrentRunningTime, getFactory, getMetadata, getPadTemplate, getPadTemplateList, getRequestPad, getStartTime, getState, getStaticPad, isLockedState, iteratePads, iterateSinkPads, iterateSrcPads, link, linkFiltered, linkMany, linkPads, linkPadsFiltered, linkPadsFull, linkPadsFull, lostState, makeFromUri, messageFull, messageFull, messageFullWithDetails, messageFullWithDetails, noMorePads, onNoMorePads, onPadAdded, onPadRemoved, padAdded, padRemoved, postMessage, provideClock, query, queryConvert, queryDuration, queryPosition, register, releasePad, releaseRequestPad, removePad, removePropertyNotifyWatch, requestPad, requestPadSimple, seek, seek, seekSimple, seekSimple, sendEvent, setBaseTime, setBus, setClock, setContext, setLockedState, setStartTime, setState, stateChanged, stateChangeReturnGetName, stateGetName, syncStateWithParent, typeSetSkipDocumentation, unlink, unlinkMany, unlinkPads

Methods inherited from class org.freedesktop.gstreamer.gst.GstObject

addControlBinding, checkUniqueness, deepNotify, defaultDeepNotify, defaultError, emitDeepNotify, getControlBinding, getControlRate, getGValueArray, getName, getParent, getPathString, getValue, getValueArray, hasActiveControlBindings, hasAncestor, hasAsAncestor, hasAsParent, onDeepNotify, ref, refSink, removeControlBinding, replace, setControlBindingDisabled, setControlBindingsDisabled, setControlRate, setName, setParent, suggestNextSync, syncValues, unparent, unref

Methods inherited from class org.gnome.gobject.GObject

addToggleRef, addWeakPointer, bindProperty, bindProperty, bindProperty, bindPropertyFull, bindPropertyFull, bindPropertyWithClosures, bindPropertyWithClosures, compatControl, connect, connect, connect, constructed, disconnect, dispatchPropertiesChanged, dispose, dupData, dupQdata, emit, emitNotify, finalize_, forceFloating, freezeNotify, get, getData, getProperty, getProperty, getProperty, getQdata, getv, interfaceFindProperty, interfaceInstallProperty, interfaceListProperties, isFloating, newInstance, newInstance, newInstance, newInstance, newv, notify_, notify_, notifyByPspec, onNotify, refSink, removeToggleRef, removeWeakPointer, replaceData, replaceQdata, runDispose, set, setData, setDataFull, setProperty, setProperty, setProperty, setQdata, setQdataFull, setv, stealData, stealQdata, takeRef, thawNotify, watchClosure, weakRef, weakUnref, withProperties

Methods inherited from class org.gnome.gobject.TypeInstance

callParent, callParent, getPrivate, readGClass, writeGClass

Methods inherited from class io.github.jwharm.javagi.base.ProxyInstance

equals, handle, hashCode

Methods inherited from class java.lang.Object

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

Constructor Details

BaseTransform

public BaseTransform(MemorySegment address)

Create a BaseTransform proxy instance for the provided memory address.

Parameters:

address - the memory address of the native object

Method Details

getType

public static Type getType()

Get the GType of the BaseTransform class

Returns:

the GType

getMemoryLayout

public static MemoryLayout getMemoryLayout()

The memory layout of the native struct.

Returns:

the memory layout

asParent

protected BaseTransform asParent()

Returns this instance as if it were its parent type. This is mostly synonymous to the Java super keyword, but will set the native typeclass function pointers to the parent type. When overriding a native virtual method in Java, "chaining up" with super.methodName() doesn't work, because it invokes the overridden function pointer again. To chain up, call asParent().methodName(). This will call the native function pointer of this virtual method in the typeclass of the parent type.

Overrides:

asParent in class Element

getAllocator

public void getAllocator(@Nullable
 @Nullable Out<Allocator> allocator,
 @Nullable
 @Nullable AllocationParams params)

Lets GstBaseTransform sub-classes know the memory allocator used by the base class and its params.

Unref the allocator after use.

