1 /*
2 * MOFLEX Fast Audio decoder
3 * Copyright (c) 2015-2016 Florian Nouwt
4 * Copyright (c) 2017 Adib Surani
5 * Copyright (c) 2020 Paul B Mahol
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 #include "libavutil/intreadwrite.h"
25
26 #include "avcodec.h"
27 #include "bytestream.h"
28 #include "codec_internal.h"
29 #include "internal.h"
30 #include "mathops.h"
31
32 typedef struct ChannelItems {
33 float f[8];
34 float last;
35 } ChannelItems;
36
37 typedef struct FastAudioContext {
38 float table[8][64];
39
40 ChannelItems *ch;
41 } FastAudioContext;
42
fastaudio_init(AVCodecContext *avctx)43 static av_cold int fastaudio_init(AVCodecContext *avctx)
44 {
45 FastAudioContext *s = avctx->priv_data;
46
47 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
48
49 for (int i = 0; i < 8; i++)
50 s->table[0][i] = (i - 159.5f) / 160.f;
51 for (int i = 0; i < 11; i++)
52 s->table[0][i + 8] = (i - 37.5f) / 40.f;
53 for (int i = 0; i < 27; i++)
54 s->table[0][i + 8 + 11] = (i - 13.f) / 20.f;
55 for (int i = 0; i < 11; i++)
56 s->table[0][i + 8 + 11 + 27] = (i + 27.5f) / 40.f;
57 for (int i = 0; i < 7; i++)
58 s->table[0][i + 8 + 11 + 27 + 11] = (i + 152.5f) / 160.f;
59
60 memcpy(s->table[1], s->table[0], sizeof(s->table[0]));
61
62 for (int i = 0; i < 7; i++)
63 s->table[2][i] = (i - 33.5f) / 40.f;
64 for (int i = 0; i < 25; i++)
65 s->table[2][i + 7] = (i - 13.f) / 20.f;
66
67 for (int i = 0; i < 32; i++)
68 s->table[3][i] = -s->table[2][31 - i];
69
70 for (int i = 0; i < 16; i++)
71 s->table[4][i] = i * 0.22f / 3.f - 0.6f;
72
73 for (int i = 0; i < 16; i++)
74 s->table[5][i] = i * 0.20f / 3.f - 0.3f;
75
76 for (int i = 0; i < 8; i++)
77 s->table[6][i] = i * 0.36f / 3.f - 0.4f;
78
79 for (int i = 0; i < 8; i++)
80 s->table[7][i] = i * 0.34f / 3.f - 0.2f;
81
82 s->ch = av_calloc(avctx->ch_layout.nb_channels, sizeof(*s->ch));
83 if (!s->ch)
84 return AVERROR(ENOMEM);
85
86 return 0;
87 }
88
read_bits(int bits, int *ppos, unsigned *src)89 static int read_bits(int bits, int *ppos, unsigned *src)
90 {
91 int r, pos;
92
93 pos = *ppos;
94 pos += bits;
95 r = src[(pos - 1) / 32] >> ((-pos) & 31);
96 *ppos = pos;
97
98 return r & ((1 << bits) - 1);
99 }
100
101 static const uint8_t bits[8] = { 6, 6, 5, 5, 4, 0, 3, 3, };
102
set_sample(int i, int j, int v, float *result, int *pads, float value)103 static void set_sample(int i, int j, int v, float *result, int *pads, float value)
104 {
105 result[i * 64 + pads[i] + j * 3] = value * (2 * v - 7);
106 }
107
fastaudio_decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)108 static int fastaudio_decode(AVCodecContext *avctx, AVFrame *frame,
109 int *got_frame, AVPacket *pkt)
110 {
111 FastAudioContext *s = avctx->priv_data;
112 GetByteContext gb;
113 int subframes;
114 int ret;
115
116 subframes = pkt->size / (40 * avctx->ch_layout.nb_channels);
117 frame->nb_samples = subframes * 256;
118 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
119 return ret;
120
121 bytestream2_init(&gb, pkt->data, pkt->size);
122
123 for (int subframe = 0; subframe < subframes; subframe++) {
124 for (int channel = 0; channel < avctx->ch_layout.nb_channels; channel++) {
125 ChannelItems *ch = &s->ch[channel];
126 float result[256] = { 0 };
127 unsigned src[10];
128 int inds[4], pads[4];
129 float m[8];
130 int pos = 0;
131
132 for (int i = 0; i < 10; i++)
133 src[i] = bytestream2_get_le32(&gb);
134
135 for (int i = 0; i < 8; i++)
136 m[7 - i] = s->table[i][read_bits(bits[i], &pos, src)];
137
138 for (int i = 0; i < 4; i++)
139 inds[3 - i] = read_bits(6, &pos, src);
140
141 for (int i = 0; i < 4; i++)
142 pads[3 - i] = read_bits(2, &pos, src);
143
144 for (int i = 0, index5 = 0; i < 4; i++) {
145 float value = av_int2float((inds[i] + 1) << 20) * powf(2.f, 116.f);
146
147 for (int j = 0, tmp = 0; j < 21; j++) {
148 set_sample(i, j, j == 20 ? tmp / 2 : read_bits(3, &pos, src), result, pads, value);
149 if (j % 10 == 9)
150 tmp = 4 * tmp + read_bits(2, &pos, src);
151 if (j == 20)
152 index5 = FFMIN(2 * index5 + tmp % 2, 63);
153 }
154
155 m[2] = s->table[5][index5];
156 }
157
158 for (int i = 0; i < 256; i++) {
159 float x = result[i];
160
161 for (int j = 0; j < 8; j++) {
162 x -= m[j] * ch->f[j];
163 ch->f[j] += m[j] * x;
164 }
165
166 memmove(&ch->f[0], &ch->f[1], sizeof(float) * 7);
167 ch->f[7] = x;
168 ch->last = x + ch->last * 0.86f;
169 result[i] = ch->last * 2.f;
170 }
171
172 memcpy(frame->extended_data[channel] + 1024 * subframe, result, 256 * sizeof(float));
173 }
174 }
175
176 *got_frame = 1;
177
178 return pkt->size;
179 }
180
fastaudio_close(AVCodecContext *avctx)181 static av_cold int fastaudio_close(AVCodecContext *avctx)
182 {
183 FastAudioContext *s = avctx->priv_data;
184
185 av_freep(&s->ch);
186
187 return 0;
188 }
189
190 const FFCodec ff_fastaudio_decoder = {
191 .p.name = "fastaudio",
192 .p.long_name = NULL_IF_CONFIG_SMALL("MobiClip FastAudio"),
193 .p.type = AVMEDIA_TYPE_AUDIO,
194 .p.id = AV_CODEC_ID_FASTAUDIO,
195 .priv_data_size = sizeof(FastAudioContext),
196 .init = fastaudio_init,
197 FF_CODEC_DECODE_CB(fastaudio_decode),
198 .close = fastaudio_close,
199 .p.capabilities = AV_CODEC_CAP_DR1,
200 .p.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
201 AV_SAMPLE_FMT_NONE },
202 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
203 };
204