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ffmpeg / libavcodec / pngdec.c @ 2912e87a

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1
/*
2
 * PNG image format
3
 * Copyright (c) 2003 Fabrice Bellard
4
 *
5
 * This file is part of Libav.
6
 *
7
 * Libav 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
 * Libav 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
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20
 */
21
#include "libavutil/imgutils.h"
22
#include "avcodec.h"
23
#include "bytestream.h"
24
#include "png.h"
25
#include "dsputil.h"
26

    
27
/* TODO:
28
 * - add 2, 4 and 16 bit depth support
29
 */
30

    
31
#include <zlib.h>
32

    
33
//#define DEBUG
34

    
35
typedef struct PNGDecContext {
36
    DSPContext dsp;
37

    
38
    const uint8_t *bytestream;
39
    const uint8_t *bytestream_start;
40
    const uint8_t *bytestream_end;
41
    AVFrame picture1, picture2;
42
    AVFrame *current_picture, *last_picture;
43

    
44
    int state;
45
    int width, height;
46
    int bit_depth;
47
    int color_type;
48
    int compression_type;
49
    int interlace_type;
50
    int filter_type;
51
    int channels;
52
    int bits_per_pixel;
53
    int bpp;
54

    
55
    uint8_t *image_buf;
56
    int image_linesize;
57
    uint32_t palette[256];
58
    uint8_t *crow_buf;
59
    uint8_t *last_row;
60
    uint8_t *tmp_row;
61
    int pass;
62
    int crow_size; /* compressed row size (include filter type) */
63
    int row_size; /* decompressed row size */
64
    int pass_row_size; /* decompress row size of the current pass */
65
    int y;
66
    z_stream zstream;
67
} PNGDecContext;
68

    
69
/* Mask to determine which y pixels can be written in a pass */
70
static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
71
    0xff, 0xff, 0x0f, 0xcc, 0x33, 0xff, 0x55,
72
};
73

    
74
/* Mask to determine which pixels to overwrite while displaying */
75
static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
76
    0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
77
};
78

    
79
/* NOTE: we try to construct a good looking image at each pass. width
80
   is the original image width. We also do pixel format conversion at
81
   this stage */
82
static void png_put_interlaced_row(uint8_t *dst, int width,
83
                                   int bits_per_pixel, int pass,
84
                                   int color_type, const uint8_t *src)
85
{
86
    int x, mask, dsp_mask, j, src_x, b, bpp;
87
    uint8_t *d;
88
    const uint8_t *s;
89

    
90
    mask = ff_png_pass_mask[pass];
91
    dsp_mask = png_pass_dsp_mask[pass];
92
    switch(bits_per_pixel) {
93
    case 1:
94
        /* we must initialize the line to zero before writing to it */
95
        if (pass == 0)
96
            memset(dst, 0, (width + 7) >> 3);
97
        src_x = 0;
98
        for(x = 0; x < width; x++) {
99
            j = (x & 7);
100
            if ((dsp_mask << j) & 0x80) {
101
                b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
102
                dst[x >> 3] |= b << (7 - j);
103
            }
104
            if ((mask << j) & 0x80)
105
                src_x++;
106
        }
107
        break;
108
    default:
109
        bpp = bits_per_pixel >> 3;
110
        d = dst;
111
        s = src;
112
        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
113
            for(x = 0; x < width; x++) {
114
                j = x & 7;
115
                if ((dsp_mask << j) & 0x80) {
116
                    *(uint32_t *)d = (s[3] << 24) | (s[0] << 16) | (s[1] << 8) | s[2];
117
                }
118
                d += bpp;
119
                if ((mask << j) & 0x80)
120
                    s += bpp;
121
            }
122
        } else {
123
            for(x = 0; x < width; x++) {
124
                j = x & 7;
125
                if ((dsp_mask << j) & 0x80) {
126
                    memcpy(d, s, bpp);
127
                }
128
                d += bpp;
129
                if ((mask << j) & 0x80)
130
                    s += bpp;
131
            }
132
        }
133
        break;
134
    }
135
}
136

