| 1 | /* |
| 2 | * APNG demuxer |
| 3 | * Copyright (c) 2014 Benoit Fouet |
| 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 | /** |
| 23 | * @file |
| 24 | * APNG demuxer. |
| 25 | * @see https://wiki.mozilla.org/APNG_Specification |
| 26 | * @see http://www.w3.org/TR/PNG |
| 27 | */ |
| 28 | |
| 29 | #include "avformat.h" |
| 30 | #include "avio_internal.h" |
| 31 | #include "internal.h" |
| 32 | #include "libavutil/imgutils.h" |
| 33 | #include "libavutil/intreadwrite.h" |
| 34 | #include "libavutil/opt.h" |
| 35 | #include "libavcodec/apng.h" |
| 36 | #include "libavcodec/png.h" |
| 37 | #include "libavcodec/bytestream.h" |
| 38 | |
| 39 | #define DEFAULT_APNG_FPS 15 |
| 40 | |
| 41 | typedef struct APNGDemuxContext { |
| 42 | const AVClass *class; |
| 43 | |
| 44 | int max_fps; |
| 45 | int default_fps; |
| 46 | |
| 47 | int64_t pkt_pts; |
| 48 | int pkt_duration; |
| 49 | |
| 50 | int is_key_frame; |
| 51 | |
| 52 | /* |
| 53 | * loop options |
| 54 | */ |
| 55 | int ignore_loop; |
| 56 | uint32_t num_frames; |
| 57 | uint32_t num_play; |
| 58 | uint32_t cur_loop; |
| 59 | } APNGDemuxContext; |
| 60 | |
| 61 | /* |
| 62 | * To be a valid APNG file, we mandate, in this order: |
| 63 | * PNGSIG |
| 64 | * IHDR |
| 65 | * ... |
| 66 | * acTL |
| 67 | * ... |
| 68 | * IDAT |
| 69 | */ |
| 70 | static int apng_probe(AVProbeData *p) |
| 71 | { |
| 72 | GetByteContext gb; |
| 73 | int state = 0; |
| 74 | uint32_t len, tag; |
| 75 | |
| 76 | bytestream2_init(&gb, p->buf, p->buf_size); |
| 77 | |
| 78 | if (bytestream2_get_be64(&gb) != PNGSIG) |
| 79 | return 0; |
| 80 | |
| 81 | for (;;) { |
| 82 | len = bytestream2_get_be32(&gb); |
| 83 | if (len > 0x7fffffff) |
| 84 | return 0; |
| 85 | |
| 86 | tag = bytestream2_get_le32(&gb); |
| 87 | /* we don't check IDAT size, as this is the last tag |
| 88 | * we check, and it may be larger than the probe buffer */ |
| 89 | if (tag != MKTAG('I', 'D', 'A', 'T') && |
| 90 | len + 4 > bytestream2_get_bytes_left(&gb)) |
| 91 | return 0; |
| 92 | |
| 93 | switch (tag) { |
| 94 | case MKTAG('I', 'H', 'D', 'R'): |
| 95 | if (len != 13) |
| 96 | return 0; |
| 97 | if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL)) |
| 98 | return 0; |
| 99 | bytestream2_skip(&gb, 9); |
| 100 | state++; |
| 101 | break; |
| 102 | case MKTAG('a', 'c', 'T', 'L'): |
| 103 | if (state != 1 || |
| 104 | len != 8 || |
| 105 | bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */ |
| 106 | return 0; |
| 107 | bytestream2_skip(&gb, 8); |
| 108 | state++; |
| 109 | break; |
| 110 | case MKTAG('I', 'D', 'A', 'T'): |
| 111 | if (state != 2) |
| 112 | return 0; |
| 113 | goto end; |
| 114 | default: |
| 115 | /* skip other tags */ |
| 116 | bytestream2_skip(&gb, len + 4); |
| 117 | break; |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | end: |
| 122 | return AVPROBE_SCORE_MAX; |
| 123 | } |
| 124 | |
| 125 | static int append_extradata(AVCodecContext *s, AVIOContext *pb, int len) |
| 126 | { |
| 127 | int previous_size = s->extradata_size; |
| 128 | int new_size, ret; |
| 129 | uint8_t *new_extradata; |
| 130 | |
| 131 | if (previous_size > INT_MAX - len) |
| 132 | return AVERROR_INVALIDDATA; |
| 133 | |
| 134 | new_size = previous_size + len; |
| 135 | new_extradata = av_realloc(s->extradata, new_size + FF_INPUT_BUFFER_PADDING_SIZE); |
| 136 | if (!new_extradata) |
| 137 | return AVERROR(ENOMEM); |
| 138 | s->extradata = new_extradata; |
| 139 | s->extradata_size = new_size; |
| 140 | |
| 141 | if ((ret = avio_read(pb, s->extradata + previous_size, len)) < 0) |
| 142 | return ret; |
| 143 | |
| 144 | return previous_size; |
