FFmpeg: libavcodec/pngdec.c Source File

00001 /*
00002  * PNG image format
00003  * Copyright (c) 2003 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 //#define DEBUG
00023 
00024 #include "libavutil/imgutils.h"
00025 #include "avcodec.h"
00026 #include "bytestream.h"
00027 #include "png.h"
00028 #include "pngdsp.h"
00029 
00030 /* TODO:
00031  * - add 16 bit depth support
00032  */
00033 
00034 #include <zlib.h>
00035 
00036 //#define DEBUG
00037 
00038 typedef struct PNGDecContext {
00039     PNGDSPContext dsp;
00040     AVCodecContext *avctx;
00041 
00042     GetByteContext gb;
00043     AVFrame picture1, picture2;
00044     AVFrame *current_picture, *last_picture;
00045 
00046     int state;
00047     int width, height;
00048     int bit_depth;
00049     int color_type;
00050     int compression_type;
00051     int interlace_type;
00052     int filter_type;
00053     int channels;
00054     int bits_per_pixel;
00055     int bpp;
00056 
00057     uint8_t *image_buf;
00058     int image_linesize;
00059     uint32_t palette[256];
00060     uint8_t *crow_buf;
00061     uint8_t *last_row;
00062     uint8_t *tmp_row;
00063     int pass;
00064     int crow_size; /* compressed row size (include filter type) */
00065     int row_size; /* decompressed row size */
00066     int pass_row_size; /* decompress row size of the current pass */
00067     int y;
00068     z_stream zstream;
00069 } PNGDecContext;
00070 
00071 /* Mask to determine which pixels are valid in a pass */
00072 static const uint8_t png_pass_mask[NB_PASSES] = {
00073     0x01, 0x01, 0x11, 0x11, 0x55, 0x55, 0xff,
00074 };
00075 
00076 /* Mask to determine which y pixels can be written in a pass */
00077 static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
00078     0xff, 0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
00079 };
00080 
00081 /* Mask to determine which pixels to overwrite while displaying */
00082 static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
00083     0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
00084 };
00085 
00086 /* NOTE: we try to construct a good looking image at each pass. width
00087    is the original image width. We also do pixel format conversion at
00088    this stage */
00089 static void png_put_interlaced_row(uint8_t *dst, int width,
00090                                    int bits_per_pixel, int pass,
00091                                    int color_type, const uint8_t *src)
00092 {
00093     int x, mask, dsp_mask, j, src_x, b, bpp;
00094     uint8_t *d;
00095     const uint8_t *s;
00096 
00097     mask = png_pass_mask[pass];
00098     dsp_mask = png_pass_dsp_mask[pass];
00099     switch(bits_per_pixel) {
00100     case 1:
00101         src_x = 0;
00102         for(x = 0; x < width; x++) {
00103             j = (x & 7);
00104             if ((dsp_mask << j) & 0x80) {
00105                 b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
00106                 dst[x >> 3] &= 0xFF7F>>j;
00107                 dst[x >> 3] |= b << (7 - j);
00108             }
00109             if ((mask << j) & 0x80)
00110                 src_x++;
00111         }
00112         break;
00113     case 2:
00114         src_x = 0;
00115         for(x = 0; x < width; x++) {
00116             int j2 = 2*(x&3);
00117             j = (x & 7);
00118             if ((dsp_mask << j) & 0x80) {
00119                 b = (src[src_x >> 2] >> (6 - 2*(src_x & 3))) & 3;
00120                 dst[x >> 2] &= 0xFF3F>>j2;
00121                 dst[x >> 2] |= b << (6 - j2);
00122             }
00123             if ((mask << j) & 0x80)
00124                 src_x++;
00125         }
00126         break;
00127     case 4:
00128         src_x = 0;
00129         for(x = 0; x < width; x++) {
00130             int j2 = 4*(x&1);
00131             j = (x & 7);
00132             if ((dsp_mask << j) & 0x80) {
00133                 b = (src[src_x >> 1] >> (4 - 4*(src_x & 1))) & 15;
00134                 dst[x >> 1] &= 0xFF0F>>j2;
00135                 dst[x >> 1] |= b << (4 - j2);
00136             }
00137             if ((mask << j) & 0x80)
00138                 src_x++;
00139         }
00140         break;
00141     default:
00142         bpp = bits_per_pixel >> 3;
