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dsd.c
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1 /*
2  * Direct Stream Digital (DSD) decoder
3  * based on BSD licensed dsd2pcm by Sebastian Gesemann
4  * Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved.
5  * Copyright (c) 2014 Peter Ross
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #include "libavcodec/internal.h"
25 #include "libavcodec/mathops.h"
26 #include "avcodec.h"
27 #include "dsd_tablegen.h"
28 #include "dsd.h"
29 
30 static av_cold void dsd_ctables_tableinit(void)
31 {
32  int t, e, m, sign;
33  double acc[CTABLES];
34  for (e = 0; e < 256; ++e) {
35  memset(acc, 0, sizeof(acc));
36  for (m = 0; m < 8; ++m) {
37  sign = (((e >> (7 - m)) & 1) * 2 - 1);
38  for (t = 0; t < CTABLES; ++t)
39  acc[t] += sign * htaps[t * 8 + m];
40  }
41  for (t = 0; t < CTABLES; ++t)
42  ctables[CTABLES - 1 - t][e] = acc[t];
43  }
44 }
45 
47 {
48  static int done = 0;
49  if (done)
50  return;
52  done = 1;
53 }
54 
55 void ff_dsd2pcm_translate(DSDContext* s, size_t samples, int lsbf,
56  const unsigned char *src, ptrdiff_t src_stride,
57  float *dst, ptrdiff_t dst_stride)
58 {
59  unsigned pos, i;
60  unsigned char* p;
61  double sum;
62 
63  pos = s->pos;
64 
65  while (samples-- > 0) {
66  s->buf[pos] = lsbf ? ff_reverse[*src] : *src;
67  src += src_stride;
68 
69  p = s->buf + ((pos - CTABLES) & FIFOMASK);
70  *p = ff_reverse[*p];
71 
72  sum = 0.0;
73  for (i = 0; i < CTABLES; i++) {
74  unsigned char a = s->buf[(pos - i) & FIFOMASK];
75  unsigned char b = s->buf[(pos - (CTABLES*2 - 1) + i) & FIFOMASK];
76  sum += ctables[i][a] + ctables[i][b];
77  }
78 
79  *dst = (float)sum;
80  dst += dst_stride;
81 
82  pos = (pos + 1) & FIFOMASK;
83  }
84 
85  s->pos = pos;
86 }
#define CTABLES
Definition: dsd_tablegen.h:31
static const double htaps[HTAPS]
The 2nd half (48 coeffs) of a 96-tap symmetric lowpass filter.
Definition: dsd_tablegen.h:55
int acc
Definition: yuv2rgb.c:554
const uint8_t ff_reverse[256]
Definition: reverse.c:23
const char * b
Definition: vf_curves.c:113
av_cold void ff_init_dsd_data(void)
Definition: dsd.c:46
#define src
Definition: vp8dsp.c:254
#define FIFOMASK
Definition: dsd.h:33
static av_cold void dsd_ctables_tableinit(void)
Definition: dsd.c:30
#define av_cold
Definition: attributes.h:82
static float ctables[CTABLES][256]
Definition: dsd_tablegen.h:74
Per-channel buffer.
Definition: dsd.h:42
#define s(width, name)
Definition: cbs_vp9.c:257
void ff_dsd2pcm_translate(DSDContext *s, size_t samples, int lsbf, const unsigned char *src, ptrdiff_t src_stride, float *dst, ptrdiff_t dst_stride)
Definition: dsd.c:55
Libavcodec external API header.
unsigned char buf[FIFOSIZE]
Definition: dsd.h:43
unsigned pos
Definition: dsd.h:44
common internal api header.