| 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 | } |