summaryrefslogtreecommitdiffstats
path: root/libavcodec/pngdec.c
blob: 871f2b2ba3f1f710747b260f244910485edf2120 (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
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
/*
 * PNG image format
 * Copyright (c) 2003 Fabrice Bellard
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "png.h"
#include "pngdsp.h"

/* TODO:
 * - add 2, 4 and 16 bit depth support
 */

#include <zlib.h>

//#define DEBUG

typedef struct PNGDecContext {
    PNGDSPContext dsp;

    GetByteContext gb;
    AVFrame picture1, picture2;
    AVFrame *current_picture, *last_picture;

    int state;
    int width, height;
    int bit_depth;
    int color_type;
    int compression_type;
    int interlace_type;
    int filter_type;
    int channels;
    int bits_per_pixel;
    int bpp;

    uint8_t *image_buf;
    int image_linesize;
    uint32_t palette[256];
    uint8_t *crow_buf;
    uint8_t *last_row;
    uint8_t *tmp_row;
    int pass;
    int crow_size; /* compressed row size (include filter type) */
    int row_size; /* decompressed row size */
    int pass_row_size; /* decompress row size of the current pass */
    int y;
    z_stream zstream;
} PNGDecContext;

/* Mask to determine which y pixels can be written in a pass */
static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
    0xff, 0xff, 0x0f, 0xcc, 0x33, 0xff, 0x55,
};

/* Mask to determine which pixels to overwrite while displaying */
static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
    0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
};

/* NOTE: we try to construct a good looking image at each pass. width
   is the original image width. We also do pixel format conversion at
   this stage */
static void png_put_interlaced_row(uint8_t *dst, int width,
                                   int bits_per_pixel, int pass,
                                   int color_type, const uint8_t *src)
{
    int x, mask, dsp_mask, j, src_x, b, bpp;
    uint8_t *d;
    const uint8_t *s;

    mask = ff_png_pass_mask[pass];
    dsp_mask = png_pass_dsp_mask[pass];
    switch(bits_per_pixel) {
    case 1:
        /* we must initialize the line to zero before writing to it */
        if (pass == 0)
            memset(dst, 0, (width + 7) >> 3);
        src_x = 0;
        for(x = 0; x < width; x++) {
            j = (x & 7);
            if ((dsp_mask << j) & 0x80) {
                b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
                dst[x >> 3] |= b << (7 - j);
            }
            if ((mask << j) & 0x80)
                src_x++;
        }
        break;
    default:
        bpp = bits_per_pixel >> 3;
        d = dst;
        s = src;
        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
            for(x = 0; x < width; x++) {
                j = x & 7;
                if ((dsp_mask << j) & 0x80) {
                    *(uint32_t *)d = (s[3] << 24) | (s[0] << 16) | (s[1] << 8) | s[2];
                }
                d += bpp;
                if ((mask << j) & 0x80)
                    s += bpp;
            }
        } else {
            for(x = 0; x < width; x++) {
                j = x & 7;
                if ((dsp_mask << j) & 0x80) {
                    memcpy(d, s, bpp);
                }
                d += bpp;
                if ((mask << j) & 0x80)
                    s += bpp;
            }
        }
        break;
    }
}

void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
{
    int i;
    for(i = 0; i < w; i++) {
        int a, b, c, p, pa, pb, pc;

        a = dst[i - bpp];
        b = top[i];
        c = top[i - bpp];

        p = b - c;
        pc = a - c;

        pa = abs(p);
        pb = abs(pc);
        pc = abs(p + pc);

        if (pa <= pb && pa <= pc)
            p = a;
        else if (pb <= pc)
            p = b;
        else
            p = c;
        dst[i] = p + src[i];
    }
}

#define UNROLL1(bpp, op) {\
                 r = dst[0];\
    if(bpp >= 2) g = dst[1];\
    if(bpp >= 3) b = dst[2];\
    if(bpp >= 4) a = dst[3];\
    for(; i < size; i+=bpp) {\
        dst[i+0] = r = op(r, src[i+0], last[i+0]);\
        if(bpp == 1) continue;\
        dst[i+1] = g = op(g, src[i+1], last[i+1]);\
        if(bpp == 2) continue;\
        dst[i+2] = b = op(b, src[i+2], last[i+2]);\
        if(bpp == 3) continue;\
        dst[i+3] = a = op(a, src[i+3], last[i+3]);\
    }\
}