| 145 | } |
| 146 | |
| 147 | static int apng_read_header(AVFormatContext *s) |
| 148 | { |
| 149 | APNGDemuxContext *ctx = s->priv_data; |
| 150 | AVIOContext *pb = s->pb; |
| 151 | uint32_t len, tag; |
| 152 | AVStream *st; |
| 153 | int ret = AVERROR_INVALIDDATA, acTL_found = 0; |
| 154 | |
| 155 | /* verify PNGSIG */ |
| 156 | if (avio_rb64(pb) != PNGSIG) |
| 157 | return ret; |
| 158 | |
| 159 | /* parse IHDR (must be first chunk) */ |
| 160 | len = avio_rb32(pb); |
| 161 | tag = avio_rl32(pb); |
| 162 | if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R')) |
| 163 | return ret; |
| 164 | |
| 165 | st = avformat_new_stream(s, NULL); |
| 166 | if (!st) |
| 167 | return AVERROR(ENOMEM); |
| 168 | |
| 169 | /* set the timebase to something large enough (1/100,000 of second) |
| 170 | * to hopefully cope with all sane frame durations */ |
| 171 | avpriv_set_pts_info(st, 64, 1, 100000); |
| 172 | st->codec->codec_type = AVMEDIA_TYPE_VIDEO; |
| 173 | st->codec->codec_id = AV_CODEC_ID_APNG; |
| 174 | st->codec->width = avio_rb32(pb); |
| 175 | st->codec->height = avio_rb32(pb); |
| 176 | if ((ret = av_image_check_size(st->codec->width, st->codec->height, 0, s)) < 0) |
| 177 | return ret; |
| 178 | |
| 179 | /* extradata will contain every chunk up to the first fcTL (excluded) */ |
| 180 | st->codec->extradata = av_malloc(len + 12 + FF_INPUT_BUFFER_PADDING_SIZE); |
| 181 | if (!st->codec->extradata) |
| 182 | return AVERROR(ENOMEM); |
| 183 | st->codec->extradata_size = len + 12; |
| 184 | AV_WB32(st->codec->extradata, len); |
| 185 | AV_WL32(st->codec->extradata+4, tag); |
| 186 | AV_WB32(st->codec->extradata+8, st->codec->width); |
| 187 | AV_WB32(st->codec->extradata+12, st->codec->height); |
| 188 | if ((ret = avio_read(pb, st->codec->extradata+16, 9)) < 0) |
| 189 | goto fail; |
| 190 | |
| 191 | while (!avio_feof(pb)) { |
| 192 | if (acTL_found && ctx->num_play != 1) { |
| 193 | int64_t size = avio_size(pb); |
| 194 | int64_t offset = avio_tell(pb); |
| 195 | if (size < 0) { |
| 196 | ret = size; |
| 197 | goto fail; |
| 198 | } else if (offset < 0) { |
| 199 | ret = offset; |
| 200 | goto fail; |
| 201 | } else if ((ret = ffio_ensure_seekback(pb, size - offset)) < 0) { |
| 202 | av_log(s, AV_LOG_WARNING, "Could not ensure seekback, will not loop\n"); |
| 203 | ctx->num_play = 1; |
| 204 | } |
| 205 | } |
| 206 | if ((ctx->num_play == 1 || !acTL_found) && |
| 207 | ((ret = ffio_ensure_seekback(pb, 4 /* len */ + 4 /* tag */)) < 0)) |
| 208 | goto fail; |
| 209 | |
| 210 | len = avio_rb32(pb); |
| 211 | if (len > 0x7fffffff) { |
| 212 | ret = AVERROR_INVALIDDATA; |
| 213 | goto fail; |
| 214 | } |
| 215 | |
| 216 | tag = avio_rl32(pb); |
| 217 | switch (tag) { |
| 218 | case MKTAG('a', 'c', 'T', 'L'): |
| 219 | if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 || |
| 220 | (ret = append_extradata(st->codec, pb, len + 12)) < 0) |
| 221 | goto fail; |
| 222 | acTL_found = 1; |
| 223 | ctx->num_frames = AV_RB32(st->codec->extradata + ret + 8); |
| 224 | ctx->num_play = AV_RB32(st->codec->extradata + ret + 12); |
| 225 | av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n", |
| 226 | ctx->num_frames, ctx->num_play); |
| 227 | break; |
| 228 | case MKTAG('f', 'c', 'T', 'L'): |
| 229 | if (!acTL_found) { |
| 230 | ret = AVERROR_INVALIDDATA; |
| 231 | goto fail; |
| 232 | } |
| 233 | if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0) |
| 234 | goto fail; |
| 235 | return 0; |
| 236 | default: |
| 237 | if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 || |
| 238 | (ret = append_extradata(st->codec, pb, len + 12)) < 0) |
