代码来自开源工程minimp3：https://github.com/lieff/minimp3
mp3的译码实现都放在一个头文件中，去掉了源代码中碍眼的宏，剩下1200多行，测试代码去掉了没什么用的测试。
minimp3_test.c
#include "minimp3.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
/**
gcc -o minimp3 minimp3_test.c
./minimp3 L.mp3 L.wav
**/
static char *wav_header(int hz, int ch, int bips, int data_bytes)
{
static char hdr[44] = "RIFFsizeWAVEfmt \x10\0\0\0\1\0ch_hz_abpsbabsdatasize";
unsigned long nAvgBytesPerSec = bips*ch*hz >> 3;
unsigned int nBlockAlign = bips*ch >> 3;
*(int * )(void*)(hdr + 0x04) = 44 + data_bytes - 8; /* File size - 8 */
*(short *)(void*)(hdr + 0x14) = 1; /* Integer PCM format */
*(short *)(void*)(hdr + 0x16) = ch;
*(int * )(void*)(hdr + 0x18) = hz;
*(int * )(void*)(hdr + 0x1C) = nAvgBytesPerSec;
*(short *)(void*)(hdr + 0x20) = nBlockAlign;
*(short *)(void*)(hdr + 0x22) = bips;
*(int * )(void*)(hdr + 0x28) = data_bytes;
return hdr;
}
static unsigned char *preload(FILE *file, int *data_size)
{
unsigned char *data;
*data_size = 0;
if (!file)
return 0;
if (fseek(file, 0, SEEK_END))
return 0;
*data_size = (int)ftell(file);//得到文件大小
if (*data_size < 0)
return 0;
if (fseek(file, 0, SEEK_SET))
return 0;
data = (unsigned char*)malloc(*data_size);//分配内存空间
if (!data)
return 0;
if ((int)fread(data, 1, *data_size, file) != *data_size)//将文件全部数据读到内存
exit(1);
return data;
}
static void decode_file(const unsigned char *buf_mp3, int mp3_size, FILE *file_out)
{
static mp3dec_t mp3d;
mp3dec_frame_info_t info;
int i, data_bytes, samples, total_samples = 0, maxdiff = 0;
double MSE = 0.0, psnr;
//跳过mp3 header
if (mp3_size > 10 && !strncmp((char *)buf_mp3, "ID3", 3))
{
int id3v2size = (((buf_mp3[6] & 0x7f) << 21) | ((buf_mp3[7] & 0x7f) << 14) |
((buf_mp3[8] & 0x7f) << 7) | (buf_mp3[9] & 0x7f)) + 10;
if (mp3_size >= id3v2size)
{
printf("info: skipping %d bytes of id3v2\n", id3v2size);
buf_mp3 += id3v2size;
mp3_size -= id3v2size;
}
}
//初始化译码结构体
mp3dec_init(&mp3d);
memset(&info, 0, sizeof(info));
//预先写入wav文件头占位
fwrite(wav_header(0, 0, 0, 0), 1, 44, file_out);
do
{
short pcm[MINIMP3_MAX_SAMPLES_PER_FRAME];
samples = mp3dec_decode_frame(&mp3d, buf_mp3, mp3_size, pcm, &info);
if (samples)
{
fwrite(pcm, samples, 2*info.channels, file_out);
}
buf_mp3 += info.frame_bytes;
mp3_size -= info.frame_bytes;
} while (info.frame_bytes);
data_bytes = ftell(file_out) - 44;
rewind(file_out);
//根据结果重新写入wav文件头
fwrite(wav_header(info.hz, info.channels, 16, data_bytes), 1, 44, file_out);
}
int main(int argc, char *argv[])
{
int mp3_size;
if(argc<3){
printf("error: no file names given\n");
return 1;
}
char *input_file_name = argv[1];
char *output_file_name = argv[2];
FILE *file_out = NULL;
file_out = fopen(output_file_name, "wb");
FILE *file_mp3 = fopen(input_file_name, "rb");
unsigned char *buf_mp3 = preload(file_mp3, &mp3_size);
if (file_mp3)
fclose(file_mp3);
if (!buf_mp3 || !mp3_size)
{
printf("error: no input data\n");
return 1;
}
decode_file(buf_mp3, mp3_size, file_out);
if (buf_mp3)
free(buf_mp3);
if (file_out)
fclose(file_out);
printf("decode mp3 OK\n");
return 0;
}
minimp3.h
#ifndef MINIMP3_H
#define MINIMP3_H
/*
https://github.com/lieff/minimp3
To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide.
This software is distributed without any warranty.
See <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
#define MINIMP3_MAX_SAMPLES_PER_FRAME (1152*2)
typedef struct
{
int frame_bytes;
int channels;
int hz;
int layer;
int bitrate_kbps;
} mp3dec_frame_info_t;
typedef struct
{
float mdct_overlap[2][9*32];
float qmf_state[15*2*32];
int reserv;
int free_format_bytes;
unsigned char header[4];
unsigned char reserv_buf[511];
} mp3dec_t;
void mp3dec_init(mp3dec_t *dec);
int mp3dec_decode_frame(mp3dec_t *dec, const unsigned char *mp3, int mp3_bytes, short *pcm, mp3dec_frame_info_t *info);
#endif /*MINIMP3_H*/
//MP3解码实现开始
#include <string.h>// memcpy memset memmove
#include <stdint.h>// (u)int(8|16|32)_t
#define MAX_FREE_FORMAT_FRAME_SIZE 1152*2 /* more than ISO spec's */
#define MAX_FRAME_SYNC_MATCHES 10
#define MAX_L3_FRAME_PAYLOAD_BYTES MAX_FREE_FORMAT_FRAME_SIZE /* MUST be >= 320000/8/32000*1152 = 1440 */
#define MAX_BITRESERVOIR_BYTES 511
#define SHORT_BLOCK_TYPE 2
#define STOP_BLOCK_TYPE 3
#define MODE_MONO 3
#define MODE_JOINT_STEREO 1
#define HDR_SIZE 4
#define HDR_IS_MONO(h) (((h[3]) & 0xC0) == 0xC0)
#define HDR_IS_MS_STEREO(h) (((h[3]) & 0xE0) == 0x60)
#define HDR_IS_FREE_FORMAT(h) (((h[2]) & 0xF0) == 0)
#define HDR_IS_CRC(h) (!((h[1]) & 1))
#define HDR_TEST_PADDING(h) ((h[2]) & 0x2)
#define HDR_TEST_MPEG1(h) ((h[1]) & 0x8)
#define HDR_TEST_NOT_MPEG25(h) ((h[1]) & 0x10)
#define HDR_TEST_I_STEREO(h) ((h[3]) & 0x10)
#define HDR_TEST_MS_STEREO(h) ((h[3]) & 0x20)
#define HDR_GET_STEREO_MODE(h) (((h[3]) >> 6) & 3)
#define HDR_GET_STEREO_MODE_EXT(h) (((h[3]) >> 4) & 3)
#define HDR_GET_LAYER(h) (((h[1]) >> 1) & 3)
#define HDR_GET_BITRATE(h) ((h[2]) >> 4)
#define HDR_GET_SAMPLE_RATE(h) (((h[2]) >> 2) & 3)
#define HDR_GET_MY_SAMPLE_RATE(h) (HDR_GET_SAMPLE_RATE(h) + (((h[1] >> 3) & 1) + ((h[1] >> 4) & 1))*3)
#define HDR_IS_FRAME_576(h) ((h[1] & 14) == 2)
#define HDR_IS_LAYER_1(h) ((h[1] & 6) == 6)
#define BITS_DEQUANTIZER_OUT -1
#define MAX_SCF (255 + BITS_DEQUANTIZER_OUT*4 - 210)
#define MAX_SCFI ((MAX_SCF + 3) & ~3)
#define MINIMP3_MIN(a, b) ((a) > (b) ? (b) : (a))
#define MINIMP3_MAX(a, b) ((a) < (b) ? (b) : (a))
//bits结构体
typedef struct
{
const uint8_t *buf;//字节数据
int pos;//当前位位置
int limit;
} bs_t;
//gr信息结构体
typedef struct
{
const uint8_t *sfbtab;
uint16_t part_23_length;
uint16_t big_values;
uint16_t scalefac_compress;
uint8_t global_gain;
uint8_t block_type;
uint8_t mixed_block_flag;
uint8_t n_long_sfb;
uint8_t n_short_sfb;
uint8_t table_select[3];
uint8_t region_count[3];
uint8_t subblock_gain[3];
uint8_t preflag;
uint8_t scalefac_scale;
uint8_t count1_table;
uint8_t scfsi;
} L3_gr_info_t;
//
typedef struct
{
bs_t bs;
uint8_t maindata[MAX_BITRESERVOIR_BYTES + MAX_L3_FRAME_PAYLOAD_BYTES];
L3_gr_info_t gr_info[4];
float grbuf[2][576];
float scf[40];
uint8_t ist_pos[2][39];
float syn[18 + 15][2*32];
} mp3dec_scratch_t;
static void bs_init(bs_t *bs, const uint8_t *data, int bytes)
{
bs->buf = data;
bs->pos = 0;
