88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
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#include "bstream.h"
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#include "mp3dec.h"
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#include <math.h>
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extern MPEG_DECODE_OPTION m_option;
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extern int m_frequency;
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extern float m_sample[2304];
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extern int m_nsb_limit;
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extern int m_max_sb;
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extern int m_stereo_sb;
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extern SBT_PROC m_sbt_proc;
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extern float m_look_c_valueL1[18];
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extern int m_nbatL1;
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//extern "sbt.c"
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void sbt_mono(float *sample, signed short *pcm, int ch);
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void sbt_dual(float *sample, signed short *pcm, int ch);
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void sbt16_mono(float *sample, signed short *pcm, int ch);
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void sbt16_dual(float *sample, signed short *pcm, int ch);
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void sbt8_mono(float *sample, signed short *pcm, int ch);
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void sbt8_dual(float *sample, signed short *pcm, int ch);
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void sbtB_mono(float *sample, unsigned char *pcm, int ch);
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void sbtB_dual(float *sample, unsigned char *pcm, int ch);
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void sbtB16_mono(float *sample, unsigned char *pcm, int ch);
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void sbtB16_dual(float *sample, unsigned char *pcm, int ch);
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void sbtB8_mono(float *sample, unsigned char *pcm, int ch);
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void sbtB8_dual(float *sample, unsigned char *pcm, int ch);
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static const SBT_PROC sbt_table[2][3][2] =
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{
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sbt_mono,
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sbt_dual,
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sbt16_mono,
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sbt16_dual,
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sbt8_mono,
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sbt8_dual,
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sbtB_mono,
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sbtB_dual,
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sbtB16_mono,
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sbtB16_dual,
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sbtB8_mono,
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sbtB8_dual,
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};
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void L1table_init()
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{
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int i, stepL1;
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for (stepL1 = 4, i = 1; i < 16; i++, stepL1 <<= 1) {
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m_look_c_valueL1[i] = (float) (2.0 / (stepL1 - 1));
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}
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}
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int L1decode_start(MPEG_HEADER* h)
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{
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int i, k, bit_code, limit;
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/*- caller limit -*/
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m_nbatL1 = 32;
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m_max_sb = m_nbatL1;
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m_nsb_limit = (m_option.freqLimit * 64L + m_frequency / 2) / m_frequency;
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/*---- limit = 0.94*(32>>reduction_code); ----*/
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limit = (32 >> m_option.reduction);
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if (limit > 8)
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limit--;
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if (m_nsb_limit > limit)
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m_nsb_limit = limit;
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if (m_nsb_limit > m_max_sb)
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m_nsb_limit = m_max_sb;
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if (h->mode != 3) { /* adjust for 2 channel modes */
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m_nbatL1 *= 2;
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m_max_sb *= 2;
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m_nsb_limit *= 2;
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}
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/* set sbt function */
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bit_code = (m_option.convert & 8) ? 1 : 0;
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k = (h->mode == 3) ? 0 : (1 + m_option.convert);
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m_sbt_proc = sbt_table[bit_code][m_option.reduction][k];//[2][3][2]
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for (i = 0; i < 768; i++)
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m_sample[i] = 0.0F;
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return 1;
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}
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