| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * Micronas SC-4 audio decoder | ||
| 3 | * Copyright (c) 2022 Paul B Mahol | ||
| 4 | * | ||
| 5 | * This file is part of FFmpeg. | ||
| 6 | * | ||
| 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. | ||
| 11 | * | ||
| 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. | ||
| 16 | * | ||
| 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 | ||
| 20 | */ | ||
| 21 | |||
| 22 | #include "libavutil/internal.h" | ||
| 23 | #include "libavutil/intreadwrite.h" | ||
| 24 | #include "avcodec.h" | ||
| 25 | #include "codec_internal.h" | ||
| 26 | #include "decode.h" | ||
| 27 | #include "bytestream.h" | ||
| 28 | #include "mathops.h" | ||
| 29 | |||
| 30 | static const int16_t steps[16] = { | ||
| 31 | 4084, 18, 41, 64, 112, 198, 355, 1122, | ||
| 32 | 1122, 355, 198, 112, 64, 41, 18, 4084, | ||
| 33 | }; | ||
| 34 | |||
| 35 | static const int16_t diffs[16] = { | ||
| 36 | 2048, 4, 135, 213, 273, 323, 373, 425, | ||
| 37 | 425, 373, 323, 273, 213, 135, 4, 2048, | ||
| 38 | }; | ||
| 39 | |||
| 40 | typedef struct ChannelContext { | ||
| 41 | unsigned last_step; | ||
| 42 | int64_t new_pred; | ||
| 43 | int64_t pred; | ||
| 44 | int64_t weights_tab[6]; | ||
| 45 | int32_t diffs_tab[6]; | ||
| 46 | } ChannelContext; | ||
| 47 | |||
| 48 | typedef struct MISC4Context { | ||
| 49 | GetByteContext gb; | ||
| 50 | |||
| 51 | uint32_t marker; | ||
| 52 | |||
| 53 | ChannelContext ch[2]; | ||
| 54 | } MISC4Context; | ||
| 55 | |||
| 56 | ✗ | static av_cold int misc4_init(AVCodecContext *avctx) | |
| 57 | { | ||
| 58 | ✗ | MISC4Context *s = avctx->priv_data; | |
| 59 | |||
| 60 | ✗ | if (avctx->sample_rate <= 0) | |
| 61 | ✗ | return AVERROR_INVALIDDATA; | |
| 62 | |||
| 63 | ✗ | if (avctx->ch_layout.nb_channels != 1 && avctx->ch_layout.nb_channels != 2) | |
| 64 | ✗ | return AVERROR_INVALIDDATA; | |
| 65 | |||
| 66 | ✗ | avctx->sample_fmt = AV_SAMPLE_FMT_S16; | |
| 67 | ✗ | switch (avctx->sample_rate) { | |
| 68 | ✗ | case 8000: | |
| 69 | case 11025: | ||
| 70 | ✗ | s->marker = 0x11b; | |
| 71 | ✗ | break; | |
| 72 | ✗ | case 16000: | |
| 73 | case 32000: | ||
| 74 | ✗ | s->marker = 0x2b2; | |
| 75 | ✗ | break; | |
| 76 | } | ||
| 77 | |||
| 78 | ✗ | return 0; | |
| 79 | } | ||
| 80 | |||
| 81 | #define FRACBITS 12 | ||
| 82 | #define WEIGHTSBITS 26 | ||
| 83 | |||
| 84 | ✗ | static int64_t prediction(int delta, ChannelContext *c) | |
| 85 | { | ||
| 86 | ✗ | const int isign = FFDIFFSIGN(delta, 0); | |
| 87 | ✗ | int64_t dotpr = 0; | |
| 88 | |||
| 89 | ✗ | c->new_pred = delta * (1LL << FRACBITS) + c->pred; | |
| 90 | |||
| 91 | ✗ | for (int i = 0; i < 6; i++) { | |
| 92 | ✗ | const int sign = FFSIGN(c->diffs_tab[i]); | |
| 93 | ✗ | c->weights_tab[i] = (c->weights_tab[i] * 255LL) / 256; | |
| 94 | ✗ | c->weights_tab[i] += (1LL << (WEIGHTSBITS + 1)) * sign * isign; | |
| 95 | } | ||
| 96 | |||
| 97 | ✗ | memmove(&c->diffs_tab[1], &c->diffs_tab[0], 5 * sizeof(int32_t)); | |
| 98 | |||
| 99 | ✗ | c->diffs_tab[0] = -delta * (1 << (FRACBITS-8)); | |
| 100 | ✗ | c->pred = c->new_pred; | |
| 101 | |||
| 102 | ✗ | dotpr = 0; | |
| 103 | ✗ | for (int i = 0; i < 6; i++) | |
| 104 | ✗ | dotpr += ((int64_t)c->diffs_tab[i] * c->weights_tab[i]) >> WEIGHTSBITS; | |
| 105 | |||
| 106 | ✗ | c->pred += dotpr; | |