00143         d = dst;
00144         s = src;
00145             for(x = 0; x < width; x++) {
00146                 j = x & 7;
00147                 if ((dsp_mask << j) & 0x80) {
00148                     memcpy(d, s, bpp);
00149                 }
00150                 d += bpp;
00151                 if ((mask << j) & 0x80)
00152                     s += bpp;
00153             }
00154         break;
00155     }
00156 }
00157 
00158 void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
00159 {
00160     int i;
00161     for(i = 0; i < w; i++) {
00162         int a, b, c, p, pa, pb, pc;
00163 
00164         a = dst[i - bpp];
00165         b = top[i];
00166         c = top[i - bpp];
00167 
00168         p = b - c;
00169         pc = a - c;
00170 
00171         pa = abs(p);
00172         pb = abs(pc);
00173         pc = abs(p + pc);
00174 
00175         if (pa <= pb && pa <= pc)
00176             p = a;
00177         else if (pb <= pc)
00178             p = b;
00179         else
00180             p = c;
00181         dst[i] = p + src[i];
00182     }
00183 }
00184 
00185 #define UNROLL1(bpp, op) {\
00186                  r = dst[0];\
00187     if(bpp >= 2) g = dst[1];\
00188     if(bpp >= 3) b = dst[2];\
00189     if(bpp >= 4) a = dst[3];\
00190     for(; i < size; i+=bpp) {\
00191         dst[i+0] = r = op(r, src[i+0], last[i+0]);\
00192         if(bpp == 1) continue;\
00193         dst[i+1] = g = op(g, src[i+1], last[i+1]);\
00194         if(bpp == 2) continue;\
00195         dst[i+2] = b = op(b, src[i+2], last[i+2]);\
00196         if(bpp == 3) continue;\
00197         dst[i+3] = a = op(a, src[i+3], last[i+3]);\
00198     }\
00199 }
00200 
00201 #define UNROLL_FILTER(op)\
00202          if(bpp == 1) UNROLL1(1, op)\
00203     else if(bpp == 2) UNROLL1(2, op)\
00204     else if(bpp == 3) UNROLL1(3, op)\
00205     else if(bpp == 4) UNROLL1(4, op)\
00206     else {\
00207         for (; i < size; i += bpp) {\
00208             int j;\
00209             for (j = 0; j < bpp; j++)\
00210                 dst[i+j] = op(dst[i+j-bpp], src[i+j], last[i+j]);\
00211         }\
00212     }
00213 
00214 /* NOTE: 'dst' can be equal to 'last' */
00215 static void png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
00216                            uint8_t *src, uint8_t *last, int size, int bpp)
00217 {
00218     int i, p, r, g, b, a;
00219 
00220     switch(filter_type) {
00221     case PNG_FILTER_VALUE_NONE:
00222         memcpy(dst, src, size);
00223         break;
00224     case PNG_FILTER_VALUE_SUB:
00225         for(i = 0; i < bpp; i++) {
00226             dst[i] = src[i];
00227         }
00228         if(bpp == 4) {
00229             p = *(int*)dst;
00230             for(; i < size; i+=bpp) {
00231                 int s = *(int*)(src+i);
00232                 p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);
00233                 *(int*)(dst+i) = p;
00234             }
00235         } else {
00236 #define OP_SUB(x,s,l) x+s
00237             UNROLL_FILTER(OP_SUB);
00238         }
00239         break;
00240     case PNG_FILTER_VALUE_UP:
00241         dsp->add_bytes_l2(dst, src, last, size);
00242         break;
00243     case PNG_FILTER_VALUE_AVG:
00244         for(i = 0; i < bpp; i++) {
00245             p = (last[i] >> 1);
00246             dst[i] = p + src[i];
00247         }
00248 #define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
00249         UNROLL_FILTER(OP_AVG);
00250         break;
00251     case PNG_FILTER_VALUE_PAETH:
00252         for(i = 0; i < bpp; i++) {
00253             p = last[i];
00254             dst[i] = p + src[i];
00255         }
00256         if(bpp > 2 && size > 4) {
00257             // would write off the end of the array if we let it process the last pixel with bpp=3
00258             int w = bpp==4 ? size : size-3;
00259             dsp->add_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);
00260             i = w;
00261         }
00262         ff_add_png_paeth_prediction(dst+i, src+i, last+i, size-i, bpp);
00263         break;
00264     }
00265 }
00266 
00267 /* This used to be called "deloco" in FFmpeg
00268  * and is actually an inverse reversible colorspace transformation */
00269 #define YUV2RGB(NAME, TYPE) \
