MPEG-Layer.rar_FreeAmp _MP3解码_player

/*____________________________________________________________________________ MP3 Decoding Libraries Lanuguages used: C, C++, ASM As much as I would love to, I cannot take full credit for writing this code. Xing Technology made MPEG-Layer 3 for us to decode. =) - ULTiMaTuM - MPEG-Layer 3 (MP3) Copyright (C) 1995-1997 Xing Technology NOTE: I only edited the bare-minimum. 90% of this is original decoding code... Hmm... that sounds strange =) ____________________________________________________________________________*/ /**** cupL3.c *************************************************** unpack Layer III mod 8/18/97 bugfix crc problem mod 10/9/97 add band_limit12 for short blocks mod 10/22/97 zero buf_ptrs in init mod 5/15/98 mpeg 2.5 mod 8/19/98 decode 22 sf bands ******************************************************************/ /*--------------------------------------- TO DO: Test mixed blocks (mixed long/short) No mixed blocks in mpeg-1 test stream being used for development -----------------------------------------*/ #include <stdlib.h> #include <stdio.h> #include <float.h> #include <math.h> #include <memory.h> #include <string.h> #include <assert.h> #include "mhead.h" /* mpeg header structure */ #include "L3.h" #include "jdw.h" /*====================================================================*/ static int mp_sr20_table[2][4] = {{441, 480, 320, -999}, {882, 960, 640, -999}}; static int mp_br_tableL3[2][16] = {{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0}, /* mpeg 2 */ {0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 0}}; /*====================================================================*/ /*-- global band tables */ /*-- short portion is 3*x !! --*/ int nBand[2][22]; /* [long/short][cb] */ int sfBandIndex[2][22]; /* [long/short][cb] */ /*====================================================================*/ /*----------------*/ extern DEC_INFO decinfo; /*----------------*/ static int mpeg25_flag; int iframe; /*-------*/ static int band_limit = (576); static int band_limit21 = (576); // limit for sf band 21 static int band_limit12 = (576); // limit for sf band 12 short int band_limit_nsb = 32; /* global for hybrid */ static int nsb_limit = 32; static int gain_adjust = 0; /* adjust gain e.g. cvt to mono */ static int id; static int ncbl_mixed; /* number of long cb's in mixed block 8 or 6 */ static int sr_index; static int outvalues; static int outbytes; static int half_outbytes; static int framebytes; static int padframebytes; static int crcbytes; static int pad; static int stereo_flag; static int nchan; static int ms_mode; static int is_mode; static unsigned int zero_level_pcm = 0; /* cb_info[igr][ch], compute by dequant, used by joint */ static CB_INFO cb_info[2][2]; static IS_SF_INFO is_sf_info; /* MPEG-2 intensity stereo */ /*---------------------------------*/ /* main data bit buffer */ #define NBUF (8*1024) #define BUF_TRIGGER (NBUF-1500) static unsigned char buf[NBUF]; static int buf_ptr0 = 0; static int buf_ptr1 = 0; static int main_pos_bit; /*---------------------------------*/ static SIDE_INFO side_info; static SCALEFACT sf[2][2]; /* [gr][ch] */ static int nsamp[2][2]; /* must start = 0, for nsamp[igr_prev] */ /*- sample union of int/float sample[ch][gr][576] */ /* static SAMPLE sample[2][2][576]; */ extern SAMPLE sample[2][2][576]; static float yout[576]; /* hybrid out, sbt in */ typedef void (*SBT_FUNCTION) (float *sample, short *pcm, int ch); void sbt_dual_L3(float *sample, short *pcm, int n); static SBT_FUNCTION sbt_L3 = sbt_dual_L3; typedef void (*XFORM_FUNCTION) (void *pcm, int igr); static void Xform_dual(void *pcm, int igr); static