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2ba45a60 DM |
1 | /* |
2 | * gsm 06.10 decoder | |
3 | * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de> | |
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 | * GSM decoder | |
25 | */ | |
26 | ||
27 | #include "get_bits.h" | |
28 | #include "gsm.h" | |
29 | #include "gsmdec_data.h" | |
30 | ||
31 | static const int requant_tab[4][8] = { | |
32 | { 0 }, | |
33 | { 0, 7 }, | |
34 | { 0, 2, 5, 7 }, | |
35 | { 0, 1, 2, 3, 4, 5, 6, 7 } | |
36 | }; | |
37 | ||
38 | static void apcm_dequant_add(GetBitContext *gb, int16_t *dst, const int *frame_bits) | |
39 | { | |
40 | int i, val; | |
41 | int maxidx = get_bits(gb, 6); | |
42 | const int16_t *tab = ff_gsm_dequant_tab[maxidx]; | |
43 | for (i = 0; i < 13; i++) { | |
44 | val = get_bits(gb, frame_bits[i]); | |
45 | dst[3*i] += tab[requant_tab[frame_bits[i]][val]]; | |
46 | } | |
47 | } | |
48 | ||
49 | static inline int gsm_mult(int a, int b) | |
50 | { | |
51 | return (a * b + (1 << 14)) >> 15; | |
52 | } | |
53 | ||
54 | static void long_term_synth(int16_t *dst, int lag, int gain_idx) | |
55 | { | |
56 | int i; | |
57 | const int16_t *src = dst - lag; | |
58 | uint16_t gain = ff_gsm_long_term_gain_tab[gain_idx]; | |
59 | for (i = 0; i < 40; i++) | |
60 | dst[i] = gsm_mult(gain, src[i]); | |
61 | } | |
62 | ||
63 | static inline int decode_log_area(int coded, int factor, int offset) | |
64 | { | |
65 | coded <<= 10; | |
66 | coded -= offset; | |
67 | return gsm_mult(coded, factor) << 1; | |
68 | } | |
69 | ||
70 | static av_noinline int get_rrp(int filtered) | |
71 | { | |
72 | int abs = FFABS(filtered); | |
73 | if (abs < 11059) abs <<= 1; | |
74 | else if (abs < 20070) abs += 11059; | |
75 | else abs = (abs >> 2) + 26112; | |
76 | return filtered < 0 ? -abs : abs; | |
77 | } | |
78 | ||
79 | static int filter_value(int in, int rrp[8], int v[9]) | |
80 | { | |
81 | int i; | |
82 | for (i = 7; i >= 0; i--) { | |
83 | in -= gsm_mult(rrp[i], v[i]); | |
84 | v[i + 1] = v[i] + gsm_mult(rrp[i], in); | |
85 | } | |
86 | v[0] = in; | |
87 | return in; | |
88 | } | |
89 | ||
90 | static void short_term_synth(GSMContext *ctx, int16_t *dst, const int16_t *src) | |
91 | { | |
92 | int i; | |
93 | int rrp[8]; | |
94 | int *lar = ctx->lar[ctx->lar_idx]; | |
95 | int *lar_prev = ctx->lar[ctx->lar_idx ^ 1]; | |
96 | for (i = 0; i < 8; i++) | |
97 | rrp[i] = get_rrp((lar_prev[i] >> 2) + (lar_prev[i] >> 1) + (lar[i] >> 2)); | |
98 | for (i = 0; i < 13; i++) | |
99 | dst[i] = filter_value(src[i], rrp, ctx->v); | |
100 | ||
101 | for (i = 0; i < 8; i++) | |
102 | rrp[i] = get_rrp((lar_prev[i] >> 1) + (lar [i] >> 1)); | |
103 | for (i = 13; i < 27; i++) | |
104 | dst[i] = filter_value(src[i], rrp, ctx->v); | |
105 | ||
106 | for (i = 0; i < 8; i++) | |
107 | rrp[i] = get_rrp((lar_prev[i] >> 2) + (lar [i] >> 1) + (lar[i] >> 2)); | |
108 | for (i = 27; i < 40; i++) | |
109 | dst[i] = filter_value(src[i], rrp, ctx->v); | |
110 | ||
111 | for (i = 0; i < 8; i++) | |
112 | rrp[i] = get_rrp(lar[i]); | |
113 | for (i = 40; i < 160; i++) | |
114 | dst[i] = filter_value(src[i], rrp, ctx->v); | |
115 | ||
116 | ctx->lar_idx ^= 1; | |
117 | } | |
118 | ||
119 | static int postprocess(int16_t *data, int msr) | |
120 | { | |
121 | int i; | |
122 | for (i = 0; i < 160; i++) { | |
123 | msr = av_clip_int16(data[i] + gsm_mult(msr, 28180)); | |
124 | data[i] = av_clip_int16(msr << 1) & ~7; | |
125 | } | |
126 | return msr; | |
127 | } | |
128 | ||
129 | static int gsm_decode_block(AVCodecContext *avctx, int16_t *samples, | |
130 | GetBitContext *gb, int mode) | |
131 | { | |
132 | GSMContext *ctx = avctx->priv_data; | |
133 | int i; | |
134 | int16_t *ref_dst = ctx->ref_buf + 120; | |
135 | int *lar = ctx->lar[ctx->lar_idx]; | |
136 | lar[0] = decode_log_area(get_bits(gb, 6), 13107, 1 << 15); | |
137 | lar[1] = decode_log_area(get_bits(gb, 6), 13107, 1 << 15); | |
138 | lar[2] = decode_log_area(get_bits(gb, 5), 13107, (1 << 14) + 2048*2); | |
139 | lar[3] = decode_log_area(get_bits(gb, 5), 13107, (1 << 14) - 2560*2); | |
140 | lar[4] = decode_log_area(get_bits(gb, 4), 19223, (1 << 13) + 94*2); | |
141 | lar[5] = decode_log_area(get_bits(gb, 4), 17476, (1 << 13) - 1792*2); | |
142 | lar[6] = decode_log_area(get_bits(gb, 3), 31454, (1 << 12) - 341*2); | |
143 | lar[7] = decode_log_area(get_bits(gb, 3), 29708, (1 << 12) - 1144*2); | |
144 | ||
145 | for (i = 0; i < 4; i++) { | |
146 | int lag = get_bits(gb, 7); | |
147 | int gain_idx = get_bits(gb, 2); | |
148 | int offset = get_bits(gb, 2); | |
149 | lag = av_clip(lag, 40, 120); | |
150 | long_term_synth(ref_dst, lag, gain_idx); | |
151 | apcm_dequant_add(gb, ref_dst + offset, ff_gsm_apcm_bits[mode][i]); | |
152 | ref_dst += 40; | |
153 | } | |
154 | memcpy(ctx->ref_buf, ctx->ref_buf + 160, 120 * sizeof(*ctx->ref_buf)); | |
155 | short_term_synth(ctx, samples, ctx->ref_buf + 120); | |
156 | // for optimal speed this could be merged with short_term_synth, | |
157 | // not done yet because it is a bit ugly | |
158 | ctx->msr = postprocess(samples, ctx->msr); | |
159 | return 0; | |
160 | } |