#include <stdio.h> #include "config.h" #include "mp_msg.h" //----------------------- mp3 audio frame header parser ----------------------- static int tabsel_123[2][3][16] = { { {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0}, {0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,0}, {0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,0} }, { {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0}, {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0}, {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0} } }; static long freqs[9] = { 44100, 48000, 32000, // MPEG 1.0 22050, 24000, 16000, // MPEG 2.0 11025, 12000, 8000}; // MPEG 2.5 int mp_mp3_get_lsf(unsigned char* hbuf){ unsigned long newhead = hbuf[0] << 24 | hbuf[1] << 16 | hbuf[2] << 8 | hbuf[3]; if( newhead & ((long)1<<20) ) { return (newhead & ((long)1<<19)) ? 0x0 : 0x1; } return 1; } /* * return frame size or -1 (bad frame) */ int mp_get_mp3_header(unsigned char* hbuf,int* chans, int* srate, int* spf, int* mpa_layer, int* br){ int stereo,ssize,lsf,framesize,padding,bitrate_index,sampling_frequency, divisor; int bitrate; int layer, mult[3] = { 12000, 144000, 144000 }; unsigned long newhead = hbuf[0] << 24 | hbuf[1] << 16 | hbuf[2] << 8 | hbuf[3]; // printf("head=0x%08X\n",newhead); #if 1 // head_check: if( (newhead & 0xffe00000) != 0xffe00000 ){ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"head_check failed\n"); return -1; } #endif layer = 4-((newhead>>17)&3); if(layer==4){ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"not layer-1/2/3\n"); return -1; } sampling_frequency = ((newhead>>10)&0x3); // valid: 0..2 if(sampling_frequency==3){ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"invalid sampling_frequency\n"); return -1; } if( newhead & ((long)1<<20) ) { // MPEG 1.0 (lsf==0) or MPEG 2.0 (lsf==1) lsf = (newhead & ((long)1<<19)) ? 0x0 : 0x1; sampling_frequency += (lsf*3); } else { // MPEG 2.5 lsf = 1; sampling_frequency += 6; } // crc = ((newhead>>16)&0x1)^0x1; bitrate_index = ((newhead>>12)&0xf); // valid: 1..14 padding = ((newhead>>9)&0x1); // fr->extension = ((newhead>>8)&0x1); // fr->mode = ((newhead>>6)&0x3); // fr->mode_ext = ((newhead>>4)&0x3); // fr->copyright = ((newhead>>3)&0x1); // fr->original = ((newhead>>2)&0x1); // fr->emphasis = newhead & 0x3; stereo = ( (((newhead>>6)&0x3)) == 3) ? 1 : 2; // !checked later through tabsel_123[]! // if(!bitrate_index || bitrate_index==15){ // mp_msg(MSGT_DEMUXER,MSGL_DBG2,"Free format not supported.\n"); // return -1; // } if(lsf) ssize = (stereo == 1) ? 9 : 17; else ssize = (stereo == 1) ? 17 : 32; if(!((newhead>>16)&0x1)) ssize += 2; // CRC bitrate = tabsel_123[lsf][layer-1][bitrate_index]; framesize = bitrate * mult[layer-1]; mp_msg(MSGT_DEMUXER,MSGL_DBG2,"FRAMESIZE: %d, layer: %d, bitrate: %d, mult: %d\n", framesize, layer, tabsel_123[lsf][layer-1][bitrate_index], mult[layer-1]); if(!framesize){ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"invalid framesize/bitrate_index\n"); return -1; } divisor = (layer == 3 ? (freqs[sampling_frequency] << lsf) : freqs[sampling_frequency]); framesize /= divisor; if(layer==1) framesize = (framesize+padding)*4; else framesize += padding; // if(framesize<=0 || framesize>MAXFRAMESIZE) return FALSE; if(srate) { *srate = freqs[sampling_frequency]; if(spf) { if(layer == 1) *spf = 384; else if(layer == 2) *spf = 1152; else if(*srate < 32000) *spf = 576; else *spf = 1152; } } if(mpa_layer) *mpa_layer = layer; if(chans) *chans = stereo; if(br) *br = bitrate; return framesize; }