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libavcodec/pngdec.c

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00001 /*
00002  * PNG image format
00003  * Copyright (c) 2003 Fabrice Bellard
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 #include "libavutil/imgutils.h"
00022 #include "avcodec.h"
00023 #include "bytestream.h"
00024 #include "png.h"
00025 #include "dsputil.h"
00026 
00027 /* TODO:
00028  * - add 2, 4 and 16 bit depth support
00029  */
00030 
00031 #include <zlib.h>
00032 
00033 //#define DEBUG
00034 
00035 typedef struct PNGDecContext {
00036     DSPContext dsp;
00037 
00038     GetByteContext gb;
00039     AVFrame picture1, picture2;
00040     AVFrame *current_picture, *last_picture;
00041 
00042     int state;
00043     int width, height;
00044     int bit_depth;
00045     int color_type;
00046     int compression_type;
00047     int interlace_type;
00048     int filter_type;
00049     int channels;
00050     int bits_per_pixel;
00051     int bpp;
00052 
00053     uint8_t *image_buf;
00054     int image_linesize;
00055     uint32_t palette[256];
00056     uint8_t *crow_buf;
00057     uint8_t *last_row;
00058     uint8_t *tmp_row;
00059     int pass;
00060     int crow_size; /* compressed row size (include filter type) */
00061     int row_size; /* decompressed row size */
00062     int pass_row_size; /* decompress row size of the current pass */
00063     int y;
00064     z_stream zstream;
00065 } PNGDecContext;
00066 
00067 /* Mask to determine which y pixels can be written in a pass */
00068 static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
00069     0xff, 0xff, 0x0f, 0xcc, 0x33, 0xff, 0x55,
00070 };
00071 
00072 /* Mask to determine which pixels to overwrite while displaying */
00073 static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
00074     0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
00075 };
00076 
00077 /* NOTE: we try to construct a good looking image at each pass. width
00078    is the original image width. We also do pixel format conversion at
00079    this stage */
00080 static void png_put_interlaced_row(uint8_t *dst, int width,
00081                                    int bits_per_pixel, int pass,
00082                                    int color_type, const uint8_t *src)
00083 {
00084     int x, mask, dsp_mask, j, src_x, b, bpp;
00085     uint8_t *d;
00086     const uint8_t *s;
00087 
00088     mask = ff_png_pass_mask[pass];
00089     dsp_mask = png_pass_dsp_mask[pass];
00090     switch(bits_per_pixel) {
00091     case 1:
00092         /* we must initialize the line to zero before writing to it */
00093         if (pass == 0)
00094             memset(dst, 0, (width + 7) >> 3);
00095         src_x = 0;
00096         for(x = 0; x < width; x++) {
00097             j = (x & 7);
00098             if ((dsp_mask << j) & 0x80) {
00099                 b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
00100                 dst[x >> 3] |= b << (7 - j);
00101             }
00102             if ((mask << j) & 0x80)
00103                 src_x++;
00104         }
00105         break;
00106     default:
00107         bpp = bits_per_pixel >> 3;
00108         d = dst;
00109         s = src;
00110         if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00111             for(x = 0; x < width; x++) {
00112                 j = x & 7;
00113                 if ((dsp_mask << j) & 0x80) {
00114                     *(uint32_t *)d = (s[3] << 24) | (s[0] << 16) | (s[1] << 8) | s[2];
00115                 }
00116                 d += bpp;
00117                 if ((mask << j) & 0x80)
00118                     s += bpp;
00119             }
00120         } else {
00121             for(x = 0; x < width; x++) {
00122                 j = x & 7;
00123                 if ((dsp_mask << j) & 0x80) {
00124                     memcpy(d, s, bpp);
00125                 }
00126                 d += bpp;
00127                 if ((mask << j) & 0x80)
00128                     s += bpp;
00129             }
00130         }
00131         break;
00132     }
00133 }
00134 
00135 void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
00136 {
00137     int i;
00138     for(i = 0; i < w; i++) {
00139         int a, b, c, p, pa, pb, pc;
