OpalMediaPatch Class Reference

#include <patch.h>

Inheritance diagram for OpalMediaPatch:


Public Member Functions
Construction
	OpalMediaPatch (OpalMediaStream &source)
	~OpalMediaPatch ()
Overrides from PObject
void	PrintOn (ostream &strm) const
Operations
virtual void	Start ()
virtual bool	OnStartMediaPatch ()
virtual void	Close ()
PBoolean	AddSink (const OpalMediaStreamPtr &stream)
void	RemoveSink (const OpalMediaStreamPtr &stream)
OpalMediaStream &	GetSource () const
OpalMediaStreamPtr	GetSink (PINDEX i=0) const
OpalMediaFormat	GetSinkFormat (PINDEX i=0) const
void	AddFilter (const PNotifier &filter, const OpalMediaFormat &stage=OpalMediaFormat())
PBoolean	RemoveFilter (const PNotifier &filter, const OpalMediaFormat &stage=OpalMediaFormat())
virtual void	FilterFrame (RTP_DataFrame &frame, const OpalMediaFormat &mediaFormat)
virtual bool	UpdateMediaFormat (const OpalMediaFormat &mediaFormat)
virtual PBoolean	ExecuteCommand (const OpalMediaCommand &command, PBoolean fromSink)
virtual void	SetCommandNotifier (const PNotifier &notifier, PBoolean fromSink)
virtual void	SetPaused (bool pause)
virtual PBoolean	PushFrame (RTP_DataFrame &frame)
bool	SetBypassPatch (OpalMediaPatch *patch)
virtual OpalTranscoder *	GetAndLockSinkTranscoder (PINDEX i=0) const
virtual void	UnLockSinkTranscoder () const
virtual void	GetStatistics (OpalMediaStatistics &statistics, bool fromSink) const
Protected Member Functions
virtual void	Main ()
bool	DispatchFrame (RTP_DataFrame &frame)
Protected Attributes
OpalMediaStream &	source
PList< Sink >	sinks
PList< Filter >	filters
bool	m_videoDecoder
bool	m_bypassActive
OpalMediaPatch *	m_bypassToPatch
OpalMediaPatch *	m_bypassFromPatch
PSyncPoint	m_bypassEnded
Thread *	patchThread
PMutex	patchThreadMutex
PReadWriteMutex	inUse
Data Structures
class	Filter
class	Sink
class	Thread

Detailed Description

Media stream "patch cord". This class is the thread of control that transfers data from one "source" OpalMediStream to one or more other "sink" OpalMediStream instances. It may use zero, one or two intermediary software codecs for each sink stream in order to match the media data formats the streams are capabile of doing natively.

Note the thread is not actually started straight away. It is expected that the Start() function is called on the patch when the creator code is ready for it to begin. For example all sink streams have been added.

Constructor & Destructor Documentation

OpalMediaPatch::OpalMediaPatch ( OpalMediaStream & source )

Create a new patch. Note the thread is not started here.

Parameters:

source

Source media stream

OpalMediaPatch::~OpalMediaPatch ( )

Destroy patch.

Member Function Documentation

void OpalMediaPatch::AddFilter	(	const PNotifier &	filter,
		const OpalMediaFormat &	stage = `OpalMediaFormat()`
	)

Add a filter to the media pipeline. Use PDECLARE_NOTIFIER(RTP_DataFrame, YourClass, YourFunction) for the filter function notifier.

PBoolean OpalMediaPatch::AddSink ( const OpalMediaStreamPtr & stream )

Add another "sink" OpalMediaStream to patch. The stream must not be a ReadOnly media stream for the patch to be able to write to it.

Parameters:

stream

Media stream to add.

virtual void OpalMediaPatch::Close ( ) [virtual]

Close the patch. This is an internal function that closes all of the sink streams and waits for the the thread to terminate. It is called when the source stream is called.

bool OpalMediaPatch::DispatchFrame ( RTP_DataFrame & frame ) [protected]

virtual PBoolean OpalMediaPatch::ExecuteCommand	(	const OpalMediaCommand &	command,
		PBoolean	fromSink
	)			`[virtual]`

Execute the command specified to the transcoder. The commands are highly context sensitive, for example VideoFastUpdate would only apply to a video transcoder.

The default behaviour passes the command on to the source or sinks and the sinks transcoders.