| 107 | ✗ | c->pred = av_clip64(c->pred, -16383 * (1 << FRACBITS), 16383 * (1 << FRACBITS)); | |
| 108 | ✗ | c->pred = c->pred * 9 / 10; | |
| 109 | |||
| 110 | ✗ | return c->new_pred; | |
| 111 | } | ||
| 112 | |||
| 113 | ✗ | static int16_t decode(ChannelContext *c, unsigned nibble) | |
| 114 | { | ||
| 115 | ✗ | int diff, diff_sign, adiff = 0, delta; | |
| 116 | uint32_t step, newstep; | ||
| 117 | int64_t pred; | ||
| 118 | |||
| 119 | ✗ | diff_sign = nibble >> 3; | |
| 120 | ✗ | diff = diffs[nibble]; | |
| 121 | ✗ | step = diff + (c->last_step >> 2); | |
| 122 | ✗ | newstep = step & 0xfff; | |
| 123 | ✗ | if (newstep >> 11 == 0) | |
| 124 | ✗ | adiff = (((step & 0x7f) + 0x80) * 128) >> | |
| 125 | ✗ | (14 - (newstep >> 7)); | |
| 126 | ✗ | delta = diff_sign ? -adiff : adiff; | |
| 127 | ✗ | delta = av_clip_intp2(delta, 15); | |
| 128 | ✗ | pred = prediction(delta, c); | |
| 129 | ✗ | nibble = steps[nibble]; | |
| 130 | ✗ | newstep = nibble * 32 - c->last_step & 0x1ffff; | |
| 131 | ✗ | newstep = ((newstep >> 5) + (newstep & 0x10000 ? 0x1000 : 0) + c->last_step) & 0x1fff; | |
| 132 | ✗ | c->last_step = av_clip(newstep, 544, 5120); | |
| 133 | |||
| 134 | ✗ | return av_clip_int16(pred >> (FRACBITS - 3)); | |
| 135 | } | ||
| 136 | |||
| 137 | ✗ | static int misc4_decode(AVCodecContext *avctx, AVFrame *frame, | |
| 138 | int *got_frame_ptr, AVPacket *pkt) | ||
| 139 | { | ||
| 140 | ✗ | MISC4Context *s = avctx->priv_data; | |
| 141 | ✗ | GetByteContext *gb = &s->gb; | |
| 142 | uint32_t hdr; | ||
| 143 | int ret; | ||
| 144 | |||
| 145 | ✗ | bytestream2_init(gb, pkt->data, pkt->size); | |
| 146 | |||
| 147 | ✗ | frame->nb_samples = 29 * (1 + (avctx->ch_layout.nb_channels == 1)); | |
| 148 | ✗ | if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) | |
| 149 | ✗ | return ret; | |
| 150 | |||
| 151 | ✗ | hdr = bytestream2_peek_be32(gb); | |
| 152 | ✗ | if (hdr == s->marker) { | |
| 153 | ✗ | bytestream2_skip(gb, 5); | |
| 154 | ✗ | } else if ((hdr >> 16) == s->marker) { | |
| 155 | ✗ | bytestream2_skip(gb, 3); | |
| 156 | } | ||
| 157 | |||
| 158 | { | ||
| 159 | ✗ | int16_t *samples = (int16_t *)frame->data[0]; | |
| 160 | ✗ | const int st = avctx->ch_layout.nb_channels == 2; | |
| 161 | int n; | ||
| 162 | |||
| 163 | ✗ | for (n = 0; n < 29; n++) { | |
| 164 | ✗ | int nibble = bytestream2_get_byte(gb); | |
| 165 | ✗ | samples[2*n+0] = decode(&s->ch[0 ], nibble >> 4); | |
| 166 | ✗ | samples[2*n+1] = decode(&s->ch[st], nibble & 15); | |
| 167 | ✗ | if (bytestream2_get_bytes_left(gb) <= 0) | |
| 168 | ✗ | break; | |
| 169 | } | ||
| 170 | |||
| 171 | ✗ | if (n == 29 && bytestream2_get_byte(gb) != 0x55) | |
| 172 | ✗ | return AVERROR_INVALIDDATA; | |
| 173 | } | ||
| 174 | |||
| 175 | ✗ | *got_frame_ptr = 1; | |
| 176 | |||
| 177 | ✗ | return bytestream2_tell(gb); | |
| 178 | } | ||
| 179 | |||
| 180 | const FFCodec ff_misc4_decoder = { | ||
| 181 | .p.name = "misc4", | ||
| 182 | CODEC_LONG_NAME("Micronas SC-4 Audio"), | ||
| 183 | .p.type = AVMEDIA_TYPE_AUDIO, | ||
| 184 | .p.id = AV_CODEC_ID_MISC4, | ||
| 185 | .priv_data_size = sizeof(MISC4Context), | ||
| 186 | .init = misc4_init, | ||
| 187 | FF_CODEC_DECODE_CB(misc4_decode), | ||
| 188 | .p.capabilities = AV_CODEC_CAP_DR1 | | ||
| 189 | AV_CODEC_CAP_CHANNEL_CONF, | ||
| 190 | }; | ||
| 191 |