bs->limit = bytes*8;
}
//取出n个bit
static uint32_t get_bits(bs_t *bs, int n)
{
uint32_t next, cache = 0, s = bs->pos & 7;
int shl = n + s;
const uint8_t *p = bs->buf + (bs->pos >> 3);
if ((bs->pos += n) > bs->limit)
return 0;
next = *p++ & (255 >> s);
while ((shl -= 8) > 0)
{
cache |= next << shl;
next = *p++;
}
return cache | (next >> -shl);
}
//验证帧同步头是否有效
static int hdr_valid(const uint8_t *h)
{
return h[0] == 0xff &&
((h[1] & 0xF0) == 0xf0 || (h[1] & 0xFE) == 0xe2) &&
(HDR_GET_LAYER(h) != 0) &&
(HDR_GET_BITRATE(h) != 15) &&
(HDR_GET_SAMPLE_RATE(h) != 3);
}
//比较两个帧同步头
static int hdr_compare(const uint8_t *h1, const uint8_t *h2)
{
return hdr_valid(h2) &&
((h1[1] ^ h2[1]) & 0xFE) == 0 &&
((h1[2] ^ h2[2]) & 0x0C) == 0 &&
!(HDR_IS_FREE_FORMAT(h1) ^ HDR_IS_FREE_FORMAT(h2));
}
//得到bitrate,单位kbps
static unsigned hdr_bitrate_kbps(const uint8_t *h)
{
static const uint8_t halfrate[2][3][15] = {
{ { 0,4,8,12,16,20,24,28,32,40,48,56,64,72,80 }, { 0,4,8,12,16,20,24,28,32,40,48,56,64,72,80 }, { 0,16,24,28,32,40,48,56,64,72,80,88,96,112,128 } },
{ { 0,16,20,24,28,32,40,48,56,64,80,96,112,128,160 }, { 0,16,24,28,32,40,48,56,64,80,96,112,128,160,192 }, { 0,16,32,48,64,80,96,112,128,144,160,176,192,208,224 } },
};
return 2*halfrate[!!HDR_TEST_MPEG1(h)][HDR_GET_LAYER(h) - 1][HDR_GET_BITRATE(h)];
}
//得到采样率
static unsigned hdr_sample_rate_hz(const uint8_t *h)
{
static const unsigned g_hz[3] = { 44100, 48000, 32000 };
return g_hz[HDR_GET_SAMPLE_RATE(h)] >> (int)!HDR_TEST_MPEG1(h) >> (int)!HDR_TEST_NOT_MPEG25(h);
}
static unsigned hdr_frame_samples(const uint8_t *h)
{
return HDR_IS_LAYER_1(h) ? 384 : (1152 >> (int)HDR_IS_FRAME_576(h));
}
static int hdr_frame_bytes(const uint8_t *h, int free_format_size)
{
int frame_bytes = hdr_frame_samples(h)*hdr_bitrate_kbps(h)*125/hdr_sample_rate_hz(h);
if (HDR_IS_LAYER_1(h))
{
frame_bytes &= ~3; /* slot align */
}
return frame_bytes ? frame_bytes : free_format_size;
}
static int hdr_padding(const uint8_t *h)
{
return HDR_TEST_PADDING(h) ? (HDR_IS_LAYER_1(h) ? 4 : 1) : 0;
}
//读side information
static int L3_read_side_info(bs_t *bs, L3_gr_info_t *gr, const uint8_t *hdr)
{
static const uint8_t g_scf_long[8][23] = {
{ 6,6,6,6,6,6,8,10,12,14,16,20,24,28,32,38,46,52,60,68,58,54,0 },
{ 12,12,12,12,12,12,16,20,24,28,32,40,48,56,64,76,90,2,2,2,2,2,0 },
{ 6,6,6,6,6,6,8,10,12,14,16,20,24,28,32,38,46,52,60,68,58,54,0 },
{ 6,6,6,6,6,6,8,10,12,14,16,18,22,26,32,38,46,54,62,70,76,36,0 },
{ 6,6,6,6,6,6,8,10,12,14,16,20,24,28,32,38,46,52,60,68,58,54,0 },
{ 4,4,4,4,4,4,6,6,8,8,10,12,16,20,24,28,34,42,50,54,76,158,0 },
{ 4,4,4,4,4,4,6,6,6,8,10,12,16,18,22,28,34,40,46,54,54,192,0 },
{ 4,4,4,4,4,4,6,6,8,10,12,16,20,24,30,38,46,56,68,84,102,26,0 }
};
static const uint8_t g_scf_short[8][40] = {
{ 4,4,4,4,4,4,4,4,4,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,24,24,24,30,30,30,40,40,40,18,18,18,0 },
{ 8,8,8,8,8,8,8,8,8,12,12,12,16,16,16,20,20,20,24,24,24,28,28,28,36,36,36,2,2,2,2,2,2,2,2,2,26,26,26,0 },
{ 4,4,4,4,4,4,4,4,4,6,6,6,6,6,6,8,8,8,10,10,10,14,14,14,18,18,18,26,26,26,32,32,32,42,42,42,18,18,18,0 },
{ 4,4,4,4,4,4,4,4,4,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,24,24,24,32,32,32,44,44,44,12,12,12,0 },
{ 4,4,4,4,4,4,4,4,4,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,24,24,24,30,30,30,40,40,40,18,18,18,0 },
{ 4,4,4,4,4,4,4,4,4,4,4,4,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,22,22,22,30,30,30,56,56,56,0 },
{ 4,4,4,4,4,4,4,4,4,4,4,4,6,6,6,6,6,6,10,10,10,12,12,12,14,14,14,16,16,16,20,20,20,26,26,26,66,66,66,0 },
{ 4,4,4,4,4,4,4,4,4,4,4,4,6,6,6,8,8,8,12,12,12,16,16,16,20,20,20,26,26,26,34,34,34,42,42,42,12,12,12,0 }
};
static const uint8_t g_scf_mixed[8][40] = {
{ 6,6,6,6,6,6,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,24,24,24,30,30,30,40,40,40,18,18,18,0 },
{ 12,12,12,4,4,4,8,8,8,12,12,12,16,16,16,20,20,20,24,24,24,28,28,28,36,36,36,2,2,2,2,2,2,2,2,2,26,26,26,0 },
{ 6,6,6,6,6,6,6,6,6,6,6,6,8,8,8,10,10,10,14,14,14,18,18,18,26,26,26,32,32,32,42,42,42,18,18,18,0 },
{ 6,6,6,6,6,6,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,24,24,24,32,32,32,44,44,44,12,12,12,0 },
{ 6,6,6,6,6,6,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,24,24,24,30,30,30,40,40,40,18,18,18,0 },
{ 4,4,4,4,4,4,6,6,4,4,4,6,6,6,8,8,8,10,10,10,12,12,12,14,14,14,18,18,18,22,22,22,30,30,30,56,56,56,0 },
{ 4,4,4,4,4,4,6,6,4,4,4,6,6,6,6,6,6,10,10,10,12,12,12,14,14,14,16,16,16,20,20,20,26,26,26,66,66,66,0 },
{ 4,4,4,4,4,4,6,6,4,4,4,6,6,6,8,8,8,12,12,12,16,16,16,20,20,20,26,26,26,34,34,34,42,42,42,12,12,12,0 }
};
unsigned tables, scfsi = 0;
int main_data_begin, part_23_sum = 0;
int sr_idx = HDR_GET_MY_SAMPLE_RATE(hdr); sr_idx -= (sr_idx != 0);
int gr_count = HDR_IS_MONO(hdr) ? 1 : 2;
if (HDR_TEST_MPEG1(hdr))
{
gr_count *= 2;
main_data_begin = get_bits(bs, 9);
scfsi = get_bits(bs, 7 + gr_count);
} else
{
main_data_begin = get_bits(bs, 8 + gr_count) >> gr_count;
}
do
{
if (HDR_IS_MONO(hdr))
{
scfsi <<= 4;
}
gr->part_23_length = (uint16_t)get_bits(bs, 12);
part_23_sum += gr->part_23_length;
gr->big_values = (uint16_t)get_bits(bs, 9);
if (gr->big_values > 288)
{
return -1;
}
gr->global_gain = (uint8_t)get_bits(bs, 8);
gr->scalefac_compress = (uint16_t)get_bits(bs, HDR_TEST_MPEG1(hdr) ? 4 : 9);
gr->sfbtab = g_scf_long[sr_idx];
gr->n_long_sfb = 22;
gr->n_short_sfb = 0;
if (get_bits(bs, 1))
{
gr->block_type = (uint8_t)get_bits(bs, 2);
if (!gr->block_type)
{
return -1;
}
gr->mixed_block_flag = (uint8_t)get_bits(bs, 1);
gr->region_count[0] = 7;
gr->region_count[1] = 255;
if (gr->block_type == SHORT_BLOCK_TYPE)
{
scfsi &= 0x0F0F;
if (!gr->mixed_block_flag)
{
gr->region_count[0] = 8;
gr->sfbtab = g_scf_short[sr_idx];
gr->n_long_sfb = 0;
gr->n_short_sfb = 39;
} else
{
gr->sfbtab = g_scf_mixed[sr_idx];
gr->n_long_sfb = HDR_TEST_MPEG1(hdr) ? 8 : 6;
gr->n_short_sfb = 30;
}
}
tables = get_bits(bs, 10);
tables <<= 5;
gr->subblock_gain[0] = (uint8_t)get_bits(bs, 3);
gr->subblock_gain[1] = (uint8_t)get_bits(bs, 3);
gr->subblock_gain[2] = (uint8_t)get_bits(bs, 3);
} else
{
gr->block_type = 0;
gr->mixed_block_flag = 0;
tables = get_bits(bs, 15);
gr->region_count[0] = (uint8_t)get_bits(bs, 4);