00270 static void deloco_ ## NAME(TYPE *dst, int size, int alpha) \
00271 { \
00272     int i; \
00273     for (i = 0; i < size; i += 3 + alpha) { \
00274         int g = dst [i+1]; \
00275         dst[i+0] += g; \
00276         dst[i+2] += g; \
00277     } \
00278 }
00279 
00280 YUV2RGB(rgb8, uint8_t)
00281 YUV2RGB(rgb16, uint16_t)
00282 
00283 /* process exactly one decompressed row */
00284 static void png_handle_row(PNGDecContext *s)
00285 {
00286     uint8_t *ptr, *last_row;
00287     int got_line;
00288 
00289     if (!s->interlace_type) {
00290         ptr = s->image_buf + s->image_linesize * s->y;
00291             if (s->y == 0)
00292                 last_row = s->last_row;
00293             else
00294                 last_row = ptr - s->image_linesize;
00295 
00296             png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
00297                            last_row, s->row_size, s->bpp);
00298         /* loco lags by 1 row so that it doesn't interfere with top prediction */
00299         if (s->filter_type == PNG_FILTER_TYPE_LOCO && s->y > 0) {
00300             if (s->bit_depth == 16) {
00301                 deloco_rgb16((uint16_t *)(ptr - s->image_linesize), s->row_size / 2,
00302                              s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
00303             } else {
00304                 deloco_rgb8(ptr - s->image_linesize, s->row_size,
00305                             s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
00306             }
00307         }
00308         s->y++;
00309         if (s->y == s->height) {
00310             s->state |= PNG_ALLIMAGE;
00311             if (s->filter_type == PNG_FILTER_TYPE_LOCO) {
00312                 if (s->bit_depth == 16) {
00313                     deloco_rgb16((uint16_t *)ptr, s->row_size / 2,
00314                                  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
00315                 } else {
00316                     deloco_rgb8(ptr, s->row_size,
00317                                 s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
00318                 }
00319             }
00320         }
00321     } else {
00322         got_line = 0;
00323         for(;;) {
00324             ptr = s->image_buf + s->image_linesize * s->y;
00325             if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
00326                 /* if we already read one row, it is time to stop to
00327                    wait for the next one */
00328                 if (got_line)
00329                     break;
00330                 png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
00331                                s->last_row, s->pass_row_size, s->bpp);
00332                 FFSWAP(uint8_t*, s->last_row, s->tmp_row);
00333                 got_line = 1;
00334             }
00335             if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
00336                 png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
00337                                        s->color_type, s->last_row);
00338             }
00339             s->y++;
00340             if (s->y == s->height) {
00341                 memset(s->last_row, 0, s->row_size);
00342                 for(;;) {
00343                     if (s->pass == NB_PASSES - 1) {
00344                         s->state |= PNG_ALLIMAGE;
00345                         goto the_end;
00346                     } else {
00347                         s->pass++;
00348                         s->y = 0;
00349                         s->pass_row_size = ff_png_pass_row_size(s->pass,
00350                                                              s->bits_per_pixel,
00351                                                              s->width);
00352                         s->crow_size = s->pass_row_size + 1;
00353                         if (s->pass_row_size != 0)
00354                             break;
00355                         /* skip pass if empty row */
00356                     }
00357                 }
00358             }
00359         }
00360     the_end: ;
00361     }
00362 }
00363 
00364 static int png_decode_idat(PNGDecContext *s, int length)
00365 {
00366     int ret;
