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package com.sun.media.sound;

import java.io.IOException;
import java.util.Vector;

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;


A-law encodes linear data, and decodes a-law data to linear data.
Author:Kara Kytle
/** * A-law encodes linear data, and decodes a-law data to linear data. * * @author Kara Kytle */
public final class AlawCodec extends SunCodec { /* Tables used for A-law decoding */ private static final byte[] ALAW_TABH = new byte[256]; private static final byte[] ALAW_TABL = new byte[256]; private static final AudioFormat.Encoding[] alawEncodings = { AudioFormat.Encoding.ALAW, AudioFormat.Encoding.PCM_SIGNED }; private static final short seg_end [] = {0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF};
Initializes the decode tables
/** * Initializes the decode tables */
static { for (int i=0;i<256;i++) { int input = i ^ 0x55; int mantissa = (input & 0xf ) << 4; int segment = (input & 0x70) >> 4; int value = mantissa+8; if(segment>=1) value+=0x100; if(segment>1) value <<= (segment -1); if( (input & 0x80)==0 ) value = -value; ALAW_TABL[i] = (byte)value; ALAW_TABH[i] = (byte)(value>>8); } }
Constructs a new ALAW codec object.
/** * Constructs a new ALAW codec object. */
public AlawCodec() { super(alawEncodings, alawEncodings); } // NEW CODE /** */ public AudioFormat.Encoding[] getTargetEncodings(AudioFormat sourceFormat){ if( sourceFormat.getEncoding().equals( AudioFormat.Encoding.PCM_SIGNED )) { if( sourceFormat.getSampleSizeInBits() == 16 ) { AudioFormat.Encoding enc[] = new AudioFormat.Encoding[1]; enc[0] = AudioFormat.Encoding.ALAW; return enc; } else { return new AudioFormat.Encoding[0]; } } else if( sourceFormat.getEncoding().equals( AudioFormat.Encoding.ALAW ) ) { if( sourceFormat.getSampleSizeInBits() == 8 ) { AudioFormat.Encoding enc[] = new AudioFormat.Encoding[1]; enc[0] = AudioFormat.Encoding.PCM_SIGNED; return enc; } else { return new AudioFormat.Encoding[0]; } } else { return new AudioFormat.Encoding[0]; } } /** */ public AudioFormat[] getTargetFormats(AudioFormat.Encoding targetEncoding, AudioFormat sourceFormat){ if( (targetEncoding.equals( AudioFormat.Encoding.PCM_SIGNED ) && sourceFormat.getEncoding().equals( AudioFormat.Encoding.ALAW)) || (targetEncoding.equals( AudioFormat.Encoding.ALAW) && sourceFormat.getEncoding().equals( AudioFormat.Encoding.PCM_SIGNED)) ) { return getOutputFormats( sourceFormat ); } else { return new AudioFormat[0]; } } /** */ public AudioInputStream getAudioInputStream(AudioFormat.Encoding targetEncoding, AudioInputStream sourceStream){ AudioFormat sourceFormat = sourceStream.getFormat(); AudioFormat.Encoding sourceEncoding = sourceFormat.getEncoding(); if( sourceEncoding.equals( targetEncoding ) ) { return sourceStream; } else { AudioFormat targetFormat = null; if( !isConversionSupported(targetEncoding,sourceStream.getFormat()) ) { throw new IllegalArgumentException("Unsupported conversion: " + sourceStream.getFormat().toString() + " to " + targetEncoding.toString()); } if( sourceEncoding.equals( AudioFormat.Encoding.ALAW ) && targetEncoding.equals( AudioFormat.Encoding.PCM_SIGNED ) ) { targetFormat = new AudioFormat( targetEncoding, sourceFormat.getSampleRate(), 16, sourceFormat.getChannels(), 2*sourceFormat.getChannels(), sourceFormat.getSampleRate(), sourceFormat.isBigEndian()); } else if( sourceEncoding.equals( AudioFormat.Encoding.PCM_SIGNED ) && targetEncoding.equals( AudioFormat.Encoding.ALAW ) ) { targetFormat = new AudioFormat( targetEncoding, sourceFormat.getSampleRate(), 8, sourceFormat.getChannels(), sourceFormat.getChannels(), sourceFormat.getSampleRate(), false); } else { throw new IllegalArgumentException("Unsupported conversion: " + sourceStream.getFormat().toString() + " to " + targetEncoding.toString()); } return getAudioInputStream( targetFormat, sourceStream ); } }
use old code...
