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| 1 | +/* |
| 2 | + * vMix decoder |
| 3 | + * Copyright (c) 2023 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 <stdio.h> |
| 23 | +#include <stdlib.h> |
| 24 | +#include <string.h> |
| 25 | + |
| 26 | +#include "libavutil/avassert.h" |
| 27 | +#include "libavutil/intreadwrite.h" |
| 28 | +#include "libavutil/mem_internal.h" |
| 29 | + |
| 30 | +#include "avcodec.h" |
| 31 | +#include "codec_internal.h" |
| 32 | +#include "decode.h" |
| 33 | +#define CACHED_BITSTREAM_READER !ARCH_X86_32 |
| 34 | +#include "golomb.h" |
| 35 | +#include "get_bits.h" |
| 36 | +#include "idctdsp.h" |
| 37 | +#include "thread.h" |
| 38 | + |
| 39 | +typedef struct SliceContext { |
| 40 | + const uint8_t *dc_ptr; |
| 41 | + const uint8_t *ac_ptr; |
| 42 | + unsigned dc_size; |
| 43 | + unsigned ac_size; |
| 44 | +} SliceContext; |
| 45 | + |
| 46 | +typedef struct VMIXContext { |
| 47 | + int nb_slices; |
| 48 | + |
| 49 | + int16_t factors[64]; |
| 50 | + uint8_t scan[64]; |
| 51 | + |
| 52 | + SliceContext slices[255]; |
| 53 | + |
| 54 | + IDCTDSPContext idsp; |
| 55 | +} VMIXContext; |
| 56 | + |
| 57 | +static const uint8_t quality[25] = { |
| 58 | + 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, |
| 59 | + 18, 20, 22, 24, 28, 32, 36, 40, 44, 48, 52, 56, 64, |
| 60 | +}; |
| 61 | + |
| 62 | +static const uint8_t quant[64] = { |
| 63 | + 16, 16, 19, 22, 22, 26, 26, 27, |
| 64 | + 16, 16, 22, 22, 26, 27, 27, 29, |
| 65 | + 19, 22, 26, 26, 27, 29, 29, 35, |
| 66 | + 22, 24, 27, 27, 29, 32, 34, 38, |
| 67 | + 26, 27, 29, 29, 32, 35, 38, 46, |
| 68 | + 27, 29, 34, 34, 35, 40, 46, 56, |
| 69 | + 29, 34, 34, 37, 40, 48, 56, 69, |
| 70 | + 34, 37, 38, 40, 48, 58, 69, 83, |
| 71 | +}; |
| 72 | + |
| 73 | +static av_cold int decode_init(AVCodecContext *avctx) |
| 74 | +{ |
| 75 | + VMIXContext *s = avctx->priv_data; |
| 76 | + |
| 77 | + avctx->bits_per_raw_sample = 8; |
| 78 | + avctx->pix_fmt = AV_PIX_FMT_YUV422P; |
| 79 | + |
| 80 | + avctx->coded_width = FFALIGN(avctx->width, 16); |
| 81 | + avctx->coded_height = FFALIGN(avctx->height, 16); |
| 82 | + |
| 83 | + ff_idctdsp_init(&s->idsp, avctx); |
| 84 | + ff_permute_scantable(s->scan, ff_zigzag_direct, |
| 85 | + s->idsp.idct_permutation); |
| 86 | + return 0; |
| 87 | +} |
| 88 | + |
| 89 | +static inline int get_se_golomb_vmix(GetBitContext *gb) |
| 90 | +{ |
| 91 | + unsigned int buf = get_ue_golomb_long(gb); |
| 92 | + int sign = (buf & 1) - 1; |
| 93 | + return ((buf >> 1) ^ (~sign)); |
| 94 | +} |
| 95 | + |
| 96 | +static int decode_dcac(AVCodecContext *avctx, |
| 97 | + GetBitContext *dc_gb, GetBitContext *ac_gb, |
| 98 | + unsigned *dcrun, unsigned *acrun, |
| 99 | + AVFrame *frame, int width, int by, int plane) |
| 100 | +{ |
| 101 | + const ptrdiff_t linesize = frame->linesize[plane]; |
| 102 | + uint8_t *dst = frame->data[plane] + by * linesize; |
| 103 | + unsigned dc_run = *dcrun, ac_run = *acrun; |
| 104 | + LOCAL_ALIGNED_32(int16_t, block, [64]); |
| 105 | + VMIXContext *s = avctx->priv_data; |