00367     s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
00368     s->zstream.next_in = (unsigned char *)s->gb.buffer;
00369     bytestream2_skip(&s->gb, length);
00370 
00371     /* decode one line if possible */
00372     while (s->zstream.avail_in > 0) {
00373         ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
00374         if (ret != Z_OK && ret != Z_STREAM_END) {
00375             av_log(s->avctx, AV_LOG_ERROR, "inflate returned %d\n", ret);
00376             return -1;
00377         }
00378         if (s->zstream.avail_out == 0) {
00379             if (!(s->state & PNG_ALLIMAGE)) {
00380                 png_handle_row(s);
00381             }
00382             s->zstream.avail_out = s->crow_size;
00383             s->zstream.next_out = s->crow_buf;
00384         }
00385     }
00386     return 0;
00387 }
00388 
00389 static int decode_frame(AVCodecContext *avctx,
00390                         void *data, int *data_size,
00391                         AVPacket *avpkt)
00392 {
00393     const uint8_t *buf = avpkt->data;
00394     int buf_size = avpkt->size;
00395     PNGDecContext * const s = avctx->priv_data;
00396     AVFrame *picture = data;
00397     AVFrame *p;
00398     uint8_t *crow_buf_base = NULL;
00399     uint32_t tag, length;
00400     int64_t sig;
00401     int ret;
00402 
00403     FFSWAP(AVFrame *, s->current_picture, s->last_picture);
00404     avctx->coded_frame= s->current_picture;
00405     p = s->current_picture;
00406 
00407     bytestream2_init(&s->gb, buf, buf_size);
00408 
00409     /* check signature */
00410     sig = bytestream2_get_be64(&s->gb);
00411     if (sig != PNGSIG &&
00412         sig != MNGSIG) {
00413         av_log(avctx, AV_LOG_ERROR, "Missing png signature\n");
00414         return -1;
00415     }
00416 
00417     s->y=
00418     s->state=0;
00419 //    memset(s, 0, sizeof(PNGDecContext));
00420     /* init the zlib */
00421     s->zstream.zalloc = ff_png_zalloc;
00422     s->zstream.zfree = ff_png_zfree;
00423     s->zstream.opaque = NULL;
00424     ret = inflateInit(&s->zstream);
00425     if (ret != Z_OK) {
00426         av_log(avctx, AV_LOG_ERROR, "inflateInit returned %d\n", ret);
00427         return -1;
00428     }
00429     for(;;) {
00430         if (bytestream2_get_bytes_left(&s->gb) <= 0) {
00431             av_log(avctx, AV_LOG_ERROR, "No bytes left\n");
00432             goto fail;
00433         }
00434 
00435         length = bytestream2_get_be32(&s->gb);
00436         if (length > 0x7fffffff || length > bytestream2_get_bytes_left(&s->gb))  {
00437             av_log(avctx, AV_LOG_ERROR, "chunk too big\n");
00438             goto fail;
00439         }
00440         tag = bytestream2_get_le32(&s->gb);
00441         if (avctx->debug & FF_DEBUG_STARTCODE)
00442             av_log(avctx, AV_LOG_DEBUG, "png: tag=%c%c%c%c length=%u\n",
00443                 (tag & 0xff),
00444                 ((tag >> 8) & 0xff),
00445                 ((tag >> 16) & 0xff),
00446                 ((tag >> 24) & 0xff), length);
00447         switch(tag) {
00448         case MKTAG('I', 'H', 'D', 'R'):
00449             if (length != 13)
00450                 goto fail;
00451             s->width  = bytestream2_get_be32(&s->gb);
00452             s->height = bytestream2_get_be32(&s->gb);
00453             if(av_image_check_size(s->width, s->height, 0, avctx)){
00454                 s->width= s->height= 0;
00455                 av_log(avctx, AV_LOG_ERROR, "Invalid image size\n");
00456                 goto fail;
00457             }
00458             s->bit_depth        = bytestream2_get_byte(&s->gb);
00459             s->color_type       = bytestream2_get_byte(&s->gb);
00460             s->compression_type = bytestream2_get_byte(&s->gb);
00461             s->filter_type      = bytestream2_get_byte(&s->gb);
00462             s->interlace_type   = bytestream2_get_byte(&s->gb);
00463             bytestream2_skip(&s->gb, 4); /* crc */
00464             s->state |= PNG_IHDR;
00465             if (avctx->debug & FF_DEBUG_PICT_INFO)
00466                 av_log(avctx, AV_LOG_DEBUG, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
00467                     s->width, s->height, s->bit_depth, s->color_type,
