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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 | return 0; | |
71 | } | |
72 | ||
73 | static 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 | ||
80 | static const int16_t * const low_inv_quants[3] = { ff_g722_low_inv_quant6, | |
81 | low_inv_quant5, | |
82 | ff_g722_low_inv_quant4 }; | |
83 | ||
84 | static 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 | ||
139 | AVCodec 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 | }; |