#define UNROLL_FILTER(op)\
         if(bpp == 1) UNROLL1(1, op)\
    else if(bpp == 2) UNROLL1(2, op)\
    else if(bpp == 3) UNROLL1(3, op)\
    else if(bpp == 4) UNROLL1(4, op)\
    else {\
        for (; i < size; i += bpp) {\
            int j;\
            for (j = 0; j < bpp; j++)\
                dst[i+j] = op(dst[i+j-bpp], src[i+j], last[i+j]);\
        }\
    }

/* NOTE: 'dst' can be equal to 'last' */
static void png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
                           uint8_t *src, uint8_t *last, int size, int bpp)
{
    int i, p, r, g, b, a;

    switch(filter_type) {
    case PNG_FILTER_VALUE_NONE:
        memcpy(dst, src, size);
        break;
    case PNG_FILTER_VALUE_SUB:
        for(i = 0; i < bpp; i++) {
            dst[i] = src[i];
        }
        if(bpp == 4) {
            p = *(int*)dst;
            for(; i < size; i+=bpp) {
                int s = *(int*)(src+i);
                p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);
                *(int*)(dst+i) = p;
            }
        } else {
#define OP_SUB(x,s,l) x+s
            UNROLL_FILTER(OP_SUB);
        }
        break;
    case PNG_FILTER_VALUE_UP:
        dsp->add_bytes_l2(dst, src, last, size);
        break;
    case PNG_FILTER_VALUE_AVG:
        for(i = 0; i < bpp; i++) {
            p = (last[i] >> 1);
            dst[i] = p + src[i];
        }
#define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
        UNROLL_FILTER(OP_AVG);
        break;
    case PNG_FILTER_VALUE_PAETH:
        for(i = 0; i < bpp; i++) {
            p = last[i];
            dst[i] = p + src[i];
        }
        if(bpp > 1 && size > 4) {
            // would write off the end of the array if we let it process the last pixel with bpp=3
            int w = bpp==4 ? size : size-3;
            dsp->add_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);
            i = w;
        }
        ff_add_png_paeth_prediction(dst+i, src+i, last+i, size-i, bpp);
        break;
    }
}

static av_always_inline void convert_to_rgb32_loco(uint8_t *dst, const uint8_t *src, int width, int loco)
{
    int j;
    unsigned int r, g, b, a;

    for(j = 0;j < width; j++) {
        r = src[0];
        g = src[1];
        b = src[2];
        a = src[3];
        if(loco) {
            r = (r+g)&0xff;
            b = (b+g)&0xff;
        }
        *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
        dst += 4;
        src += 4;
    }
}

static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width, int loco)
{
    if(loco)
        convert_to_rgb32_loco(dst, src, width, 1);
    else
        convert_to_rgb32_loco(dst, src, width, 0);
}

static void deloco_rgb24(uint8_t *dst, int size)
{
    int i;
    for(i=0; i<size; i+=3) {
        int g = dst[i+1];
        dst[i+0] += g;
        dst[i+2] += g;
    }
}

/* process exactly one decompressed row */
static void png_handle_row(PNGDecContext *s)
{
    uint8_t *ptr, *last_row;
    int got_line;

    if (!s->interlace_type) {
        ptr = s->image_buf + s->image_linesize * s->y;
        /* need to swap bytes correctly for RGB_ALPHA */
        if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
            png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
                           s->last_row, s->row_size, s->bpp);
            convert_to_rgb32(ptr, s->tmp_row, s->width, s->filter_type == PNG_FILTER_TYPE_LOCO);
            FFSWAP(uint8_t*, s->last_row, s->tmp_row);
        } else {
            /* in normal case, we avoid one copy */
            if (s->y == 0)
                last_row = s->last_row;
            else
                last_row = ptr - s->image_linesize;

