2 * MOFLEX Fast Audio decoder
3 * Copyright (c) 2020 Paul B Mahol
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 #include "libavutil/intreadwrite.h"
25 #include "bytestream.h"
29 typedef struct ChannelItems {
34 typedef struct FastAudioContext {
40 static av_cold int fastaudio_init(AVCodecContext *avctx)
42 FastAudioContext *s = avctx->priv_data;
44 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
46 for (int i = 0; i < 8; i++)
47 s->table[0][i] = (i - 159.5f) / 160.f;
48 for (int i = 0; i < 11; i++)
49 s->table[0][i + 8] = (i - 37.5f) / 40.f;
50 for (int i = 0; i < 27; i++)
51 s->table[0][i + 8 + 11] = (i - 13.f) / 20.f;
52 for (int i = 0; i < 11; i++)
53 s->table[0][i + 8 + 11 + 27] = (i + 27.5f) / 40.f;
54 for (int i = 0; i < 7; i++)
55 s->table[0][i + 8 + 11 + 27 + 11] = (i + 152.5f) / 160.f;
57 memcpy(s->table[1], s->table[0], sizeof(s->table[0]));
59 for (int i = 0; i < 7; i++)
60 s->table[2][i] = (i - 33.5f) / 40.f;
61 for (int i = 0; i < 25; i++)
62 s->table[2][i + 7] = (i - 13.f) / 20.f;
64 for (int i = 0; i < 32; i++)
65 s->table[3][i] = -s->table[2][31 - i];
67 for (int i = 0; i < 16; i++)
68 s->table[4][i] = i * 0.22f / 3.f - 0.6f;
70 for (int i = 0; i < 16; i++)
71 s->table[5][i] = i * 0.20f / 3.f - 0.3f;
73 for (int i = 0; i < 8; i++)
74 s->table[6][i] = i * 0.36f / 3.f - 0.4f;
76 for (int i = 0; i < 8; i++)
77 s->table[7][i] = i * 0.34f / 3.f - 0.2f;
79 s->ch = av_calloc(avctx->channels, sizeof(*s->ch));
81 return AVERROR(ENOMEM);
86 static int read_bits(int bits, int *ppos, unsigned *src)
92 r = src[(pos - 1) / 32] >> (32 - pos % 32);
95 return r & ((1 << bits) - 1);
98 static const uint8_t bits[8] = { 6, 6, 5, 5, 4, 0, 3, 3, };
100 static void set_sample(int i, int j, int v, float *result, int *pads, float value)
102 result[i * 64 + pads[i] + j * 3] = value * (2 * v - 7);
105 static int fastaudio_decode(AVCodecContext *avctx, void *data,
106 int *got_frame, AVPacket *pkt)
108 FastAudioContext *s = avctx->priv_data;
110 AVFrame *frame = data;
114 subframes = pkt->size / (40 * avctx->channels);
115 frame->nb_samples = subframes * 256;
116 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
119 bytestream2_init(&gb, pkt->data, pkt->size);
121 for (int subframe = 0; subframe < subframes; subframe++) {
122 for (int channel = 0; channel < avctx->channels; channel++) {
123 ChannelItems *ch = &s->ch[channel];
124 float result[256] = { 0 };
126 int inds[4], pads[4];
130 for (int i = 0; i < 10; i++)
131 src[i] = bytestream2_get_le32(&gb);
133 for (int i = 0; i < 8; i++)
134 m[7 - i] = s->table[i][read_bits(bits[i], &pos, src)];
136 for (int i = 0; i < 4; i++)
137 inds[3 - i] = read_bits(6, &pos, src);
139 for (int i = 0; i < 4; i++)
140 pads[3 - i] = read_bits(2, &pos, src);
142 for (int i = 0, index5 = 0; i < 4; i++) {
143 float value = av_int2float((inds[i] + 1) << 20) * powf(2.f, 116.f);
145 for (int j = 0, tmp = 0; j < 21; j++) {
146 set_sample(i, j, j == 20 ? tmp / 2 : read_bits(3, &pos, src), result, pads, value);
148 tmp = 4 * tmp + read_bits(2, &pos, src);
150 index5 = FFMIN(2 * index5 + tmp % 2, 63);
153 m[2] = s->table[5][index5];
156 for (int i = 0; i < 256; i++) {
159 for (int j = 0; j < 8; j++) {
160 x -= m[j] * ch->f[j];
161 ch->f[j] += m[j] * x;
164 memmove(&ch->f[0], &ch->f[1], sizeof(float) * 7);
166 ch->last = x + ch->last * 0.86f;
167 result[i] = ch->last * 2.f;
170 memcpy(frame->extended_data[channel] + 1024 * subframe, result, 256 * sizeof(float));
179 static av_cold int fastaudio_close(AVCodecContext *avctx)
181 FastAudioContext *s = avctx->priv_data;
188 AVCodec ff_fastaudio_decoder = {
190 .long_name = NULL_IF_CONFIG_SMALL("MobiClip FastAudio"),
191 .type = AVMEDIA_TYPE_AUDIO,
192 .id = AV_CODEC_ID_FASTAUDIO,
193 .priv_data_size = sizeof(FastAudioContext),
194 .init = fastaudio_init,
195 .decode = fastaudio_decode,
196 .close = fastaudio_close,
197 .capabilities = AV_CODEC_CAP_DR1,
198 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
199 AV_SAMPLE_FMT_NONE },