path: root/libavcodec/g722dec.c (plain)
blob: 0bfa82a394384d3d9fa620a080a6d7252495014a

1	/*
2	* Copyright (c) CMU 1993 Computer Science, Speech Group
3	* Chengxiang Lu and Alex Hauptmann
4	* Copyright (c) 2005 Steve Underwood <steveu at coppice.org>
5	* Copyright (c) 2009 Kenan Gillet
6	* Copyright (c) 2010 Martin Storsjo
7	*
8	* This file is part of FFmpeg.
9	*
10	* FFmpeg is free software; you can redistribute it and/or
11	* modify it under the terms of the GNU Lesser General Public
12	* License as published by the Free Software Foundation; either
13	* version 2.1 of the License, or (at your option) any later version.
14	*
15	* FFmpeg is distributed in the hope that it will be useful,
16	* but WITHOUT ANY WARRANTY; without even the implied warranty of
17	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18	* Lesser General Public License for more details.
19	*
20	* You should have received a copy of the GNU Lesser General Public
21	* License along with FFmpeg; if not, write to the Free Software
22	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23	*/
24
25	/**
26	* @file
27	* G.722 ADPCM audio decoder
28	*
29	* This G.722 decoder is a bit-exact implementation of the ITU G.722
30	* specification for all three specified bitrates - 64000bps, 56000bps
31	* and 48000bps. It passes the ITU tests.
32	*
33	* @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits
34	* respectively of each byte are ignored.
35	*/
36
37	#include "libavutil/channel_layout.h"
38	#include "libavutil/opt.h"
39	#include "avcodec.h"
40	#include "get_bits.h"
41	#include "g722.h"
42	#include "internal.h"
43
44	#define OFFSET(x) offsetof(G722Context, x)
45	#define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
46	static const AVOption options[] = {
47	{ "bits_per_codeword", "Bits per G722 codeword", OFFSET(bits_per_codeword), AV_OPT_TYPE_INT, { .i64 = 8 }, 6, 8, AD },
48	{ NULL }
49	};
50
51	static const AVClass g722_decoder_class = {
52	.class_name = "g722 decoder",
53	.item_name = av_default_item_name,
54	.option = options,
55	.version = LIBAVUTIL_VERSION_INT,
56	};
57
58	static av_cold int g722_decode_init(AVCodecContext * avctx)
59	{
60	G722Context *c = avctx->priv_data;
61
62	avctx->channels = 1;
63	avctx->channel_layout = AV_CH_LAYOUT_MONO;
64	avctx->sample_fmt = AV_SAMPLE_FMT_S16;
65
66	c->band[0].scale_factor = 8;
67	c->band[1].scale_factor = 2;
68	c->prev_samples_pos = 22;
69
70	ff_g722dsp_init(&c->dsp);
71
72	return 0;
73	}
74
75	static const int16_t low_inv_quant5[32] = {
76	-35, -35, -2919, -2195, -1765, -1458, -1219, -1023,
77	-858, -714, -587, -473, -370, -276, -190, -110,
78	2919, 2195, 1765, 1458, 1219, 1023, 858, 714,
79	587, 473, 370, 276, 190, 110, 35, -35
80	};
81
82	static const int16_t * const low_inv_quants[3] = { ff_g722_low_inv_quant6,
83	low_inv_quant5,
84	ff_g722_low_inv_quant4 };
85
86	static int g722_decode_frame(AVCodecContext *avctx, void *data,
87	int *got_frame_ptr, AVPacket *avpkt)
88	{
89	G722Context *c = avctx->priv_data;
90	AVFrame *frame = data;
91	int16_t *out_buf;
92	int j, ret;
93	const int skip = 8 - c->bits_per_codeword;
94	const int16_t *quantizer_table = low_inv_quants[skip];
95	GetBitContext gb;
96
97	/* get output buffer */
98	frame->nb_samples = avpkt->size * 2;
99	if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
100	return ret;
101	out_buf = (int16_t *)frame->data[0];
102
103	init_get_bits(&gb, avpkt->data, avpkt->size * 8);
104
105	for (j = 0; j < avpkt->size; j++) {
106	int ilow, ihigh, rlow, rhigh, dhigh;
107	int xout[2];
108
109	ihigh = get_bits(&gb, 2);
110	ilow = get_bits(&gb, 6 - skip);
111	skip_bits(&gb, skip);
112
113	rlow = av_clip_intp2((c->band[0].scale_factor * quantizer_table[ilow] >> 10)
114	+ c->band[0].s_predictor, 14);
115
116	ff_g722_update_low_predictor(&c->band[0], ilow >> (2 - skip));
117
118	dhigh = c->band[1].scale_factor * ff_g722_high_inv_quant[ihigh] >> 10;
119	rhigh = av_clip_intp2(dhigh + c->band[1].s_predictor, 14);
120
121	ff_g722_update_high_predictor(&c->band[1], dhigh, ihigh);
122
123	c->prev_samples[c->prev_samples_pos++] = rlow + rhigh;
124	c->prev_samples[c->prev_samples_pos++] = rlow - rhigh;
125	c->dsp.apply_qmf(c->prev_samples + c->prev_samples_pos - 24, xout);
126	*out_buf++ = av_clip_int16(xout[0] >> 11);
127	*out_buf++ = av_clip_int16(xout[1] >> 11);
128	if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {
129	memmove(c->prev_samples, c->prev_samples + c->prev_samples_pos - 22,
130	22 * sizeof(c->prev_samples[0]));
131	c->prev_samples_pos = 22;
132	}
133	}
134
135	*got_frame_ptr = 1;
136
137	return avpkt->size;
138	}
139
140	AVCodec ff_adpcm_g722_decoder = {
141	.name = "g722",
142	.long_name = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),
143	.type = AVMEDIA_TYPE_AUDIO,
144	.id = AV_CODEC_ID_ADPCM_G722,
145	.priv_data_size = sizeof(G722Context),
146	.init = g722_decode_init,
147	.decode = g722_decode_frame,
148	.capabilities = AV_CODEC_CAP_DR1,
149	.priv_class = &g722_decoder_class,
150	};
151