00468                     s->compression_type, s->filter_type, s->interlace_type);
00469             break;
00470         case MKTAG('I', 'D', 'A', 'T'):
00471             if (!(s->state & PNG_IHDR)) {
00472                 av_log(avctx, AV_LOG_ERROR, "IDAT without IHDR\n");
00473                 goto fail;
00474             }
00475             if (!(s->state & PNG_IDAT)) {
00476                 /* init image info */
00477                 avctx->width = s->width;
00478                 avctx->height = s->height;
00479 
00480                 s->channels = ff_png_get_nb_channels(s->color_type);
00481                 s->bits_per_pixel = s->bit_depth * s->channels;
00482                 s->bpp = (s->bits_per_pixel + 7) >> 3;
00483                 s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
00484 
00485                 if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
00486                     s->color_type == PNG_COLOR_TYPE_RGB) {
00487                     avctx->pix_fmt = PIX_FMT_RGB24;
00488                 } else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
00489                            s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00490                     avctx->pix_fmt = PIX_FMT_RGBA;
00491                 } else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
00492                            s->color_type == PNG_COLOR_TYPE_GRAY) {
00493                     avctx->pix_fmt = PIX_FMT_GRAY8;
00494                 } else if (s->bit_depth == 16 &&
00495                            s->color_type == PNG_COLOR_TYPE_GRAY) {
00496                     avctx->pix_fmt = PIX_FMT_GRAY16BE;
00497                 } else if (s->bit_depth == 16 &&
00498                            s->color_type == PNG_COLOR_TYPE_RGB) {
00499                     avctx->pix_fmt = PIX_FMT_RGB48BE;
00500                 } else if (s->bit_depth == 16 &&
00501                            s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00502                     avctx->pix_fmt = PIX_FMT_RGBA64BE;
00503                 } else if ((s->bits_per_pixel == 1 || s->bits_per_pixel == 2 || s->bits_per_pixel == 4 || s->bits_per_pixel == 8) &&
00504                            s->color_type == PNG_COLOR_TYPE_PALETTE) {
00505                     avctx->pix_fmt = PIX_FMT_PAL8;
00506                 } else if (s->bit_depth == 1) {
00507                     avctx->pix_fmt = PIX_FMT_MONOBLACK;
00508                 } else if (s->bit_depth == 8 &&
00509                            s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
00510                     avctx->pix_fmt = PIX_FMT_Y400A;
00511                 } else {
00512                     av_log(avctx, AV_LOG_ERROR, "unsupported bit depth %d "
00513                                                 "and color type %d\n",
00514                                                  s->bit_depth, s->color_type);
00515                     goto fail;
00516                 }
00517                 if(p->data[0])
00518                     avctx->release_buffer(avctx, p);
00519 
00520                 p->reference= 3;
00521                 if(avctx->get_buffer(avctx, p) < 0){
00522                     av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00523                     goto fail;
00524                 }
00525                 p->pict_type= AV_PICTURE_TYPE_I;
00526                 p->key_frame= 1;
00527                 p->interlaced_frame = !!s->interlace_type;
00528 
00529                 /* compute the compressed row size */
00530                 if (!s->interlace_type) {
00531                     s->crow_size = s->row_size + 1;
00532                 } else {
00533                     s->pass = 0;
00534                     s->pass_row_size = ff_png_pass_row_size(s->pass,
00535                                                          s->bits_per_pixel,
00536                                                          s->width);
00537                     s->crow_size = s->pass_row_size + 1;
00538                 }
00539                 av_dlog(avctx, "row_size=%d crow_size =%d\n",
00540                         s->row_size, s->crow_size);
00541                 s->image_buf = p->data[0];
00542                 s->image_linesize = p->linesize[0];
