javazoom.jl.decoder
Class Decoder

java.lang.Object
  javazoom.jl.decoder.Decoder

All Implemented Interfaces:

DecoderErrors, JavaLayerErrors

public class Decoder
extends java.lang.Object
implements DecoderErrors

The Decoder class encapsulates the details of decoding an MPEG audio frame.

Since:

0.0.5

Version:

0.0.7 12/12/99

Nested Class Summary

static class

Decoder.Params The Params class presents the customizable aspects of the decoder.

Field Summary

Fields inherited from interface javazoom.jl.decoder.DecoderErrors

ILLEGAL_SUBBAND_ALLOCATION, UNKNOWN_ERROR, UNSUPPORTED_LAYER

Fields inherited from interface javazoom.jl.decoder.JavaLayerErrors

BITSTREAM_ERROR, DECODER_ERROR

Constructor Summary

Decoder()
Creates a new Decoder instance with default parameters.

Decoder(Decoder.Params params0)
Creates a new Decoder instance with default parameters.

Method Summary

Obuffer	decodeFrame(Header header, Bitstream stream) Decodes one frame from an MPEG audio bitstream.
static Decoder.Params	getDefaultParams()
int	getOutputBlockSize() Retrieves the maximum number of samples that will be written to the output buffer when one frame is decoded.
int	getOutputChannels() Retrieves the number of channels of PCM samples output by this decoder.
int	getOutputFrequency() Retrieves the sample frequency of the PCM samples output by this decoder.
protected DecoderException	newDecoderException(int errorcode)
protected DecoderException	newDecoderException(int errorcode, java.lang.Throwable throwable)
protected FrameDecoder	retrieveDecoder(Header header, Bitstream stream, int layer)
void	setEqualizer(Equalizer eq)
void	setOutputBuffer(Obuffer out) Changes the output buffer.

Methods inherited from class java.lang.Object

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

Constructor Detail

Decoder

public Decoder()

Creates a new Decoder instance with default parameters.

Decoder

public Decoder(Decoder.Params params0)

Creates a new Decoder instance with default parameters.

Parameters:

params - The Params instance that describes the customizable aspects of the decoder.

Method Detail

getDefaultParams

public static Decoder.Params getDefaultParams()

setEqualizer

public void setEqualizer(Equalizer eq)

decodeFrame

public Obuffer decodeFrame(Header header,
                           Bitstream stream)
                    throws DecoderException

Decodes one frame from an MPEG audio bitstream.

Parameters:

header - The header describing the frame to decode.

bitstream - The bistream that provides the bits for te body of the frame.

Returns:

A SampleBuffer containing the decoded samples.

Throws:

DecoderException

setOutputBuffer

public void setOutputBuffer(Obuffer out)

Changes the output buffer. This will take effect the next time decodeFrame() is called.

getOutputFrequency

public int getOutputFrequency()

Retrieves the sample frequency of the PCM samples output by this decoder. This typically corresponds to the sample rate encoded in the MPEG audio stream.

Parameters:

the - sample rate (in Hz) of the samples written to the output buffer when decoding.

getOutputChannels

public int getOutputChannels()

Retrieves the number of channels of PCM samples output by this decoder. This usually corresponds to the number of channels in the MPEG audio stream, although it may differ.

Returns:

The number of output channels in the decoded samples: 1 for mono, or 2 for stereo.

getOutputBlockSize

public int getOutputBlockSize()

Retrieves the maximum number of samples that will be written to the output buffer when one frame is decoded. This can be used to help calculate the size of other buffers whose size is based upon the number of samples written to the output buffer. NB: this is an upper bound and fewer samples may actually be written, depending upon the sample rate and number of channels.

Returns:

The maximum number of samples that are written to the output buffer when decoding a single frame of MPEG audio.

newDecoderException

protected DecoderException newDecoderException(int errorcode)

newDecoderException

protected DecoderException newDecoderException(int errorcode,
                                               java.lang.Throwable throwable)

retrieveDecoder

protected FrameDecoder retrieveDecoder(Header header,
                                       Bitstream stream,
                                       int layer)
                                throws DecoderException

Throws:

DecoderException