gr->region_count[1] = (uint8_t)get_bits(bs, 3);
gr->region_count[2] = 255;
}
gr->table_select[0] = (uint8_t)(tables >> 10);
gr->table_select[1] = (uint8_t)((tables >> 5) & 31);
gr->table_select[2] = (uint8_t)((tables) & 31);
gr->preflag = HDR_TEST_MPEG1(hdr) ? get_bits(bs, 1) : (gr->scalefac_compress >= 500);
gr->scalefac_scale = (uint8_t)get_bits(bs, 1);
gr->count1_table = (uint8_t)get_bits(bs, 1);
gr->scfsi = (uint8_t)((scfsi >> 12) & 15);
scfsi <<= 4;
gr++;
} while(--gr_count);
if (part_23_sum + bs->pos > bs->limit + main_data_begin*8)
{
return -1;
}
return main_data_begin;
}
//读取尺度因子
static void L3_read_scalefactors(uint8_t *scf, uint8_t *ist_pos, const uint8_t *scf_size, const uint8_t *scf_count, bs_t *bitbuf, int scfsi)
{
int i, k;
for (i = 0; i < 4 && scf_count[i]; i++, scfsi *= 2)
{
int cnt = scf_count[i];
if (scfsi & 8)
{
memcpy(scf, ist_pos, cnt);
} else
{
int bits = scf_size[i];
if (!bits)
{
memset(scf, 0, cnt);
memset(ist_pos, 0, cnt);
} else
{
int max_scf = (scfsi < 0) ? (1 << bits) - 1 : -1;
for (k = 0; k < cnt; k++)
{
int s = get_bits(bitbuf, bits);
ist_pos[k] = (s == max_scf ? -1 : s);
scf[k] = s;
}
}
}
ist_pos += cnt;
scf += cnt;
}
scf[0] = scf[1] = scf[2] = 0;
}
//
static float L3_ldexp_q2(float y, int exp_q2)
{
static const float g_expfrac[4] = { 9.31322575e-10f,7.83145814e-10f,6.58544508e-10f,5.53767716e-10f };
int e;
do
{
e = MINIMP3_MIN(30*4, exp_q2);
y *= g_expfrac[e & 3]*(1 << 30 >> (e >> 2));
} while ((exp_q2 -= e) > 0);
return y;
}
//尺度因子译码
static void L3_decode_scalefactors(const uint8_t *hdr, uint8_t *ist_pos, bs_t *bs, const L3_gr_info_t *gr, float *scf, int ch)
{
static const uint8_t g_scf_partitions[3][28] = {
{ 6,5,5, 5,6,5,5,5,6,5, 7,3,11,10,0,0, 7, 7, 7,0, 6, 6,6,3, 8, 8,5,0 },
{ 8,9,6,12,6,9,9,9,6,9,12,6,15,18,0,0, 6,15,12,0, 6,12,9,6, 6,18,9,0 },
{ 9,9,6,12,9,9,9,9,9,9,12,6,18,18,0,0,12,12,12,0,12, 9,9,6,15,12,9,0 }
};
const uint8_t *scf_partition = g_scf_partitions[!!gr->n_short_sfb + !gr->n_long_sfb];
uint8_t scf_size[4], iscf[40];
int i, scf_shift = gr->scalefac_scale + 1, gain_exp, scfsi = gr->scfsi;
float gain;
if (HDR_TEST_MPEG1(hdr))
{
static const uint8_t g_scfc_decode[16] = { 0,1,2,3, 12,5,6,7, 9,10,11,13, 14,15,18,19 };
int part = g_scfc_decode[gr->scalefac_compress];
scf_size[1] = scf_size[0] = (uint8_t)(part >> 2);
scf_size[3] = scf_size[2] = (uint8_t)(part & 3);
} else
{
static const uint8_t g_mod[6*4] = { 5,5,4,4,5,5,4,1,4,3,1,1,5,6,6,1,4,4,4,1,4,3,1,1 };
int k, modprod, sfc, ist = HDR_TEST_I_STEREO(hdr) && ch;
sfc = gr->scalefac_compress >> ist;
for (k = ist*3*4; sfc >= 0; sfc -= modprod, k += 4)
{
for (modprod = 1, i = 3; i >= 0; i--)
{
scf_size[i] = (uint8_t)(sfc / modprod % g_mod[k + i]);
modprod *= g_mod[k + i];
}
}
scf_partition += k;
scfsi = -16;
}
L3_read_scalefactors(iscf, ist_pos, scf_size, scf_partition, bs, scfsi);
if (gr->n_short_sfb)
{
int sh = 3 - scf_shift;
for (i = 0; i < gr->n_short_sfb; i += 3)
{
iscf[gr->n_long_sfb + i + 0] += gr->subblock_gain[0] << sh;
iscf[gr->n_long_sfb + i + 1] += gr->subblock_gain[1] << sh;
iscf[gr->n_long_sfb + i + 2] += gr->subblock_gain[2] << sh;
}
} else if (gr->preflag)
{
static const uint8_t g_preamp[10] = { 1,1,1,1,2,2,3,3,3,2 };
for (i = 0; i < 10; i++)
{
iscf[11 + i] += g_preamp[i];
}
}
gain_exp = gr->global_gain + BITS_DEQUANTIZER_OUT*4 - 210 - (HDR_IS_MS_STEREO(hdr) ? 2 : 0);
gain = L3_ldexp_q2(1 << (MAX_SCFI/4), MAX_SCFI - gain_exp);
for (i = 0; i < (int)(gr->n_long_sfb + gr->n_short_sfb); i++)
{
scf[i] = L3_ldexp_q2(gain, iscf[i] << scf_shift);
}
}
//计算x^(4/3)
static float L3_pow_43(int x)
{
static const float g_pow43[129] = {
0,1,2.519842f,4.326749f,6.349604f,8.549880f,10.902724f,13.390518f,16.000000f,18.720754f,21.544347f,24.463781f,27.473142f,30.567351f,33.741992f,36.993181f,40.317474f,43.711787f,47.173345f,50.699631f,54.288352f,57.937408f,61.644865f,65.408941f,69.227979f,73.100443f,77.024898f,81.000000f,85.024491f,89.097188f,93.216975f,97.382800f,101.593667f,105.848633f,110.146801f,114.487321f,118.869381f,123.292209f,127.755065f,132.257246f,136.798076f,141.376907f,145.993119f,150.646117f,155.335327f,160.060199f,164.820202f,169.614826f,174.443577f,179.305980f,184.201575f,189.129918f,194.090580f,199.083145f,204.107210f,209.162385f,214.248292f,219.364564f,224.510845f,229.686789f,234.892058f,240.126328f,245.389280f,250.680604f,256.000000f,261.347174f,266.721841f,272.123723f,277.552547f,283.008049f,288.489971f,293.998060f,299.532071f,305.091761f,310.676898f,316.287249f,321.922592f,327.582707f,333.267377f,338.976394f,344.709550f,350.466646f,356.247482f,362.051866f,367.879608f,373.730522f,379.604427f,385.501143f,391.420496f,397.362314f,403.326427f,409.312672f,415.320884f,421.350905f,427.402579f,433.475750f,439.570269f,445.685987f,451.822757f,457.980436f,464.158883f,470.357960f,476.577530f,482.817459f,489.077615f,495.357868f,501.658090f,507.978156f,514.317941f,520.677324f,527.056184f,533.454404f,539.871867f,546.308458f,552.764065f,559.238575f,565.731879f,572.243870f,578.774440f,585.323483f,591.890898f,598.476581f,605.080431f,611.702349f,618.342238f,625.000000f,631.675540f,638.368763f,645.079578f
};
float frac;
int sign, mult = 256;
if (x < 129)
{
return g_pow43[x];
}
if (x < 1024)
{
mult = 16;
x <<= 3;
}
sign = 2*x & 64;
frac = (float)((x & 63) - sign) / ((x & ~63) + sign);
return g_pow43[(x + sign) >> 6]*(1.f + frac*((4.f/3) + frac*(2.f/9)))*mult;
}
static void L3_huffman(float *dst, bs_t *bs, const L3_gr_info_t *gr_info, const float *scf, int layer3gr_limit)
{
static const float g_pow43_signed[32] = { 0,0,1,-1,2.519842f,-2.519842f,4.326749f,-4.326749f,6.349604f,-6.349604f,8.549880f,-8.549880f,10.902724f,-10.902724f,13.390518f,-13.390518f,16.000000f,-16.000000f,18.720754f,-18.720754f,21.544347f,-21.544347f,24.463781f,-24.463781f,27.473142f,-27.473142f,30.567351f,-30.567351f,33.741992f,-33.741992f,36.993181f,-36.993181f };
static const int16_t tab0[32] = { 0, };
static const int16_t tab1[] = { 785,785,785,785,784,784,784,784,513,513,513,513,513,513,513,513,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256 };
static const int16_t tab2[] = { -255,1313,1298,1282,785,785,785,785,784,784,784,784,769,769,769,769,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,290,288 };