    
137
void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
138
{
139
    int i;
140
    for(i = 0; i < w; i++) {
141
        int a, b, c, p, pa, pb, pc;
142

    
143
        a = dst[i - bpp];
144
        b = top[i];
145
        c = top[i - bpp];
146

    
147
        p = b - c;
148
        pc = a - c;
149

    
150
        pa = abs(p);
151
        pb = abs(pc);
152
        pc = abs(p + pc);
153

    
154
        if (pa <= pb && pa <= pc)
155
            p = a;
156
        else if (pb <= pc)
157
            p = b;
158
        else
159
            p = c;
160
        dst[i] = p + src[i];
161
    }
162
}
163

    
164
#define UNROLL1(bpp, op) {\
165
                 r = dst[0];\
166
    if(bpp >= 2) g = dst[1];\
167
    if(bpp >= 3) b = dst[2];\
168
    if(bpp >= 4) a = dst[3];\
169
    for(; i < size; i+=bpp) {\
170
        dst[i+0] = r = op(r, src[i+0], last[i+0]);\
171
        if(bpp == 1) continue;\
172
        dst[i+1] = g = op(g, src[i+1], last[i+1]);\
173
        if(bpp == 2) continue;\
174
        dst[i+2] = b = op(b, src[i+2], last[i+2]);\
175
        if(bpp == 3) continue;\
176
        dst[i+3] = a = op(a, src[i+3], last[i+3]);\
177
    }\
178
}
179

    
180
#define UNROLL_FILTER(op)\
181
         if(bpp == 1) UNROLL1(1, op)\
182
    else if(bpp == 2) UNROLL1(2, op)\
183
    else if(bpp == 3) UNROLL1(3, op)\
184
    else if(bpp == 4) UNROLL1(4, op)\
185
    else {\
186
        for (; i < size; i += bpp) {\
187
            int j;\
188
            for (j = 0; j < bpp; j++)\
189
                dst[i+j] = op(dst[i+j-bpp], src[i+j], last[i+j]);\
190
        }\
191
    }
192

    
193
/* NOTE: 'dst' can be equal to 'last' */
194
static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
195
                           uint8_t *src, uint8_t *last, int size, int bpp)
196
{
197
    int i, p, r, g, b, a;
198

    
199
    switch(filter_type) {
200
    case PNG_FILTER_VALUE_NONE:
201
        memcpy(dst, src, size);
202
        break;
203
    case PNG_FILTER_VALUE_SUB:
204
        for(i = 0; i < bpp; i++) {
205
            dst[i] = src[i];
206
        }
207
        if(bpp == 4) {
208
            p = *(int*)dst;
209
            for(; i < size; i+=bpp) {
210
                int s = *(int*)(src+i);
211
                p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);
212
                *(int*)(dst+i) = p;
213
            }
214
        } else {
215
#define OP_SUB(x,s,l) x+s
216
            UNROLL_FILTER(OP_SUB);
217
        }
218
        break;
219
    case PNG_FILTER_VALUE_UP:
220
        dsp->add_bytes_l2(dst, src, last, size);
221
        break;
222
    case PNG_FILTER_VALUE_AVG:
223
        for(i = 0; i < bpp; i++) {
224
            p = (last[i] >> 1);
225
            dst[i] = p + src[i];
226
        }
227
#define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
228
        UNROLL_FILTER(OP_AVG);
229
        break;
230
    case PNG_FILTER_VALUE_PAETH:
231
        for(i = 0; i < bpp; i++) {
232
            p = last[i];
233
            dst[i] = p + src[i];
234
        }
235
        if(bpp > 1 && size > 4) {
236
            // would write off the end of the array if we let it process the last pixel with bpp=3
237
            int w = bpp==4 ? size : size-3;
238
            dsp->add_png_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);
239
            i = w;
240
        }
241
        ff_add_png_paeth_prediction(dst+i, src+i, last+i, size-i, bpp);
242
        break;
243
    }
244
}
245

    
246
static av_always_inline void convert_to_rgb32_loco(uint8_t *dst, const uint8_t *src, int width, int loco)
247
{
248
    int j;
249
    unsigned int r, g, b, a;
250

    
251
    for(j = 0;j < width; j++) {
252
        r = src[0];
253
        g = src[1];
254
        b = src[2];
255
        a = src[3];
256
        if(loco) {
257
            r = (r+g)&0xff;
258
            b = (b+g)&0xff;
259
        }
260
        *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
261
        dst += 4;
262
        src += 4;
263
    }
264
}
265

    
266
static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width, int loco)
267
{
268
    if(loco)
269
        convert_to_rgb32_loco(dst, src, width, 1);
270
    else
271
        convert_to_rgb32_loco(dst, src, width, 0);
272
}
273

    
274
static void deloco_rgb24(uint8_t *dst, int size)
275
{
276
    int i;
277
    for(i=0; i<size; i+=3) {
278
        int g = dst[i+1];
279
        dst[i+0] += g;
280
        dst[i+2] += g;
281
    }
282
}
283

    
284
/* process exactly one decompressed row */
285
static void png_handle_row(PNGDecContext *s)
286
{
287
    uint8_t *ptr, *last_row;
288
    int got_line;
289

    
290
    if (!s->interlace_type) {
291
        ptr = s->image_buf + s->image_linesize * s->y;
292
        /* need to swap bytes correctly for RGB_ALPHA */
293
        if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
294
            png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
295
                           s->last_row, s->row_size, s->bpp);
296
            convert_to_rgb32(ptr, s->tmp_row, s->width, s->filter_type == PNG_FILTER_TYPE_LOCO);
297
            FFSWAP(uint8_t*, s->last_row, s->tmp_row);
298
        } else {
299
            /* in normal case, we avoid one copy */
300
            if (s->y == 0)
301
                last_row = s->last_row;
302
            else
303
                last_row = ptr - s->image_linesize;
304

    
305
            png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
306
                           last_row, s->row_size, s->bpp);
307
        }
308
        /* loco lags by 1 row so that it doesn't interfere with top prediction */
309
        if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
310
            s->color_type == PNG_COLOR_TYPE_RGB && s->y > 0)
311
            deloco_rgb24(ptr - s->image_linesize, s->row_size);
312
        s->y++;
313
        if (s->y == s->height) {
314
            s->state |= PNG_ALLIMAGE;
315
            if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
316
                s->color_type == PNG_COLOR_TYPE_RGB)
317
                deloco_rgb24(ptr, s->row_size);
318
        }
319
    } else {
320
        got_line = 0;
321
        for(;;) {
322
            ptr = s->image_buf + s->image_linesize * s->y;
323
            if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
324
                /* if we already read one row, it is time to stop to
325
                   wait for the next one */
326
                if (got_line)
327
                    break;
328
                png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
329
                               s->last_row, s->pass_row_size, s->bpp);
330
                FFSWAP(uint8_t*, s->last_row, s->tmp_row);
331
                got_line = 1;
332
            }
333
            if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
334
                /* NOTE: RGB32 is handled directly in png_put_interlaced_row */
335
                png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
336
                                       s->color_type, s->last_row);
337
            }
338
            s->y++;
339
            if (s->y == s->height) {
340
                for(;;) {
341
                    if (s->pass == NB_PASSES - 1) {
342
                        s->state |= PNG_ALLIMAGE;
343
                        goto the_end;
344
                    } else {
345
                        s->pass++;
346
                        s->y = 0;
347
                        s->pass_row_size = ff_png_pass_row_size(s->pass,
348
                                                             s->bits_per_pixel,
349
                                                             s->width);
350
                        s->crow_size = s->pass_row_size + 1;
351
                        if (s->pass_row_size != 0)
352
                            break;
353
                        /* skip pass if empty row */
354
                    }
355
                }
356
            }
357
        }
358
    the_end: ;
359
    }
360
}
361

    
362
static int png_decode_idat(PNGDecContext *s, int length)
363
{
364
    int ret;
365
    s->zstream.avail_in = length;
366
    s->zstream.next_in = s->bytestream;
367
    s->bytestream += length;
368