Parameters:

allocator - the GstAllocator used

params - the GstAllocationParams of allocator

getBufferPool

public BufferPool getBufferPool()

isInPlace

public boolean isInPlace()

See if this BaseTransform is configured as a in_place transform.

Returns:

true if the transform is configured in in_place mode.

MT safe.

isPassthrough

public boolean isPassthrough()

See if this BaseTransform is configured as a passthrough transform.

Returns:

true if the transform is configured in passthrough mode.

MT safe.

isQosEnabled

public boolean isQosEnabled()

Queries if the transform will handle QoS.

Returns:

true if QoS is enabled.

MT safe.

reconfigure

public boolean reconfigure()

Negotiates src pad caps with downstream elements if the source pad is marked as needing reconfiguring. Unmarks GST_PAD_FLAG_NEED_RECONFIGURE in any case. But marks it again if negotiation fails.

Do not call this in the GstBaseTransformClass::transform or GstBaseTransformClass::transform_ip vmethod. Call this in GstBaseTransformClass::submit_input_buffer, GstBaseTransformClass::prepare_output_buffer or in GstBaseTransformClass::generate_output _before_ any output buffer is allocated.

It will be default be called when handling an ALLOCATION query or at the very beginning of the default GstBaseTransformClass::submit_input_buffer implementation.

Returns:

true if the negotiation succeeded, else false.

reconfigureSink

public void reconfigureSink()

Instructs this BaseTransform to request renegotiation upstream. This function is typically called after properties on the transform were set that influence the input format.

reconfigureSrc

public void reconfigureSrc()

Instructs this BaseTransform to renegotiate a new downstream transform on the next buffer. This function is typically called after properties on the transform were set that influence the output format.

setGapAware

public void setGapAware(boolean gapAware)

If gapAware is false (the default), output buffers will have the BufferFlags.GAP flag unset.

If set to true, the element must handle output buffers with this flag set correctly, i.e. it can assume that the buffer contains neutral data but must unset the flag if the output is no neutral data.

MT safe.

Parameters:

gapAware - New state

setInPlace

public void setInPlace(boolean inPlace)

Determines whether a non-writable buffer will be copied before passing to the transform_ip function.

• Always true if no transform function is implemented.
• Always false if ONLY transform function is implemented.

MT safe.

Parameters:

inPlace - Boolean value indicating that we would like to operate on in_place buffers.

setPassthrough

public void setPassthrough(boolean passthrough)

Set passthrough mode for this filter by default. This is mostly useful for filters that do not care about negotiation.

Always true for filters which don't implement either a transform or transform_ip or generate_output method.

MT safe.

Parameters:

passthrough - boolean indicating passthrough mode.

setPreferPassthrough

public void setPreferPassthrough(boolean preferPassthrough)

If preferPassthrough is true (the default), this BaseTransform will check and prefer passthrough caps from the list of caps returned by the transform_caps vmethod.

If set to false, the element must order the caps returned from the transform_caps function in such a way that the preferred format is first in the list. This can be interesting for transforms that can do passthrough transforms but prefer to do something else, like a capsfilter.

MT safe.

Parameters:

preferPassthrough - New state

setQosEnabled

public void setQosEnabled(boolean enabled)

Enable or disable QoS handling in the transform.

MT safe.

Parameters:

enabled - new state

updateQos

public void updateQos(double proportion,
 ClockTimeDiff diff,
 ClockTime timestamp)

Set the QoS parameters in the transform. This function is called internally when a QOS event is received but subclasses can provide custom information when needed.

MT safe.

Parameters:

proportion - the proportion

diff - the diff against the clock

timestamp - the timestamp of the buffer generating the QoS expressed in running_time.

updateSrcCaps

public boolean updateSrcCaps(Caps updatedCaps)

Updates the srcpad caps and sends the caps downstream. This function can be used by subclasses when they have already negotiated their caps but found a change in them (or computed new information). This way, they can notify downstream about that change without losing any buffer.

