#include <transcoders.h>

Inheritance diagram for OpalTranscoder:

Collaboration diagram for OpalTranscoder:

Public Member Functions
Construction
	OpalTranscoder (const OpalMediaFormat &inputMediaFormat, const OpalMediaFormat &outputMediaFormat)

Public Member Functions inherited from OpalMediaFormatPair
	OpalMediaFormatPair (const OpalMediaFormat &inputMediaFormat, const OpalMediaFormat &outputMediaFormat)

void	PrintOn (ostream &strm) const

virtual Comparison	Compare (const PObject &obj) const

const OpalMediaFormat &	GetInputFormat () const

const OpalMediaFormat &	GetOutputFormat () const

Protected Member Functions
virtual bool	OnCreated (const OpalMediaFormat &srcFormat, const OpalMediaFormat &destFormat, const BYTE *instance, unsigned instanceLen)

	PDECLARE_MUTEX (updateMutex)

Protected Attributes
PINDEX	maxOutputSize

PNotifier	commandNotifier

unsigned	m_sessionID

bool	outputIsRTP

bool	inputIsRTP

bool	acceptEmptyPayload

bool	acceptOtherPayloads

unsigned	m_inClockRate

unsigned	m_outClockRate

RTP_DataFrame::PayloadTypes	m_lastPayloadType

unsigned	m_consecutivePayloadTypeMismatches

Protected Attributes inherited from OpalMediaFormatPair
OpalMediaFormat	inputMediaFormat

OpalMediaFormat	outputMediaFormat

Operations
virtual bool	UpdateMediaFormats (const OpalMediaFormat &inputMediaFormat, const OpalMediaFormat &outputMediaFormat)

virtual PBoolean	ExecuteCommand (const OpalMediaCommand &command)

virtual PINDEX	GetOptimalDataFrameSize (PBoolean input) const =0

virtual PBoolean	ConvertFrames (const RTP_DataFrame &input, RTP_DataFrameList &output)

virtual PBoolean	Convert (const RTP_DataFrame &input, RTP_DataFrame &output)=0

PINDEX	GetMaxOutputSize () const

void	SetMaxOutputSize (PINDEX size)

void	SetCommandNotifier (const PNotifier &notifier)

const PNotifier &	GetCommandNotifier () const

void	NotifyCommand (const OpalMediaCommand &command) const
	Notify command notifier of command. More...

unsigned	GetSessionID () const
	Get session ID for the transcoder (from OpalMediaStream) More...

void	SetSessionID (unsigned id)
	Set session ID for the transcoder (from OpalMediaStream) More...

RTP_DataFrame::PayloadTypes	GetPayloadType (PBoolean input) const

virtual bool	AcceptComfortNoise () const

virtual bool	AcceptEmptyPayload () const

virtual bool	AcceptOtherPayloads () const

virtual void	GetStatistics (OpalMediaStatistics &statistics) const

void	CopyTimestamp (RTP_DataFrame &dst, const RTP_DataFrame &src, bool inToOut) const

static OpalTranscoder *	Create (const OpalMediaFormat &srcFormat, const OpalMediaFormat &dstFormat, const BYTE *instance=NULL, unsigned instanceLen=0)

static bool	SelectFormats (const OpalMediaType &mediaType, const OpalMediaFormatList &srcFormats, const OpalMediaFormatList &dstFormats, const OpalMediaFormatList &masterFormats, OpalMediaFormat &srcFormat, OpalMediaFormat &dstFormat)

static bool	FindIntermediateFormat (const OpalMediaFormat &srcFormat, const OpalMediaFormat &dstFormat, OpalMediaFormat &intermediateFormat)

static OpalMediaFormatList	GetDestinationFormats (const OpalMediaFormat &srcFormat)

static OpalMediaFormatList	GetSourceFormats (const OpalMediaFormat &dstFormat)

static OpalMediaFormatList	GetPossibleFormats (const OpalMediaFormatList &formats)

Detailed Description

This class embodies the implementation of a specific transcoder instance used to convert data from one format to another.

An application may create a descendent off this class and override functions as required for implementing a transcoder.