static const int16_t tab3[] = { -255,1313,1298,1282,769,769,769,769,529,529,529,529,529,529,529,529,528,528,528,528,528,528,528,528,512,512,512,512,512,512,512,512,290,288 };
static const int16_t tab5[] = { -253,-318,-351,-367,785,785,785,785,784,784,784,784,769,769,769,769,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,819,818,547,547,275,275,275,275,561,560,515,546,289,274,288,258 };
static const int16_t tab6[] = { -254,-287,1329,1299,1314,1312,1057,1057,1042,1042,1026,1026,784,784,784,784,529,529,529,529,529,529,529,529,769,769,769,769,768,768,768,768,563,560,306,306,291,259 };
static const int16_t tab7[] = { -252,-413,-477,-542,1298,-575,1041,1041,784,784,784,784,769,769,769,769,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,-383,-399,1107,1092,1106,1061,849,849,789,789,1104,1091,773,773,1076,1075,341,340,325,309,834,804,577,577,532,532,516,516,832,818,803,816,561,561,531,531,515,546,289,289,288,258 };
static const int16_t tab8[] = { -252,-429,-493,-559,1057,1057,1042,1042,529,529,529,529,529,529,529,529,784,784,784,784,769,769,769,769,512,512,512,512,512,512,512,512,-382,1077,-415,1106,1061,1104,849,849,789,789,1091,1076,1029,1075,834,834,597,581,340,340,339,324,804,833,532,532,832,772,818,803,817,787,816,771,290,290,290,290,288,258 };
static const int16_t tab9[] = { -253,-349,-414,-447,-463,1329,1299,-479,1314,1312,1057,1057,1042,1042,1026,1026,785,785,785,785,784,784,784,784,769,769,769,769,768,768,768,768,-319,851,821,-335,836,850,805,849,341,340,325,336,533,533,579,579,564,564,773,832,578,548,563,516,321,276,306,291,304,259 };
static const int16_t tab10[] = { -251,-572,-733,-830,-863,-879,1041,1041,784,784,784,784,769,769,769,769,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,-511,-527,-543,1396,1351,1381,1366,1395,1335,1380,-559,1334,1138,1138,1063,1063,1350,1392,1031,1031,1062,1062,1364,1363,1120,1120,1333,1348,881,881,881,881,375,374,359,373,343,358,341,325,791,791,1123,1122,-703,1105,1045,-719,865,865,790,790,774,774,1104,1029,338,293,323,308,-799,-815,833,788,772,818,803,816,322,292,307,320,561,531,515,546,289,274,288,258 };
static const int16_t tab11[] = { -251,-525,-605,-685,-765,-831,-846,1298,1057,1057,1312,1282,785,785,785,785,784,784,784,784,769,769,769,769,512,512,512,512,512,512,512,512,1399,1398,1383,1367,1382,1396,1351,-511,1381,1366,1139,1139,1079,1079,1124,1124,1364,1349,1363,1333,882,882,882,882,807,807,807,807,1094,1094,1136,1136,373,341,535,535,881,775,867,822,774,-591,324,338,-671,849,550,550,866,864,609,609,293,336,534,534,789,835,773,-751,834,804,308,307,833,788,832,772,562,562,547,547,305,275,560,515,290,290 };
static const int16_t tab12[] = { -252,-397,-477,-557,-622,-653,-719,-735,-750,1329,1299,1314,1057,1057,1042,1042,1312,1282,1024,1024,785,785,785,785,784,784,784,784,769,769,769,769,-383,1127,1141,1111,1126,1140,1095,1110,869,869,883,883,1079,1109,882,882,375,374,807,868,838,881,791,-463,867,822,368,263,852,837,836,-543,610,610,550,550,352,336,534,534,865,774,851,821,850,805,593,533,579,564,773,832,578,578,548,548,577,577,307,276,306,291,516,560,259,259 };
static const int16_t tab13[] = { -250,-2107,-2507,-2764,-2909,-2974,-3007,-3023,1041,1041,1040,1040,769,769,769,769,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,-767,-1052,-1213,-1277,-1358,-1405,-1469,-1535,-1550,-1582,-1614,-1647,-1662,-1694,-1726,-1759,-1774,-1807,-1822,-1854,-1886,1565,-1919,-1935,-1951,-1967,1731,1730,1580,1717,-1983,1729,1564,-1999,1548,-2015,-2031,1715,1595,-2047,1714,-2063,1610,-2079,1609,-2095,1323,1323,1457,1457,1307,1307,1712,1547,1641,1700,1699,1594,1685,1625,1442,1442,1322,1322,-780,-973,-910,1279,1278,1277,1262,1276,1261,1275,1215,1260,1229,-959,974,974,989,989,-943,735,478,478,495,463,506,414,-1039,1003,958,1017,927,942,987,957,431,476,1272,1167,1228,-1183,1256,-1199,895,895,941,941,1242,1227,1212,1135,1014,1014,490,489,503,487,910,1013,985,925,863,894,970,955,1012,847,-1343,831,755,755,984,909,428,366,754,559,-1391,752,486,457,924,997,698,698,983,893,740,740,908,877,739,739,667,667,953,938,497,287,271,271,683,606,590,712,726,574,302,302,738,736,481,286,526,725,605,711,636,724,696,651,589,681,666,710,364,467,573,695,466,466,301,465,379,379,709,604,665,679,316,316,634,633,436,436,464,269,424,394,452,332,438,363,347,408,393,448,331,422,362,407,392,421,346,406,391,376,375,359,1441,1306,-2367,1290,-2383,1337,-2399,-2415,1426,1321,-2431,1411,1336,-2447,-2463,-2479,1169,1169,1049,1049,1424,1289,1412,1352,1319,-2495,1154,1154,1064,1064,1153,1153,416,390,360,404,403,389,344,374,373,343,358,372,327,357,342,311,356,326,1395,1394,1137,1137,1047,1047,1365,1392,1287,1379,1334,1364,1349,1378,1318,1363,792,792,792,792,1152,1152,1032,1032,1121,1121,1046,1046,1120,1120,1030,1030,-2895,1106,1061,1104,849,849,789,789,1091,1076,1029,1090,1060,1075,833,833,309,324,532,532,832,772,818,803,561,561,531,560,515,546,289,274,288,258 };
static const int16_t tab15[] = { -250,-1179,-1579,-1836,-1996,-2124,-2253,-2333,-2413,-2477,-2542,-2574,-2607,-2622,-2655,1314,1313,1298,1312,1282,785,785,785,785,1040,1040,1025,1025,768,768,768,768,-766,-798,-830,-862,-895,-911,-927,-943,-959,-975,-991,-1007,-1023,-1039,-1055,-1070,1724,1647,-1103,-1119,1631,1767,1662,1738,1708,1723,-1135,1780,1615,1779,1599,1677,1646,1778,1583,-1151,1777,1567,1737,1692,1765,1722,1707,1630,1751,1661,1764,1614,1736,1676,1763,1750,1645,1598,1721,1691,1762,1706,1582,1761,1566,-1167,1749,1629,767,766,751,765,494,494,735,764,719,749,734,763,447,447,748,718,477,506,431,491,446,476,461,505,415,430,475,445,504,399,460,489,414,503,383,474,429,459,502,502,746,752,488,398,501,473,413,472,486,271,480,270,-1439,-1455,1357,-1471,-1487,-1503,1341,1325,-1519,1489,1463,1403,1309,-1535,1372,1448,1418,1476,1356,1462,1387,-1551,1475,1340,1447,1402,1386,-1567,1068,1068,1474,1461,455,380,468,440,395,425,410,454,364,467,466,464,453,269,409,448,268,432,1371,1473,1432,1417,1308,1460,1355,1446,1459,1431,1083,1083,1401,1416,1458,1445,1067,1067,1370,1457,1051,1051,1291,1430,1385,1444,1354,1415,1400,1443,1082,1082,1173,1113,1186,1066,1185,1050,-1967,1158,1128,1172,1097,1171,1081,-1983,1157,1112,416,266,375,400,1170,1142,1127,1065,793,793,1169,1033,1156,1096,1141,1111,1155,1080,1126,1140,898,898,808,808,897,897,792,792,1095,1152,1032,1125,1110,1139,1079,1124,882,807,838,881,853,791,-2319,867,368,263,822,852,837,866,806,865,-2399,851,352,262,534,534,821,836,594,594,549,549,593,593,533,533,848,773,579,579,564,578,548,563,276,276,577,576,306,291,516,560,305,305,275,259 };