/** * use old code... */
public AudioInputStream getAudioInputStream(AudioFormat targetFormat, AudioInputStream sourceStream){ return getConvertedStream( targetFormat, sourceStream ); } // OLD CODE
Opens the codec with the specified parameters.
Params:
  • stream – stream from which data to be processed should be read
  • outputFormat – desired data format of the stream after processing
Throws:
Returns:stream from which processed data may be read
/** * Opens the codec with the specified parameters. * @param stream stream from which data to be processed should be read * @param outputFormat desired data format of the stream after processing * @return stream from which processed data may be read * @throws IllegalArgumentException if the format combination supplied is * not supported. */
/* public AudioInputStream getConvertedStream(AudioFormat outputFormat, AudioInputStream stream) { */ private AudioInputStream getConvertedStream(AudioFormat outputFormat, AudioInputStream stream) { AudioInputStream cs = null; AudioFormat inputFormat = stream.getFormat(); if( inputFormat.matches(outputFormat) ) { cs = stream; } else { cs = (AudioInputStream) (new AlawCodecStream(stream, outputFormat)); } return cs; }
Obtains the set of output formats supported by the codec given a particular input format. If no output formats are supported for this input format, returns an array of length 0.
Returns:array of supported output formats.
/** * Obtains the set of output formats supported by the codec * given a particular input format. * If no output formats are supported for this input format, * returns an array of length 0. * @return array of supported output formats. */
/* public AudioFormat[] getOutputFormats(AudioFormat inputFormat) { */ private AudioFormat[] getOutputFormats(AudioFormat inputFormat) { Vector formats = new Vector(); AudioFormat format; if ( AudioFormat.Encoding.PCM_SIGNED.equals(inputFormat.getEncoding())) { format = new AudioFormat(AudioFormat.Encoding.ALAW, inputFormat.getSampleRate(), 8, inputFormat.getChannels(), inputFormat.getChannels(), inputFormat.getSampleRate(), false ); formats.addElement(format); } if (AudioFormat.Encoding.ALAW.equals(inputFormat.getEncoding())) { format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED, inputFormat.getSampleRate(), 16, inputFormat.getChannels(), inputFormat.getChannels()*2, inputFormat.getSampleRate(), false ); formats.addElement(format); format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED, inputFormat.getSampleRate(), 16, inputFormat.getChannels(), inputFormat.getChannels()*2, inputFormat.getSampleRate(), true ); formats.addElement(format); } AudioFormat[] formatArray = new AudioFormat[formats.size()]; for (int i = 0; i < formatArray.length; i++) { formatArray[i] = (AudioFormat)(formats.elementAt(i)); } return formatArray; } final class AlawCodecStream extends AudioInputStream { // tempBuffer required only for encoding (when encode is true) private static final int tempBufferSize = 64; private byte tempBuffer [] = null;
True to encode to a-law, false to decode to linear
/** * True to encode to a-law, false to decode to linear */