00140 
00141         a = dst[i - bpp];
00142         b = top[i];
00143         c = top[i - bpp];
00144 
00145         p = b - c;
00146         pc = a - c;
00147 
00148         pa = abs(p);
00149         pb = abs(pc);
00150         pc = abs(p + pc);
00151 
00152         if (pa <= pb && pa <= pc)
00153             p = a;
00154         else if (pb <= pc)
00155             p = b;
00156         else
00157             p = c;
00158         dst[i] = p + src[i];
00159     }
00160 }
00161 
00162 #define UNROLL1(bpp, op) {\
00163                  r = dst[0];\
00164     if(bpp >= 2) g = dst[1];\
00165     if(bpp >= 3) b = dst[2];\
00166     if(bpp >= 4) a = dst[3];\
00167     for(; i < size; i+=bpp) {\
00168         dst[i+0] = r = op(r, src[i+0], last[i+0]);\
00169         if(bpp == 1) continue;\
00170         dst[i+1] = g = op(g, src[i+1], last[i+1]);\
00171         if(bpp == 2) continue;\
00172         dst[i+2] = b = op(b, src[i+2], last[i+2]);\
00173         if(bpp == 3) continue;\
00174         dst[i+3] = a = op(a, src[i+3], last[i+3]);\
00175     }\
00176 }
00177 
00178 #define UNROLL_FILTER(op)\
00179          if(bpp == 1) UNROLL1(1, op)\
00180     else if(bpp == 2) UNROLL1(2, op)\
00181     else if(bpp == 3) UNROLL1(3, op)\
00182     else if(bpp == 4) UNROLL1(4, op)\
00183     else {\
00184         for (; i < size; i += bpp) {\
00185             int j;\
00186             for (j = 0; j < bpp; j++)\
00187                 dst[i+j] = op(dst[i+j-bpp], src[i+j], last[i+j]);\
00188         }\
00189     }
00190 
00191 /* NOTE: 'dst' can be equal to 'last' */
00192 static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
00193                            uint8_t *src, uint8_t *last, int size, int bpp)
00194 {
00195     int i, p, r, g, b, a;
00196 
00197     switch(filter_type) {
00198     case PNG_FILTER_VALUE_NONE:
00199         memcpy(dst, src, size);
00200         break;
00201     case PNG_FILTER_VALUE_SUB:
00202         for(i = 0; i < bpp; i++) {
00203             dst[i] = src[i];
00204         }
00205         if(bpp == 4) {
00206             p = *(int*)dst;
00207             for(; i < size; i+=bpp) {
00208                 int s = *(int*)(src+i);
00209                 p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);
00210                 *(int*)(dst+i) = p;
00211             }
00212         } else {
00213 #define OP_SUB(x,s,l) x+s
00214             UNROLL_FILTER(OP_SUB);
00215         }
00216         break;
00217     case PNG_FILTER_VALUE_UP:
00218         dsp->add_bytes_l2(dst, src, last, size);
00219         break;
00220     case PNG_FILTER_VALUE_AVG:
00221         for(i = 0; i < bpp; i++) {
00222             p = (last[i] >> 1);
00223             dst[i] = p + src[i];
00224         }
00225 #define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
00226         UNROLL_FILTER(OP_AVG);
00227         break;
00228     case PNG_FILTER_VALUE_PAETH:
00229         for(i = 0; i < bpp; i++) {
00230             p = last[i];
00231             dst[i] = p + src[i];
00232         }
00233         if(bpp > 1 && size > 4) {
00234             // would write off the end of the array if we let it process the last pixel with bpp=3
00235             int w = bpp==4 ? size : size-3;
00236             dsp->add_png_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);
00237             i = w;
00238         }
00239         ff_add_png_paeth_prediction(dst+i, src+i, last+i, size-i, bpp);
00240         break;
00241     }
00242 }
00243 
00244 static av_always_inline void convert_to_rgb32_loco(uint8_t *dst, const uint8_t *src, int width, int loco)
00245 {
00246     int j;
00247     unsigned int r, g, b, a;
00248 
00249     for(j = 0;j < width; j++) {
00250         r = src[0];
00251         g = src[1];
00252         b = src[2];
00253         a = src[3];
00254         if(loco) {
00255             r = (r+g)&0xff;
00256             b = (b+g)&0xff;
00257         }
00258         *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
00259         dst += 4;
00260         src += 4;
00261     }
00262 }
00263 
00264 static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width, int loco)
00265 {
00266     if(loco)
00267         convert_to_rgb32_loco(dst, src, width, 1);
00268     else