static const int16_t tab16[] = { -251,-892,-2058,-2620,-2828,-2957,-3023,-3039,1041,1041,1040,1040,769,769,769,769,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,256,-511,-527,-543,-559,1530,-575,-591,1528,1527,1407,1526,1391,1023,1023,1023,1023,1525,1375,1268,1268,1103,1103,1087,1087,1039,1039,1523,-604,815,815,815,815,510,495,509,479,508,463,507,447,431,505,415,399,-734,-782,1262,-815,1259,1244,-831,1258,1228,-847,-863,1196,-879,1253,987,987,748,-767,493,493,462,477,414,414,686,669,478,446,461,445,474,429,487,458,412,471,1266,1264,1009,1009,799,799,-1019,-1276,-1452,-1581,-1677,-1757,-1821,-1886,-1933,-1997,1257,1257,1483,1468,1512,1422,1497,1406,1467,1496,1421,1510,1134,1134,1225,1225,1466,1451,1374,1405,1252,1252,1358,1480,1164,1164,1251,1251,1238,1238,1389,1465,-1407,1054,1101,-1423,1207,-1439,830,830,1248,1038,1237,1117,1223,1148,1236,1208,411,426,395,410,379,269,1193,1222,1132,1235,1221,1116,976,976,1192,1162,1177,1220,1131,1191,963,963,-1647,961,780,-1663,558,558,994,993,437,408,393,407,829,978,813,797,947,-1743,721,721,377,392,844,950,828,890,706,706,812,859,796,960,948,843,934,874,571,571,-1919,690,555,689,421,346,539,539,944,779,918,873,932,842,903,888,570,570,931,917,674,674,-2575,1562,-2591,1609,-2607,1654,1322,1322,1441,1441,1696,1546,1683,1593,1669,1624,1426,1426,1321,1321,1639,1680,1425,1425,1305,1305,1545,1668,1608,1623,1667,1592,1638,1666,1320,1320,1652,1607,1409,1409,1304,1304,1288,1288,1664,1637,1395,1395,1335,1335,1622,1636,1394,1394,1319,1319,1606,1621,1392,1392,1137,1137,1137,1137,345,390,360,375,404,373,1047,-2751,-2767,-2783,1062,1121,1046,-2799,1077,-2815,1106,1061,789,789,1105,1104,263,355,310,340,325,354,352,262,339,324,1091,1076,1029,1090,1060,1075,833,833,788,788,1088,1028,818,818,803,803,561,561,531,531,816,771,546,546,289,274,288,258 };
static const int16_t tab24[] = { -253,-317,-381,-446,-478,-509,1279,1279,-811,-1179,-1451,-1756,-1900,-2028,-2189,-2253,-2333,-2414,-2445,-2511,-2526,1313,1298,-2559,1041,1041,1040,1040,1025,1025,1024,1024,1022,1007,1021,991,1020,975,1019,959,687,687,1018,1017,671,671,655,655,1016,1015,639,639,758,758,623,623,757,607,756,591,755,575,754,559,543,543,1009,783,-575,-621,-685,-749,496,-590,750,749,734,748,974,989,1003,958,988,973,1002,942,987,957,972,1001,926,986,941,971,956,1000,910,985,925,999,894,970,-1071,-1087,-1102,1390,-1135,1436,1509,1451,1374,-1151,1405,1358,1480,1420,-1167,1507,1494,1389,1342,1465,1435,1450,1326,1505,1310,1493,1373,1479,1404,1492,1464,1419,428,443,472,397,736,526,464,464,486,457,442,471,484,482,1357,1449,1434,1478,1388,1491,1341,1490,1325,1489,1463,1403,1309,1477,1372,1448,1418,1433,1476,1356,1462,1387,-1439,1475,1340,1447,1402,1474,1324,1461,1371,1473,269,448,1432,1417,1308,1460,-1711,1459,-1727,1441,1099,1099,1446,1386,1431,1401,-1743,1289,1083,1083,1160,1160,1458,1445,1067,1067,1370,1457,1307,1430,1129,1129,1098,1098,268,432,267,416,266,400,-1887,1144,1187,1082,1173,1113,1186,1066,1050,1158,1128,1143,1172,1097,1171,1081,420,391,1157,1112,1170,1142,1127,1065,1169,1049,1156,1096,1141,1111,1155,1080,1126,1154,1064,1153,1140,1095,1048,-2159,1125,1110,1137,-2175,823,823,1139,1138,807,807,384,264,368,263,868,838,853,791,867,822,852,837,866,806,865,790,-2319,851,821,836,352,262,850,805,849,-2399,533,533,835,820,336,261,578,548,563,577,532,532,832,772,562,562,547,547,305,275,560,515,290,290,288,258 };
static const uint8_t tab32[] = { 130,162,193,209,44,28,76,140,9,9,9,9,9,9,9,9,190,254,222,238,126,94,157,157,109,61,173,205 };
static const uint8_t tab33[] = { 252,236,220,204,188,172,156,140,124,108,92,76,60,44,28,12 };
static const int16_t * const tabindex[2*16] = { tab0,tab1,tab2,tab3,tab0,tab5,tab6,tab7,tab8,tab9,tab10,tab11,tab12,tab13,tab0,tab15,tab16,tab16,tab16,tab16,tab16,tab16,tab16,tab16,tab24,tab24,tab24,tab24,tab24,tab24,tab24,tab24 };
static const uint8_t g_linbits[] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,2,3,4,6,8,10,13,4,5,6,7,8,9,11,13 };
#define PEEK_BITS(n) (bs_cache >> (32 - n))
#define FLUSH_BITS(n) { bs_cache <<= (n); bs_sh += (n); }
#define CHECK_BITS while (bs_sh >= 0) { bs_cache |= (uint32_t)*bs_next_ptr++ << bs_sh; bs_sh -= 8; }
#define BSPOS ((bs_next_ptr - bs->buf)*8 - 24 + bs_sh)
float one = 0.0f;
int ireg = 0, big_val_cnt = gr_info->big_values;
const uint8_t *sfb = gr_info->sfbtab;
const uint8_t *bs_next_ptr = bs->buf + bs->pos/8;
uint32_t bs_cache = (((bs_next_ptr[0]*256u + bs_next_ptr[1])*256u + bs_next_ptr[2])*256u + bs_next_ptr[3]) << (bs->pos & 7);
int pairs_to_decode, np, bs_sh = (bs->pos & 7) - 8;
bs_next_ptr += 4;
while (big_val_cnt > 0)
{
int tab_num = gr_info->table_select[ireg];
int sfb_cnt = gr_info->region_count[ireg++];
const short *codebook = tabindex[tab_num];
int linbits = g_linbits[tab_num];
do
{
np = *sfb++ / 2;
pairs_to_decode = MINIMP3_MIN(big_val_cnt, np);
one = *scf++;
do
{
int j, w = 5;
int leaf = codebook[PEEK_BITS(w)];
while (leaf < 0)
{
FLUSH_BITS(w);
w = leaf & 7;
leaf = codebook[PEEK_BITS(w) - (leaf >> 3)];
}
FLUSH_BITS(leaf >> 8);
for (j = 0; j < 2; j++, dst++, leaf >>= 4)
{
int lsb = leaf & 0x0F;
if (lsb == 15 && linbits)
{
lsb += PEEK_BITS(linbits);
FLUSH_BITS(linbits);
CHECK_BITS;
*dst = one*L3_pow_43(lsb)*((int32_t)bs_cache < 0 ? -1: 1);
} else
{
*dst = g_pow43_signed[lsb*2 + (bs_cache >> 31)]*one;
}
FLUSH_BITS(lsb ? 1 : 0);
}
CHECK_BITS;
} while (--pairs_to_decode);
} while ((big_val_cnt -= np) > 0 && --sfb_cnt >= 0);
}
for (np = 1 - big_val_cnt;; dst += 4)
{
const uint8_t *codebook_count1 = (gr_info->count1_table) ? tab33 : tab32;
int leaf = codebook_count1[PEEK_BITS(4)];
if (!(leaf & 8))
{
leaf = codebook_count1[(leaf >> 3) + (bs_cache << 4 >> (32 - (leaf & 3)))];
}
FLUSH_BITS(leaf & 7);
if (BSPOS > layer3gr_limit)
{
break;
}
#define RELOAD_SCALEFACTOR if (!--np) { np = *sfb++/2; if (!np) break; one = *scf++; }
