MP3InternalsHuffman.hh

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/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
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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 Lesser General Public License for
more details.
 
You should have received a copy of the GNU Lesser General Public License
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**********/
// "liveMedia"
// Copyright (c) 1996-2024 Live Networks, Inc.  All rights reserved.
// MP3 internal implementation details (Huffman encoding)
// C++ header
 
#ifndef _MP3_INTERNALS_HUFFMAN_HH
#define _MP3_INTERNALS_HUFFMAN_HH
 
#ifndef _MP3_INTERNALS_HH
#include "MP3Internals.hh"
#endif
 
void updateSideInfoForHuffman(MP3SideInfo& sideInfo, Boolean isMPEG2,
                              unsigned char const* mainDataPtr,
                              unsigned p23L0, unsigned p23L1,
                              unsigned& part23Length0a,
                              unsigned& part23Length0aTruncation,
                              unsigned& part23Length0b,
                              unsigned& part23Length0bTruncation,
                              unsigned& part23Length1a,
                              unsigned& part23Length1aTruncation,
                              unsigned& part23Length1b,
                              unsigned& part23Length1bTruncation);
 
#define SSLIMIT 18
 
class MP3HuffmanEncodingInfo {
public:
  MP3HuffmanEncodingInfo(Boolean includeDecodedValues = False);
  ~MP3HuffmanEncodingInfo();
 
public:
  unsigned numSamples;
  unsigned allBitOffsets[SBLIMIT*SSLIMIT + 1];
  unsigned reg1Start, reg2Start, bigvalStart; /* special bit offsets */
  unsigned* decodedValues;
};
 
/* forward */
void MP3HuffmanDecode(MP3SideInfo::gr_info_s_t* gr, Boolean isMPEG2,
                      unsigned char const* fromBasePtr,
                      unsigned fromBitOffset, unsigned fromLength,
                      unsigned& scaleFactorsLength,
                      MP3HuffmanEncodingInfo& hei);
 
extern unsigned char huffdec[]; // huffman table data
 
// The following are used if we process Huffman-decoded values
#ifdef FOUR_BYTE_SAMPLES
#define BYTES_PER_SAMPLE_VALUE 4
#else
#ifdef TWO_BYTE_SAMPLES
#define BYTES_PER_SAMPLE_VALUE 2
#else
// ONE_BYTE_SAMPLES
#define BYTES_PER_SAMPLE_VALUE 1
#endif
#endif
 
#ifdef DO_HUFFMAN_ENCODING
unsigned MP3HuffmanEncode(MP3SideInfo::gr_info_s_t const* gr,
                          unsigned char const* fromPtr,
                          unsigned char* toPtr, unsigned toBitOffset,
                          unsigned numHuffBits);
#endif
 
#endif