OPAL  Version 3.10.4
OpalFramedTranscoder Class Reference

#include <transcoders.h>

Inheritance diagram for OpalFramedTranscoder:
OpalTranscoder OpalMediaFormatPair OpalEmptyFramedAudioTranscoder OpalPluginFramedAudioTranscoder

Public Member Functions

Construction
 OpalFramedTranscoder (const OpalMediaFormat &inputMediaFormat, const OpalMediaFormat &outputMediaFormat)
Operations
virtual bool UpdateMediaFormats (const OpalMediaFormat &inputMediaFormat, const OpalMediaFormat &outputMediaFormat)
virtual PINDEX GetOptimalDataFrameSize (PBoolean input) const
virtual PBoolean Convert (const RTP_DataFrame &input, RTP_DataFrame &output)
virtual PBoolean ConvertFrame (const BYTE *input, BYTE *output)
virtual PBoolean ConvertFrame (const BYTE *input, PINDEX &consumed, BYTE *output, PINDEX &created)
virtual PBoolean ConvertSilentFrame (BYTE *output)

Protected Member Functions

void CalculateSizes ()

Protected Attributes

PINDEX inputBytesPerFrame
PINDEX outputBytesPerFrame
PINDEX maxOutputDataSize

Detailed Description

This class defines a transcoder implementation class that will encode/decode fixed sized blocks. That is each input block of n bytes is encoded to exactly m bytes of data, eg GSM etc.

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


Constructor & Destructor Documentation

OpalFramedTranscoder::OpalFramedTranscoder ( const OpalMediaFormat inputMediaFormat,
const OpalMediaFormat outputMediaFormat 
)

Create a new framed transcoder implementation.

Parameters:
inputMediaFormatInput media format
outputMediaFormatOutput media format

Member Function Documentation

virtual PBoolean OpalFramedTranscoder::Convert ( const RTP_DataFrame input,
RTP_DataFrame 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 into the RTP_DataFrame provided.

Returns FALSE if the conversion fails.

Parameters:
inputInput data
outputOutput data

Implements OpalTranscoder.

virtual PBoolean OpalFramedTranscoder::ConvertFrame ( const BYTE *  input,
BYTE *  output 
) [virtual]

Convert a frame of data from one format to another. This function implicitly knows the input and output frame sizes.

Parameters:
inputInput data
outputOutput data
virtual PBoolean OpalFramedTranscoder::ConvertFrame ( const BYTE *  input,
PINDEX &  consumed,
BYTE *  output,
PINDEX &  created 
) [virtual]
Parameters:
inputInput data
consumednumber of input bytes consumed
outputOutput data
creatednumber of output bytes created

Reimplemented in OpalEmptyFramedAudioTranscoder, and OpalPluginFramedAudioTranscoder.

virtual PBoolean OpalFramedTranscoder::ConvertSilentFrame ( BYTE *  output) [virtual]
Parameters:
outputOutput data

Reimplemented in OpalPluginFramedAudioTranscoder.

virtual PINDEX OpalFramedTranscoder::GetOptimalDataFrameSize ( PBoolean  input) const [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:
inputFlag for input or output data size

Implements OpalTranscoder.

virtual bool OpalFramedTranscoder::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:
inputMediaFormatInput media format
outputMediaFormatOutput media format

Reimplemented from OpalTranscoder.

Reimplemented in OpalPluginFramedAudioTranscoder.


Field Documentation


The documentation for this class was generated from the following file: