summaryrefslogtreecommitdiffstats
path: root/libavformat/apngdec.c
blob: ffff03710a0e441b6ac8fc4c9c87ef5051360bf3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
/*
 * APNG demuxer
 * Copyright (c) 2014 Benoit Fouet
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * APNG demuxer.
 * @see https://wiki.mozilla.org/APNG_Specification
 * @see http://www.w3.org/TR/PNG
 */

#include "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#include "libavutil/imgutils.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "libavcodec/apng.h"
#include "libavcodec/png.h"
#include "libavcodec/bytestream.h"

#define DEFAULT_APNG_FPS 15

typedef struct APNGDemuxContext {
    const AVClass *class;

    int max_fps;
    int default_fps;

    int64_t pkt_pts;
    int pkt_duration;

    int is_key_frame;

    /*
     * loop options
     */
    int ignore_loop;
    uint32_t num_frames;
    uint32_t num_play;
    uint32_t cur_loop;
} APNGDemuxContext;

/*
 * To be a valid APNG file, we mandate, in this order:
 *     PNGSIG
 *     IHDR
 *     ...
 *     acTL
 *     ...
 *     IDAT
 */
static int apng_probe(AVProbeData *p)
{
    GetByteContext gb;
    int state = 0;
    uint32_t len, tag;

    bytestream2_init(&gb, p->buf, p->buf_size);

    if (bytestream2_get_be64(&gb) != PNGSIG)
        return 0;

    for (;;) {
        len = bytestream2_get_be32(&gb);
        if (len > 0x7fffffff)
            return 0;

        tag = bytestream2_get_le32(&gb);
        /* we don't check IDAT size, as this is the last tag
         * we check, and it may be larger than the probe buffer */
        if (tag != MKTAG('I', 'D', 'A', 'T') &&
            len + 4 > bytestream2_get_bytes_left(&gb))
            return 0;

        switch (tag) {
        case MKTAG('I', 'H', 'D', 'R'):
            if (len != 13)
                return 0;
            if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
                return 0;
            bytestream2_skip(&gb, 9);
            state++;
            break;
        case MKTAG('a', 'c', 'T', 'L'):
            if (state != 1 ||
                len != 8 ||
                bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
                return 0;
            bytestream2_skip(&gb, 8);
            state++;
            break;
        case MKTAG('I', 'D', 'A', 'T'):
            if (state != 2)
                return 0;
            goto end;
        default:
            /* skip other tags */
            bytestream2_skip(&gb, len + 4);
            break;
        }
    }

end:
    return AVPROBE_SCORE_MAX;
}

static int append_extradata(AVCodecParameters *par, AVIOContext *pb, int len)
{
    int previous_size = par->extradata_size;
    int new_size, ret;
    uint8_t *new_extradata;

    if (previous_size > INT_MAX - len)
        return AVERROR_INVALIDDATA;

    new_size = previous_size + len;
    new_extradata = av_realloc(par->extradata, new_size + AV_INPUT_BUFFER_PADDING_SIZE);
    if (!new_extradata)
        return AVERROR(ENOMEM);
    par->extradata = new_extradata;
    par->extradata_size = new_size;

    if ((ret = avio_read(pb, par->extradata + previous_size, len)) < 0)
        return ret;

    return previous_size;
}

static int apng_read_header(AVFormatContext *s)
{
    APNGDemuxContext *ctx = s->priv_data;
    AVIOContext *pb = s->pb;
    uint32_t len, tag;
    AVStream *st;
    int acTL_found = 0;
    int64_t ret = AVERROR_INVALIDDATA;

    /* verify PNGSIG */
    if (avio_rb64(pb) != PNGSIG)
        return ret;

    /* parse IHDR (must be first chunk) */
    len = avio_rb32(pb);
    tag = avio_rl32(pb);
    if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R'))
        return ret;

    st = avformat_new_stream(s, NULL);
    if (!st)
        return AVERROR(ENOMEM);

    /* set the timebase to something large enough (1/100,000 of second)
     * to hopefully cope with all sane frame durations */
    avpriv_set_pts_info(st, 64, 1, 100000);
    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
    st->codecpar->codec_id   = AV_CODEC_ID_APNG;
    st->codecpar->width      = avio_rb32(pb);
    st->codecpar->height     = avio_rb32(pb);
    if ((ret = av_image_check_size(st->codecpar->width, st->codecpar->height, 0, s)) < 0)
        return ret;

    /* extradata will contain every chunk up to the first fcTL (excluded) */
    st->codecpar->extradata = av_malloc(len + 12 + AV_INPUT_BUFFER_PADDING_SIZE);
    if (!st->codecpar->extradata)
        return AVERROR(ENOMEM);
    st->codecpar->extradata_size = len + 12;
    AV_WB32(st->codecpar->extradata,    len);
    AV_WL32(st->codecpar->extradata+4,  tag);
    AV_WB32(st->codecpar->extradata+8,  st->codecpar->width);
    AV_WB32(st->codecpar->extradata+12, st->codecpar->height);
    if ((ret = avio_read(pb, st->codecpar->extradata+16, 9)) < 0)
        goto fail;

    while (!avio_feof(pb)) {
        if (acTL_found && ctx->num_play != 1) {
            int64_t size   = avio_size(pb);
            int64_t offset = avio_tell(pb);
            if (size < 0) {
                ret = size;
                goto fail;
            } else if (offset < 0) {
                ret = offset;
                goto fail;
            } else if ((ret = ffio_ensure_seekback(pb, size - offset)) < 0) {
                av_log(s, AV_LOG_WARNING, "Could not ensure seekback, will not loop\n");
                ctx->num_play = 1;
            }
        }
        if ((ctx->num_play == 1 || !acTL_found) &&
            ((ret = ffio_ensure_seekback(pb, 4 /* len */ + 4 /* tag */)) < 0))
            goto fail;

        len = avio_rb32(pb);
        if (len > 0x7fffffff) {
            ret = AVERROR_INVALIDDATA;
            goto fail;
        }

        tag = avio_rl32(pb);
        switch (tag) {
        case MKTAG('a', 'c', 'T', 'L'):
            if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
                (ret = append_extradata(st->codecpar, pb, len + 12)) < 0)
                goto fail;
            acTL_found = 1;
            ctx->num_frames = AV_RB32(st->codecpar->extradata + ret + 8);
            ctx->num_play   = AV_RB32(st->codecpar->extradata + ret + 12);
            av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n",
                                    ctx->num_frames, ctx->num_play);
            break;
        case MKTAG('f', 'c', 'T', 'L'):
            if (!acTL_found) {
               ret = AVERROR_INVALIDDATA;
               goto fail;
            }
            if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
                goto fail;
            return 0;
        default:
            if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
                (ret = append_extradata(st->codecpar, pb, len + 12)) < 0)
                goto fail;
        }
    }

fail:
    if (st->codecpar->extradata_size) {
        av_freep(&st->codecpar->extradata);
        st->codecpar->extradata_size = 0;
    }
    return ret;
}

static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt)
{
    uint32_t sequence_number, width, height, x_offset, y_offset;
    uint16_t delay_num, delay_den;
    uint8_t dispose_op, blend_op;

    sequence_number = avio_rb32(s->pb);
    width           = avio_rb32(s->pb);
    height          = avio_rb32(s->pb);
    x_offset        = avio_rb32(s->pb);
    y_offset        = avio_rb32(s->pb);
    delay_num       = avio_rb16(s->pb);
    delay_den       = avio_rb16(s->pb);
    dispose_op      = avio_r8(s->pb);
    blend_op        = avio_r8(s->pb);
    avio_skip(s->pb, 4); /* crc */

    /* default is hundredths of seconds */
    if (!delay_den)
        delay_den = 100;
    if (!delay_num || (ctx->max_fps && delay_den / delay_num > ctx->max_fps)) {
        delay_num = 1;
        delay_den = ctx->default_fps;
    }
    ctx->pkt_duration = av_rescale_q(delay_num,
                                     (AVRational){ 1, delay_den },
                                     s->streams[0]->time_base);

    av_log(s, AV_LOG_DEBUG, "%s: "
            "sequence_number: %"PRId32", "
            "width: %"PRIu32", "
            "height: %"PRIu32", "
            "x_offset: %"PRIu32", "
            "y_offset: %"PRIu32", "
            "delay_num: %"PRIu16", "
            "delay_den: %"PRIu16", "
            "dispose_op: %d, "
            "blend_op: %d\n",
            __FUNCTION__,
            sequence_number,
            width,
            height,
            x_offset,
            y_offset,
            delay_num,
            delay_den,
            dispose_op,
            blend_op);