    
369
    if(s->bytestream > s->bytestream_end)
370
        return -1;
371

    
372
    /* decode one line if possible */
373
    while (s->zstream.avail_in > 0) {
374
        ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
375
        if (ret != Z_OK && ret != Z_STREAM_END) {
376
            return -1;
377
        }
378
        if (s->zstream.avail_out == 0) {
379
            if (!(s->state & PNG_ALLIMAGE)) {
380
                png_handle_row(s);
381
            }
382
            s->zstream.avail_out = s->crow_size;
383
            s->zstream.next_out = s->crow_buf;
384
        }
385
    }
386
    return 0;
387
}
388

    
389
static int decode_frame(AVCodecContext *avctx,
390
                        void *data, int *data_size,
391
                        AVPacket *avpkt)
392
{
393
    const uint8_t *buf = avpkt->data;
394
    int buf_size = avpkt->size;
395
    PNGDecContext * const s = avctx->priv_data;
396
    AVFrame *picture = data;
397
    AVFrame *p;
398
    uint8_t *crow_buf_base = NULL;
399
    uint32_t tag, length;
400
    int ret, crc;
401

    
402
    FFSWAP(AVFrame *, s->current_picture, s->last_picture);
403
    avctx->coded_frame= s->current_picture;
404
    p = s->current_picture;
405

    
406
    s->bytestream_start=
407
    s->bytestream= buf;
408
    s->bytestream_end= buf + buf_size;
409

    
410
    /* check signature */
411
    if (memcmp(s->bytestream, ff_pngsig, 8) != 0 &&
412
        memcmp(s->bytestream, ff_mngsig, 8) != 0)
413
        return -1;
414
    s->bytestream+= 8;
415
    s->y=
416
    s->state=0;
417
//    memset(s, 0, sizeof(PNGDecContext));
418
    /* init the zlib */
419
    s->zstream.zalloc = ff_png_zalloc;
420
    s->zstream.zfree = ff_png_zfree;
421
    s->zstream.opaque = NULL;
422
    ret = inflateInit(&s->zstream);
423
    if (ret != Z_OK)
424
        return -1;
425
    for(;;) {
426
        int tag32;
427
        if (s->bytestream >= s->bytestream_end)
428
            goto fail;
429
        length = bytestream_get_be32(&s->bytestream);
430
        if (length > 0x7fffffff)
431
            goto fail;
432
        tag32 = bytestream_get_be32(&s->bytestream);
433
        tag = av_bswap32(tag32);
434
        av_dlog(avctx, "png: tag=%c%c%c%c length=%u\n",
435
                (tag & 0xff),
436
                ((tag >> 8) & 0xff),
437
                ((tag >> 16) & 0xff),
438
                ((tag >> 24) & 0xff), length);
439
        switch(tag) {
440
        case MKTAG('I', 'H', 'D', 'R'):
441
            if (length != 13)
442
                goto fail;
443
            s->width = bytestream_get_be32(&s->bytestream);
444
            s->height = bytestream_get_be32(&s->bytestream);
445
            if(av_image_check_size(s->width, s->height, 0, avctx)){
446
                s->width= s->height= 0;
447
                goto fail;
448
            }
449
            s->bit_depth = *s->bytestream++;
450
            s->color_type = *s->bytestream++;
451
            s->compression_type = *s->bytestream++;
452
            s->filter_type = *s->bytestream++;
453
            s->interlace_type = *s->bytestream++;
454
            crc = bytestream_get_be32(&s->bytestream);
455
            s->state |= PNG_IHDR;
456
            av_dlog(avctx, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
457
                    s->width, s->height, s->bit_depth, s->color_type,
458
                    s->compression_type, s->filter_type, s->interlace_type);
459
            break;
460
        case MKTAG('I', 'D', 'A', 'T'):
461
            if (!(s->state & PNG_IHDR))
462
                goto fail;
463
            if (!(s->state & PNG_IDAT)) {
464
                /* init image info */
465
                avctx->width = s->width;
466
                avctx->height = s->height;
467