| 106 | + const int16_t *factors = s->factors; |
| 107 | + const uint8_t *scan = s->scan; |
| 108 | + const int add = plane ? 0 : 1024; |
| 109 | + int i, dc_v = 0, ac_v = 0, dc = 0; |
| 110 | + |
| 111 | + for (int y = 0; y < 2; y++) { |
| 112 | + for (int x = 0; x < width; x += 8) { |
| 113 | + memset(block, 0, sizeof(*block)*64); |
| 114 | + |
| 115 | + if (dc_run > 0) { |
| 116 | + dc_run--; |
| 117 | + } else { |
| 118 | + dc_v = get_se_golomb_vmix(dc_gb); |
| 119 | + dc += dc_v; |
| 120 | + if (!dc_v) |
| 121 | + dc_run = get_ue_golomb_long(dc_gb); |
| 122 | + } |
| 123 | + |
| 124 | + for (int n = 0; n < 64; n++) { |
| 125 | + if (ac_run > 0) { |
| 126 | + ac_run--; |
| 127 | + continue; |
| 128 | + } |
| 129 | + |
| 130 | + ac_v = get_se_golomb_vmix(ac_gb); |
| 131 | + i = scan[n]; |
| 132 | + block[i] = (ac_v * factors[i]) >> 4; |
| 133 | + if (!ac_v) |
| 134 | + ac_run = get_ue_golomb_long(ac_gb); |
| 135 | + } |
| 136 | + |
| 137 | + block[0] = ((dc + add) * 16) >> 4; |
| 138 | + s->idsp.idct_put(dst + x, linesize, block); |
| 139 | + } |
| 140 | + |
| 141 | + dst += 8 * linesize; |
| 142 | + } |
| 143 | + |
| 144 | + *dcrun = dc_run; |
| 145 | + *acrun = ac_run; |
| 146 | + |
| 147 | + return 0; |
| 148 | +} |
| 149 | + |
| 150 | +static int decode_slice(AVCodecContext *avctx, AVFrame *frame, |
| 151 | + const uint8_t *dc_src, unsigned dc_slice_size, |
| 152 | + const uint8_t *ac_src, unsigned ac_slice_size, |
| 153 | + int by) |
| 154 | +{ |
| 155 | + unsigned dc_run = 0, ac_run = 0; |
| 156 | + GetBitContext dc_gb, ac_gb; |
| 157 | + int ret; |
| 158 | + |
| 159 | + ret = init_get_bits8(&dc_gb, dc_src, dc_slice_size); |
| 160 | + if (ret < 0) |
| 161 | + return ret; |
| 162 | + |
| 163 | + ret = init_get_bits8(&ac_gb, ac_src, ac_slice_size); |
| 164 | + if (ret < 0) |
| 165 | + return ret; |
| 166 | + |
| 167 | + for (int p = 0; p < 3; p++) { |
| 168 | + const int rshift = !!p; |
| 169 | + ret = decode_dcac(avctx, &dc_gb, &ac_gb, |
| 170 | + &dc_run, &ac_run, frame, |
| 171 | + frame->width >> rshift, by, p); |
| 172 | + if (ret < 0) |
| 173 | + return ret; |
| 174 | + |
| 175 | + if (get_bits_left(&dc_gb) < 0) |
| 176 | + return AVERROR_INVALIDDATA; |
| 177 | + if (get_bits_left(&ac_gb) < 0) |
| 178 | + return AVERROR_INVALIDDATA; |
| 179 | + |
| 180 | + align_get_bits(&dc_gb); |
| 181 | + align_get_bits(&ac_gb); |
| 182 | + } |
| 183 | + |
| 184 | + if (get_bits_left(&dc_gb) > 0) |
| 185 | + return AVERROR_INVALIDDATA; |
| 186 | + if (get_bits_left(&ac_gb) > 0) |
| 187 | + return AVERROR_INVALIDDATA; |
| 188 | + |
| 189 | + return 0; |
| 190 | +} |
| 191 | + |
| 192 | +static int decode_slices(AVCodecContext *avctx, void *arg, |
| 193 | + int n, int thread_nb) |
| 194 | +{ |
| 195 | + VMIXContext *s = avctx->priv_data; |
| 196 | + const uint8_t *dc_slice_ptr = s->slices[n].dc_ptr; |
| 197 | + const uint8_t *ac_slice_ptr = s->slices[n].ac_ptr; |
| 198 | + unsigned dc_slice_size = s->slices[n].dc_size; |
| 199 | + unsigned ac_slice_size = s->slices[n].ac_size; |
| 200 | + AVFrame *frame = arg; |
| 201 | + |