| 239 | goto fail; |
| 240 | } |
| 241 | } |
| 242 | |
| 243 | fail: |
| 244 | if (st->codec->extradata_size) { |
| 245 | av_freep(&st->codec->extradata); |
| 246 | st->codec->extradata_size = 0; |
| 247 | } |
| 248 | return ret; |
| 249 | } |
| 250 | |
| 251 | static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt) |
| 252 | { |
| 253 | uint32_t sequence_number, width, height, x_offset, y_offset; |
| 254 | uint16_t delay_num, delay_den; |
| 255 | uint8_t dispose_op, blend_op; |
| 256 | |
| 257 | sequence_number = avio_rb32(s->pb); |
| 258 | width = avio_rb32(s->pb); |
| 259 | height = avio_rb32(s->pb); |
| 260 | x_offset = avio_rb32(s->pb); |
| 261 | y_offset = avio_rb32(s->pb); |
| 262 | delay_num = avio_rb16(s->pb); |
| 263 | delay_den = avio_rb16(s->pb); |
| 264 | dispose_op = avio_r8(s->pb); |
| 265 | blend_op = avio_r8(s->pb); |
| 266 | avio_skip(s->pb, 4); /* crc */ |
| 267 | |
| 268 | /* default is hundredths of seconds */ |
| 269 | if (!delay_den) |
| 270 | delay_den = 100; |
| 271 | if (!delay_num || delay_den / delay_num > ctx->max_fps) { |
| 272 | delay_num = 1; |
| 273 | delay_den = ctx->default_fps; |
| 274 | } |
| 275 | ctx->pkt_duration = av_rescale_q(delay_num, |
| 276 | (AVRational){ 1, delay_den }, |
| 277 | s->streams[0]->time_base); |
| 278 | |
| 279 | av_log(s, AV_LOG_DEBUG, "%s: " |
| 280 | "sequence_number: %"PRId32", " |
| 281 | "width: %"PRIu32", " |
| 282 | "height: %"PRIu32", " |
| 283 | "x_offset: %"PRIu32", " |
| 284 | "y_offset: %"PRIu32", " |
| 285 | "delay_num: %"PRIu16", " |
| 286 | "delay_den: %"PRIu16", " |
| 287 | "dispose_op: %d, " |
| 288 | "blend_op: %d\n", |
| 289 | __FUNCTION__, |
| 290 | sequence_number, |
| 291 | width, |
| 292 | height, |
| 293 | x_offset, |
| 294 | y_offset, |
| 295 | delay_num, |
| 296 | delay_den, |
| 297 | dispose_op, |
| 298 | blend_op); |
| 299 | |
| 300 | if (width != s->streams[0]->codec->width || |
| 301 | height != s->streams[0]->codec->height || |
| 302 | x_offset != 0 || |
| 303 | y_offset != 0) { |
| 304 | if (sequence_number == 0 || |
| 305 | x_offset >= s->streams[0]->codec->width || |
| 306 | width > s->streams[0]->codec->width - x_offset || |
| 307 | y_offset >= s->streams[0]->codec->height || |
| 308 | height > s->streams[0]->codec->height - y_offset) |
| 309 | return AVERROR_INVALIDDATA; |
| 310 | ctx->is_key_frame = 0; |
| 311 | } else { |
| 312 | if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS) |
| 313 | dispose_op = APNG_DISPOSE_OP_BACKGROUND; |
| 314 | ctx->is_key_frame = dispose_op == APNG_DISPOSE_OP_BACKGROUND || |
| 315 | blend_op == APNG_BLEND_OP_SOURCE; |
| 316 | } |
| 317 | |
| 318 | return 0; |
| 319 | } |
| 320 | |
| 321 | static int apng_read_packet(AVFormatContext *s, AVPacket *pkt) |
| 322 | { |
| 323 | APNGDemuxContext *ctx = s->priv_data; |
| 324 | int ret; |
| 325 | int64_t size; |
| 326 | AVIOContext *pb = s->pb; |
| 327 | uint32_t len, tag; |
| 328 | |
| 329 | /* |
| 330 | * fcTL chunk length, in bytes: |
| 331 | * 4 (length) |
| 332 | * 4 (tag) |
| 333 | * 26 (actual chunk) |
| 334 | * 4 (crc) bytes |
| 335 | * and needed next: |
| 336 | * 4 (length) |
| 337 | * 4 (tag (must be fdAT or IDAT)) |
| 338 | */ |
| 339 | /* if num_play is not 1, then the seekback is already guaranteed */ |
| 340 | if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0) |
| 341 | return ret; |
| 342 | |
| 343 | len = avio_rb32(pb); |
| 344 | tag = avio_rl32(pb); |
| 345 | switch (tag) { |
| 346 | case MKTAG('f', 'c', 'T', 'L'): |
| 347 | if (len != 26) |
| 348 | return AVERROR_INVALIDDATA; |
| 349 | |
| 350 | if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0) |