    
468
                s->channels = ff_png_get_nb_channels(s->color_type);
469
                s->bits_per_pixel = s->bit_depth * s->channels;
470
                s->bpp = (s->bits_per_pixel + 7) >> 3;
471
                s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
472

    
473
                if (s->bit_depth == 8 &&
474
                    s->color_type == PNG_COLOR_TYPE_RGB) {
475
                    avctx->pix_fmt = PIX_FMT_RGB24;
476
                } else if (s->bit_depth == 8 &&
477
                           s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
478
                    avctx->pix_fmt = PIX_FMT_RGB32;
479
                } else if (s->bit_depth == 8 &&
480
                           s->color_type == PNG_COLOR_TYPE_GRAY) {
481
                    avctx->pix_fmt = PIX_FMT_GRAY8;
482
                } else if (s->bit_depth == 16 &&
483
                           s->color_type == PNG_COLOR_TYPE_GRAY) {
484
                    avctx->pix_fmt = PIX_FMT_GRAY16BE;
485
                } else if (s->bit_depth == 16 &&
486
                           s->color_type == PNG_COLOR_TYPE_RGB) {
487
                    avctx->pix_fmt = PIX_FMT_RGB48BE;
488
                } else if (s->bit_depth == 1 &&
489
                           s->color_type == PNG_COLOR_TYPE_GRAY) {
490
                    avctx->pix_fmt = PIX_FMT_MONOBLACK;
491
                } else if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
492
                    avctx->pix_fmt = PIX_FMT_PAL8;
493
                } else if (s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
494
                    avctx->pix_fmt = PIX_FMT_Y400A;
495
                } else {
496
                    goto fail;
497
                }
498
                if(p->data[0])
499
                    avctx->release_buffer(avctx, p);
500

    
501
                p->reference= 0;
502
                if(avctx->get_buffer(avctx, p) < 0){
503
                    av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
504
                    goto fail;
505
                }
506
                p->pict_type= FF_I_TYPE;
507
                p->key_frame= 1;
508
                p->interlaced_frame = !!s->interlace_type;
509

    
510
                /* compute the compressed row size */
511
                if (!s->interlace_type) {
512
                    s->crow_size = s->row_size + 1;
513
                } else {
514
                    s->pass = 0;
515
                    s->pass_row_size = ff_png_pass_row_size(s->pass,
516
                                                         s->bits_per_pixel,
517
                                                         s->width);
518
                    s->crow_size = s->pass_row_size + 1;
519
                }
520
                av_dlog(avctx, "row_size=%d crow_size =%d\n",
521
                        s->row_size, s->crow_size);
522
                s->image_buf = p->data[0];
523
                s->image_linesize = p->linesize[0];
524
                /* copy the palette if needed */
525
                if (s->color_type == PNG_COLOR_TYPE_PALETTE)
526
                    memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
527
                /* empty row is used if differencing to the first row */
528
                s->last_row = av_mallocz(s->row_size);
529
                if (!s->last_row)
530
                    goto fail;
531
                if (s->interlace_type ||
532
                    s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
533
                    s->tmp_row = av_malloc(s->row_size);
534
                    if (!s->tmp_row)
535
                        goto fail;
536
                }
537
                /* compressed row */
538
                crow_buf_base = av_malloc(s->row_size + 16);
539
                if (!crow_buf_base)
540
                    goto fail;
541

    
542
                /* we want crow_buf+1 to be 16-byte aligned */
543
                s->crow_buf = crow_buf_base + 15;
544
                s->zstream.avail_out = s->crow_size;
545
                s->zstream.next_out = s->crow_buf;
546
            }
547
            s->state |= PNG_IDAT;
548
            if (png_decode_idat(s, length) < 0)
549
                goto fail;
550
            /* skip crc */
551
            crc = bytestream_get_be32(&s->bytestream);
552
            break;
553
        case MKTAG('P', 'L', 'T', 'E'):
554
            {
555
                int n, i, r, g, b;
556