00269         convert_to_rgb32_loco(dst, src, width, 0);
00270 }
00271 
00272 static void deloco_rgb24(uint8_t *dst, int size)
00273 {
00274     int i;
00275     for(i=0; i<size; i+=3) {
00276         int g = dst[i+1];
00277         dst[i+0] += g;
00278         dst[i+2] += g;
00279     }
00280 }
00281 
00282 /* process exactly one decompressed row */
00283 static void png_handle_row(PNGDecContext *s)
00284 {
00285     uint8_t *ptr, *last_row;
00286     int got_line;
00287 
00288     if (!s->interlace_type) {
00289         ptr = s->image_buf + s->image_linesize * s->y;
00290         /* need to swap bytes correctly for RGB_ALPHA */
00291         if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00292             png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
00293                            s->last_row, s->row_size, s->bpp);
00294             convert_to_rgb32(ptr, s->tmp_row, s->width, s->filter_type == PNG_FILTER_TYPE_LOCO);
00295             FFSWAP(uint8_t*, s->last_row, s->tmp_row);
00296         } else {
00297             /* in normal case, we avoid one copy */
00298             if (s->y == 0)
00299                 last_row = s->last_row;
00300             else
00301                 last_row = ptr - s->image_linesize;
00302 
00303             png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
00304                            last_row, s->row_size, s->bpp);
00305         }
00306         /* loco lags by 1 row so that it doesn't interfere with top prediction */
00307         if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
00308             s->color_type == PNG_COLOR_TYPE_RGB && s->y > 0)
00309             deloco_rgb24(ptr - s->image_linesize, s->row_size);
00310         s->y++;
00311         if (s->y == s->height) {
00312             s->state |= PNG_ALLIMAGE;
00313             if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
00314                 s->color_type == PNG_COLOR_TYPE_RGB)
00315                 deloco_rgb24(ptr, s->row_size);
00316         }
00317     } else {
00318         got_line = 0;
00319         for(;;) {
00320             ptr = s->image_buf + s->image_linesize * s->y;
00321             if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
00322                 /* if we already read one row, it is time to stop to
00323                    wait for the next one */
00324                 if (got_line)
00325                     break;
00326                 png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
00327                                s->last_row, s->pass_row_size, s->bpp);
00328                 FFSWAP(uint8_t*, s->last_row, s->tmp_row);
00329                 got_line = 1;
00330             }
00331             if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
00332                 /* NOTE: RGB32 is handled directly in png_put_interlaced_row */
00333                 png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
00334                                        s->color_type, s->last_row);
00335             }
00336             s->y++;
00337             if (s->y == s->height) {
00338                 for(;;) {
00339                     if (s->pass == NB_PASSES - 1) {
00340                         s->state |= PNG_ALLIMAGE;
00341                         goto the_end;
00342                     } else {
00343                         s->pass++;
00344                         s->y = 0;
00345                         s->pass_row_size = ff_png_pass_row_size(s->pass,
00346                                                              s->bits_per_pixel,
00347                                                              s->width);
00348                         s->crow_size = s->pass_row_size + 1;
00349                         if (s->pass_row_size != 0)
00350                             break;
00351                         /* skip pass if empty row */
00352                     }
00353                 }
00354             }
00355         }
00356     the_end: ;
00357     }
00358 }
00359 
00360 static int png_decode_idat(PNGDecContext *s, int length)
00361 {
00362     int ret;
00363     s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
00364     s->zstream.next_in = s->gb.buffer;
00365     bytestream2_skip(&s->gb, length);
00366 
00367     /* decode one line if possible */
00368     while (s->zstream.avail_in > 0) {
00369         ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
00370         if (ret != Z_OK && ret != Z_STREAM_END) {
00371             return -1;
00372         }
00373         if (s->zstream.avail_out == 0) {
00374             if (!(s->state & PNG_ALLIMAGE)) {
00375                 png_handle_row(s);
00376             }
00377             s->zstream.avail_out = s->crow_size;
00378             s->zstream.next_out = s->crow_buf;
00379         }
00380     }
00381     return 0;
00382 }
00383 
00384 static int decode_frame(AVCodecContext *avctx,
00385                         void *data, int *data_size,
00386                         AVPacket *avpkt)
00387 {
00388     const uint8_t *buf = avpkt->data;
00389     int buf_size = avpkt->size;
00390     PNGDecContext * const s = avctx->priv_data;
00391     AVFrame *picture = data;
00392     AVFrame *p;
00393     uint8_t *crow_buf_base = NULL;
00394     uint32_t tag, length;
00395     int ret;
00396 
00397     FFSWAP(AVFrame *, s->current_picture, s->last_picture);
00398     avctx->coded_frame= s->current_picture;
00399     p = s->current_picture;
00400 
00401     /* check signature */
00402     if (buf_size < 8 ||
00403         memcmp(buf, ff_pngsig, 8) != 0 &&
00404         memcmp(buf, ff_mngsig, 8) != 0)
00405         return -1;
00406 
00407     bytestream2_init(&s->gb, buf + 8, buf_size - 8);
00408     s->y=
00409     s->state=0;
00410 //    memset(s, 0, sizeof(PNGDecContext));
00411     /* init the zlib */
00412     s->zstream.zalloc = ff_png_zalloc;
00413     s->zstream.zfree = ff_png_zfree;
00414     s->zstream.opaque = NULL;
00415     ret = inflateInit(&s->zstream);
00416     if (ret != Z_OK)
00417         return -1;
00418     for(;;) {
00419         if (bytestream2_get_bytes_left(&s->gb) <= 0)
00420             goto fail;
00421         length = bytestream2_get_be32(&s->gb);
00422         if (length > 0x7fffffff)
00423             goto fail;
00424         tag = bytestream2_get_le32(&s->gb);
00425         av_dlog(avctx, "png: tag=%c%c%c%c length=%u\n",
00426                 (tag & 0xff),
00427                 ((tag >> 8) & 0xff),
00428                 ((tag >> 16) & 0xff),
00429                 ((tag >> 24) & 0xff), length);
00430         switch(tag) {
00431         case MKTAG('I', 'H', 'D', 'R'):
00432             if (length != 13)
00433                 goto fail;
00434             s->width  = bytestream2_get_be32(&s->gb);
00435             s->height = bytestream2_get_be32(&s->gb);
00436             if(av_image_check_size(s->width, s->height, 0, avctx)){
00437                 s->width= s->height= 0;
00438                 goto fail;
00439             }
00440             s->bit_depth        = bytestream2_get_byte(&s->gb);
00441             s->color_type       = bytestream2_get_byte(&s->gb);
00442             s->compression_type = bytestream2_get_byte(&s->gb);
00443             s->filter_type      = bytestream2_get_byte(&s->gb);
00444             s->interlace_type   = bytestream2_get_byte(&s->gb);
00445             bytestream2_skip(&s->gb, 4); /* crc */
00446             s->state |= PNG_IHDR;
00447             av_dlog(avctx, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
00448                     s->width, s->height, s->bit_depth, s->color_type,
00449                     s->compression_type, s->filter_type, s->interlace_type);
00450             break;
00451         case MKTAG('I', 'D', 'A', 'T'):
00452             if (!(s->state & PNG_IHDR))
00453                 goto fail;
00454             if (!(s->state & PNG_IDAT)) {
00455                 /* init image info */
00456                 avctx->width = s->width;
00457                 avctx->height = s->height;
00458 
00459                 s->channels = ff_png_get_nb_channels(s->color_type);
00460                 s->bits_per_pixel = s->bit_depth * s->channels;
00461                 s->bpp = (s->bits_per_pixel + 7) >> 3;
00462                 s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
00463 
00464                 if (s->bit_depth == 8 &&
00465                     s->color_type == PNG_COLOR_TYPE_RGB) {
00466                     avctx->pix_fmt = PIX_FMT_RGB24;