| 202 | + return decode_slice(avctx, frame, dc_slice_ptr, dc_slice_size, |
| 203 | + ac_slice_ptr, ac_slice_size, n * 16); |
| 204 | +} |
| 205 | + |
| 206 | +static int decode_frame(AVCodecContext *avctx, |
| 207 | + AVFrame *frame, int *got_frame, |
| 208 | + AVPacket *avpkt) |
| 209 | +{ |
| 210 | + VMIXContext *s = avctx->priv_data; |
| 211 | + unsigned offset = 3, q; |
| 212 | + int ret; |
| 213 | + |
| 214 | + if (avpkt->size <= 7) |
| 215 | + return AVERROR_INVALIDDATA; |
| 216 | + |
| 217 | + if (avpkt->data[0] != 0x01) |
| 218 | + return AVERROR_INVALIDDATA; |
| 219 | + |
| 220 | + q = av_clip(99 - av_clip(avpkt->data[1], 0, 99), 0, FF_ARRAY_ELEMS(quality) - 1); |
| 221 | + for (int n = 0; n < 64; n++) |
| 222 | + s->factors[n] = quant[n] * quality[q]; |
| 223 | + |
| 224 | + s->nb_slices = avpkt->data[2]; |
| 225 | + if (!s->nb_slices || s->nb_slices > (avctx->height + 15) / 16) |
| 226 | + return AVERROR_INVALIDDATA; |
| 227 | + |
| 228 | + for (int n = 0; n < s->nb_slices; n++) { |
| 229 | + unsigned slice_size; |
| 230 | + |
| 231 | + if (offset + 4 > avpkt->size) |
| 232 | + return AVERROR_INVALIDDATA; |
| 233 | + |
| 234 | + slice_size = AV_RL32(avpkt->data + offset); |
| 235 | + if (slice_size > avpkt->size) |
| 236 | + return AVERROR_INVALIDDATA; |
| 237 | + |
| 238 | + if (avpkt->size - slice_size - 4LL < offset) |
| 239 | + return AVERROR_INVALIDDATA; |
| 240 | + |
| 241 | + s->slices[n].dc_size = slice_size; |
| 242 | + s->slices[n].dc_ptr = avpkt->data + offset + 4; |
| 243 | + offset += slice_size + 4; |
| 244 | + } |
| 245 | + |
| 246 | + for (int n = 0; n < s->nb_slices; n++) { |
| 247 | + unsigned slice_size; |
| 248 | + |
| 249 | + if (offset + 4 > avpkt->size) |
| 250 | + return AVERROR_INVALIDDATA; |
| 251 | + |
| 252 | + slice_size = AV_RL32(avpkt->data + offset); |
| 253 | + if (slice_size > avpkt->size) |
| 254 | + return AVERROR_INVALIDDATA; |
| 255 | + |
| 256 | + if (avpkt->size - slice_size - 4LL < offset) |
| 257 | + return AVERROR_INVALIDDATA; |
| 258 | + |
| 259 | + s->slices[n].ac_size = slice_size; |
| 260 | + s->slices[n].ac_ptr = avpkt->data + offset + 4; |
| 261 | + offset += slice_size + 4; |
| 262 | + } |
| 263 | + |
| 264 | + ret = ff_thread_get_buffer(avctx, frame, 0); |
| 265 | + if (ret < 0) |
| 266 | + return ret; |
| 267 | + |
| 268 | + avctx->execute2(avctx, decode_slices, frame, NULL, s->nb_slices); |
| 269 | + |
| 270 | + frame->pict_type = AV_PICTURE_TYPE_I; |
| 271 | + frame->flags |= AV_FRAME_FLAG_KEY; |
| 272 | + |
| 273 | + *got_frame = 1; |
| 274 | + |
| 275 | + return avpkt->size; |
| 276 | +} |
| 277 | + |
| 278 | +const FFCodec ff_vmix_decoder = { |
| 279 | + .p.name = "vmix", |
| 280 | + CODEC_LONG_NAME("vMix Video"), |
| 281 | + .p.type = AVMEDIA_TYPE_VIDEO, |
| 282 | + .p.id = AV_CODEC_ID_VMIX, |
| 283 | + .priv_data_size = sizeof(VMIXContext), |
| 284 | + .init = decode_init, |
| 285 | + FF_CODEC_DECODE_CB(decode_frame), |
| 286 | + .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS | |
| 287 | + AV_CODEC_CAP_SLICE_THREADS, |
| 288 | +}; |