            png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
                           last_row, s->row_size, s->bpp);
        }
        /* loco lags by 1 row so that it doesn't interfere with top prediction */
        if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
            s->color_type == PNG_COLOR_TYPE_RGB && s->y > 0)
            deloco_rgb24(ptr - s->image_linesize, s->row_size);
        s->y++;
        if (s->y == s->height) {
            s->state |= PNG_ALLIMAGE;
            if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
                s->color_type == PNG_COLOR_TYPE_RGB)
                deloco_rgb24(ptr, s->row_size);
        }
    } else {
        got_line = 0;
        for(;;) {
            ptr = s->image_buf + s->image_linesize * s->y;
            if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
                /* if we already read one row, it is time to stop to
                   wait for the next one */
                if (got_line)
                    break;
                png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
                               s->last_row, s->pass_row_size, s->bpp);
                FFSWAP(uint8_t*, s->last_row, s->tmp_row);
                got_line = 1;
            }
            if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
                /* NOTE: RGB32 is handled directly in png_put_interlaced_row */
                png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
                                       s->color_type, s->last_row);
            }
            s->y++;
            if (s->y == s->height) {
                for(;;) {
                    if (s->pass == NB_PASSES - 1) {
                        s->state |= PNG_ALLIMAGE;
                        goto the_end;
                    } else {
                        s->pass++;
                        s->y = 0;
                        s->pass_row_size = ff_png_pass_row_size(s->pass,
                                                             s->bits_per_pixel,
                                                             s->width);
                        s->crow_size = s->pass_row_size + 1;
                        if (s->pass_row_size != 0)
                            break;
                        /* skip pass if empty row */
                    }
                }
            }
        }
    the_end: ;
    }
}

static int png_decode_idat(PNGDecContext *s, int length)
{
    int ret;
    s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
    s->zstream.next_in = s->gb.buffer;
    bytestream2_skip(&s->gb, length);

    /* decode one line if possible */
    while (s->zstream.avail_in > 0) {
        ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
        if (ret != Z_OK && ret != Z_STREAM_END) {
            return -1;
        }
        if (s->zstream.avail_out == 0) {
            if (!(s->state & PNG_ALLIMAGE)) {
                png_handle_row(s);
            }
            s->zstream.avail_out = s->crow_size;
            s->zstream.next_out = s->crow_buf;
        }
    }
    return 0;
}

static int decode_frame(AVCodecContext *avctx,
                        void *data, int *data_size,
                        AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    PNGDecContext * const s = avctx->priv_data;
    AVFrame *picture = data;
    AVFrame *p;
    uint8_t *crow_buf_base = NULL;
    uint32_t tag, length;
    int ret;

    FFSWAP(AVFrame *, s->current_picture, s->last_picture);
    avctx->coded_frame= s->current_picture;
    p = s->current_picture;

    /* check signature */
    if (buf_size < 8 ||
        memcmp(buf, ff_pngsig, 8) != 0 &&
        memcmp(buf, ff_mngsig, 8) != 0)
        return -1;

