/**********
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This library is free software; you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License as published by the
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Free Software Foundation; either version 3 of the License, or (at your
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option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)
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This library is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
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more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this library; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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**********/
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// "liveMedia"
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// Copyright (c) 1996-2017 Live Networks, Inc. All rights reserved.
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// MP3 internal implementation details
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// C++ header
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#ifndef _MP3_INTERNALS_HH
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#define _MP3_INTERNALS_HH
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#ifndef _BOOLEAN_HH
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#include "Boolean.hh"
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#endif
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#ifndef _BIT_VECTOR_HH
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#include "BitVector.hh"
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#endif
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typedef struct MP3SideInfo {
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unsigned main_data_begin;
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unsigned private_bits;
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typedef struct gr_info_s {
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int scfsi;
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unsigned part2_3_length;
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unsigned big_values;
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unsigned global_gain;
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unsigned scalefac_compress;
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unsigned window_switching_flag;
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unsigned block_type;
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unsigned mixed_block_flag;
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unsigned table_select[3];
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unsigned region0_count;
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unsigned region1_count;
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unsigned subblock_gain[3];
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unsigned maxband[3];
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unsigned maxbandl;
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unsigned maxb;
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unsigned region1start;
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unsigned region2start;
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unsigned preflag;
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unsigned scalefac_scale;
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unsigned count1table_select;
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double *full_gain[3];
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double *pow2gain;
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} gr_info_s_t;
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struct {
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gr_info_s_t gr[2];
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} ch[2];
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} MP3SideInfo_t;
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#define SBLIMIT 32
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#define MAX_MP3_FRAME_SIZE 2500 /* also big enough for an 'ADU'ized frame */
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class MP3FrameParams {
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public:
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MP3FrameParams();
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~MP3FrameParams();
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// 4-byte MPEG header:
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unsigned hdr;
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// a buffer that can be used to hold the rest of the frame:
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unsigned char frameBytes[MAX_MP3_FRAME_SIZE];
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// public parameters derived from the header
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void setParamsFromHeader(); // this sets them
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Boolean isMPEG2;
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unsigned layer; // currently only 3 is supported
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unsigned bitrate; // in kbps
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unsigned samplingFreq;
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Boolean isStereo;
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Boolean isFreeFormat;
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unsigned frameSize; // doesn't include the initial 4-byte header
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unsigned sideInfoSize;
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Boolean hasCRC;
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void setBytePointer(unsigned char const* restOfFrame,
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unsigned totNumBytes) {// called during setup
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bv.setup((unsigned char*)restOfFrame, 0, 8*totNumBytes);
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}
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// other, public parameters used when parsing input (perhaps get rid of)
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unsigned oldHdr, firstHdr;
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// Extract (unpack) the side info from the frame into a struct:
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void getSideInfo(MP3SideInfo& si);
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// The bit pointer used for reading data from frame data
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unsigned getBits(unsigned numBits) { return bv.getBits(numBits); }
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unsigned get1Bit() { return bv.get1Bit(); }
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private:
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BitVector bv;
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// other, private parameters derived from the header
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unsigned bitrateIndex;
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unsigned samplingFreqIndex;
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Boolean isMPEG2_5;
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Boolean padding;
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Boolean extension;
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unsigned mode;
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unsigned mode_ext;
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Boolean copyright;
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Boolean original;
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unsigned emphasis;
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unsigned stereo;
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private:
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unsigned computeSideInfoSize();
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};
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unsigned ComputeFrameSize(unsigned bitrate, unsigned samplingFreq,
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Boolean usePadding, Boolean isMPEG2,
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unsigned char layer);
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Boolean GetADUInfoFromMP3Frame(unsigned char const* framePtr,
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unsigned totFrameSize,
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unsigned& hdr, unsigned& frameSize,
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MP3SideInfo& sideInfo, unsigned& sideInfoSize,
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unsigned& backpointer, unsigned& aduSize);
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Boolean ZeroOutMP3SideInfo(unsigned char* framePtr, unsigned totFrameSize,
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unsigned newBackpointer);
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unsigned TranscodeMP3ADU(unsigned char const* fromPtr, unsigned fromSize,
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unsigned toBitrate,
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unsigned char* toPtr, unsigned toMaxSize,
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unsigned& availableBytesForBackpointer);
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// returns the size of the resulting ADU (0 on failure)
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#endif
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