#define DEQ_COUNT1(s) if (leaf & (128 >> s)) { dst[s] = ((int32_t)bs_cache < 0) ? -one : one; FLUSH_BITS(1) }
RELOAD_SCALEFACTOR;
DEQ_COUNT1(0);
DEQ_COUNT1(1);
RELOAD_SCALEFACTOR;
DEQ_COUNT1(2);
DEQ_COUNT1(3);
CHECK_BITS;
}
bs->pos = layer3gr_limit;
}
static void L3_midside_stereo(float *left, int n)
{
int i = 0;
float *right = left + 576;
for (; i < n; i++)
{
float a = left[i];
float b = right[i];
left[i] = a + b;
right[i] = a - b;
}
}
static void L3_intensity_stereo_band(float *left, int n, float kl, float kr)
{
int i;
for (i = 0; i < n; i++)
{
left[i + 576] = left[i]*kr;
left[i] = left[i]*kl;
}
}
static void L3_stereo_top_band(const float *right, const uint8_t *sfb, int nbands, int max_band[3])
{
int i, k;
max_band[0] = max_band[1] = max_band[2] = -1;
for (i = 0; i < nbands; i++)
{
for (k = 0; k < sfb[i]; k += 2)
{
if (right[k] != 0 || right[k + 1] != 0)
{
max_band[i % 3] = i;
break;
}
}
right += sfb[i];
}
}
static void L3_stereo_process(float *left, const uint8_t *ist_pos, const uint8_t *sfb, const uint8_t *hdr, int max_band[3], int mpeg2_sh)
{
static const float g_pan[7*2] = { 0,1,0.21132487f,0.78867513f,0.36602540f,0.63397460f,0.5f,0.5f,0.63397460f,0.36602540f,0.78867513f,0.21132487f,1,0 };
unsigned i, max_pos = HDR_TEST_MPEG1(hdr) ? 7 : 64;
for (i = 0; sfb[i]; i++)
{
unsigned ipos = ist_pos[i];
if ((int)i > max_band[i % 3] && ipos < max_pos)
{
float kl, kr, s = HDR_TEST_MS_STEREO(hdr) ? 1.41421356f : 1;
if (HDR_TEST_MPEG1(hdr))
{
kl = g_pan[2*ipos];
kr = g_pan[2*ipos + 1];
} else
{
kl = 1;
kr = L3_ldexp_q2(1, (ipos + 1) >> 1 << mpeg2_sh);
if (ipos & 1)
{
kl = kr;
kr = 1;
}
}
L3_intensity_stereo_band(left, sfb[i], kl*s, kr*s);
} else if (HDR_TEST_MS_STEREO(hdr))
{
L3_midside_stereo(left, sfb[i]);
}
left += sfb[i];
}
}
static void L3_intensity_stereo(float *left, uint8_t *ist_pos, const L3_gr_info_t *gr, const uint8_t *hdr)
{
int max_band[3], n_sfb = gr->n_long_sfb + gr->n_short_sfb;
int i, max_blocks = gr->n_short_sfb ? 3 : 1;
L3_stereo_top_band(left + 576, gr->sfbtab, n_sfb, max_band);
if (gr->n_long_sfb)
{
max_band[0] = max_band[1] = max_band[2] = MINIMP3_MAX(MINIMP3_MAX(max_band[0], max_band[1]), max_band[2]);
}
for (i = 0; i < max_blocks; i++)
{
int default_pos = HDR_TEST_MPEG1(hdr) ? 3 : 0;
int itop = n_sfb - max_blocks + i;
int prev = itop - max_blocks;
ist_pos[itop] = max_band[i] >= prev ? default_pos : ist_pos[prev];
}
L3_stereo_process(left, ist_pos, gr->sfbtab, hdr, max_band, gr[1].scalefac_compress & 1);
}
//重排序
static void L3_reorder(float *grbuf, float *scratch, const uint8_t *sfb)
{
int i, len;
float *src = grbuf, *dst = scratch;
for (;0 != (len = *sfb); sfb += 3, src += 2*len)
{
for (i = 0; i < len; i++, src++)
{
*dst++ = src[0*len];
*dst++ = src[1*len];
*dst++ = src[2*len];
}
}
memcpy(grbuf, scratch, (dst - scratch)*sizeof(float));
}
static void L3_antialias(float *grbuf, int nbands)
{
static const float g_aa[2][8] = {
{0.85749293f,0.88174200f,0.94962865f,0.98331459f,0.99551782f,0.99916056f,0.99989920f,0.99999316f},
{0.51449576f,0.47173197f,0.31337745f,0.18191320f,0.09457419f,0.04096558f,0.01419856f,0.00369997f}
};
for (; nbands > 0; nbands--, grbuf += 18)
{
int i = 0;
for(; i < 8; i++)
{
float u = grbuf[18 + i];
float d = grbuf[17 - i];
grbuf[18 + i] = u*g_aa[0][i] - d*g_aa[1][i];
grbuf[17 - i] = u*g_aa[1][i] + d*g_aa[0][i];
}
}
}
static void L3_dct3_9(float *y)
{
float s0, s1, s2, s3, s4, s5, s6, s7, s8, t0, t2, t4;
s0 = y[0]; s2 = y[2]; s4 = y[4]; s6 = y[6]; s8 = y[8];
t0 = s0 + s6*0.5f;
s0 -= s6;
t4 = (s4 + s2)*0.93969262f;
t2 = (s8 + s2)*0.76604444f;
s6 = (s4 - s8)*0.17364818f;
s4 += s8 - s2;
s2 = s0 - s4*0.5f;
y[4] = s4 + s0;
s8 = t0 - t2 + s6;
s0 = t0 - t4 + t2;
s4 = t0 + t4 - s6;
s1 = y[1]; s3 = y[3]; s5 = y[5]; s7 = y[7];
s3 *= 0.86602540f;
t0 = (s5 + s1)*0.98480775f;
t4 = (s5 - s7)*0.34202014f;
t2 = (s1 + s7)*0.64278761f;
s1 = (s1 - s5 - s7)*0.86602540f;
s5 = t0 - s3 - t2;
s7 = t4 - s3 - t0;
s3 = t4 + s3 - t2;
y[0] = s4 - s7;
y[1] = s2 + s1;
y[2] = s0 - s3;
y[3] = s8 + s5;
y[5] = s8 - s5;
y[6] = s0 + s3;
y[7] = s2 - s1;
y[8] = s4 + s7;
}
static void L3_imdct36(float *grbuf, float *overlap, const float *window, int nbands)
{
int i, j;
static const float g_twid9[18] = {
0.73727734f,0.79335334f,0.84339145f,0.88701083f,0.92387953f,0.95371695f,0.97629601f,0.99144486f,0.99904822f,0.67559021f,0.60876143f,0.53729961f,0.46174861f,0.38268343f,0.30070580f,0.21643961f,0.13052619f,0.04361938f
};
for (j = 0; j < nbands; j++, grbuf += 18, overlap += 9)
{
float co[9], si[9];
co[0] = -grbuf[0];
si[0] = grbuf[17];
for (i = 0; i < 4; i++)
{
si[8 - 2*i] = grbuf[4*i + 1] - grbuf[4*i + 2];
co[1 + 2*i] = grbuf[4*i + 1] + grbuf[4*i + 2];
si[7 - 2*i] = grbuf[4*i + 4] - grbuf[4*i + 3];
co[2 + 2*i] = -(grbuf[4*i + 3] + grbuf[4*i + 4]);
}
L3_dct3_9(co);
L3_dct3_9(si);
si[1] = -si[1];
si[3] = -si[3];
si[5] = -si[5];
si[7] = -si[7];
i = 0;
for (; i < 9; i++)
{
float ovl = overlap[i];
float sum = co[i]*g_twid9[9 + i] + si[i]*g_twid9[0 + i];
overlap[i] = co[i]*g_twid9[0 + i] - si[i]*g_twid9[9 + i];
grbuf[i] = ovl*window[0 + i] - sum*window[9 + i];
grbuf[17 - i] = ovl*window[9 + i] + sum*window[0 + i];
}
}
}
static void L3_idct3(float x0, float x1, float x2, float *dst)
{
float m1 = x1*0.86602540f;
float a1 = x0 - x2*0.5f;
dst[1] = x0 + x2;
dst[0] = a1 + m1;
dst[2] = a1 - m1;
}
static void L3_imdct12(float *x, float *dst, float *overlap)
{
static const float g_twid3[6] = { 0.79335334f,0.92387953f,0.99144486f, 0.60876143f,0.38268343f,0.13052619f };
float co[3], si[3];
int i;
L3_idct3(-x[0], x[6] + x[3], x[12] + x[9], co);
L3_idct3(x[15], x[12] - x[9], x[6] - x[3], si);
si[1] = -si[1];
for (i = 0; i < 3; i++)
{
float ovl = overlap[i];
float sum = co[i]*g_twid3[3 + i] + si[i]*g_twid3[0 + i];
overlap[i] = co[i]*g_twid3[0 + i] - si[i]*g_twid3[3 + i];
dst[i] = ovl*g_twid3[2 - i] - sum*g_twid3[5 - i];
dst[5 - i] = ovl*g_twid3[5 - i] + sum*g_twid3[2 - i];
}
}
static void L3_imdct_short(float *grbuf, float *overlap, int nbands)
{
for (;nbands > 0; nbands--, overlap += 9, grbuf += 18)
{
float tmp[18];
memcpy(tmp, grbuf, sizeof(tmp));
memcpy(grbuf, overlap, 6*sizeof(float));