    bytestream2_init(&s->gb, buf + 8, buf_size - 8);
    s->y=
    s->state=0;
//    memset(s, 0, sizeof(PNGDecContext));
    /* init the zlib */
    s->zstream.zalloc = ff_png_zalloc;
    s->zstream.zfree = ff_png_zfree;
    s->zstream.opaque = NULL;
    ret = inflateInit(&s->zstream);
    if (ret != Z_OK)
        return -1;
    for(;;) {
        if (bytestream2_get_bytes_left(&s->gb) <= 0)
            goto fail;
        length = bytestream2_get_be32(&s->gb);
        if (length > 0x7fffffff)
            goto fail;
        tag = bytestream2_get_le32(&s->gb);
        av_dlog(avctx, "png: tag=%c%c%c%c length=%u\n",
                (tag & 0xff),
                ((tag >> 8) & 0xff),
                ((tag >> 16) & 0xff),
                ((tag >> 24) & 0xff), length);
        switch(tag) {
        case MKTAG('I', 'H', 'D', 'R'):
            if (length != 13)
                goto fail;
            s->width  = bytestream2_get_be32(&s->gb);
            s->height = bytestream2_get_be32(&s->gb);
            if(av_image_check_size(s->width, s->height, 0, avctx)){
                s->width= s->height= 0;
                goto fail;
            }
            s->bit_depth        = bytestream2_get_byte(&s->gb);
            s->color_type       = bytestream2_get_byte(&s->gb);
            s->compression_type = bytestream2_get_byte(&s->gb);
            s->filter_type      = bytestream2_get_byte(&s->gb);
            s->interlace_type   = bytestream2_get_byte(&s->gb);
            bytestream2_skip(&s->gb, 4); /* crc */
            s->state |= PNG_IHDR;
            av_dlog(avctx, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
                    s->width, s->height, s->bit_depth, s->color_type,
                    s->compression_type, s->filter_type, s->interlace_type);
            break;
        case MKTAG('I', 'D', 'A', 'T'):
            if (!(s->state & PNG_IHDR))
                goto fail;
            if (!(s->state & PNG_IDAT)) {
                /* init image info */
                avctx->width = s->width;
                avctx->height = s->height;

                s->channels = ff_png_get_nb_channels(s->color_type);
                s->bits_per_pixel = s->bit_depth * s->channels;
                s->bpp = (s->bits_per_pixel + 7) >> 3;
                s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;

                if (s->bit_depth == 8 &&
                    s->color_type == PNG_COLOR_TYPE_RGB) {
                    avctx->pix_fmt = PIX_FMT_RGB24;
                } else if (s->bit_depth == 8 &&
                           s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
                    avctx->pix_fmt = PIX_FMT_RGB32;
                } else if (s->bit_depth == 8 &&
                           s->color_type == PNG_COLOR_TYPE_GRAY) {
                    avctx->pix_fmt = PIX_FMT_GRAY8;
                } else if (s->bit_depth == 16 &&
                           s->color_type == PNG_COLOR_TYPE_GRAY) {
                    avctx->pix_fmt = PIX_FMT_GRAY16BE;
                } else if (s->bit_depth == 16 &&
                           s->color_type == PNG_COLOR_TYPE_RGB) {
                    avctx->pix_fmt = PIX_FMT_RGB48BE;
                } else if (s->bit_depth == 1 &&
                           s->color_type == PNG_COLOR_TYPE_GRAY) {
                    avctx->pix_fmt = PIX_FMT_MONOBLACK;
                } else if (s->bit_depth == 8 &&
                           s->color_type == PNG_COLOR_TYPE_PALETTE) {
                    avctx->pix_fmt = PIX_FMT_PAL8;
                } else if (s->bit_depth == 8 &&
                           s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
                    avctx->pix_fmt = PIX_FMT_Y400A;
                } else {
                    goto fail;
                }
                if(p->data[0])
                    avctx->release_buffer(avctx, p);

                p->reference= 0;
                if(avctx->get_buffer(avctx, p) < 0){
                    av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
                    goto fail;
                }
                p->pict_type= AV_PICTURE_TYPE_I;
                p->key_frame= 1;
                p->interlaced_frame = !!s->interlace_type;

                /* compute the compressed row size */
                if (!s->interlace_type) {
                    s->crow_size = s->row_size + 1;
                } else {
                    s->pass = 0;
                    s->pass_row_size = ff_png_pass_row_size(s->pass,
                                                         s->bits_per_pixel,
                                                         s->width);
                    s->crow_size = s->pass_row_size + 1;
                }
                av_dlog(avctx, "row_size=%d crow_size =%d\n",
                        s->row_size, s->crow_size);
                s->image_buf = p->data[0];
                s->image_linesize = p->linesize[0];
                /* copy the palette if needed */
                if (s->color_type == PNG_COLOR_TYPE_PALETTE)
                    memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
                /* empty row is used if differencing to the first row */
                s->last_row = av_mallocz(s->row_size);
                if (!s->last_row)
                    goto fail;
                if (s->interlace_type ||
                    s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
                    s->tmp_row = av_malloc(s->row_size);
                    if (!s->tmp_row)
                        goto fail;
                }
                /* compressed row */
                crow_buf_base = av_malloc(s->row_size + 16);
                if (!crow_buf_base)
                    goto fail;