| 351 | return ret; |
| 352 | |
| 353 | /* fcTL must precede fdAT or IDAT */ |
| 354 | len = avio_rb32(pb); |
| 355 | tag = avio_rl32(pb); |
| 356 | if (len > 0x7fffffff || |
| 357 | tag != MKTAG('f', 'd', 'A', 'T') && |
| 358 | tag != MKTAG('I', 'D', 'A', 'T')) |
| 359 | return AVERROR_INVALIDDATA; |
| 360 | |
| 361 | size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */; |
| 362 | if (size > INT_MAX) |
| 363 | return AVERROR(EINVAL); |
| 364 | |
| 365 | if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0 || |
| 366 | (ret = av_append_packet(pb, pkt, size)) < 0) |
| 367 | return ret; |
| 368 | |
| 369 | if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0) |
| 370 | return ret; |
| 371 | |
| 372 | len = avio_rb32(pb); |
| 373 | tag = avio_rl32(pb); |
| 374 | while (tag && |
| 375 | tag != MKTAG('f', 'c', 'T', 'L') && |
| 376 | tag != MKTAG('I', 'E', 'N', 'D')) { |
| 377 | if (len > 0x7fffffff) |
| 378 | return AVERROR_INVALIDDATA; |
| 379 | if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 || |
| 380 | (ret = av_append_packet(pb, pkt, len + 12)) < 0) |
| 381 | return ret; |
| 382 | if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0) |
| 383 | return ret; |
| 384 | len = avio_rb32(pb); |
| 385 | tag = avio_rl32(pb); |
| 386 | } |
| 387 | if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0) |
| 388 | return ret; |
| 389 | |
| 390 | if (ctx->is_key_frame) |
| 391 | pkt->flags |= AV_PKT_FLAG_KEY; |
| 392 | pkt->pts = ctx->pkt_pts; |
| 393 | pkt->duration = ctx->pkt_duration; |
| 394 | ctx->pkt_pts += ctx->pkt_duration; |
| 395 | return ret; |
| 396 | case MKTAG('I', 'E', 'N', 'D'): |
| 397 | ctx->cur_loop++; |
| 398 | if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) { |
| 399 | avio_seek(pb, -8, SEEK_CUR); |
| 400 | return AVERROR_EOF; |
| 401 | } |
| 402 | if ((ret = avio_seek(pb, s->streams[0]->codec->extradata_size + 8, SEEK_SET)) < 0) |
| 403 | return ret; |
| 404 | return 0; |
| 405 | default: |
| 406 | { |
| 407 | char tag_buf[32]; |
| 408 | |
| 409 | av_get_codec_tag_string(tag_buf, sizeof(tag_buf), tag); |
| 410 | avpriv_request_sample(s, "In-stream tag=%s (0x%08X) len=%"PRIu32, tag_buf, tag, len); |
| 411 | avio_skip(pb, len + 4); |
| 412 | } |
| 413 | } |
| 414 | |
| 415 | /* Handle the unsupported yet cases */ |
| 416 | return AVERROR_PATCHWELCOME; |
| 417 | } |
| 418 | |
| 419 | static const AVOption options[] = { |
| 420 | { "ignore_loop", "ignore loop setting" , offsetof(APNGDemuxContext, ignore_loop), |
| 421 | AV_OPT_TYPE_INT, { .i64 = 1 } , 0, 1 , AV_OPT_FLAG_DECODING_PARAM }, |
| 422 | { "max_fps" , "maximum framerate (0 is no limit)" , offsetof(APNGDemuxContext, max_fps), |
| 423 | AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM }, |
| 424 | { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps), |
| 425 | AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM }, |
| 426 | { NULL }, |
| 427 | }; |
| 428 | |
| 429 | static const AVClass demuxer_class = { |
| 430 | .class_name = "APNG demuxer", |
| 431 | .item_name = av_default_item_name, |
| 432 | .option = options, |
| 433 | .version = LIBAVUTIL_VERSION_INT, |
| 434 | .category = AV_CLASS_CATEGORY_DEMUXER, |
| 435 | }; |
| 436 | |
| 437 | AVInputFormat ff_apng_demuxer = { |
| 438 | .name = "apng", |
| 439 | .long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"), |
| 440 | .priv_data_size = sizeof(APNGDemuxContext), |
| 441 | .read_probe = apng_probe, |
| 442 | .read_header = apng_read_header, |
| 443 | .read_packet = apng_read_packet, |
| 444 | .flags = AVFMT_GENERIC_INDEX, |
| 445 | .priv_class = &demuxer_class, |
| 446 | }; |