kolibrios/programs/media/ac97snd/trunk/mpg/common.c
Sergey Semyonov (Serge) 86db9e1fc4 updated ac97snd
git-svn-id: svn://kolibrios.org@228 a494cfbc-eb01-0410-851d-a64ba20cac60
2006-12-02 08:47:11 +00:00

137 lines
3.8 KiB
C

#include <stdlib.h>
#include "mpg123.h"
int tabsel_123[2][3][16] = {
{ {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,},
{0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,},
{0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,} },
{ {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,},
{0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,},
{0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,} }
};
long freqs[9] = { 44100, 48000, 32000,
22050, 24000, 16000 ,
11025 , 12000 , 8000 };
#define HDRCMPMASK 0xfffffd00
struct bitstream_info bsi;
int ssize;
unsigned long read_header(BYTE *mpeg)
{ unsigned long hdr;
hdr = *mpeg++;
hdr <<= 8;
hdr |= *mpeg++;
hdr <<= 8;
hdr |= *mpeg++;
hdr <<= 8;
hdr |= *mpeg++;
return hdr;
};
int head_check(unsigned long head)
{
if( (head & 0xffe00000) != 0xffe00000)
return FALSE;
if(!((head>>17)&3))
return FALSE;
if( ((head>>12)&0xf) == 0xf)
return FALSE;
if( ((head>>10)&0x3) == 0x3 )
return FALSE;
return TRUE;
}
int decode_header(struct frame *fr,unsigned long newhead)
{
if( newhead & (1<<20) ) {
fr->lsf = (newhead & (1<<19)) ? 0x0 : 0x1;
fr->mpeg25 = 0;
}
else {
fr->lsf = 1;
fr->mpeg25 = 1;
}
fr->lay = 4-((newhead>>17)&3);
if( ((newhead>>10)&0x3) == 0x3) {
fprintf(stderr,"Stream error, reserved sampling rate\n");
return 0;
}
if(fr->mpeg25) {
fr->sampling_frequency = 6 + ((newhead>>10)&0x3);
}
else
fr->sampling_frequency = ((newhead>>10)&0x3) + (fr->lsf*3);
fr->error_protection = ((newhead>>16)&0x1)^0x1;
if(fr->mpeg25) /* allow Bitrate change for 2.5 ... */
fr->bitrate_index = ((newhead>>12)&0xf);
fr->bitrate_index = ((newhead>>12)&0xf);
fr->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;
fr->stereo = (fr->mode == MPG_MD_MONO) ? 1 : 2;
if(!fr->bitrate_index)
{
fprintf(stderr, "Stream error, free format bitrate index not supported\n");
return 0;
}
switch(fr->lay)
{
case 1:
fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ?
(fr->mode_ext<<2)+4 : 32;
fr->framesize = (long) tabsel_123[fr->lsf][0][fr->bitrate_index] * 12000;
fr->framesize /= freqs[fr->sampling_frequency];
fr->framesize = ((fr->framesize+fr->padding)<<2)-4;
break;
case 2:
fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ?
(fr->mode_ext<<2)+4 : fr->II_sblimit;
fr->framesize = (long) tabsel_123[fr->lsf][1][fr->bitrate_index] * 144000;
fr->framesize /= freqs[fr->sampling_frequency];
fr->framesize += fr->padding - 4;
break;
case 3:
fr->do_layer = do_layer3;
if(fr->lsf)
ssize = (fr->stereo == 1) ? 9 : 17;
else
ssize = (fr->stereo == 1) ? 17 : 32;
if(fr->error_protection)
ssize += 2;
fr->framesize = (long) tabsel_123[fr->lsf][2][fr->bitrate_index] * 144000;
fr->framesize /= freqs[fr->sampling_frequency]<<(fr->lsf);
fr->framesize = fr->framesize + fr->padding - 4;
break;
default:
return (0);
}
return 1;
}
//void set_pointer(long backstep)
//{
// bsi.wordpointer = bsbuf + ssize - backstep;
// if (backstep)
// memcpy(bsi.wordpointer,bsbufold+fsizeold-backstep,backstep);
// bsi.bitindex = 0;
//}