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Encoder and Decoder for FLAC files including Java Sound SPI
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package org.jflac.frame;

/**
 * libFLAC - Free Lossless Audio Codec library
 * Copyright (C) 2001,2002,2003  Josh Coalson
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA  02111-1307, USA.
 */

import java.io.IOException;

import org.jflac.ChannelData;
import org.jflac.LPCPredictor;
import org.jflac.io.BitInputStream;
import org.jflac.util.BitMath;

/**
 * LPC FLAC subframe (channel).
 * @author kc7bfi
 */
public class ChannelLPC extends Channel {
    private static final int SUBFRAME_LPC_QLP_COEFF_PRECISION_LEN = 4; /* bits */
    private static final int SUBFRAME_LPC_QLP_SHIFT_LEN = 5; /* bits */
    private static final int MAX_LPC_ORDER = 32;

    private EntropyCodingMethod entropyCodingMethod; // The residual coding method.
    private int order; // The FIR order.
    private int qlpCoeffPrecision; // Quantized FIR filter coefficient precision in bits.
    private int quantizationLevel; // The qlp coeff shift needed.
    private int[] qlpCoeff = new int[MAX_LPC_ORDER]; // FIR filter coefficients.
    private int[] warmup = new int[MAX_LPC_ORDER]; // Warmup samples to prime the predictor, length == order.

    /**
     * The constructor.
     * @param is            The InputBitStream
     * @param header        The FLAC Frame Header
     * @param channelData   The decoded channel data (output)
     * @param bps           The bits-per-second
     * @param wastedBits    The bits waisted in the frame
     * @param order         The predicate order
     * @throws IOException  Thrown if error reading from the InputBitStream
     */
    public ChannelLPC(BitInputStream is, Header header, ChannelData channelData, int bps, int wastedBits, int order) throws IOException {
        super(header, wastedBits);

        this.order = order;

        // read warm-up samples
        //System.out.println("Order="+order);
        for (int u = 0; u < order; u++) {
            warmup[u] = is.readRawInt(bps);
        }
        //for (int i = 0; i < order; i++) System.out.println("Warm "+i+" "+warmup[i]);

        // read qlp coeff precision
        int u32 = is.readRawUInt(SUBFRAME_LPC_QLP_COEFF_PRECISION_LEN);
        if (u32 == (1 << SUBFRAME_LPC_QLP_COEFF_PRECISION_LEN) - 1) {
            throw new IOException("STREAM_DECODER_ERROR_STATUS_LOST_SYNC");
        }
        qlpCoeffPrecision = u32 + 1;
        //System.out.println("qlpCoeffPrecision="+qlpCoeffPrecision);

        // read qlp shift
        quantizationLevel = is.readRawInt(SUBFRAME_LPC_QLP_SHIFT_LEN);
        //System.out.println("quantizationLevel="+quantizationLevel);

        // read quantized lp coefficiencts
        for (int u = 0; u < order; u++) {
            qlpCoeff[u] = is.readRawInt(qlpCoeffPrecision);
        }

        // read entropy coding method info
        int codingType = is.readRawUInt(ENTROPY_CODING_METHOD_TYPE_LEN);
        //System.out.println("codingType="+codingType);
        switch (codingType) {            
            case ENTROPY_CODING_METHOD_PARTITIONED_RICE2 :
            case ENTROPY_CODING_METHOD_PARTITIONED_RICE :	
                entropyCodingMethod = new EntropyPartitionedRice();
                ((EntropyPartitionedRice) entropyCodingMethod).order = is.readRawUInt(ENTROPY_CODING_METHOD_PARTITIONED_RICE_ORDER_LEN);
                ((EntropyPartitionedRice) entropyCodingMethod).contents = channelData.getPartitionedRiceContents();
                break;
            default :
                throw new IOException("STREAM_DECODER_UNPARSEABLE_STREAM");
        }
 
        // read residual
        if (entropyCodingMethod instanceof EntropyPartitionedRice) {
            ((EntropyPartitionedRice) entropyCodingMethod).readResidual(is, 
                order,
                ((EntropyPartitionedRice) entropyCodingMethod).order,
                header,
                channelData.getResidual(), 
                (codingType == ENTROPY_CODING_METHOD_PARTITIONED_RICE2));
        }
        
        //System.out.println();
        //for (int i = 0; i < header.blockSize; i++) {System.out.print(channelData.residual[i]+" ");
        //if (i%200==0)System.out.println();
        //}
        //System.out.println();

        // decode the subframe
        System.arraycopy(warmup, 0, channelData.getOutput(), 0, order);
        if (bps + qlpCoeffPrecision + BitMath.ilog2(order) <= 32) {
            if (bps <= 16 && qlpCoeffPrecision <= 16)
                LPCPredictor.restoreSignal(channelData.getResidual(), header.blockSize - order, qlpCoeff, order, quantizationLevel, channelData.getOutput(), order);
            else
                LPCPredictor.restoreSignal(channelData.getResidual(), header.blockSize - order, qlpCoeff, order, quantizationLevel, channelData.getOutput(), order);
        } else {
            LPCPredictor.restoreSignalWide(channelData.getResidual(), header.blockSize - order, qlpCoeff, order, quantizationLevel, channelData.getOutput(), order);
        }
    }
    
    /**
     * @see java.lang.Object#toString()
     */
    public String toString() {
        StringBuffer sb = new StringBuffer("ChannelLPC: Order=" + order +  " WastedBits=" + wastedBits);
        sb.append(" qlpCoeffPrecision=" + qlpCoeffPrecision + " quantizationLevel=" + quantizationLevel);
        sb.append("\n\t\tqlpCoeff: ");
        for (int i = 0; i < order; i++) sb.append(qlpCoeff[i] + " ");
        sb.append("\n\t\tWarmup: ");
        for (int i = 0; i < order; i++) sb.append(warmup[i] + " ");
        sb.append("\n\t\tParameter: ");
        for (int i = 0; i < (1 << ((EntropyPartitionedRice) entropyCodingMethod).order); i++) sb.append(((EntropyPartitionedRice) entropyCodingMethod).contents.parameters[i] + " ");
        //sb.append("\n\t\tResidual: ");
        //for (int i = 0; i < header.blockSize; i++) sb.append(residual[i] + " ");
        return sb.toString();
    }

}