Parameters:

command	Command to execute.
fromSink	Flag for source or sink

virtual void OpalMediaPatch::FilterFrame	(	RTP_DataFrame &	frame,
		const OpalMediaFormat &	mediaFormat
	)			`[virtual]`

Filter a frame. Calls all filter functions.

virtual OpalTranscoder* OpalMediaPatch::GetAndLockSinkTranscoder ( PINDEX i = 0 ) const [virtual]

Get the transcoder used within a sink stream

OpalMediaStreamPtr OpalMediaPatch::GetSink ( PINDEX i = 0 ) const

Get the media stream for a sink stream

OpalMediaFormat OpalMediaPatch::GetSinkFormat ( PINDEX i = 0 ) const

Get the media format for a sink stream

OpalMediaStream& OpalMediaPatch::GetSource ( ) const [inline]

Get the current source stream for patch.

virtual void OpalMediaPatch::GetStatistics	(	OpalMediaStatistics &	statistics,
		bool	fromSink
	)			const `[virtual]`

virtual void OpalMediaPatch::Main ( ) [protected, virtual]

Called from the associated patch thread

virtual bool OpalMediaPatch::OnStartMediaPatch ( ) [virtual]

Indicate the patch has started. Typically called from the beginning of the patch thread.

Default behaviour make sure jitter buffer is created.

Returns bool indicating all media streams are asynchronous so the patch should assure no thread startvation

void OpalMediaPatch::PrintOn ( ostream & strm ) const

Standard stream print function. The PObject class has a << operator defined that calls this function polymorphically.

Parameters:

strm

Stream to output text representation

virtual PBoolean OpalMediaPatch::PushFrame ( RTP_DataFrame & frame ) [virtual]

Push a frame out to all the sink streams, transcoding as necessary.

Parameters:

frame

Frame to push

PBoolean OpalMediaPatch::RemoveFilter	(	const PNotifier &	filter,
		const OpalMediaFormat &	stage = `OpalMediaFormat()`
	)

Remove a filter from the media pipeline.

void OpalMediaPatch::RemoveSink ( const OpalMediaStreamPtr & stream )

Add existing "sink" OpalMediaStream to patch. If the stream is not a sink of this patch then this function does nothing.

Parameters:

stream

Media stream to remove

bool OpalMediaPatch::SetBypassPatch ( OpalMediaPatch * patch )

Set bypass patch instance.

This can be useful for back to back calls that happen to be the same media format and you wish to avoid double decoding and encoding of media. Note this scenario is not the same as two OpalConnections within the same OpalCall, but two completely independent OpalCall where one connection is to be bypassed. For example, two OpalCall instances might have two SIPConnection instances and two OpalMixerConnection instances connected via a single OpalMixerNode. Now while there are ONLY two calls in the node, it is a waste to decode the audio, add to mixer and re-encode it again. In practice this is identical to just bypassing the mixer node completely, until a third party is added, then we need to switch back to normal (non-bypassed) operation.

Note it is up to the caller to assure the patch instance lifetimes are correct for the bypass.

Returns:: true if bypass was set, false if conflict with another bypass.

virtual void OpalMediaPatch::SetCommandNotifier	(	const PNotifier &	notifier,
		PBoolean	fromSink
	)			`[virtual]`

Set a notifier to receive commands generated by the transcoder. The commands are highly context sensitive, for example VideoFastUpdate would only apply to a video transcoder.

The default behaviour passes the command on to the source or sinks and the sinks transcoders.

Parameters:

notifier	Command to execute.
fromSink	Flag for source or sink

virtual void OpalMediaPatch::SetPaused ( bool pause ) [virtual]

Set streams to paused.

virtual void OpalMediaPatch::Start ( ) [virtual]

Start the patch. The default implementation simply starts the patch thread, which in turn calls Main()

Reimplemented in OpalPassiveMediaPatch.

virtual void OpalMediaPatch::UnLockSinkTranscoder ( ) const [virtual]

virtual bool OpalMediaPatch::UpdateMediaFormat ( const OpalMediaFormat & mediaFormat ) [virtual]

Update the source/sink media format. This can be used to adjust the parameters of a codec at run time. Note you cannot change the basic media format, eg change GSM0610 to G.711, only options for that format, eg 6k3 mode to 5k3 mode in G.723.1. If the formats are different then a OpalMediaFormat::Merge() is performed.

The default behaviour updates the source/sink media stream and the output side of any relevant transcoders.

Parameters:

mediaFormat

New media format