FFmpeg  4.4
alacdsp.c
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1 /*
2  * ALAC (Apple Lossless Audio Codec) decoder
3  * Copyright (c) 2005 David Hammerton
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 #include "libavutil/attributes.h"
23 #include "alacdsp.h"
24 #include "config.h"
25 
26 static void decorrelate_stereo(int32_t *buffer[2], int nb_samples,
27  int decorr_shift, int decorr_left_weight)
28 {
29  int i;
30 
31  for (i = 0; i < nb_samples; i++) {
32  int32_t a, b;
33 
34  a = buffer[0][i];
35  b = buffer[1][i];
36 
37  a -= (b * decorr_left_weight) >> decorr_shift;
38  b += a;
39 
40  buffer[0][i] = b;
41  buffer[1][i] = a;
42  }
43 }
44 
45 static void append_extra_bits(int32_t *buffer[2], int32_t *extra_bits_buffer[2],
46  int extra_bits, int channels, int nb_samples)
47 {
48  int i, ch;
49 
50  for (ch = 0; ch < channels; ch++)
51  for (i = 0; i < nb_samples; i++)
52  buffer[ch][i] = ((unsigned)buffer[ch][i] << extra_bits) | extra_bits_buffer[ch][i];
53 }
54 
56 {
57  c->decorrelate_stereo = decorrelate_stereo;
58  c->append_extra_bits[0] =
59  c->append_extra_bits[1] = append_extra_bits;
60 
61  if (ARCH_X86)
63 }
void ff_alacdsp_init_x86(ALACDSPContext *c)
Definition: alacdsp_init.c:31
channels
Definition: aptx.h:33
Macro definitions for various function/variable attributes.
#define av_cold
Definition: attributes.h:88
int32_t
#define ARCH_X86
Definition: config.h:39
int i
Definition: input.c:407
#define extra_bits(eb)
Definition: intrax8.c:125
static void decorrelate_stereo(int32_t *buffer[2], int nb_samples, int decorr_shift, int decorr_left_weight)
Definition: alacdsp.c:26
av_cold void ff_alacdsp_init(ALACDSPContext *c)
Definition: alacdsp.c:55
static void append_extra_bits(int32_t *buffer[2], int32_t *extra_bits_buffer[2], int extra_bits, int channels, int nb_samples)
Definition: alacdsp.c:45
static char buffer[20]
Definition: seek.c:32
const char * b
Definition: vf_curves.c:118
static double c[64]