Constructor & Destructor Documentation

OpalTranscoder::OpalTranscoder	(	const OpalMediaFormat &	inputMediaFormat,
		const OpalMediaFormat &	outputMediaFormat
	)

Create a new transcoder implementation.

Parameters

inputMediaFormat	Input media format
outputMediaFormat	Output media format

Member Function Documentation

virtual bool OpalTranscoder::AcceptComfortNoise ( ) const

inlinevirtual

Reimplemented in OpalPluginStreamedAudioTranscoder, and OpalPluginFramedAudioTranscoder.

virtual bool OpalTranscoder::AcceptEmptyPayload ( ) const

inlinevirtual

References acceptEmptyPayload.

virtual bool OpalTranscoder::AcceptOtherPayloads ( ) const

inlinevirtual

References acceptOtherPayloads.

virtual PBoolean OpalTranscoder::Convert	(	const RTP_DataFrame &	input,
		RTP_DataFrame &	output
	)

pure virtual

Convert the data from one format to another. This function takes the input data as a RTP_DataFrame and converts it to its output format, placing it into the RTP_DataFrame provided.

Returns false if the conversion fails.

Parameters

input	Input data
output	Output data

Implemented in OpalStreamedTranscoder, OpalFramedTranscoder, OpalVideoTranscoder, and Opal_G711_PCM.

virtual PBoolean OpalTranscoder::ConvertFrames	(	const RTP_DataFrame &	input,
		RTP_DataFrameList &	output
	)

virtual

Convert the data from one format to another. This function takes the input data as a RTP_DataFrame and converts it to its output format, placing it (possibly) into multiple RTP_DataFrame objects.

The default behaviour makes sure the output list has only one element in it and calls the Convert() function.

Returns false if the conversion fails.

Parameters

input	Input data
output	Output data

Reimplemented in OpalPluginVideoTranscoder, OpalRFC4175Decoder, and OpalRFC4175Encoder.

void OpalTranscoder::CopyTimestamp	(	RTP_DataFrame &	dst,
		const RTP_DataFrame &	src,
		bool	inToOut
	)		const

static OpalTranscoder* OpalTranscoder::Create	(	const OpalMediaFormat &	srcFormat,
		const OpalMediaFormat &	dstFormat,
		const BYTE *	instance = `NULL`,
		unsigned	instanceLen = `0`
	)

static

Create an instance of a media conversion function. Returns NULL if there is no registered media transcoder between the two named formats.

Parameters

srcFormat	Name of source format
dstFormat	Name of destination format
instance	Unique instance identifier for transcoder
instanceLen	Length of instance identifier

virtual PBoolean OpalTranscoder::ExecuteCommand ( const OpalMediaCommand & command )

virtual

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

The default behaviour simply returns false.

Returns: true if command is handled.

Parameters

command Command to execute.

Reimplemented in OpalPluginVideoTranscoder, OpalPluginStreamedAudioTranscoder, OpalPluginFramedAudioTranscoder, and OpalVideoTranscoder.

static bool OpalTranscoder::FindIntermediateFormat	(	const OpalMediaFormat &	srcFormat,
		const OpalMediaFormat &	dstFormat,
		OpalMediaFormat &	intermediateFormat
	)

static

Find media intermediate format for transcoders. This function attempts to find the intermediate media format that will allow two transcoders to be used to get data from the source format to the destination format.

If there is a transcoder that can go directly from the source format to the destination format then the function returns true but the intermediateFormat parmaeter will be an invlid format.

Returns false if there is no registered media transcoder that can be used between the two named formats.

Parameters

srcFormat	Selected destination format to be used
dstFormat	Selected destination format to be used
intermediateFormat	Intermediate format that can be used

const PNotifier& OpalTranscoder::GetCommandNotifier ( ) const

inline

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

References commandNotifier.

static OpalMediaFormatList OpalTranscoder::GetDestinationFormats ( const OpalMediaFormat & srcFormat )

static

Get a list of possible destination media formats for the destination.

Parameters

srcFormat Selected source format

PINDEX OpalTranscoder::GetMaxOutputSize ( ) const

inline

Get maximum output size.