00543                 /* copy the palette if needed */
00544                 if (avctx->pix_fmt == PIX_FMT_PAL8)
00545                     memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
00546                 /* empty row is used if differencing to the first row */
00547                 s->last_row = av_mallocz(s->row_size);
00548                 if (!s->last_row)
00549                     goto fail;
00550                 if (s->interlace_type ||
00551                     s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00552                     s->tmp_row = av_malloc(s->row_size);
00553                     if (!s->tmp_row)
00554                         goto fail;
00555                 }
00556                 /* compressed row */
00557                 crow_buf_base = av_malloc(s->row_size + 16);
00558                 if (!crow_buf_base)
00559                     goto fail;
00560 
00561                 /* we want crow_buf+1 to be 16-byte aligned */
00562                 s->crow_buf = crow_buf_base + 15;
00563                 s->zstream.avail_out = s->crow_size;
00564                 s->zstream.next_out = s->crow_buf;
00565             }
00566             s->state |= PNG_IDAT;
00567             if (png_decode_idat(s, length) < 0)
00568                 goto fail;
00569             bytestream2_skip(&s->gb, 4); /* crc */
00570             break;
00571         case MKTAG('P', 'L', 'T', 'E'):
00572             {
00573                 int n, i, r, g, b;
00574 
00575                 if ((length % 3) != 0 || length > 256 * 3)
00576                     goto skip_tag;
00577                 /* read the palette */
00578                 n = length / 3;
00579                 for(i=0;i<n;i++) {
00580                     r = bytestream2_get_byte(&s->gb);
00581                     g = bytestream2_get_byte(&s->gb);
00582                     b = bytestream2_get_byte(&s->gb);
00583                     s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
00584                 }
00585                 for(;i<256;i++) {
00586                     s->palette[i] = (0xff << 24);
00587                 }
00588                 s->state |= PNG_PLTE;
00589                 bytestream2_skip(&s->gb, 4); /* crc */
00590             }
00591             break;
00592         case MKTAG('t', 'R', 'N', 'S'):
00593             {
00594                 int v, i;
00595 
00596                 /* read the transparency. XXX: Only palette mode supported */
00597                 if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
00598                     length > 256 ||
00599                     !(s->state & PNG_PLTE))
00600                     goto skip_tag;
00601                 for(i=0;i<length;i++) {
00602                     v = bytestream2_get_byte(&s->gb);
00603                     s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
00604                 }
00605                 bytestream2_skip(&s->gb, 4); /* crc */
00606             }
00607             break;
00608         case MKTAG('I', 'E', 'N', 'D'):
00609             if (!(s->state & PNG_ALLIMAGE))
00610                 av_log(avctx, AV_LOG_ERROR, "IEND without all image\n");
00611             if (!(s->state & (PNG_ALLIMAGE|PNG_IDAT))) {
00612                 goto fail;
00613             }
00614             bytestream2_skip(&s->gb, 4); /* crc */
00615             goto exit_loop;
00616         default:
00617             /* skip tag */
00618         skip_tag:
00619             bytestream2_skip(&s->gb, length + 4);
00620             break;
00621         }
00622     }
00623  exit_loop:
00624 
00625     if(s->bits_per_pixel == 1 && s->color_type == PNG_COLOR_TYPE_PALETTE){
00626         int i, j;
00627         uint8_t *pd = s->current_picture->data[0];
00628         for(j=0; j < s->height; j++) {
00629             for(i=s->width/8-1; i>=0; i--) {
00630                 pd[8*i+7]=  pd[i]    &1;
00631                 pd[8*i+6]= (pd[i]>>1)&1;
00632                 pd[8*i+5]= (pd[i]>>2)&1;
00633                 pd[8*i+4]= (pd[i]>>3)&1;
00634                 pd[8*i+3]= (pd[i]>>4)&1;
00635                 pd[8*i+2]= (pd[i]>>5)&1;
00636                 pd[8*i+1]= (pd[i]>>6)&1;
00637                 pd[8*i+0]=  pd[i]>>7;
