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