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  1. /*
  2.  * Musepack decoder core
  3.  * Copyright (c) 2006 Konstantin Shishkov
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. /**
  23.  * @file
  24.  * Musepack decoder core
  25.  * MPEG Audio Layer 1/2 -like codec with frames of 1152 samples
  26.  * divided into 32 subbands.
  27.  */
  28.  
  29. #include "libavutil/attributes.h"
  30. #include "avcodec.h"
  31. #include "get_bits.h"
  32. #include "mpegaudiodsp.h"
  33. #include "mpegaudio.h"
  34.  
  35. #include "mpc.h"
  36. #include "mpcdata.h"
  37.  
  38. av_cold void ff_mpc_init(void)
  39. {
  40.     ff_mpa_synth_init_fixed(ff_mpa_synth_window_fixed);
  41. }
  42.  
  43. /**
  44.  * Process decoded Musepack data and produce PCM
  45.  */
  46. static void mpc_synth(MPCContext *c, int16_t **out, int channels)
  47. {
  48.     int dither_state = 0;
  49.     int i, ch;
  50.  
  51.     for(ch = 0;  ch < channels; ch++){
  52.         for(i = 0; i < SAMPLES_PER_BAND; i++) {
  53.             ff_mpa_synth_filter_fixed(&c->mpadsp,
  54.                                 c->synth_buf[ch], &(c->synth_buf_offset[ch]),
  55.                                 ff_mpa_synth_window_fixed, &dither_state,
  56.                                 out[ch] + 32 * i, 1,
  57.                                 c->sb_samples[ch][i]);
  58.         }
  59.     }
  60. }
  61.  
  62. void ff_mpc_dequantize_and_synth(MPCContext * c, int maxband, int16_t **out,
  63.                                  int channels)
  64. {
  65.     int i, j, ch;
  66.     Band *bands = c->bands;
  67.     int off;
  68.     float mul;
  69.  
  70.     /* dequantize */
  71.     memset(c->sb_samples, 0, sizeof(c->sb_samples));
  72.     off = 0;
  73.     for(i = 0; i <= maxband; i++, off += SAMPLES_PER_BAND){
  74.         for(ch = 0; ch < 2; ch++){
  75.             if(bands[i].res[ch]){
  76.                 j = 0;
  77.                 mul = (mpc_CC+1)[bands[i].res[ch]] * mpc_SCF[bands[i].scf_idx[ch][0] & 0xFF];
  78.                 for(; j < 12; j++)
  79.                     c->sb_samples[ch][j][i] = mul * c->Q[ch][j + off];
  80.                 mul = (mpc_CC+1)[bands[i].res[ch]] * mpc_SCF[bands[i].scf_idx[ch][1] & 0xFF];
  81.                 for(; j < 24; j++)
  82.                     c->sb_samples[ch][j][i] = mul * c->Q[ch][j + off];
  83.                 mul = (mpc_CC+1)[bands[i].res[ch]] * mpc_SCF[bands[i].scf_idx[ch][2] & 0xFF];
  84.                 for(; j < 36; j++)
  85.                     c->sb_samples[ch][j][i] = mul * c->Q[ch][j + off];
  86.             }
  87.         }
  88.         if(bands[i].msf){
  89.             int t1, t2;
  90.             for(j = 0; j < SAMPLES_PER_BAND; j++){
  91.                 t1 = c->sb_samples[0][j][i];
  92.                 t2 = c->sb_samples[1][j][i];
  93.                 c->sb_samples[0][j][i] = t1 + t2;
  94.                 c->sb_samples[1][j][i] = t1 - t2;
  95.             }
  96.         }
  97.     }
  98.  
  99.     mpc_synth(c, out, channels);
  100. }
  101.