Parameters:

updatedCaps - An updated version of the srcpad caps to be pushed downstream

Returns:

true if the caps could be sent downstream false otherwise

acceptCaps

protected boolean acceptCaps(PadDirection direction,
 Caps caps)

Optional. Subclasses can override this method to check if caps can be handled by the element. The default implementation might not be the most optimal way to check this in all cases.

beforeTransform

protected void beforeTransform(Buffer buffer)

Optional. This method is called right before the base class will start processing. Dynamic properties or other delayed configuration could be performed in this method.

copyMetadata

protected boolean copyMetadata(Buffer input,
 Buffer outbuf)

Optional. Copy the metadata from the input buffer to the output buffer. The default implementation will copy the flags, timestamps and offsets of the buffer.

decideAllocation

protected boolean decideAllocation(Query query)

Setup the allocation parameters for allocating output buffers. The passed in query contains the result of the downstream allocation query. This function is only called when not operating in passthrough mode. The default implementation will remove all memory dependent metadata. If there is a filterMeta method implementation, it will be called for all metadata API in the downstream query, otherwise the metadata API is removed.

filterMeta

protected boolean filterMeta(Query query,
 Type api,
 Structure params)

Return true if the metadata API should be proposed in the upstream allocation query. The default implementation is null and will cause all metadata to be removed.

fixateCaps

protected Caps fixateCaps(PadDirection direction,
 Caps caps,
 Caps othercaps)

generateOutput

protected FlowReturn generateOutput(Out<Buffer> outbuf)

getUnitSize

protected boolean getUnitSize(Caps caps,
 Out<Long> size)

prepareOutputBuffer

protected FlowReturn prepareOutputBuffer(Buffer input,
 Out<Buffer> outbuf)

proposeAllocation

protected boolean proposeAllocation(Query decideQuery,
 Query query)

Propose buffer allocation parameters for upstream elements. This function must be implemented if the element reads or writes the buffer content. The query that was passed to the decide_allocation is passed in this method (or null when the element is in passthrough mode). The default implementation will pass the query downstream when in passthrough mode and will copy all the filtered metadata API in non-passthrough mode.

query

protected boolean query(PadDirection direction,
 Query query)

Optional. Handle a requested query. Subclasses that implement this must chain up to the parent if they didn't handle the query

setCaps

protected boolean setCaps(Caps incaps,
 Caps outcaps)

Allows the subclass to be notified of the actual caps set.

sinkEvent

protected boolean sinkEvent(Event event)

srcEvent

protected boolean srcEvent(Event event)

start

protected boolean start()

Optional. Called when the element starts processing. Allows opening external resources.

stop

protected boolean stop()

Optional. Called when the element stops processing. Allows closing external resources.

submitInputBuffer

protected FlowReturn submitInputBuffer(boolean isDiscont,
 Buffer input)

Function which accepts a new input buffer and pre-processes it. The default implementation performs caps (re)negotiation, then QoS if needed, and places the input buffer into the queuedBuf member variable. If the buffer is dropped due to QoS, it returns GST_BASE_TRANSFORM_FLOW_DROPPED. If this input buffer is not contiguous with any previous input buffer, then isDiscont is set to true. (Since: 1.6)

transform

protected FlowReturn transform(Buffer inbuf,
 Buffer outbuf)

Required if the element does not operate in-place. Transforms one incoming buffer to one outgoing buffer. The function is allowed to change size/timestamp/duration of the outgoing buffer.

transformCaps

protected Caps transformCaps(PadDirection direction,
 Caps caps,
 Caps filter)

Optional. Given the pad in this direction and the given caps, what caps are allowed on the other pad in this element ?

transformIp

protected FlowReturn transformIp(Buffer buf)

Required if the element operates in-place. Transform the incoming buffer in-place.

transformMeta

protected boolean transformMeta(Buffer outbuf,
 Meta meta,
 Buffer inbuf)

Optional. Transform the metadata on the input buffer to the output buffer. By default this method copies all meta without tags. Subclasses can implement this method and return true if the metadata is to be copied.

transformSize

protected boolean transformSize(PadDirection direction,
 Caps caps,
 long size,
 Caps othercaps,
 Out<Long> othersize)

builder

public static BaseTransform.Builder<? extends BaseTransform.Builder> builder()

A BaseTransform.Builder object constructs a BaseTransform with the specified properties. Use the various set...() methods to set properties, and finish construction with BaseTransform.Builder.build().