00467                 } else if (s->bit_depth == 8 &&
00468                            s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00469                     avctx->pix_fmt = PIX_FMT_RGB32;
00470                 } else if (s->bit_depth == 8 &&
00471                            s->color_type == PNG_COLOR_TYPE_GRAY) {
00472                     avctx->pix_fmt = PIX_FMT_GRAY8;
00473                 } else if (s->bit_depth == 16 &&
00474                            s->color_type == PNG_COLOR_TYPE_GRAY) {
00475                     avctx->pix_fmt = PIX_FMT_GRAY16BE;
00476                 } else if (s->bit_depth == 16 &&
00477                            s->color_type == PNG_COLOR_TYPE_RGB) {
00478                     avctx->pix_fmt = PIX_FMT_RGB48BE;
00479                 } else if (s->bit_depth == 1 &&
00480                            s->color_type == PNG_COLOR_TYPE_GRAY) {
00481                     avctx->pix_fmt = PIX_FMT_MONOBLACK;
00482                 } else if (s->bit_depth == 8 &&
00483                            s->color_type == PNG_COLOR_TYPE_PALETTE) {
00484                     avctx->pix_fmt = PIX_FMT_PAL8;
00485                 } else if (s->bit_depth == 8 &&
00486                            s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
00487                     avctx->pix_fmt = PIX_FMT_Y400A;
00488                 } else {
00489                     goto fail;
00490                 }
00491                 if(p->data[0])
00492                     avctx->release_buffer(avctx, p);
00493 
00494                 p->reference= 0;
00495                 if(avctx->get_buffer(avctx, p) < 0){
00496                     av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00497                     goto fail;
00498                 }
00499                 p->pict_type= AV_PICTURE_TYPE_I;
00500                 p->key_frame= 1;
00501                 p->interlaced_frame = !!s->interlace_type;
00502 
00503                 /* compute the compressed row size */
00504                 if (!s->interlace_type) {
00505                     s->crow_size = s->row_size + 1;
00506                 } else {
00507                     s->pass = 0;
00508                     s->pass_row_size = ff_png_pass_row_size(s->pass,
00509                                                          s->bits_per_pixel,
00510                                                          s->width);
00511                     s->crow_size = s->pass_row_size + 1;
00512                 }
00513                 av_dlog(avctx, "row_size=%d crow_size =%d\n",
00514                         s->row_size, s->crow_size);
00515                 s->image_buf = p->data[0];
00516                 s->image_linesize = p->linesize[0];
00517                 /* copy the palette if needed */
00518                 if (s->color_type == PNG_COLOR_TYPE_PALETTE)
00519                     memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
00520                 /* empty row is used if differencing to the first row */
00521                 s->last_row = av_mallocz(s->row_size);
00522                 if (!s->last_row)
00523                     goto fail;
00524                 if (s->interlace_type ||
00525                     s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00526                     s->tmp_row = av_malloc(s->row_size);
00527                     if (!s->tmp_row)
00528                         goto fail;
00529                 }
00530                 /* compressed row */
00531                 crow_buf_base = av_malloc(s->row_size + 16);
00532                 if (!crow_buf_base)
00533                     goto fail;
00534 
00535                 /* we want crow_buf+1 to be 16-byte aligned */
00536                 s->crow_buf = crow_buf_base + 15;
00537                 s->zstream.avail_out = s->crow_size;
00538                 s->zstream.next_out = s->crow_buf;
00539             }
00540             s->state |= PNG_IDAT;
00541             if (png_decode_idat(s, length) < 0)
00542                 goto fail;
00543             bytestream2_skip(&s->gb, 4); /* crc */
00544             break;
00545         case MKTAG('P', 'L', 'T', 'E'):
00546             {
00547                 int n, i, r, g, b;
00548 
00549                 if ((length % 3) != 0 || length > 256 * 3)
