FFmpeg
mpc.c
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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 <string.h>
30 #include "libavutil/intmath.h"
31 #include "mpegaudiodsp.h"
32 
33 #include "mpc.h"
34 #include "mpcdata.h"
35 
36 /**
37  * Process decoded Musepack data and produce PCM
38  */
39 static void mpc_synth(MPCContext *c, int16_t **out, int channels)
40 {
41  int dither_state = 0;
42  int i, ch;
43 
44  for(ch = 0; ch < channels; ch++){
45  for(i = 0; i < SAMPLES_PER_BAND; i++) {
47  c->synth_buf[ch], &(c->synth_buf_offset[ch]),
48  ff_mpa_synth_window_fixed, &dither_state,
49  out[ch] + 32 * i, 1,
50  c->sb_samples[ch][i]);
51  }
52  }
53 }
54 
55 void ff_mpc_dequantize_and_synth(MPCContext * c, int maxband, int16_t **out,
56  int channels)
57 {
58  int i, j, ch;
59  Band *bands = c->bands;
60  int off;
61  float mul;
62 
63  /* dequantize */
64  memset(c->sb_samples, 0, sizeof(c->sb_samples));
65  off = 0;
66  for(i = 0; i <= maxband; i++, off += SAMPLES_PER_BAND){
67  for(ch = 0; ch < 2; ch++){
68  if(bands[i].res[ch]){
69  j = 0;
70  mul = (mpc_CC+1)[bands[i].res[ch]] * mpc_SCF[bands[i].scf_idx[ch][0] & 0xFF];
71  for(; j < 12; j++)
72  c->sb_samples[ch][j][i] = av_clipf(mul * c->Q[ch][j + off], INT32_MIN, INT32_MAX);
73  mul = (mpc_CC+1)[bands[i].res[ch]] * mpc_SCF[bands[i].scf_idx[ch][1] & 0xFF];
74  for(; j < 24; j++)
75  c->sb_samples[ch][j][i] = av_clipf(mul * c->Q[ch][j + off], INT32_MIN, INT32_MAX);
76  mul = (mpc_CC+1)[bands[i].res[ch]] * mpc_SCF[bands[i].scf_idx[ch][2] & 0xFF];
77  for(; j < 36; j++)
78  c->sb_samples[ch][j][i] = av_clipf(mul * c->Q[ch][j + off], INT32_MIN, INT32_MAX);
79  }
80  }
81  if(bands[i].msf){
82  unsigned t1, t2;
83  for(j = 0; j < SAMPLES_PER_BAND; j++){
84  t1 = c->sb_samples[0][j][i];
85  t2 = c->sb_samples[1][j][i];
86  c->sb_samples[0][j][i] = t1 + t2;
87  c->sb_samples[1][j][i] = t1 - t2;
88  }
89  }
90  }
91 
93 }
out
FILE * out
Definition: movenc.c:54
MPCContext
Definition: mpc.h:54
t1
#define t1
Definition: regdef.h:29
ff_mpa_synth_window_fixed
int32_t ff_mpa_synth_window_fixed[]
mpc_CC
static const float mpc_CC[18+1]
Definition: mpcdata.h:25
ff_mpc_dequantize_and_synth
void ff_mpc_dequantize_and_synth(MPCContext *c, int maxband, int16_t **out, int channels)
Definition: mpc.c:55
mpc_synth
static void mpc_synth(MPCContext *c, int16_t **out, int channels)
Process decoded Musepack data and produce PCM.
Definition: mpc.c:39
mpc_SCF
static const float mpc_SCF[256]
Definition: mpcdata.h:33
channels
channels
Definition: aptx.h:33
bands
static const float bands[]
Definition: af_superequalizer.c:56
ff_mpa_synth_filter_fixed
void ff_mpa_synth_filter_fixed(MPADSPContext *s, int32_t *synth_buf_ptr, int *synth_buf_offset, int32_t *window, int *dither_state, int16_t *samples, ptrdiff_t incr, int32_t *sb_samples)
mul
static float mul(float src0, float src1)
Definition: dnn_backend_native_layer_mathbinary.c:39
mpc.h
av_clipf
#define av_clipf
Definition: common.h:144
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
SAMPLES_PER_BAND
#define SAMPLES_PER_BAND
Definition: mpc.h:42
i
int i
Definition: input.c:406
mpcdata.h
t2
#define t2
Definition: regdef.h:30
Band
Subband structure - hold all variables for each subband.
Definition: mpc.h:46
mpegaudiodsp.h
intmath.h