src/atrac/atrac1_dequantiser.cpp


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#include "atrac1_dequantiser.h"


namespace NAtrac1 {
using namespace NBitStream;

TAtrac1Dequantiser::TAtrac1Dequantiser() {
}

void TAtrac1Dequantiser::Dequant(TBitStream* stream, const TBlockSize& bs, double specs[512]) {
    uint32_t wordLens[MAX_BFUS];
    uint32_t idScaleFactors[MAX_BFUS];
    const uint32_t numBFUs = BfuAmountTab[stream->Read(3)];
    stream->Read(2);
    stream->Read(3);

    for (uint32_t i = 0; i < numBFUs; i++) {
        wordLens[i] = stream->Read(4);
    }

    for (uint32_t i = 0; i < numBFUs; i++) {
        idScaleFactors[i] = stream->Read(6);
    }
    for (uint32_t i = numBFUs; i < MAX_BFUS; i++) {
        wordLens[i] = idScaleFactors[i] = 0;
    }

    for (uint32_t bandNum = 0; bandNum < QMF_BANDS; bandNum++) {
        for (uint32_t bfuNum = BlocksPerBand[bandNum]; bfuNum < BlocksPerBand[bandNum + 1]; bfuNum++) {
            const uint32_t numSpecs = SpecsPerBlock[bfuNum];
            const uint32_t wordLen = !!wordLens[bfuNum] + wordLens[bfuNum];
            const double scaleFactor = ScaleTable[idScaleFactors[bfuNum]];
            const uint32_t startPos = bs.LogCount[bandNum] ? SpecsStartShort[bfuNum] : SpecsStartLong[bfuNum]; 
            if (wordLen) {
                double maxQuant = 1.0 / (double)((1 << (wordLen - 1)) - 1);
                //cout << "BFU ("<< bfuNum << ") :" <<  "wordLen " << wordLen << " maxQuant " << maxQuant << " scaleFactor " << scaleFactor << " id " << idScaleFactors[bfuNum] << " num Specs " << numSpecs << " short: "<< (int)bs.LogCount[bandNum] << endl;
                for (uint32_t i = 0; i < numSpecs; i++ ) {
                    specs[startPos + i] = scaleFactor * maxQuant * MakeSign(stream->Read(wordLen), wordLen);
                }
            } else {
                memset(&specs[startPos], 0, numSpecs * sizeof(double));
            }
        }

    } 
}

}