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140 lines
2.4 KiB
140 lines
2.4 KiB
/*
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initializer/resyncer/frame detection etc.. for mpeg audio
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Copyright (C) 2000 Martin Vogt
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation.
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For more information look at the file COPYRIGHT in this package
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*/
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#ifndef __MPEGAUDIOSTREAM_H
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#define __MPEGAUDIOSTREAM_H
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// we include this for the big_endian define
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#include "mpegAudioBitWindow.h"
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#define _MAX_MPEG_BUFFERSIZE 4096
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/**
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Here we go from the frame to the bitlevel.
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*/
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class MpegAudioStream {
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char* buffer;
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int len;
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int bitindex;
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public:
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MpegAudioStream();
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~MpegAudioStream();
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void setFrame(unsigned char* prt,int len);
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// Bit functions
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inline char* getBuffer() { return buffer; }
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inline int getBufferSize() { return _MAX_MPEG_BUFFERSIZE ;}
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inline void sync() { bitindex=(bitindex+7)&0xFFFFFFF8; }
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inline int issync() { return (bitindex&7);};
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/**
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Now follow ugly inline function. The performance gain is 1.5 %
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on a 400 MHz AMD
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*/
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inline int getbyte() {
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int r=(unsigned char)buffer[bitindex>>3];
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bitindex+=8;
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return r;
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}
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inline int getbits9(int bits) {
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register unsigned short a;
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{
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int offset=bitindex>>3;
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a=(((unsigned char)buffer[offset])<<8) |
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((unsigned char)buffer[offset+1]);
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}
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a<<=(bitindex&7);
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bitindex+=bits;
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return (int)((unsigned int)(a>>(16-bits)));
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}
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inline int getbits8() {
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register unsigned short a;
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{
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int offset=bitindex>>3;
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a=(((unsigned char)buffer[offset])<<8) |
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((unsigned char)buffer[offset+1]);
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}
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a<<=(bitindex&7);
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bitindex+=8;
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return (int)((unsigned int)(a>>8));
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}
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inline int getbit() {
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register int r=(buffer[bitindex>>3]>>(7-(bitindex&7)))&1;
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bitindex++;
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return r;
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}
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inline int getbits(int bits) {
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union
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{
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char store[4];
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int current;
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}u;
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int bi;
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if(!bits)return 0;
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u.current=0;
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bi=(bitindex&7);
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u.store[_KEY]=buffer[bitindex>>3]<<bi;
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bi=8-bi;
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bitindex+=bi;
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while(bits) {
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if(!bi) {
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u.store[_KEY]=buffer[bitindex>>3];
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bitindex+=8;
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bi=8;
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}
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if(bits>=bi) {
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u.current<<=bi;
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bits-=bi;
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bi=0;
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} else {
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u.current<<=bits;
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bi-=bits;
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bits=0;
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}
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}
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bitindex-=bi;
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return (u.current>>8);
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}
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};
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#endif
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