XFORM_FUNCTION Xform = Xform_dual; IN_OUT L3audio_decode_MPEG1(unsigned char *bs, unsigned char *pcm); IN_OUT L3audio_decode_MPEG2(unsigned char *bs, unsigned char *pcm); typedef IN_OUT(*DECODE_FUNCTION) (unsigned char *bs, unsigned char *pcm); static DECODE_FUNCTION decode_function = L3audio_decode_MPEG1; /*====================================================================*/ int hybrid(void *xin, void *xprev, float *y, int btype, int nlong, int ntot, int nprev); int hybrid_sum(void *xin, void *xin_left, float *y, int btype, int nlong, int ntot); void sum_f_bands(void *a, void *b, int n); void FreqInvert(float *y, int n); void antialias(void *x, int n); void ms_process(void *x, int n); /* sum-difference stereo */ void is_process_MPEG1(void *x, /* intensity stereo */ SCALEFACT * sf, CB_INFO cb_info[2], /* [ch] */ int nsamp, int ms_mode); void is_process_MPEG2(void *x, /* intensity stereo */ SCALEFACT * sf, CB_INFO cb_info[2], /* [ch] */ IS_SF_INFO * is_sf_info, int nsamp, int ms_mode); void unpack_huff(void *xy, int n, int ntable); int unpack_huff_quad(void *vwxy, int n, int nbits, int ntable); void dequant(SAMPLE sample[], int *nsamp, SCALEFACT * sf, GR * gr, CB_INFO * cb_info, int ncbl_mixed); void unpack_sf_sub_MPEG1(SCALEFACT * scalefac, GR * gr, int scfsi, /* bit flag */ int igr); void unpack_sf_sub_MPEG2(SCALEFACT sf[], /* return intensity scale */ GR * grdat, int is_and_ch, IS_SF_INFO * is_sf_info); /*====================================================================*/ /* get bits from bitstream in endian independent way */ BITDAT bitdat; /* global for inline use by Huff */ /*------------- initialize bit getter -------------*/ static void bitget_init(unsigned char *buf) { bitdat.bs_ptr0 = bitdat.bs_ptr = buf; bitdat.bits = 0; bitdat.bitbuf = 0; } /*------------- initialize bit getter -------------*/ static void bitget_init_end(unsigned char *buf_end) { bitdat.bs_ptr_end = buf_end; } /*------------- get n bits from bitstream -------------*/ int bitget_bits_used() { int n; /* compute bits used from last init call */ n = ((bitdat.bs_ptr - bitdat.bs_ptr0) << 3) - bitdat.bits; return n; } /*------------- check for n bits in bitbuf -------------*/ void bitget_check(int n) { if (bitdat.bits < n) { while (bitdat.bits <= 24) { bitdat.bitbuf = (bitdat.bitbuf << 8) | *bitdat.bs_ptr++; bitdat.bits += 8; } } } /*------------- get n bits from bitstream -------------*/ unsigned int bitget(int n) { unsigned int x; if (bitdat.bits < n) { /* refill bit buf if necessary */ while (bitdat.bits <= 24) { bitdat.bitbuf = (bitdat.bitbuf << 8) | *bitdat.bs_ptr++; bitdat.bits += 8; } } bitdat.bits -= n; x = bitdat.bitbuf >> bitdat.bits; bitdat.bitbuf -= x << bitdat.bits; return x; } /*------------- get 1 bit from bitstream -------------*/ unsigned int bitget_1bit() { unsigned int x; if (bitdat.bits <= 0) { /* refill bit buf if necessary */ while (bitdat.bits <= 24) { bitdat.bitbuf = (bitdat.bitbuf << 8) | *bitdat.bs_ptr++; bitdat.bits += 8; } } bitdat.bits--; x = bitdat.bitbuf >> bitdat.bits; bitdat.bitbuf -= x << bitdat.bits; return x; } /*====================================================================*/ static void Xform_mono(void *pcm, int igr) { int igr_prev, n1, n2; /*--- hybrid + sbt ---*/ n1 = n2 = nsamp[igr][0]; /* total number bands */ if (side_info.gr[igr][0].block_type == 2) { /* long bands */ n1 = 0; if (side_info.gr[igr][0].mixed_block_flag) n1 = sfBandIndex[0][ncbl_mixed - 1]; } if (n1 > band_limit) n1 = band_limit; if (n2 > band_limit) n2 = band_limit; igr_prev = igr ^ 1; nsamp[igr][0] = hybrid(sample[0][igr], sample[0][igr_prev], yout, side_info.gr[igr][0].block_type, n1, n2, nsamp[igr_prev][0]); FreqInve