    
557
                if ((length % 3) != 0 || length > 256 * 3)
558
                    goto skip_tag;
559
                /* read the palette */
560
                n = length / 3;
561
                for(i=0;i<n;i++) {
562
                    r = *s->bytestream++;
563
                    g = *s->bytestream++;
564
                    b = *s->bytestream++;
565
                    s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
566
                }
567
                for(;i<256;i++) {
568
                    s->palette[i] = (0xff << 24);
569
                }
570
                s->state |= PNG_PLTE;
571
                crc = bytestream_get_be32(&s->bytestream);
572
            }
573
            break;
574
        case MKTAG('t', 'R', 'N', 'S'):
575
            {
576
                int v, i;
577

    
578
                /* read the transparency. XXX: Only palette mode supported */
579
                if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
580
                    length > 256 ||
581
                    !(s->state & PNG_PLTE))
582
                    goto skip_tag;
583
                for(i=0;i<length;i++) {
584
                    v = *s->bytestream++;
585
                    s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
586
                }
587
                crc = bytestream_get_be32(&s->bytestream);
588
            }
589
            break;
590
        case MKTAG('I', 'E', 'N', 'D'):
591
            if (!(s->state & PNG_ALLIMAGE))
592
                goto fail;
593
            crc = bytestream_get_be32(&s->bytestream);
594
            goto exit_loop;
595
        default:
596
            /* skip tag */
597
        skip_tag:
598
            s->bytestream += length + 4;
599
            break;
600
        }
601
    }
602
 exit_loop:
603
     /* handle p-frames only if a predecessor frame is available */
604
     if(s->last_picture->data[0] != NULL) {
605
         if(!(avpkt->flags & AV_PKT_FLAG_KEY)) {
606
            int i, j;
607
            uint8_t *pd = s->current_picture->data[0];
608
            uint8_t *pd_last = s->last_picture->data[0];
609

    
610
            for(j=0; j < s->height; j++) {
611
                for(i=0; i < s->width * s->bpp; i++) {
612
                    pd[i] += pd_last[i];
613
                }
614
                pd += s->image_linesize;
615
                pd_last += s->image_linesize;
616
            }
617
        }
618
    }
619

    
620
    *picture= *s->current_picture;
621
    *data_size = sizeof(AVFrame);
622

    
623
    ret = s->bytestream - s->bytestream_start;
624
 the_end:
625
    inflateEnd(&s->zstream);
626
    av_free(crow_buf_base);
627
    s->crow_buf = NULL;
628
    av_freep(&s->last_row);
629
    av_freep(&s->tmp_row);
630
    return ret;
631
 fail:
632
    ret = -1;
633
    goto the_end;
634
}
635

    
636
static av_cold int png_dec_init(AVCodecContext *avctx){
637
    PNGDecContext *s = avctx->priv_data;
638

    
639
    s->current_picture = &s->picture1;
640
    s->last_picture = &s->picture2;
641
    avcodec_get_frame_defaults(&s->picture1);
642
    avcodec_get_frame_defaults(&s->picture2);
643
    dsputil_init(&s->dsp, avctx);
644

    
645
    return 0;
646
}
647

    
648
static av_cold int png_dec_end(AVCodecContext *avctx)
649
{
650
    PNGDecContext *s = avctx->priv_data;
651

    
652
    if (s->picture1.data[0])
653
        avctx->release_buffer(avctx, &s->picture1);
654
    if (s->picture2.data[0])
655
        avctx->release_buffer(avctx, &s->picture2);
656

    
657
    return 0;
658
}
659

    
660
AVCodec ff_png_decoder = {
661
    "png",
662
    AVMEDIA_TYPE_VIDEO,
663
    CODEC_ID_PNG,
664
    sizeof(PNGDecContext),
665
    png_dec_init,
666
    NULL,
667
    png_dec_end,
668
    decode_frame,
669
    CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
670
    NULL,
671
    .max_lowres = 5,
672
    .long_name = NULL_IF_CONFIG_SMALL("PNG image"),
673
};