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
dsd_ctables_tableinit(void)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
ff_init_dsd_data(void)46 av_cold void ff_init_dsd_data(void)
47 {
48 static int done = 0;
49 if (done)
50 return;
51 dsd_ctables_tableinit();
52 done = 1;
53 }
54
ff_dsd2pcm_translate(DSDContext * s,size_t samples,int lsbf,const uint8_t * src,ptrdiff_t src_stride,float * dst,ptrdiff_t dst_stride)55 void ff_dsd2pcm_translate(DSDContext* s, size_t samples, int lsbf,
56 const uint8_t *src, ptrdiff_t src_stride,
57 float *dst, ptrdiff_t dst_stride)
58 {
59 uint8_t buf[FIFOSIZE];
60 unsigned pos, i;
61 uint8_t* p;
62 double sum;
63
64 pos = s->pos;
65
66 memcpy(buf, s->buf, sizeof(buf));
67
68 while (samples-- > 0) {
69 buf[pos] = lsbf ? ff_reverse[*src] : *src;
70 src += src_stride;
71
72 p = buf + ((pos - CTABLES) & FIFOMASK);
73 *p = ff_reverse[*p];
74
75 sum = 0.0;
76 for (i = 0; i < CTABLES; i++) {
77 uint8_t a = buf[(pos - i) & FIFOMASK];
78 uint8_t b = buf[(pos - (CTABLES*2 - 1) + i) & FIFOMASK];
79 sum += ctables[i][a] + ctables[i][b];
80 }
81
82 *dst = (float)sum;
83 dst += dst_stride;
84
85 pos = (pos + 1) & FIFOMASK;
86 }
87
88 s->pos = pos;
89 memcpy(s->buf, buf, sizeof(buf));
90 }
91