libavformat/apngdec.c

   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 "demux.h"
  32 #include "internal.h"
  33 #include "libavutil/imgutils.h"
  34 #include "libavutil/intreadwrite.h"
  35 #include "libavutil/mem.h"
  36 #include "libavutil/opt.h"
  37 #include "libavcodec/apng.h"
  38 #include "libavcodec/png.h"
  39 #include "libavcodec/bytestream.h"
  40
  41 #define DEFAULT_APNG_FPS 15
  42
  43 typedef struct APNGDemuxContext {
  44     const AVClass *class;
  45
  46     int max_fps;
  47     int default_fps;
  48
  49     int pkt_duration;
  50
  51     int is_key_frame;
  52
  53     /*
  54      * loop options
  55      */
  56     int ignore_loop;
  57     uint32_t num_frames;
  58     uint32_t num_play;
  59     uint32_t cur_loop;
  60 } APNGDemuxContext;
  61
  62 /*
  63  * To be a valid APNG file, we mandate, in this order:
  64  *     PNGSIG
  65  *     IHDR
  66  *     ...
  67  *     acTL
  68  *     ...
  69  *     IDAT
  70  */
  71 static int apng_probe(const AVProbeData *p)
  72 {
  73     GetByteContext gb;
  74     int state = 0;
  75     uint32_t len, tag;
  76
  77     bytestream2_init(&gb, p->buf, p->buf_size);
  78
  79     if (bytestream2_get_be64(&gb) != PNGSIG)
  80         return 0;
  81
  82     for (;;) {
  83         len = bytestream2_get_be32(&gb);
  84         if (len > 0x7fffffff)
  85             return 0;
  86
  87         tag = bytestream2_get_le32(&gb);
  88         /* we don't check IDAT size, as this is the last tag
  89          * we check, and it may be larger than the probe buffer */
  90         if (tag != MKTAG('I', 'D', 'A', 'T') &&
  91             len + 4 > bytestream2_get_bytes_left(&gb))
  92             return 0;
  93
  94         switch (tag) {
  95         case MKTAG('I', 'H', 'D', 'R'):
  96             if (len != 13)
  97                 return 0;
  98             if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
  99                 return 0;
 100             bytestream2_skip(&gb, 9);
 101             state++;
 102             break;
 103         case MKTAG('a', 'c', 'T', 'L'):
 104             if (state != 1 ||
 105                 len != 8 ||
 106                 bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
 107                 return 0;
 108             bytestream2_skip(&gb, 8);
 109             state++;
 110             break;
 111         case MKTAG('I', 'D', 'A', 'T'):
 112             if (state != 2)
 113                 return 0;
 114             goto end;
 115         default:
 116             /* skip other tags */
 117             bytestream2_skip(&gb, len + 4);
 118             break;
 119         }
 120     }
 121
 122 end:
 123     return AVPROBE_SCORE_MAX;
 124 }
 125
 126 static int append_extradata(AVCodecParameters *par, AVIOContext *pb, int len)
 127 {
 128     int previous_size = par->extradata_size;
 129     int new_size, ret;
 130     uint8_t *new_extradata;
 131
 132     if (len > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE - previous_size)
 133         return AVERROR_INVALIDDATA;
 134
 135     new_size = previous_size + len;
 136     new_extradata = av_realloc(par->extradata, new_size + AV_INPUT_BUFFER_PADDING_SIZE);
 137     if (!new_extradata)
 138         return AVERROR(ENOMEM);
 139     memset(new_extradata + new_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
 140     par->extradata = new_extradata;
 141     par->extradata_size = new_size;
 142
 143     if ((ret = ffio_read_size(pb, par->extradata + previous_size, len)) < 0)
 144         return ret;
 145
 146     return previous_size;
 147 }
 148
 149 static int apng_read_header(AVFormatContext *s)
 150 {
 151     APNGDemuxContext *ctx = s->priv_data;
 152     AVIOContext *pb = s->pb;
 153     uint32_t len, tag;
 154     AVStream *st;
 155     int acTL_found = 0;
 156     int64_t ret;
 157
 158     /* verify PNGSIG */
 159     if (avio_rb64(pb) != PNGSIG)
 160         return AVERROR_INVALIDDATA;
 161
 162     /* parse IHDR (must be first chunk) */
 163     len = avio_rb32(pb);
 164     tag = avio_rl32(pb);
 165     if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R'))
 166         return AVERROR_INVALIDDATA;
 167
 168     st = avformat_new_stream(s, NULL);
 169     if (!st)
 170         return AVERROR(ENOMEM);
 171
 172     /* set the timebase to something large enough (1/100,000 of second)
 173      * to hopefully cope with all sane frame durations */
 174     avpriv_set_pts_info(st, 64, 1, 100000);
 175     st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
 176     st->codecpar->codec_id   = AV_CODEC_ID_APNG;
 177     st->codecpar->width      = avio_rb32(pb);
 178     st->codecpar->height     = avio_rb32(pb);
 179     if ((ret = av_image_check_size(st->codecpar->width, st->codecpar->height, 0, s)) < 0)
 180         return ret;
 181
 182     /* extradata will contain every chunk up to the first fcTL (excluded) */
