MPEG解码程序源代码

/* MPEG AUDIO LAYER 3 DECODER */ /* Bjorn Wesen 1997 */ /*#define USE_DATA */ #undef ROCKFORD #ifndef DSP #define DECVERBOSE #endif #include "mp3dec.h" #ifdef DSPSIMUL #include <stdio.h> #include <stdlib.h> #include <math.h> #else #ifdef DSP #include "c3x_start.h" #include "c3x_control.h" #endif #endif #ifdef INT_MATH mpfloat operator+(mpfloat a, mpfloat b) { return mpfloat(a._val + b._val); } mpfloat operator-(mpfloat a, mpfloat b) { return mpfloat(a._val - b._val); } mpfloat operator-(mpfloat a) { return mpfloat(-a._val); } mpfloat operator*(mpfloat a, mpfloat b) { return mpfloat(a._val * b._val); } mpfloat operator/(mpfloat a, mpfloat b) { return mpfloat(a._val / b._val); } #endif static float Frame_sampfreqs[4] = { 44.1, 48, 32, 0 }; static int Frame_bitrates[15] = { 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 }; /* scalefac_compress indexes into this table to find the sizes of the scalefactor bitfields */ static int Frame_slen[2][16] = { { 0, 0, 0, 0, 3, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4 }, { 0, 1, 2, 3, 0, 1, 2, 3, 1, 2, 3, 1, 2, 3, 2, 3 } }; /* for each samplerate there is a special division of the 576 frequency lines into bands */ struct Frame_band Frame_bands[3] = { { { 0,4,8,12,16,20,24,30,36,44,52, 62,74,90,110,134,162,196,238,288,342,418,576 }, { 0,4,8,12,16,22,30,40,52,66,84,106,136,192 }}, { { 0,4,8,12,16,20,24,30,36,42,50, 60,72,88,106,128,156,190,230,276,330,384,576 }, { 0,4,8,12,16,22,28,38,50,64,80,100,126,192 }}, { { 0,4,8,12,16,20,24,30,36,44,54, 66,82,102,126,156,194,240,296,364,448,550,576 }, { 0,4,8,12,16,22,30,42,58,78,104,138,180,192 }} }; static Bitstream Frame_bitbuf; /* used for keeping the main data */ #ifdef DECVERBOSE void dump_floats(mpfloat *f, int num) { int i; printf("\n"); for(i = 0; i < num; i++) { if(i && !(i % 5)) printf("\n"); printf("%10f ", f[i]); } printf("\n"); } void dump_ints(int *f, int num) { int i; printf("\n"); for(i = 0; i < num; i++) { if(i && !(i % 5)) printf("\n"); printf("%8d ", f[i]); } printf("\n"); } #endif int frameNum = 0; #ifdef UNIX int main(int argc, char **argv) { FILE *fp; int i = 0; char nameb[256]; PCMSample samples[576*4]; int numframes = 1024; Bitstream my_bs; Frame my_frame; my_bs.buffer32 = (unsigned long *)malloc(0x2000 * 4); if(argc < 2) exit(0); if(argc == 3) numframes = atoi(argv[2]); Frame_init(); HuffmanTable_init(); Granule_init(); sprintf(nameb, "%s.mp3", argv[1]); Bitstream_open(&my_bs, nameb); sprintf(nameb, "%s.raw", argv[1]); fp = fopen(nameb, "wb"); printf("Decoding...\n"); do { fprintf(stderr, "\r[%6d]", i++); fflush(stderr); frameNum++; Frame_load(&my_frame, &my_bs, samples); fwrite(samples, 2, 576*4, fp); /* Frame_dump(&my_frame); */ } while(!Bitstream32_fillbuffer(&my_bs) && i < numframes); printf("\n"); Bitstream_close(&my_bs); fclose(fp); exit(0); } #endif #ifdef DSP #include "testmp.h" //static unsigned char inbuffer[20000]; main() { int i, jayjay; #ifdef DSP_LOFI PCMSample samples[288*40]; #else PCMSample samples[576*4]; #endif int numframes = 40; Bitstream my_bs; Frame my_frame; static unsigned char bit_reservoir[BITSTREAM_BUFSIZE + 4]; static unsigned char buffel[BITSTREAM_BUFSIZE + 4]; #ifdef DSPSIMUL FILE *output; #else #ifndef ROCKFORD init_da(); #endif #endif #ifdef ROCKFORD for(jayjay = 0; jayjay < 10;) { #endif i = 0; Frame_init(); Frame_bitbuf.buffer = bit_reservoir; HuffmanTable_init(); Granule_init(); Bitstream_open(&my_bs, 0); my_bs.buffer = buffel; Bitstream_fillbuffer(&my_bs); #ifdef