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 Libav.
9 *
10 * Libav 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 * Libav 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 Libav; 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 "avcodec.h"
38#include "get_bits.h"
39#include "g722.h"
40#include "libavutil/opt.h"
41
42#define OFFSET(x) offsetof(G722Context, x)
43#define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
44static const AVOption options[] = {
45    { "bits_per_codeword", "Bits per G722 codeword", OFFSET(bits_per_codeword), AV_OPT_TYPE_FLAGS, { 8 }, 6, 8, AD },
46    { NULL }
47};
48
49static const AVClass g722_decoder_class = {
50    .class_name = "g722 decoder",
51    .item_name  = av_default_item_name,
52    .option     = options,
53    .version    = LIBAVUTIL_VERSION_INT,
54};
55
56static av_cold int g722_decode_init(AVCodecContext * avctx)
57{
58    G722Context *c = avctx->priv_data;
59
60    if (avctx->channels != 1) {
61        av_log(avctx, AV_LOG_ERROR, "Only mono tracks are allowed.\n");
62        return AVERROR_INVALIDDATA;
63    }
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    avcodec_get_frame_defaults(&c->frame);
71    avctx->coded_frame = &c->frame;
72
73    return 0;
74}
75
76static const int16_t low_inv_quant5[32] = {
77     -35,   -35, -2919, -2195, -1765, -1458, -1219, -1023,
78    -858,  -714,  -587,  -473,  -370,  -276,  -190,  -110,
79    2919,  2195,  1765,  1458,  1219,  1023,   858,   714,
80     587,   473,   370,   276,   190,   110,    35,   -35
81};
82
83static const int16_t *low_inv_quants[3] = { ff_g722_low_inv_quant6,
84                                                    low_inv_quant5,
85                                            ff_g722_low_inv_quant4 };
86
87static int g722_decode_frame(AVCodecContext *avctx, void *data,
88                             int *got_frame_ptr, AVPacket *avpkt)
89{
90    G722Context *c = avctx->priv_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    c->frame.nb_samples = avpkt->size * 2;
99    if ((ret = avctx->get_buffer(avctx, &c->frame)) < 0) {
100        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
101        return ret;
102    }
103    out_buf = (int16_t *)c->frame.data[0];
104
105    init_get_bits(&gb, avpkt->data, avpkt->size * 8);
106
107    for (j = 0; j < avpkt->size; j++) {
108        int ilow, ihigh, rlow, rhigh, dhigh;
109        int xout1, xout2;
110
111        ihigh = get_bits(&gb, 2);
112        ilow = get_bits(&gb, 6 - skip);
113        skip_bits(&gb, skip);
114
115        rlow = av_clip((c->band[0].scale_factor * quantizer_table[ilow] >> 10)
116                      + c->band[0].s_predictor, -16384, 16383);
117
118        ff_g722_update_low_predictor(&c->band[0], ilow >> (2 - skip));
119
120        dhigh = c->band[1].scale_factor * ff_g722_high_inv_quant[ihigh] >> 10;
121        rhigh = av_clip(dhigh + c->band[1].s_predictor, -16384, 16383);
122
123        ff_g722_update_high_predictor(&c->band[1], dhigh, ihigh);
124
125        c->prev_samples[c->prev_samples_pos++] = rlow + rhigh;
126        c->prev_samples[c->prev_samples_pos++] = rlow - rhigh;
127        ff_g722_apply_qmf(c->prev_samples + c->prev_samples_pos - 24,
128                          &xout1, &xout2);
129        *out_buf++ = av_clip_int16(xout1 >> 11);
130        *out_buf++ = av_clip_int16(xout2 >> 11);
131        if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {
132            memmove(c->prev_samples, c->prev_samples + c->prev_samples_pos - 22,
133                    22 * sizeof(c->prev_samples[0]));
134            c->prev_samples_pos = 22;
135        }
136    }
137
138    *got_frame_ptr   = 1;
139    *(AVFrame *)data = c->frame;
140
141    return avpkt->size;
142}
143
144AVCodec ff_adpcm_g722_decoder = {
145    .name           = "g722",
146    .type           = AVMEDIA_TYPE_AUDIO,
147    .id             = CODEC_ID_ADPCM_G722,
148    .priv_data_size = sizeof(G722Context),
149    .init           = g722_decode_init,
150    .decode         = g722_decode_frame,
151    .capabilities   = CODEC_CAP_DR1,
152    .long_name      = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),
153    .priv_class     = &g722_decoder_class,
154};
155