 183     ret = ff_alloc_extradata(st->codecpar, len + 12);
 184     if (ret < 0)
 185         return ret;
 186     AV_WB32(st->codecpar->extradata,    len);
 187     AV_WL32(st->codecpar->extradata+4,  tag);
 188     AV_WB32(st->codecpar->extradata+8,  st->codecpar->width);
 189     AV_WB32(st->codecpar->extradata+12, st->codecpar->height);
 190     if ((ret = ffio_read_size(pb, st->codecpar->extradata + 16, 9)) < 0)
 191         return ret;
 192
 193     while (1) {
 194         if (acTL_found && ctx->num_play != 1) {
 195             int64_t size   = avio_size(pb);
 196             int64_t offset = avio_tell(pb);
 197             if (size < 0) {
 198                 return size;
 199             } else if (offset < 0) {
 200                 return offset;
 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             return ret;
 209
 210         len = avio_rb32(pb);
 211         if (len > INT_MAX - 12)
 212             return AVERROR_INVALIDDATA;
 213
 214         tag = avio_rl32(pb);
 215         switch (tag) {
 216         case MKTAG('a', 'c', 'T', 'L'):
 217             if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
 218                 (ret = append_extradata(st->codecpar, pb, len + 12)) < 0)
 219                 return ret;
 220             acTL_found = 1;
 221             ctx->num_frames = AV_RB32(st->codecpar->extradata + ret + 8);
 222             ctx->num_play   = AV_RB32(st->codecpar->extradata + ret + 12);
 223             av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n",
 224                                     ctx->num_frames, ctx->num_play);
 225             break;
 226         case MKTAG('f', 'c', 'T', 'L'):
 227             if (!acTL_found || len != APNG_FCTL_CHUNK_SIZE) {
 228                 return AVERROR_INVALIDDATA;
 229             }
 230             if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
 231                 return ret;
 232             return 0;
 233         default:
 234             if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
 235                 (ret = append_extradata(st->codecpar, pb, len + 12)) < 0)
 236                 return ret;
 237         }
 238     }
 239 }
 240
 241 static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt)
 242 {
 243     uint32_t sequence_number, width, height, x_offset, y_offset;
 244     uint16_t delay_num, delay_den;
 245     uint8_t dispose_op, blend_op;
 246
 247     sequence_number = avio_rb32(s->pb);
 248     width           = avio_rb32(s->pb);
 249     height          = avio_rb32(s->pb);
 250     x_offset        = avio_rb32(s->pb);
 251     y_offset        = avio_rb32(s->pb);
 252     delay_num       = avio_rb16(s->pb);
 253     delay_den       = avio_rb16(s->pb);
 254     dispose_op      = avio_r8(s->pb);
 255     blend_op        = avio_r8(s->pb);
 256     avio_skip(s->pb, 4); /* crc */
 257
 258     /* default is hundredths of seconds */
 259     if (!delay_den)
 260         delay_den = 100;
 261     if (!delay_num || (ctx->max_fps && delay_den / delay_num > ctx->max_fps)) {
 262         delay_num = 1;
 263         delay_den = ctx->default_fps;
 264     }
 265     ctx->pkt_duration = av_rescale_q(delay_num,
 266                                      (AVRational){ 1, delay_den },
 267                                      s->streams[0]->time_base);
 268
 269     av_log(s, AV_LOG_DEBUG, "%s: "
 270             "sequence_number: %"PRId32", "
 271             "width: %"PRIu32", "
 272             "height: %"PRIu32", "
 273             "x_offset: %"PRIu32", "
 274             "y_offset: %"PRIu32", "
 275             "delay_num: %"PRIu16", "
 276             "delay_den: %"PRIu16", "
 277             "dispose_op: %d, "
 278             "blend_op: %d\n",
 279             __func__,
 280             sequence_number,
 281             width,
 282             height,
 283             x_offset,
 284             y_offset,
 285             delay_num,
 286             delay_den,
 287             dispose_op,
 288             blend_op);
 289
 290     if (width != s->streams[0]->codecpar->width ||
 291         height != s->streams[0]->codecpar->height ||
 292         x_offset != 0 ||
 293         y_offset != 0) {
 294         if (sequence_number == 0 ||
 295             x_offset >= s->streams[0]->codecpar->width ||
 296             width > s->streams[0]->codecpar->width - x_offset ||
 297             y_offset >= s->streams[0]->codecpar->height ||
 298             height > s->streams[0]->codecpar->height - y_offset)
 299             return AVERROR_INVALIDDATA;
 300         ctx->is_key_frame = 0;
 301     } else {
 302         if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS)
 303             dispose_op = APNG_DISPOSE_OP_BACKGROUND;
 304         ctx->is_key_frame = dispose_op == APNG_DISPOSE_OP_BACKGROUND ||
 305                             blend_op   == APNG_BLEND_OP_SOURCE;