References maxOutputSize.

virtual PINDEX OpalTranscoder::GetOptimalDataFrameSize ( PBoolean input ) const

pure virtual

Get the optimal size for data frames to be converted. This function returns the size of frames that will be most efficient in conversion. A RTP_DataFrame will attempt to provide or use data in multiples of this size. Note that it may not do so, so the transcoder must be able to handle any sized packets.

Parameters

input Flag for input or output data size

Implemented in OpalStreamedTranscoder, OpalFramedTranscoder, and OpalVideoTranscoder.

RTP_DataFrame::PayloadTypes OpalTranscoder::GetPayloadType ( PBoolean input ) const

Parameters

input Flag for input or output data size

static OpalMediaFormatList OpalTranscoder::GetPossibleFormats ( const OpalMediaFormatList & formats )

static

Get a list of possible media formats that can do bi-directional media.

Parameters

formats Destination format list

unsigned OpalTranscoder::GetSessionID ( ) const

inline

Get session ID for the transcoder (from OpalMediaStream)

References m_sessionID.

static OpalMediaFormatList OpalTranscoder::GetSourceFormats ( const OpalMediaFormat & dstFormat )

static

Get a list of possible source media formats for the destination.

Parameters

dstFormat Selected destination format

virtual void OpalTranscoder::GetStatistics ( OpalMediaStatistics & statistics ) const

virtual

Reimplemented in OpalPluginVideoTranscoder, OpalPluginFramedAudioTranscoder, and OpalVideoTranscoder.

void OpalTranscoder::NotifyCommand ( const OpalMediaCommand & command ) const

Notify command notifier of command.

virtual bool OpalTranscoder::OnCreated	(	const OpalMediaFormat &	srcFormat,
		const OpalMediaFormat &	destFormat,
		const BYTE *	instance,
		unsigned	instanceLen
	)

protectedvirtual

Initialise the just created transcoder

Parameters

srcFormat	Source media format
destFormat	Destination media format
instance	Unique instance identifier for transcoder
instanceLen	Length of instance identifier

Reimplemented in OpalPluginVideoTranscoder, OpalPluginStreamedAudioTranscoder, and OpalPluginFramedAudioTranscoder.

OpalTranscoder::PDECLARE_MUTEX ( updateMutex )

protected

static bool OpalTranscoder::SelectFormats	(	const OpalMediaType &	mediaType,
		const OpalMediaFormatList &	srcFormats,
		const OpalMediaFormatList &	dstFormats,
		const OpalMediaFormatList &	masterFormats,
		OpalMediaFormat &	srcFormat,
		OpalMediaFormat &	dstFormat
	)

static

Find media format(s) for transcoders. This function attempts to find and intermediate media format that will allow two transcoders to be used to get data from the source format to the destination format.

There could be many possible matches between the two lists, so preference is given to the order of the destination formats.

At least one of the two selected medai formats (source or destination) must also be of the specified media type ("audio", "video" etc).

Returns false if there is no registered media transcoder that can be used to get from src to dst for the media type.

Parameters

mediaType	Media type for selection.
srcFormats	Names of possible source formats
dstFormats	Names of possible destination formats
masterFormats	Master list of formats for merging options
srcFormat	Selected source format to be used
dstFormat	Selected destination format to be used

void OpalTranscoder::SetCommandNotifier ( const PNotifier & notifier )

inline

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

Parameters

notifier Command to execute.

References commandNotifier.

void OpalTranscoder::SetMaxOutputSize ( PINDEX size )

Set the maximum output size.

void OpalTranscoder::SetSessionID ( unsigned id )

inline

Set session ID for the transcoder (from OpalMediaStream)

References m_sessionID.

virtual bool OpalTranscoder::UpdateMediaFormats	(	const OpalMediaFormat &	inputMediaFormat,
		const OpalMediaFormat &	outputMediaFormat
	)

virtual

Update the input and output media formats. 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.

If a format is empty (invalid) it is ignored and does not update the internal variable. In this way only the input or output side can be updated.

The default behaviour updates the inputMediaFormat and outputMediaFormat member variables.

Parameters