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 "libavutil/thread.h"
25 #include "libavcodec/internal.h"
26 #include "libavcodec/mathops.h"
27 #include "avcodec.h"
28 #include "dsd_tablegen.h"
29 #include "dsd.h"
30
dsd_ctables_tableinit(void)31 static av_cold void dsd_ctables_tableinit(void)
32 {
33 int t, e, m, sign;
34 double acc[CTABLES];
35 for (e = 0; e < 256; ++e) {
36 memset(acc, 0, sizeof(acc));
37 for (m = 0; m < 8; ++m) {
38 sign = (((e >> (7 - m)) & 1) * 2 - 1);
39 for (t = 0; t < CTABLES; ++t)
40 acc[t] += sign * htaps[t * 8 + m];
41 }
42 for (t = 0; t < CTABLES; ++t)
43 ctables[CTABLES - 1 - t][e] = acc[t];
44 }
45 }
46
ff_init_dsd_data(void)47 av_cold void ff_init_dsd_data(void)
48 {
49 static AVOnce init_static_once = AV_ONCE_INIT;
50 ff_thread_once(&init_static_once, dsd_ctables_tableinit);
51 }
52
ff_dsd2pcm_translate(DSDContext * s,size_t samples,int lsbf,const uint8_t * src,ptrdiff_t src_stride,float * dst,ptrdiff_t dst_stride)53 void ff_dsd2pcm_translate(DSDContext* s, size_t samples, int lsbf,
54 const uint8_t *src, ptrdiff_t src_stride,
55 float *dst, ptrdiff_t dst_stride)
56 {
57 uint8_t buf[FIFOSIZE];
58 unsigned pos, i;
59 uint8_t* p;
60 double sum;
61
62 pos = s->pos;
63
64 memcpy(buf, s->buf, sizeof(buf));
65
66 while (samples-- > 0) {
67 buf[pos] = lsbf ? ff_reverse[*src] : *src;
68 src += src_stride;
69
70 p = buf + ((pos - CTABLES) & FIFOMASK);
71 *p = ff_reverse[*p];
72
73 sum = 0.0;
74 for (i = 0; i < CTABLES; i++) {
75 uint8_t a = buf[(pos - i) & FIFOMASK];
76 uint8_t b = buf[(pos - (CTABLES*2 - 1) + i) & FIFOMASK];
77 sum += ctables[i][a] + ctables[i][b];
78 }
79
80 *dst = (float)sum;
81 dst += dst_stride;
82
83 pos = (pos + 1) & FIFOMASK;
84 }
85
86 s->pos = pos;
87 memcpy(s->buf, buf, sizeof(buf));
88 }
89