 306     }
 307
 308     return 0;
 309 }
 310
 311 static int apng_read_packet(AVFormatContext *s, AVPacket *pkt)
 312 {
 313     APNGDemuxContext *ctx = s->priv_data;
 314     int64_t ret;
 315     int64_t size;
 316     AVIOContext *pb = s->pb;
 317     uint32_t len, tag;
 318
 319     /*
 320      * fcTL chunk length, in bytes:
 321      *  4 (length)
 322      *  4 (tag)
 323      * 26 (actual chunk)
 324      *  4 (crc) bytes
 325      * and needed next:
 326      *  4 (length)
 327      *  4 (tag (must be fdAT or IDAT))
 328      */
 329     /* if num_play is not 1, then the seekback is already guaranteed */
 330     if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0)
 331         return ret;
 332
 333     len = avio_rb32(pb);
 334     tag = avio_rl32(pb);
 335
 336     if (avio_feof(pb))
 337         return AVERROR_EOF;
 338
 339     switch (tag) {
 340     case MKTAG('f', 'c', 'T', 'L'):
 341         if (len != APNG_FCTL_CHUNK_SIZE)
 342             return AVERROR_INVALIDDATA;
 343
 344         if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0)
 345             return ret;
 346
 347         /* fcTL must precede fdAT or IDAT */
 348         len = avio_rb32(pb);
 349         tag = avio_rl32(pb);
 350         if (len > 0x7fffffff ||
 351             tag != MKTAG('f', 'd', 'A', 'T') &&
 352             tag != MKTAG('I', 'D', 'A', 'T'))
 353             return AVERROR_INVALIDDATA;
 354
 355         size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */;
 356         if (size > INT_MAX)
 357             return AVERROR(EINVAL);
 358
 359         if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0 ||
 360             (ret = av_append_packet(pb, pkt, size)) < 0)
 361             return ret;
 362
 363         if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
 364             return ret;
 365
 366         len = avio_rb32(pb);
 367         tag = avio_rl32(pb);
 368         while (tag &&
 369                tag != MKTAG('f', 'c', 'T', 'L') &&
 370                tag != MKTAG('I', 'E', 'N', 'D')) {
 371             if (len > 0x7fffffff)
 372                 return AVERROR_INVALIDDATA;
 373             if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
 374                 (ret = av_append_packet(pb, pkt, len + 12)) < 0)
 375                 return ret;
 376             if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
 377                 return ret;
 378             len = avio_rb32(pb);
 379             tag = avio_rl32(pb);
 380         }
 381         if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
 382             return ret;
 383
 384         if (ctx->is_key_frame)
 385             pkt->flags |= AV_PKT_FLAG_KEY;
 386         pkt->pts = pkt->dts = AV_NOPTS_VALUE;
 387         pkt->duration = ctx->pkt_duration;
 388         return ret;
 389     case MKTAG('I', 'E', 'N', 'D'):
 390         ctx->cur_loop++;
 391         if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) {
 392             avio_seek(pb, -8, SEEK_CUR);
 393             return AVERROR_EOF;
 394         }
 395         if ((ret = avio_seek(pb, s->streams[0]->codecpar->extradata_size + 8, SEEK_SET)) < 0)
 396             return ret;
 397         return 0;
 398     default:
 399         avpriv_request_sample(s, "In-stream tag=%s (0x%08"PRIX32") len=%"PRIu32,
 400                               av_fourcc2str(tag), tag, len);
 401         avio_skip(pb, len + 4);
 402     }
 403
 404     /* Handle the unsupported yet cases */
 405     return AVERROR_PATCHWELCOME;
 406 }
 407
 408 static const AVOption options[] = {
 409     { "ignore_loop", "ignore loop setting"                         , offsetof(APNGDemuxContext, ignore_loop),
 410       AV_OPT_TYPE_BOOL, { .i64 = 1 }              , 0, 1      , AV_OPT_FLAG_DECODING_PARAM },
 411     { "max_fps"    , "maximum framerate (0 is no limit)"           , offsetof(APNGDemuxContext, max_fps),
 412       AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
 413     { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps),
 414       AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
 415     { NULL },
 416 };
 417
 418 static const AVClass demuxer_class = {
 419     .class_name = "APNG demuxer",
 420     .item_name  = av_default_item_name,
 421     .option     = options,
 422     .version    = LIBAVUTIL_VERSION_INT,
 423     .category   = AV_CLASS_CATEGORY_DEMUXER,
 424 };
 425
 426 const FFInputFormat ff_apng_demuxer = {
 427     .p.name         = "apng",
 428     .p.long_name    = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
 429     .p.flags        = AVFMT_GENERIC_INDEX,
 430     .p.priv_class   = &demuxer_class,
 431     .priv_data_size = sizeof(APNGDemuxContext),
 432     .read_probe     = apng_probe,
 433     .read_header    = apng_read_header,
 434     .read_packet    = apng_read_packet,
 435 };