    if (width != s->streams[0]->codecpar->width ||
        height != s->streams[0]->codecpar->height ||
        x_offset != 0 ||
        y_offset != 0) {
        if (sequence_number == 0 ||
            x_offset >= s->streams[0]->codecpar->width ||
            width > s->streams[0]->codecpar->width - x_offset ||
            y_offset >= s->streams[0]->codecpar->height ||
            height > s->streams[0]->codecpar->height - y_offset)
            return AVERROR_INVALIDDATA;
        ctx->is_key_frame = 0;
    } else {
        if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS)
            dispose_op = APNG_DISPOSE_OP_BACKGROUND;
        ctx->is_key_frame = dispose_op == APNG_DISPOSE_OP_BACKGROUND ||
                            blend_op   == APNG_BLEND_OP_SOURCE;
    }

    return 0;
}

static int apng_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    APNGDemuxContext *ctx = s->priv_data;
    int64_t ret;
    int64_t size;
    AVIOContext *pb = s->pb;
    uint32_t len, tag;

    /*
     * fcTL chunk length, in bytes:
     *  4 (length)
     *  4 (tag)
     * 26 (actual chunk)
     *  4 (crc) bytes
     * and needed next:
     *  4 (length)
     *  4 (tag (must be fdAT or IDAT))
     */
    /* if num_play is not 1, then the seekback is already guaranteed */
    if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0)
        return ret;

    len = avio_rb32(pb);
    tag = avio_rl32(pb);
    switch (tag) {
    case MKTAG('f', 'c', 'T', 'L'):
        if (len != 26)
            return AVERROR_INVALIDDATA;

        if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0)
            return ret;

        /* fcTL must precede fdAT or IDAT */
        len = avio_rb32(pb);
        tag = avio_rl32(pb);
        if (len > 0x7fffffff ||
            tag != MKTAG('f', 'd', 'A', 'T') &&
            tag != MKTAG('I', 'D', 'A', 'T'))
            return AVERROR_INVALIDDATA;

        size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */;
        if (size > INT_MAX)
            return AVERROR(EINVAL);

        if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0 ||
            (ret = av_append_packet(pb, pkt, size)) < 0)
            return ret;

        if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
            return ret;

        len = avio_rb32(pb);
        tag = avio_rl32(pb);
        while (tag &&
               tag != MKTAG('f', 'c', 'T', 'L') &&
               tag != MKTAG('I', 'E', 'N', 'D')) {
            if (len > 0x7fffffff)
                return AVERROR_INVALIDDATA;
            if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
                (ret = av_append_packet(pb, pkt, len + 12)) < 0)
                return ret;
            if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
                return ret;
            len = avio_rb32(pb);
            tag = avio_rl32(pb);
        }
        if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
            return ret;

        if (ctx->is_key_frame)
            pkt->flags |= AV_PKT_FLAG_KEY;
        pkt->pts = ctx->pkt_pts;
        pkt->duration = ctx->pkt_duration;
        ctx->pkt_pts += ctx->pkt_duration;
        return ret;
    case MKTAG('I', 'E', 'N', 'D'):
        ctx->cur_loop++;
        if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) {
            avio_seek(pb, -8, SEEK_CUR);
            return AVERROR_EOF;
        }
        if ((ret = avio_seek(pb, s->streams[0]->codecpar->extradata_size + 8, SEEK_SET)) < 0)
            return ret;
        return 0;
    default:
        avpriv_request_sample(s, "In-stream tag=%s (0x%08"PRIX32") len=%"PRIu32,
                              av_fourcc2str(tag), tag, len);
        avio_skip(pb, len + 4);
    }

    /* Handle the unsupported yet cases */
    return AVERROR_PATCHWELCOME;
}

static const AVOption options[] = {
    { "ignore_loop", "ignore loop setting"                         , offsetof(APNGDemuxContext, ignore_loop),
      AV_OPT_TYPE_BOOL, { .i64 = 1 }              , 0, 1      , AV_OPT_FLAG_DECODING_PARAM },
    { "max_fps"    , "maximum framerate (0 is no limit)"           , offsetof(APNGDemuxContext, max_fps),
      AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
    { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps),
      AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
    { NULL },
};

static const AVClass demuxer_class = {
    .class_name = "APNG demuxer",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
    .category   = AV_CLASS_CATEGORY_DEMUXER,
};

AVInputFormat ff_apng_demuxer = {
    .name           = "apng",
    .long_name      = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
    .priv_data_size = sizeof(APNGDemuxContext),
    .read_probe     = apng_probe,
    .read_header    = apng_read_header,
    .read_packet    = apng_read_packet,
    .flags          = AVFMT_GENERIC_INDEX,
    .priv_class     = &demuxer_class,
};
OpenPOWER on IntegriCloud