path: root/libavcodec/gsmdec_template.c (plain)
blob: 4e40a20106a0c890a3da20fd5dd160827618c995

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 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
42	static inline int gsm_mult(int a, int b)
43	{
44	return (int)(a * (SUINT)b + (1 << 14)) >> 15;
45	}
46
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
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
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
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
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
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
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