L3_imdct12(tmp, grbuf + 6, overlap + 6);
L3_imdct12(tmp + 1, grbuf + 12, overlap + 6);
L3_imdct12(tmp + 2, overlap, overlap + 6);
}
}
static void L3_change_sign(float *grbuf)
{
int b, i;
for (b = 0, grbuf += 18; b < 32; b += 2, grbuf += 36)
for (i = 1; i < 18; i += 2)
grbuf[i] = -grbuf[i];
}
static void L3_imdct_gr(float *grbuf, float *overlap, unsigned block_type, unsigned n_long_bands)
{
static const float g_mdct_window[2][18] = {
{ 0.99904822f,0.99144486f,0.97629601f,0.95371695f,0.92387953f,0.88701083f,0.84339145f,0.79335334f,0.73727734f,0.04361938f,0.13052619f,0.21643961f,0.30070580f,0.38268343f,0.46174861f,0.53729961f,0.60876143f,0.67559021f },
{ 1,1,1,1,1,1,0.99144486f,0.92387953f,0.79335334f,0,0,0,0,0,0,0.13052619f,0.38268343f,0.60876143f }
};
if (n_long_bands)
{
L3_imdct36(grbuf, overlap, g_mdct_window[0], n_long_bands);
grbuf += 18*n_long_bands;
overlap += 9*n_long_bands;
}
if (block_type == SHORT_BLOCK_TYPE)
L3_imdct_short(grbuf, overlap, 32 - n_long_bands);
else
L3_imdct36(grbuf, overlap, g_mdct_window[block_type == STOP_BLOCK_TYPE], 32 - n_long_bands);
}
static void L3_save_reservoir(mp3dec_t *h, mp3dec_scratch_t *s)
{
int pos = (s->bs.pos + 7)/8u;
int remains = s->bs.limit/8u - pos;
if (remains > MAX_BITRESERVOIR_BYTES)
{
pos += remains - MAX_BITRESERVOIR_BYTES;
remains = MAX_BITRESERVOIR_BYTES;
}
if (remains > 0)
{
memmove(h->reserv_buf, s->maindata + pos, remains);
}
h->reserv = remains;
}
static int L3_restore_reservoir(mp3dec_t *h, bs_t *bs, mp3dec_scratch_t *s, int main_data_begin)
{
int frame_bytes = (bs->limit - bs->pos)/8;
int bytes_have = MINIMP3_MIN(h->reserv, main_data_begin);
memcpy(s->maindata, h->reserv_buf + MINIMP3_MAX(0, h->reserv - main_data_begin), MINIMP3_MIN(h->reserv, main_data_begin));
memcpy(s->maindata + bytes_have, bs->buf + bs->pos/8, frame_bytes);
bs_init(&s->bs, s->maindata, bytes_have + frame_bytes);
return h->reserv >= main_data_begin;
}
static void L3_decode(mp3dec_t *h, mp3dec_scratch_t *s, L3_gr_info_t *gr_info, int nch)
{
int ch;
for (ch = 0; ch < nch; ch++)
{
int layer3gr_limit = s->bs.pos + gr_info[ch].part_23_length;
L3_decode_scalefactors(h->header, s->ist_pos[ch], &s->bs, gr_info + ch, s->scf, ch);
L3_huffman(s->grbuf[ch], &s->bs, gr_info + ch, s->scf, layer3gr_limit);
}
if (HDR_TEST_I_STEREO(h->header))
{
L3_intensity_stereo(s->grbuf[0], s->ist_pos[1], gr_info, h->header);
} else if (HDR_IS_MS_STEREO(h->header))
{
L3_midside_stereo(s->grbuf[0], 576);
}
for (ch = 0; ch < nch; ch++, gr_info++)
{
int aa_bands = 31;
int n_long_bands = (gr_info->mixed_block_flag ? 2 : 0) << (int)(HDR_GET_MY_SAMPLE_RATE(h->header) == 2);
if (gr_info->n_short_sfb)
{
aa_bands = n_long_bands - 1;
L3_reorder(s->grbuf[ch] + n_long_bands*18, s->syn[0], gr_info->sfbtab + gr_info->n_long_sfb);
}
L3_antialias(s->grbuf[ch], aa_bands);
L3_imdct_gr(s->grbuf[ch], h->mdct_overlap[ch], gr_info->block_type, n_long_bands);
L3_change_sign(s->grbuf[ch]);
}
}
static void mp3d_DCT_II(float *grbuf, int n)
{
static const float g_sec[24] = {
10.19000816f,0.50060302f,0.50241929f,3.40760851f,0.50547093f,0.52249861f,2.05778098f,0.51544732f,0.56694406f,1.48416460f,0.53104258f,0.64682180f,1.16943991f,0.55310392f,0.78815460f,0.97256821f,0.58293498f,1.06067765f,0.83934963f,0.62250412f,1.72244716f,0.74453628f,0.67480832f,5.10114861f
};
int i, k = 0;
for (; k < n; k++)
{
float t[4][8], *x, *y = grbuf + k;
for (x = t[0], i = 0; i < 8; i++, x++)
{
float x0 = y[i*18];
float x1 = y[(15 - i)*18];
float x2 = y[(16 + i)*18];
float x3 = y[(31 - i)*18];
float t0 = x0 + x3;
float t1 = x1 + x2;
float t2 = (x1 - x2)*g_sec[3*i + 0];
float t3 = (x0 - x3)*g_sec[3*i + 1];
x[0] = t0 + t1;
x[8] = (t0 - t1)*g_sec[3*i + 2];
x[16] = t3 + t2;
x[24] = (t3 - t2)*g_sec[3*i + 2];
}
for (x = t[0], i = 0; i < 4; i++, x += 8)
{
float x0 = x[0], x1 = x[1], x2 = x[2], x3 = x[3], x4 = x[4], x5 = x[5], x6 = x[6], x7 = x[7], xt;
xt = x0 - x7; x0 += x7;
x7 = x1 - x6; x1 += x6;
x6 = x2 - x5; x2 += x5;
x5 = x3 - x4; x3 += x4;
x4 = x0 - x3; x0 += x3;
x3 = x1 - x2; x1 += x2;
x[0] = x0 + x1;
x[4] = (x0 - x1)*0.70710677f;
x5 = x5 + x6;
x6 = (x6 + x7)*0.70710677f;
x7 = x7 + xt;
x3 = (x3 + x4)*0.70710677f;
x5 -= x7*0.198912367f; /* rotate by PI/8 */
x7 += x5*0.382683432f;
x5 -= x7*0.198912367f;
x0 = xt - x6; xt += x6;
x[1] = (xt + x7)*0.50979561f;
x[2] = (x4 + x3)*0.54119611f;
x[3] = (x0 - x5)*0.60134488f;
x[5] = (x0 + x5)*0.89997619f;
x[6] = (x4 - x3)*1.30656302f;
x[7] = (xt - x7)*2.56291556f;
}
for (i = 0; i < 7; i++, y += 4*18)
{
y[0*18] = t[0][i];
y[1*18] = t[2][i] + t[3][i] + t[3][i + 1];
y[2*18] = t[1][i] + t[1][i + 1];
y[3*18] = t[2][i + 1] + t[3][i] + t[3][i + 1];
}
y[0*18] = t[0][7];
y[1*18] = t[2][7] + t[3][7];
y[2*18] = t[1][7];
y[3*18] = t[3][7];
}
}
static short mp3d_scale_pcm(float sample)
{
if (sample > 32767.0) return (short) 32767;
if (sample < -32768.0) return (short)-32768;
int s = (int)(sample + .5f);
s -= (s < 0); /* away from zero, to be compliant */
if (s > 32767) return (short) 32767;
if (s < -32768) return (short)-32768;
return (short)s;
}
static void mp3d_synth_pair(short *pcm, int nch, const float *z)
{
float a;
a = (z[14*64] - z[ 0]) * 29;
a += (z[ 1*64] + z[13*64]) * 213;
a += (z[12*64] - z[ 2*64]) * 459;
a += (z[ 3*64] + z[11*64]) * 2037;
a += (z[10*64] - z[ 4*64]) * 5153;
a += (z[ 5*64] + z[ 9*64]) * 6574;
a += (z[ 8*64] - z[ 6*64]) * 37489;
a += z[ 7*64] * 75038;
pcm[0] = mp3d_scale_pcm(a);
z += 2;
a = z[14*64] * 104;
a += z[12*64] * 1567;
a += z[10*64] * 9727;
a += z[ 8*64] * 64019;
a += z[ 6*64] * -9975;
a += z[ 4*64] * -45;
a += z[ 2*64] * 146;
a += z[ 0*64] * -5;
pcm[16*nch] = mp3d_scale_pcm(a);
}
static void mp3d_synth(float *xl, short *dstl, int nch, float *lins)
{
int i;
float *xr = xl + 576*(nch - 1);
short *dstr = dstl + (nch - 1);
static const float g_win[] = {
-1,26,-31,208,218,401,-519,2063,2000,4788,-5517,7134,5959,35640,-39336,74992,
-1,24,-35,202,222,347,-581,2080,1952,4425,-5879,7640,5288,33791,-41176,74856,
-1,21,-38,196,225,294,-645,2087,1893,4063,-6237,8092,4561,31947,-43006,74630,
-1,19,-41,190,227,244,-711,2085,1822,3705,-6589,8492,3776,30112,-44821,74313,
-1,17,-45,183,228,197,-779,2075,1739,3351,-6935,8840,2935,28289,-46617,73908,