boolean encode = false; AudioFormat encodeFormat; AudioFormat decodeFormat; byte tabByte1[] = null; byte tabByte2[] = null; int highByte = 0; int lowByte = 1; AlawCodecStream(AudioInputStream stream, AudioFormat outputFormat) { super(stream, outputFormat, -1); AudioFormat inputFormat = stream.getFormat(); // throw an IllegalArgumentException if not ok if ( ! (isConversionSupported(outputFormat, inputFormat)) ) { throw new IllegalArgumentException("Unsupported conversion: " + inputFormat.toString() + " to " + outputFormat.toString()); } //$$fb 2002-07-18: fix for 4714846: JavaSound ULAW (8-bit) encoder erroneously depends on endian-ness boolean PCMIsBigEndian; // determine whether we are encoding or decoding if (AudioFormat.Encoding.ALAW.equals(inputFormat.getEncoding())) { encode = false; encodeFormat = inputFormat; decodeFormat = outputFormat; PCMIsBigEndian = outputFormat.isBigEndian(); } else { encode = true; encodeFormat = outputFormat; decodeFormat = inputFormat; PCMIsBigEndian = inputFormat.isBigEndian(); tempBuffer = new byte[tempBufferSize]; } if (PCMIsBigEndian) { tabByte1 = ALAW_TABH; tabByte2 = ALAW_TABL; highByte = 0; lowByte = 1; } else { tabByte1 = ALAW_TABL; tabByte2 = ALAW_TABH; highByte = 1; lowByte = 0; } // set the AudioInputStream length in frames if we know it if (stream instanceof AudioInputStream) { frameLength = ((AudioInputStream)stream).getFrameLength(); } // set framePos to zero framePos = 0; frameSize = inputFormat.getFrameSize(); if( frameSize==AudioSystem.NOT_SPECIFIED ) { frameSize=1; } } /* * $$jb 2/23/99 * Used to determine segment number in aLaw encoding */ private short search(short val, short table[], short size) { for(short i = 0; i < size; i++) { if (val <= table[i]) { return i; } } return size; }
Note that this won't actually read anything; must read in two-byte units.
/** * Note that this won't actually read anything; must read in * two-byte units. */
public int read() throws IOException { byte[] b = new byte[1]; return (int)read(b, 0, b.length); } public int read(byte[] b) throws IOException { return read(b, 0, b.length); } public int read(byte[] b, int off, int len) throws IOException { // don't read fractional frames if( len%frameSize != 0 ) { len -= (len%frameSize); } if (encode) { short QUANT_MASK = 0xF; short SEG_SHIFT = 4; short mask; short seg; int adj; int i; short sample; byte enc; int readCount = 0; int currentPos = off; int readLeft = len*2; int readLen = ( (readLeft>tempBufferSize) ? tempBufferSize : readLeft ); while ((readCount = super.read(tempBuffer,0,readLen))>0) { for (i = 0; i < readCount; i+=2) { /* Get the sample from the tempBuffer */ sample = (short)(( (tempBuffer[i + highByte]) << 8) & 0xFF00); sample |= (short)( (tempBuffer[i + lowByte]) & 0xFF); if(sample >= 0) { mask = 0xD5; } else { mask = 0x55; sample = (short)(-sample - 8); } /* Convert the scaled magnitude to segment number. */ seg = search(sample, seg_end, (short) 8); /* * Combine the sign, segment, quantization bits */ if (seg >= 8) { /* out of range, return maximum value. */ enc = (byte) (0x7F ^ mask); } else { enc = (byte) (seg << SEG_SHIFT); if(seg < 2) { enc |= (byte) ( (sample >> 4) & QUANT_MASK); } else { enc |= (byte) ( (sample >> (seg + 3)) & QUANT_MASK ); } enc ^= mask; } /* Now put the encoded sample where it belongs */ b[currentPos] = enc; currentPos++; } /* And update pointers and counters for next iteration */ readLeft -= readCount; readLen = ( (readLeft>tempBufferSize) ? tempBufferSize : readLeft ); } if( currentPos==off && readCount<0 ) { // EOF or error return readCount; } return (currentPos - off); /* Number of bytes written to new buffer */ } else { int i; int readLen = len/2; int readOffset = off + len/2; int readCount = super.read(b, readOffset, readLen); for (i = off; i < (off + (readCount*2)); i+=2) { b[i] = (byte)tabByte1[b[readOffset] & 0xFF]; b[i+1] = (byte)tabByte2[b[readOffset] & 0xFF]; readOffset++; } if( readCount<0 ) { // EOF or error return readCount; } return (i - off); } } } // end class AlawCodecStream } // end class ALAW