/* * gsm 06.10 decoder * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de> * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * GSM decoder */ #include "get_bits.h" #include "gsm.h" #include "gsmdec_data.h" static void apcm_dequant_add(GetBitContext *gb, int16_t *dst) { int i; int maxidx = get_bits(gb, 6); const int16_t *tab = ff_gsm_dequant_tab[maxidx]; for (i = 0; i < 13; i++) dst[3*i] += tab[get_bits(gb, 3)]; } static inline int gsm_mult(int a, int b) { return (a * b + (1 << 14)) >> 15; } static void long_term_synth(int16_t *dst, int lag, int gain_idx) { int i; const int16_t *src = dst - lag; uint16_t gain = ff_gsm_long_term_gain_tab[gain_idx]; for (i = 0; i < 40; i++) dst[i] = gsm_mult(gain, src[i]); } static inline int decode_log_area(int coded, int factor, int offset) { coded <<= 10; coded -= offset; return gsm_mult(coded, factor) << 1; } static av_noinline int get_rrp(int filtered) { int abs = FFABS(filtered); if (abs < 11059) abs <<= 1; else if (abs < 20070) abs += 11059; else abs = (abs >> 2) + 26112; return filtered < 0 ? -abs : abs; } static int filter_value(int in, int rrp[8], int v[9]) { int i; for (i = 7; i >= 0; i--) { in -= gsm_mult(rrp[i], v[i]); v[i + 1] = v[i] + gsm_mult(rrp[i], in); } v[0] = in; return in; } static void short_term_synth(GSMContext *ctx, int16_t *dst, const int16_t *src) { int i; int rrp[8]; int *lar = ctx->lar[ctx->lar_idx]; int *lar_prev = ctx->lar[ctx->lar_idx ^ 1]; for (i = 0; i < 8; i++) rrp[i] = get_rrp((lar_prev[i] >> 2) + (lar_prev[i] >> 1) + (lar[i] >> 2)); for (i = 0; i < 13; i++) dst[i] = filter_value(src[i], rrp, ctx->v); for (i = 0; i < 8; i++) rrp[i] = get_rrp((lar_prev[i] >> 1) + (lar [i] >> 1)); for (i = 13; i < 27; i++) dst[i] = filter_value(src[i], rrp, ctx->v); for (i = 0; i < 8; i++) rrp[i] = get_rrp((lar_prev[i] >> 2) + (lar [i] >> 1) + (lar[i] >> 2)); for (i = 27; i < 40; i++) dst[i] = filter_value(src[i], rrp, ctx->v); for (i = 0; i < 8; i++) rrp[i] = get_rrp(lar[i]); for (i = 40; i < 160; i++) dst[i] = filter_value(src[i], rrp, ctx->v); ctx->lar_idx ^= 1; } static int postprocess(int16_t *data, int msr) { int i; for (i = 0; i < 160; i++) { msr = av_clip_int16(data[i] + gsm_mult(msr, 28180)); data[i] = av_clip_int16(msr << 1) & ~7; } return msr; } static int gsm_decode_block(AVCodecContext *avctx, int16_t *samples, GetBitContext *gb) { GSMContext *ctx = avctx->priv_data; int i; int16_t *ref_dst = ctx->ref_buf + 120; int *lar = ctx->lar[ctx->lar_idx]; lar[0] = decode_log_area(get_bits(gb, 6), 13107, 1 << 15); lar[1] = decode_log_area(get_bits(gb, 6), 13107, 1 << 15); lar[2] = decode_log_area(get_bits(gb, 5), 13107, (1 << 14) + 2048*2); lar[3] = decode_log_area(get_bits(gb, 5), 13107, (1 << 14) - 2560*2); lar[4] = decode_log_area(get_bits(gb, 4), 19223, (1 << 13) + 94*2); lar[5] = decode_log_area(get_bits(gb, 4), 17476, (1 << 13) - 1792*2); lar[6] = decode_log_area(get_bits(gb, 3), 31454, (1 << 12) - 341*2); lar[7] = decode_log_area(get_bits(gb, 3), 29708, (1 << 12) - 1144*2); for (i = 0; i < 4; i++) { int lag = get_bits(gb, 7); int gain_idx = get_bits(gb, 2); int offset = get_bits(gb, 2); lag = av_clip(lag, 40, 120); long_term_synth(ref_dst, lag, gain_idx); apcm_dequant_add(gb, ref_dst + offset); ref_dst += 40; } memcpy(ctx->ref_buf, ctx->ref_buf + 160, 120 * sizeof(*ctx->ref_buf)); short_term_synth(ctx, samples, ctx->ref_buf + 120); // for optimal speed this could be merged with short_term_synth, // not done yet because it is a bit ugly ctx->msr = postprocess(samples, ctx->msr); return 0; }