-1,16,-49,176,228,153,-848,2057,1644,3004,-7271,9139,2037,26482,-48390,73415,
-2,14,-53,169,227,111,-919,2032,1535,2663,-7597,9389,1082,24694,-50137,72835,
-2,13,-58,161,224,72,-991,2001,1414,2330,-7910,9592,70,22929,-51853,72169,
-2,11,-63,154,221,36,-1064,1962,1280,2006,-8209,9750,-998,21189,-53534,71420,
-2,10,-68,147,215,2,-1137,1919,1131,1692,-8491,9863,-2122,19478,-55178,70590,
-3,9,-73,139,208,-29,-1210,1870,970,1388,-8755,9935,-3300,17799,-56778,69679,
-3,8,-79,132,200,-57,-1283,1817,794,1095,-8998,9966,-4533,16155,-58333,68692,
-4,7,-85,125,189,-83,-1356,1759,605,814,-9219,9959,-5818,14548,-59838,67629,
-4,7,-91,117,177,-106,-1428,1698,402,545,-9416,9916,-7154,12980,-61289,66494,
-5,6,-97,111,163,-127,-1498,1634,185,288,-9585,9838,-8540,11455,-62684,65290
};
float *zlin = lins + 15*64;
const float *w = g_win;
zlin[4*15] = xl[18*16];
zlin[4*15 + 1] = xr[18*16];
zlin[4*15 + 2] = xl[0];
zlin[4*15 + 3] = xr[0];
zlin[4*31] = xl[1 + 18*16];
zlin[4*31 + 1] = xr[1 + 18*16];
zlin[4*31 + 2] = xl[1];
zlin[4*31 + 3] = xr[1];
mp3d_synth_pair(dstr, nch, lins + 4*15 + 1);
mp3d_synth_pair(dstr + 32*nch, nch, lins + 4*15 + 64 + 1);
mp3d_synth_pair(dstl, nch, lins + 4*15);
mp3d_synth_pair(dstl + 32*nch, nch, lins + 4*15 + 64);
for (i = 14; i >= 0; i--)
{
#define LOAD(k) float w0 = *w++; float w1 = *w++; float *vz = &zlin[4*i - k*64]; float *vy = &zlin[4*i - (15 - k)*64];
#define S0(k) { int j; LOAD(k); for (j = 0; j < 4; j++) b[j] = vz[j]*w1 + vy[j]*w0, a[j] = vz[j]*w0 - vy[j]*w1; }
#define S1(k) { int j; LOAD(k); for (j = 0; j < 4; j++) b[j] += vz[j]*w1 + vy[j]*w0, a[j] += vz[j]*w0 - vy[j]*w1; }
#define S2(k) { int j; LOAD(k); for (j = 0; j < 4; j++) b[j] += vz[j]*w1 + vy[j]*w0, a[j] += vy[j]*w1 - vz[j]*w0; }
float a[4], b[4];
zlin[4*i] = xl[18*(31 - i)];
zlin[4*i + 1] = xr[18*(31 - i)];
zlin[4*i + 2] = xl[1 + 18*(31 - i)];
zlin[4*i + 3] = xr[1 + 18*(31 - i)];
zlin[4*(i + 16)] = xl[1 + 18*(1 + i)];
zlin[4*(i + 16) + 1] = xr[1 + 18*(1 + i)];
zlin[4*(i - 16) + 2] = xl[18*(1 + i)];
zlin[4*(i - 16) + 3] = xr[18*(1 + i)];
S0(0) S2(1) S1(2) S2(3) S1(4) S2(5) S1(6) S2(7)
dstr[(15 - i)*nch] = mp3d_scale_pcm(a[1]);
dstr[(17 + i)*nch] = mp3d_scale_pcm(b[1]);
dstl[(15 - i)*nch] = mp3d_scale_pcm(a[0]);
dstl[(17 + i)*nch] = mp3d_scale_pcm(b[0]);
dstr[(47 - i)*nch] = mp3d_scale_pcm(a[3]);
dstr[(49 + i)*nch] = mp3d_scale_pcm(b[3]);
dstl[(47 - i)*nch] = mp3d_scale_pcm(a[2]);
dstl[(49 + i)*nch] = mp3d_scale_pcm(b[2]);
}
}
static void mp3d_synth_granule(float *qmf_state, float *grbuf, int nbands, int nch, short *pcm, float *lins)
{
int i;
for (i = 0; i < nch; i++)
{
mp3d_DCT_II(grbuf + 576*i, nbands);
}
memcpy(lins, qmf_state, sizeof(float)*15*64);
for (i = 0; i < nbands; i += 2)
{
mp3d_synth(grbuf + i, pcm + 32*nch*i, nch, lins + i*64);
}
#ifndef MINIMP3_NONSTANDARD_BUT_LOGICAL
if (nch == 1)
{
for (i = 0; i < 15*64; i += 2)
{
qmf_state[i] = lins[nbands*64 + i];
}
} else
#endif
{
memcpy(qmf_state, lins + nbands*64, sizeof(float)*15*64);
}
}
static int mp3d_match_frame(const uint8_t *hdr, int mp3_bytes, int frame_bytes)
{
int i, nmatch;
for (i = 0, nmatch = 0; nmatch < MAX_FRAME_SYNC_MATCHES; nmatch++)
{
i += hdr_frame_bytes(hdr + i, frame_bytes) + hdr_padding(hdr + i);
if (i + HDR_SIZE > mp3_bytes)
return nmatch > 0;
if (!hdr_compare(hdr, hdr + i))
return 0;
}
return 1;
}
static int mp3d_find_frame(const uint8_t *mp3, int mp3_bytes, int *free_format_bytes, int *ptr_frame_bytes)
{
int i, k;
for (i = 0; i < mp3_bytes - HDR_SIZE; i++, mp3++)
{
if (hdr_valid(mp3))
{
int frame_bytes = hdr_frame_bytes(mp3, *free_format_bytes);
int frame_and_padding = frame_bytes + hdr_padding(mp3);
for (k = HDR_SIZE; !frame_bytes && k < MAX_FREE_FORMAT_FRAME_SIZE && i + 2*k < mp3_bytes - HDR_SIZE; k++)
{
if (hdr_compare(mp3, mp3 + k))
{
int fb = k - hdr_padding(mp3);
int nextfb = fb + hdr_padding(mp3 + k);
if (i + k + nextfb + HDR_SIZE > mp3_bytes || !hdr_compare(mp3, mp3 + k + nextfb))
continue;
frame_and_padding = k;
frame_bytes = fb;
*free_format_bytes = fb;
}
}
if ((frame_bytes && i + frame_and_padding <= mp3_bytes &&
mp3d_match_frame(mp3, mp3_bytes - i, frame_bytes)) ||
(!i && frame_and_padding == mp3_bytes))
{
*ptr_frame_bytes = frame_and_padding;
return i;
}
*free_format_bytes = 0;
}
}
*ptr_frame_bytes = 0;
return i;
}
void mp3dec_init(mp3dec_t *dec)
{
dec->header[0] = 0;
}
int mp3dec_decode_frame(mp3dec_t *dec, const uint8_t *mp3, int mp3_bytes, short *pcm, mp3dec_frame_info_t *info)
{
int i = 0, igr, frame_size = 0, success = 1;
const uint8_t *hdr;
bs_t bs_frame[1];
mp3dec_scratch_t scratch;
if (mp3_bytes > 4 && dec->header[0] == 0xff && hdr_compare(dec->header, mp3))
{
frame_size = hdr_frame_bytes(mp3, dec->free_format_bytes) + hdr_padding(mp3);
if (frame_size != mp3_bytes && (frame_size + HDR_SIZE > mp3_bytes || !hdr_compare(mp3, mp3 + frame_size)))
{
frame_size = 0;
}
}
if (!frame_size)
{
memset(dec, 0, sizeof(mp3dec_t));
i = mp3d_find_frame(mp3, mp3_bytes, &dec->free_format_bytes, &frame_size);
if (!frame_size || i + frame_size > mp3_bytes)
{
info->frame_bytes = i;
return 0;
}
}
hdr = mp3 + i;
memcpy(dec->header, hdr, HDR_SIZE);
info->frame_bytes = i + frame_size;
info->channels = HDR_IS_MONO(hdr) ? 1 : 2;
info->hz = hdr_sample_rate_hz(hdr);
info->layer = 4 - HDR_GET_LAYER(hdr);
info->bitrate_kbps = hdr_bitrate_kbps(hdr);
bs_init(bs_frame, hdr + HDR_SIZE, frame_size - HDR_SIZE);
if (HDR_IS_CRC(hdr))
{
get_bits(bs_frame, 16);
}
if (info->layer == 3)
{
int main_data_begin = L3_read_side_info(bs_frame, scratch.gr_info, hdr);
if (main_data_begin < 0 || bs_frame->pos > bs_frame->limit)
{
mp3dec_init(dec);
return 0;
}
success = L3_restore_reservoir(dec, bs_frame, &scratch, main_data_begin);
if (success)
{
for (igr = 0; igr < (HDR_TEST_MPEG1(hdr) ? 2 : 1); igr++, pcm += 576*info->channels)
{
memset(scratch.grbuf[0], 0, 576*2*sizeof(float));
L3_decode(dec, &scratch, scratch.gr_info + igr*info->channels, info->channels);
mp3d_synth_granule(dec->qmf_state, scratch.grbuf[0], 18, info->channels, pcm, scratch.syn[0]);
}
}
L3_save_reservoir(dec, &scratch);
} else
{
return 0;
}
return success*hdr_frame_samples(dec->header);
}