DSPSIMUL output = fopen("outfil.raw", "wb"); #endif do { frameNum++; Frame_load(&my_frame, &my_bs, samples + 288*i); #ifdef DSPSIMUL fprintf(stderr, "."); fflush(stderr); fwrite(samples, 1, 576*4, output); #else /*play_buffer((void *)(samples + 288*i));*/ #endif i++; Bitstream_fillbuffer(&my_bs); } while(i < numframes); #ifdef ROCKFORD } #else play_buffer((void *)samples); #endif #ifdef DSPSIMUL fprintf(stderr, "\n"); fclose(output); exit(0); #endif while(1); } #endif static int Frame_bitbuf_framestart = 0; void Frame_init() { Bitstream_open(&Frame_bitbuf, 0); } void Frame_load(Frame *f, Bitstream *bs, PCMSample *samps) { int ch, scfsi_band, gr, i, previous_end, alignbits, trash, part2_start; f->samples = samps; /* seek the sync word */ if(!Bitstream_seek_sync(bs)) { #ifndef DSP printf("Couldn't find sync.\n"); #endif return; } /* check that the ID is 1, describing ISO/IEC 11172-3 audio */ if(!Bitstream32_get1(bs)) { #ifndef DSP printf("Incorrect frame ID = 0!\n"); #endif return; } /* check that its a layer 3 frame */ if(Bitstream32_get(bs, 2) != LAYER3) { #ifndef DSP printf("Not a layer-3 frame!\n"); #endif return; } /* read the header */ f->CRC_enable = !Bitstream32_get1(bs); /* meaning of this bit is inverted */ f->bitrate_index = Bitstream32_get(bs, 4); f->sampling_frequency = Bitstream32_get(bs, 2); f->padding_bit = Bitstream32_get1(bs); (void)Bitstream32_get1(bs); /* skip the private bit, we dont use it */ f->mode = Bitstream32_get(bs, 2); f->channels = (f->mode == MODE_SINGLE_CHANNEL) ? 1 : 2; f->mode_extension = Bitstream32_get(bs, 2); f->copyright = Bitstream32_get1(bs); f->originality = Bitstream32_get1(bs); f->emphasis = Bitstream32_get(bs, 2); /* if this frame has a CRC, read it */ if(f->CRC_enable) f->CRC = Bitstream32_get(bs, 16); /* now read the Layer-3 audio_data part of the frame */ /* the following data constitutes the side information stream - - main_data_begin pointer - side info for both granules (scfsi) - side info granule 1 - side info granule 2 */ /* read the starting offset of the main data */ f->main_data_begin = Bitstream32_get(bs, 9); /* read private parts */ if(f->channels == 1) (void)Bitstream32_get(bs, 5); /* 5 private bits for single_channel */ else (void)Bitstream32_get(bs, 3); /* 3 private bits for other modes */ /* read scalefactor selection information, 4 bits per channel */ for(ch = 0; ch < f->channels; ch++) for(scfsi_band = 0; scfsi_band < 4; scfsi_band++) f->scfsi[ch][scfsi_band] = Bitstream32_get1(bs); /* read the side info for the channels for each granule */ for(gr = 0; gr < 2; gr++) for(ch = 0; ch < f->channels; ch++) Granule_decode_info(&f->gr[gr][ch], bs); /* calculate the size of this header in bytes */ f->header_size = 4 + 2 * f->CRC_enable + (f->channels == 1 ? 17 : 32); /* calculate the size of the main_data block of this frame */ /* the distance between two consequitive syncwords is determined from the formula: N = 144 * bitrate / sampling_frequency + padding */ /* then we find the size of the main data by taking that number and subtracting the size of the header and padding */ f->main_data_size = (int)(((144 * Frame_bitrates[f->bitrate_index]) / Frame_sampfreqs[f->sampling_frequency])) + f->padding_bit - f->header_size; /* extract all main data of this frame and insert it into the bitbuffer */ /* ## TODO check if main data is bytealigned, if so, we can copy it much faster */ for(i = f->main_data_size; i > 0; i--) Bitstream_putbyte(&Frame_bitbuf, Bitstream32_get(bs, 8))