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
46static 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
51static 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
58static 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    return 0;
71}
72
73static const int16_t low_inv_quant5[32] = {
74     -35,   -35, -2919, -2195, -1765, -1458, -1219, -1023,
75    -858,  -714,  -587,  -473,  -370,  -276,  -190,  -110,
76    2919,  2195,  1765,  1458,  1219,  1023,   858,   714,
77     587,   473,   370,   276,   190,   110,    35,   -35
78};
79
80static const int16_t *low_inv_quants[3] = { ff_g722_low_inv_quant6,
81                                                    low_inv_quant5,
82                                            ff_g722_low_inv_quant4 };
83
84static int g722_decode_frame(AVCodecContext *avctx, void *data,
85                             int *got_frame_ptr, AVPacket *avpkt)
86{
87    G722Context *c = avctx->priv_data;
88    AVFrame *frame = data;
89    int16_t *out_buf;
90    int j, ret;
91    const int skip = 8 - c->bits_per_codeword;
92    const int16_t *quantizer_table = low_inv_quants[skip];
93    GetBitContext gb;
94
95    /* get output buffer */
96    frame->nb_samples = avpkt->size * 2;
97    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
98        return ret;
99    out_buf = (int16_t *)frame->data[0];
100
101    init_get_bits(&gb, avpkt->data, avpkt->size * 8);
102
103    for (j = 0; j < avpkt->size; j++) {
104        int ilow, ihigh, rlow, rhigh, dhigh;
105        int xout1, xout2;
106
107        ihigh = get_bits(&gb, 2);
108        ilow = get_bits(&gb, 6 - skip);
109        skip_bits(&gb, skip);
110
111        rlow = av_clip((c->band[0].scale_factor * quantizer_table[ilow] >> 10)
112                      + c->band[0].s_predictor, -16384, 16383);
113
114        ff_g722_update_low_predictor(&c->band[0], ilow >> (2 - skip));
115
116        dhigh = c->band[1].scale_factor * ff_g722_high_inv_quant[ihigh] >> 10;
117        rhigh = av_clip(dhigh + c->band[1].s_predictor, -16384, 16383);
118
119        ff_g722_update_high_predictor(&c->band[1], dhigh, ihigh);
120
121        c->prev_samples[c->prev_samples_pos++] = rlow + rhigh;
122        c->prev_samples[c->prev_samples_pos++] = rlow - rhigh;
123        ff_g722_apply_qmf(c->prev_samples + c->prev_samples_pos - 24,
124                          &xout1, &xout2);
125        *out_buf++ = av_clip_int16(xout1 >> 11);
126        *out_buf++ = av_clip_int16(xout2 >> 11);
127        if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {
128            memmove(c->prev_samples, c->prev_samples + c->prev_samples_pos - 22,
129                    22 * sizeof(c->prev_samples[0]));
130            c->prev_samples_pos = 22;
131        }
132    }
133
134    *got_frame_ptr = 1;
135
136    return avpkt->size;
137}
138
139AVCodec ff_adpcm_g722_decoder = {
140    .name           = "g722",
141    .long_name      = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),
142    .type           = AVMEDIA_TYPE_AUDIO,
143    .id             = AV_CODEC_ID_ADPCM_G722,
144    .priv_data_size = sizeof(G722Context),
145    .init           = g722_decode_init,
146    .decode         = g722_decode_frame,
147    .capabilities   = CODEC_CAP_DR1,
148    .priv_class     = &g722_decoder_class,
149};
150