00638             }
00639             pd += s->image_linesize;
00640         }
00641     }
00642     if(s->bits_per_pixel == 2){
00643         int i, j;
00644         uint8_t *pd = s->current_picture->data[0];
00645         for(j=0; j < s->height; j++) {
00646             if (s->color_type == PNG_COLOR_TYPE_PALETTE){
00647             for(i=s->width/4-1; i>=0; i--) {
00648                 pd[4*i+3]=  pd[i]    &3;
00649                 pd[4*i+2]= (pd[i]>>2)&3;
00650                 pd[4*i+1]= (pd[i]>>4)&3;
00651                 pd[4*i+0]=  pd[i]>>6;
00652             }
00653             } else {
00654                 for(i=s->width/4-1; i>=0; i--) {
00655                     pd[4*i+3]= ( pd[i]    &3)*0x55;
00656                     pd[4*i+2]= ((pd[i]>>2)&3)*0x55;
00657                     pd[4*i+1]= ((pd[i]>>4)&3)*0x55;
00658                     pd[4*i+0]= ( pd[i]>>6   )*0x55;
00659                 }
00660             }
00661             pd += s->image_linesize;
00662         }
00663     }
00664     if(s->bits_per_pixel == 4){
00665         int i, j;
00666         uint8_t *pd = s->current_picture->data[0];
00667         for(j=0; j < s->height; j++) {
00668             if (s->color_type == PNG_COLOR_TYPE_PALETTE){
00669             for(i=s->width/2-1; i>=0; i--) {
00670                 pd[2*i+1]= pd[i]&15;
00671                 pd[2*i+0]= pd[i]>>4;
00672             }
00673             } else {
00674                 for(i=s->width/2-1; i>=0; i--) {
00675                     pd[2*i+1]= (pd[i]&15)*0x11;
00676                     pd[2*i+0]= (pd[i]>>4)*0x11;
00677                 }
00678             }
00679             pd += s->image_linesize;
00680         }
00681     }
00682 
00683      /* handle p-frames only if a predecessor frame is available */
00684      if(s->last_picture->data[0] != NULL) {
00685          if(   !(avpkt->flags & AV_PKT_FLAG_KEY)
00686             && s->last_picture->width == s->current_picture->width
00687             && s->last_picture->height== s->current_picture->height
00688          ) {
00689             int i, j;
00690             uint8_t *pd = s->current_picture->data[0];
00691             uint8_t *pd_last = s->last_picture->data[0];
00692 
00693             for(j=0; j < s->height; j++) {
00694                 for(i=0; i < s->width * s->bpp; i++) {
00695                     pd[i] += pd_last[i];
00696                 }
00697                 pd += s->image_linesize;
00698                 pd_last += s->image_linesize;
00699             }
00700         }
00701     }
00702 
00703     *picture= *s->current_picture;
00704     *data_size = sizeof(AVFrame);
00705 
00706     ret = bytestream2_tell(&s->gb);
00707  the_end:
00708     inflateEnd(&s->zstream);
00709     av_free(crow_buf_base);
00710     s->crow_buf = NULL;
00711     av_freep(&s->last_row);
00712     av_freep(&s->tmp_row);
00713     return ret;
00714  fail:
00715     ret = -1;
00716     goto the_end;
00717 }
00718 
00719 static av_cold int png_dec_init(AVCodecContext *avctx)
00720 {
00721     PNGDecContext *s = avctx->priv_data;
00722 
00723     s->current_picture = &s->picture1;
00724     s->last_picture = &s->picture2;
00725     avcodec_get_frame_defaults(&s->picture1);
00726     avcodec_get_frame_defaults(&s->picture2);
00727 
00728     ff_pngdsp_init(&s->dsp);
00729 
00730     s->avctx = avctx;
00731 
00732     return 0;
00733 }
00734 
00735 static av_cold int png_dec_end(AVCodecContext *avctx)
00736 {
00737     PNGDecContext *s = avctx->priv_data;
00738 
00739     if (s->picture1.data[0])
00740         avctx->release_buffer(avctx, &s->picture1);
00741     if (s->picture2.data[0])
00742         avctx->release_buffer(avctx, &s->picture2);
00743 
00744     return 0;
00745 }
00746 
00747 AVCodec ff_png_decoder = {
00748     .name           = "png",
00749     .type           = AVMEDIA_TYPE_VIDEO,
00750     .id             = AV_CODEC_ID_PNG,
00751     .priv_data_size = sizeof(PNGDecContext),
00752     .init           = png_dec_init,
00753     .close          = png_dec_end,
00754     .decode         = decode_frame,
00755     .capabilities   = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
00756     .long_name      = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
00757 };