                /* we want crow_buf+1 to be 16-byte aligned */
                s->crow_buf = crow_buf_base + 15;
                s->zstream.avail_out = s->crow_size;
                s->zstream.next_out = s->crow_buf;
            }
            s->state |= PNG_IDAT;
            if (png_decode_idat(s, length) < 0)
                goto fail;
            bytestream2_skip(&s->gb, 4); /* crc */
            break;
        case MKTAG('P', 'L', 'T', 'E'):
            {
                int n, i, r, g, b;

                if ((length % 3) != 0 || length > 256 * 3)
                    goto skip_tag;
                /* read the palette */
                n = length / 3;
                for(i=0;i<n;i++) {
                    r = bytestream2_get_byte(&s->gb);
                    g = bytestream2_get_byte(&s->gb);
                    b = bytestream2_get_byte(&s->gb);
                    s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
                }
                for(;i<256;i++) {
                    s->palette[i] = (0xff << 24);
                }
                s->state |= PNG_PLTE;
                bytestream2_skip(&s->gb, 4); /* crc */
            }
            break;
        case MKTAG('t', 'R', 'N', 'S'):
            {
                int v, i;

                /* read the transparency. XXX: Only palette mode supported */
                if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
                    length > 256 ||
                    !(s->state & PNG_PLTE))
                    goto skip_tag;
                for(i=0;i<length;i++) {
                    v = bytestream2_get_byte(&s->gb);
                    s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
                }
                bytestream2_skip(&s->gb, 4); /* crc */
            }
            break;
        case MKTAG('I', 'E', 'N', 'D'):
            if (!(s->state & PNG_ALLIMAGE))
                goto fail;
            bytestream2_skip(&s->gb, 4); /* crc */
            goto exit_loop;
        default:
            /* skip tag */
        skip_tag:
            bytestream2_skip(&s->gb, length + 4);
            break;
        }
    }
 exit_loop:
     /* handle p-frames only if a predecessor frame is available */
     if(s->last_picture->data[0] != NULL) {
         if(!(avpkt->flags & AV_PKT_FLAG_KEY)) {
            int i, j;
            uint8_t *pd = s->current_picture->data[0];
            uint8_t *pd_last = s->last_picture->data[0];

            for(j=0; j < s->height; j++) {
                for(i=0; i < s->width * s->bpp; i++) {
                    pd[i] += pd_last[i];
                }
                pd += s->image_linesize;
                pd_last += s->image_linesize;
            }
        }
    }

    *picture= *s->current_picture;
    *data_size = sizeof(AVFrame);

    ret = bytestream2_tell(&s->gb);
 the_end:
    inflateEnd(&s->zstream);
    av_free(crow_buf_base);
    s->crow_buf = NULL;
    av_freep(&s->last_row);
    av_freep(&s->tmp_row);
    return ret;
 fail:
    ret = -1;
    goto the_end;
}

static av_cold int png_dec_init(AVCodecContext *avctx){
    PNGDecContext *s = avctx->priv_data;

    s->current_picture = &s->picture1;
    s->last_picture = &s->picture2;
    avcodec_get_frame_defaults(&s->picture1);
    avcodec_get_frame_defaults(&s->picture2);
    ff_pngdsp_init(&s->dsp);

    return 0;
}

static av_cold int png_dec_end(AVCodecContext *avctx)
{
    PNGDecContext *s = avctx->priv_data;

    if (s->picture1.data[0])
        avctx->release_buffer(avctx, &s->picture1);
    if (s->picture2.data[0])
        avctx->release_buffer(avctx, &s->picture2);

    return 0;
}

AVCodec ff_png_decoder = {
    .name           = "png",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_PNG,
    .priv_data_size = sizeof(PNGDecContext),
    .init           = png_dec_init,
    .close          = png_dec_end,
    .decode         = decode_frame,
    .capabilities   = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
    .long_name      = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
};
OpenPOWER on IntegriCloud