00550                     goto skip_tag;
00551                 /* read the palette */
00552                 n = length / 3;
00553                 for(i=0;i<n;i++) {
00554                     r = bytestream2_get_byte(&s->gb);
00555                     g = bytestream2_get_byte(&s->gb);
00556                     b = bytestream2_get_byte(&s->gb);
00557                     s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
00558                 }
00559                 for(;i<256;i++) {
00560                     s->palette[i] = (0xff << 24);
00561                 }
00562                 s->state |= PNG_PLTE;
00563                 bytestream2_skip(&s->gb, 4); /* crc */
00564             }
00565             break;
00566         case MKTAG('t', 'R', 'N', 'S'):
00567             {
00568                 int v, i;
00569 
00570                 /* read the transparency. XXX: Only palette mode supported */
00571                 if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
00572                     length > 256 ||
00573                     !(s->state & PNG_PLTE))
00574                     goto skip_tag;
00575                 for(i=0;i<length;i++) {
00576                     v = bytestream2_get_byte(&s->gb);
00577                     s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
00578                 }
00579                 bytestream2_skip(&s->gb, 4); /* crc */
00580             }
00581             break;
00582         case MKTAG('I', 'E', 'N', 'D'):
00583             if (!(s->state & PNG_ALLIMAGE))
00584                 goto fail;
00585             bytestream2_skip(&s->gb, 4); /* crc */
00586             goto exit_loop;
00587         default:
00588             /* skip tag */
00589         skip_tag:
00590             bytestream2_skip(&s->gb, length + 4);
00591             break;
00592         }
00593     }
00594  exit_loop:
00595      /* handle p-frames only if a predecessor frame is available */
00596      if(s->last_picture->data[0] != NULL) {
00597          if(!(avpkt->flags & AV_PKT_FLAG_KEY)) {
00598             int i, j;
00599             uint8_t *pd = s->current_picture->data[0];
00600             uint8_t *pd_last = s->last_picture->data[0];
00601 
00602             for(j=0; j < s->height; j++) {
00603                 for(i=0; i < s->width * s->bpp; i++) {
00604                     pd[i] += pd_last[i];
00605                 }
00606                 pd += s->image_linesize;
00607                 pd_last += s->image_linesize;
00608             }
00609         }
00610     }
00611 
00612     *picture= *s->current_picture;
00613     *data_size = sizeof(AVFrame);
00614 
00615     ret = bytestream2_tell(&s->gb);
00616  the_end:
00617     inflateEnd(&s->zstream);
00618     av_free(crow_buf_base);
00619     s->crow_buf = NULL;
00620     av_freep(&s->last_row);
00621     av_freep(&s->tmp_row);
00622     return ret;
00623  fail:
00624     ret = -1;
00625     goto the_end;
00626 }
00627 
00628 static av_cold int png_dec_init(AVCodecContext *avctx){
00629     PNGDecContext *s = avctx->priv_data;
00630 
00631     s->current_picture = &s->picture1;
00632     s->last_picture = &s->picture2;
00633     avcodec_get_frame_defaults(&s->picture1);
00634     avcodec_get_frame_defaults(&s->picture2);
00635     dsputil_init(&s->dsp, avctx);
00636 
00637     return 0;
00638 }
00639 
00640 static av_cold int png_dec_end(AVCodecContext *avctx)
00641 {
00642     PNGDecContext *s = avctx->priv_data;
00643 
00644     if (s->picture1.data[0])
00645         avctx->release_buffer(avctx, &s->picture1);
00646     if (s->picture2.data[0])
00647         avctx->release_buffer(avctx, &s->picture2);
00648 
00649     return 0;
00650 }
00651 
00652 AVCodec ff_png_decoder = {
00653     .name           = "png",
00654     .type           = AVMEDIA_TYPE_VIDEO,
00655     .id             = CODEC_ID_PNG,
00656     .priv_data_size = sizeof(PNGDecContext),
00657     .init           = png_dec_init,
00658     .close          = png_dec_end,
00659     .decode         = decode_frame,
00660     .capabilities   = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
00661     .long_name = NULL_IF_CONFIG_SMALL("PNG image"),
00662 };
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