100 lines
2.4 KiB
C++
100 lines
2.4 KiB
C++
/*
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* Chromaprint -- Audio fingerprinting toolkit
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* Copyright (C) 2010 Lukas Lalinsky <lalinsky@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
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* USA
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*/
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#include "fingerprint_decompressor.h"
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#include "debug.h"
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#include "utils.h"
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using namespace std;
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using namespace Chromaprint;
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static const int kMaxNormalValue = 7;
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static const int kNormalBits = 3;
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static const int kExceptionBits = 5;
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FingerprintDecompressor::FingerprintDecompressor()
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{
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}
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void FingerprintDecompressor::UnpackBits()
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{
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int i = 0, last_bit = 0, value = 0;
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for (size_t j = 0; j < m_bits.size(); j++) {
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int bit = m_bits[j];
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if (bit == 0) {
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m_result[i] = (i > 0) ? value ^ m_result[i - 1] : value;
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value = 0;
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last_bit = 0;
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i++;
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continue;
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}
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bit += last_bit;
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last_bit = bit;
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value |= 1 << (bit - 1);
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}
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}
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void FingerprintDecompressor::ReadNormalBits(BitStringReader *reader)
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{
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size_t i = 0;
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while (i < m_result.size()) {
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int bit = reader->Read(kNormalBits);
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if (bit == 0) {
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i++;
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}
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m_bits.push_back(bit);
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}
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}
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void FingerprintDecompressor::ReadExceptionBits(BitStringReader *reader)
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{
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for (size_t i = 0; i < m_bits.size(); i++) {
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if (m_bits[i] == kMaxNormalValue) {
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m_bits[i] += reader->Read(kExceptionBits);
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}
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}
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}
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std::vector<int32_t> FingerprintDecompressor::Decompress(const string &data, int *algorithm)
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{
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if (algorithm) {
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*algorithm = data[0];
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}
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int length =
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((unsigned char)(data[1]) << 16) |
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((unsigned char)(data[2]) << 8) |
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((unsigned char)(data[3]) );
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BitStringReader reader(data);
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reader.Read(8);
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reader.Read(8);
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reader.Read(8);
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reader.Read(8);
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m_result = vector<int32_t>(length, -1);
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reader.Reset();
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ReadNormalBits(&reader);
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reader.Reset();
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ReadExceptionBits(&reader);
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UnpackBits();
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return m_result;
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}
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