| @@ -0,0 +1,186 @@ |
| | 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 | avctx->sample_fmt = AV_SAMPLE_FMT_S16; |
| | 61 | switch (avctx->sample_rate) { |
| | 62 | case 8000: |
| | 63 | case 11025: |
| | 64 | s->marker = 0x11b; |
| | 65 | break; |
| | 66 | case 16000: |
| | 67 | case 32000: |
| | 68 | s->marker = 0x2b2; |
| | 69 | break; |
| | 70 | } |
| | 71 | |
| | 72 | return 0; |
| | 73 | } |
| | 74 | |
| | 75 | #define FRACBITS 12 |
| | 76 | #define WEIGHTSBITS 26 |
| | 77 | |
| | 78 | static int64_t prediction(int delta, ChannelContext *c) |
| | 79 | { |
| | 80 | const int isign = FFDIFFSIGN(delta, 0); |
| | 81 | int64_t dotpr = 0; |
| | 82 | |
| | 83 | c->new_pred = delta * (1LL << FRACBITS) + c->pred; |
| | 84 | |
| | 85 | for (int i = 0; i < 6; i++) { |
| | 86 | const int sign = FFSIGN(c->diffs_tab[i]); |
| | 87 | c->weights_tab[i] = (c->weights_tab[i] * 255LL) / 256; |
| | 88 | c->weights_tab[i] += (1LL << (WEIGHTSBITS + 1)) * sign * isign; |
| | 89 | } |
| | 90 | |
| | 91 | memmove(&c->diffs_tab[1], &c->diffs_tab[0], 5 * sizeof(int32_t)); |
| | 92 | |
| | 93 | c->diffs_tab[0] = -delta * (1 << (FRACBITS-8)); |
| | 94 | c->pred = c->new_pred; |
| | 95 | |
| | 96 | dotpr = 0; |
| | 97 | for (int i = 0; i < 6; i++) |
| | 98 | dotpr += ((int64_t)c->diffs_tab[i] * c->weights_tab[i]) >> WEIGHTSBITS; |
| | 99 | |
| | 100 | c->pred += dotpr; |
| | 101 | c->pred = av_clip64(c->pred, -16383 * (1 << FRACBITS), 16383 * (1 << FRACBITS)); |
| | 102 | c->pred = c->pred * 9 / 10; |
| | 103 | |
| | 104 | return c->new_pred; |
| | 105 | } |
| | 106 | |
| | 107 | static int16_t decode(ChannelContext *c, unsigned nibble) |
| | 108 | { |
| | 109 | int diff, diff_sign, adiff = 0, delta; |
| | 110 | uint32_t step, newstep; |
| | 111 | int64_t pred; |
| | 112 | |
| | 113 | diff_sign = nibble >> 3; |
| | 114 | diff = diffs[nibble]; |
| | 115 | step = diff + (c->last_step >> 2); |
| | 116 | newstep = step & 0xfff; |
| | 117 | if (newstep >> 11 == 0) |
| | 118 | adiff = (((step & 0x7f) + 0x80) * 128) >> |
| | 119 | (14 - (newstep >> 7)); |
| | 120 | delta = diff_sign ? -adiff : adiff; |
| | 121 | delta = av_clip_intp2(delta, 15); |
| | 122 | pred = prediction(delta, c); |
| | 123 | nibble = steps[nibble]; |
| | 124 | newstep = nibble * 32 - c->last_step & 0x1ffff; |
| | 125 | newstep = ((newstep >> 5) + (newstep & 0x10000 ? 0x1000 : 0) + c->last_step) & 0x1fff; |
| | 126 | c->last_step = av_clip(newstep, 544, 5120); |
| | 127 | |
| | 128 | return av_clip_int16(pred >> (FRACBITS - 3)); |
| | 129 | } |
| | 130 | |
| | 131 | static int misc4_decode(AVCodecContext *avctx, AVFrame *frame, |
| | 132 | int *got_frame_ptr, AVPacket *pkt) |
| | 133 | { |
| | 134 | MISC4Context *s = avctx->priv_data; |
| | 135 | GetByteContext *gb = &s->gb; |
| | 136 | uint32_t hdr; |
| | 137 | int ret; |
| | 138 | |
| | 139 | bytestream2_init(gb, pkt->data, pkt->size); |
| | 140 | |
| | 141 | frame->nb_samples = 29 * (1 + (avctx->ch_layout.nb_channels == 1)); |
| | 142 | if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) |
| | 143 | return ret; |
| | 144 | |
| | 145 | hdr = bytestream2_peek_be32(gb); |
| | 146 | if (hdr == s->marker) { |
| | 147 | bytestream2_skip(gb, 5); |
| | 148 | } else if ((hdr >> 16) == s->marker) { |
| | 149 | bytestream2_skip(gb, 3); |
| | 150 | } |
| | 151 | |
| | 152 | { |
| | 153 | int16_t *samples = (int16_t *)frame->data[0]; |
| | 154 | const int st = avctx->ch_layout.nb_channels == 2; |
| | 155 | int n; |
| | 156 | |
| | 157 | for (n = 0; n < 29; n++) { |
| | 158 | int nibble = bytestream2_get_byte(gb); |
| | 159 | samples[2*n+0] = decode(&s->ch[0 ], nibble >> 4); |
| | 160 | samples[2*n+1] = decode(&s->ch[st], nibble & 15); |
| | 161 | if (bytestream2_get_bytes_left(gb) <= 0) |
| | 162 | break; |
| | 163 | } |
| | 164 | |
| | 165 | if (n == 29 && bytestream2_get_byte(gb) != 0x55) |
| | 166 | return AVERROR_INVALIDDATA; |
| | 167 | } |
| | 168 | |
| | 169 | *got_frame_ptr = 1; |
| | 170 | |
| | 171 | return bytestream2_tell(gb); |
| | 172 | } |
| | 173 | |
| | 174 | const FFCodec ff_misc4_decoder = { |
| | 175 | .p.name = "misc4", |
| | 176 | CODEC_LONG_NAME("Micronas SC-4 Audio"), |
| | 177 | .p.type = AVMEDIA_TYPE_AUDIO, |
| | 178 | .p.id = AV_CODEC_ID_MISC4, |
| | 179 | .priv_data_size = sizeof(MISC4Context), |
| | 180 | .init = misc4_init, |
| | 181 | FF_CODEC_DECODE_CB(misc4_decode), |
| | 182 | .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_SUBFRAMES | |
| | 183 | AV_CODEC_CAP_CHANNEL_CONF, |
| | 184 | .p.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16, |
| | 185 | AV_SAMPLE_FMT_NONE }, |
| | 186 | }; |