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libavcodec/msrledec.c

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00001 /*
00002  * Microsoft RLE decoder
00003  * Copyright (C) 2008 Konstantin Shishkov
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 
00029 #include "libavutil/intreadwrite.h"
00030 #include "avcodec.h"
00031 #include "msrledec.h"
00032 
00033 #define FETCH_NEXT_STREAM_BYTE() \
00034     if (stream_ptr >= data_size) \
00035     { \
00036       av_log(avctx, AV_LOG_ERROR, " MS RLE: stream ptr just went out of bounds (1)\n"); \
00037       return -1; \
00038     } \
00039     stream_byte = data[stream_ptr++];
00040 
00041 static int msrle_decode_pal4(AVCodecContext *avctx, AVPicture *pic,
00042                               const uint8_t *data, int data_size)
00043 {
00044     int stream_ptr = 0;
00045     unsigned char rle_code;
00046     unsigned char extra_byte, odd_pixel;
00047     unsigned char stream_byte;
00048     int pixel_ptr = 0;
00049     int row_dec = pic->linesize[0];
00050     int row_ptr = (avctx->height - 1) * row_dec;
00051     int frame_size = row_dec * avctx->height;
00052     int i;
00053 
00054     while (row_ptr >= 0) {
00055         FETCH_NEXT_STREAM_BYTE();
00056         rle_code = stream_byte;
00057         if (rle_code == 0) {
00058             /* fetch the next byte to see how to handle escape code */
00059             FETCH_NEXT_STREAM_BYTE();
00060             if (stream_byte == 0) {
00061                 /* line is done, goto the next one */
00062                 row_ptr -= row_dec;
00063                 pixel_ptr = 0;
00064             } else if (stream_byte == 1) {
00065                 /* decode is done */
00066                 return 0;
00067             } else if (stream_byte == 2) {
00068                 /* reposition frame decode coordinates */
00069                 FETCH_NEXT_STREAM_BYTE();
00070                 pixel_ptr += stream_byte;
00071                 FETCH_NEXT_STREAM_BYTE();
00072                 row_ptr -= stream_byte * row_dec;
00073         } else {
00074             // copy pixels from encoded stream
00075             odd_pixel =  stream_byte & 1;
00076             rle_code = (stream_byte + 1) / 2;
00077             extra_byte = rle_code & 0x01;
00078             if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
00079                 (row_ptr < 0)) {
00080                 av_log(avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
00081                 return -1;
00082             }
00083 
00084             for (i = 0; i < rle_code; i++) {
00085                 if (pixel_ptr >= avctx->width)
00086                     break;
00087                 FETCH_NEXT_STREAM_BYTE();
00088                 pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
00089                 pixel_ptr++;
00090                 if (i + 1 == rle_code && odd_pixel)
00091                     break;
00092                 if (pixel_ptr >= avctx->width)
00093                     break;
00094                 pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
00095                 pixel_ptr++;
00096             }
00097 
00098             // if the RLE code is odd, skip a byte in the stream
00099             if (extra_byte)
00100               stream_ptr++;
00101             }
00102         } else {
00103             // decode a run of data
00104             if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
00105                 (row_ptr < 0)) {
00106                 av_log(avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
00107                 return -1;
00108             }
00109             FETCH_NEXT_STREAM_BYTE();
00110             for (i = 0; i < rle_code; i++) {
00111                 if (pixel_ptr >= avctx->width)
00112                     break;
00113                 if ((i & 1) == 0)
00114                     pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
00115                 else
00116                     pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
00117                 pixel_ptr++;
00118             }
00119         }
00120     }
00121 
00122     /* one last sanity check on the way out */
00123     if (stream_ptr < data_size) {
00124         av_log(avctx, AV_LOG_ERROR, " MS RLE: ended frame decode with bytes left over (%d < %d)\n",
00125             stream_ptr, data_size);
00126         return -1;
00127     }
00128 
00129     return 0;
00130 }
00131 
00132 
00133 static int msrle_decode_8_16_24_32(AVCodecContext *avctx, AVPicture *pic, int depth,
00134                                     const uint8_t *data, int srcsize)
00135 {
00136     uint8_t *output, *output_end;
00137     const uint8_t* src = data;
00138     int p1, p2, line=avctx->height - 1, pos=0, i;
00139     uint16_t av_uninit(pix16);
00140     uint32_t av_uninit(pix32);
00141 
00142     output = pic->data[0] + (avctx->height - 1) * pic->linesize[0];
00143     output_end = pic->data[0] + (avctx->height) * pic->linesize[0];
00144     while(src < data + srcsize) {
00145         p1 = *src++;
00146         if(p1 == 0) { //Escape code
00147             p2 = *src++;
00148             if(p2 == 0) { //End-of-line
00149                 output = pic->data[0] + (--line) * pic->linesize[0];
00150                 if (line < 0 && !(src+1 < data + srcsize && AV_RB16(src) == 1)) {
00151                     av_log(avctx, AV_LOG_ERROR, "Next line is beyond picture bounds\n");
00152                     return -1;
00153                 }
00154                 pos = 0;
00155                 continue;
00156             } else if(p2 == 1) { //End-of-picture
00157                 return 0;
00158             } else if(p2 == 2) { //Skip
00159                 p1 = *src++;
00160                 p2 = *src++;
00161                 line -= p2;
00162                 if (line < 0){
00163                     av_log(avctx, AV_LOG_ERROR, "Skip beyond picture bounds\n");
00164                     return -1;
00165                 }
00166                 pos += p1;
00167                 output = pic->data[0] + line * pic->linesize[0] + pos * (depth >> 3);
00168                 continue;
00169             }
00170             // Copy data
00171             if ((pic->linesize[0] > 0 && output + p2 * (depth >> 3) > output_end)
00172               ||(pic->linesize[0] < 0 && output + p2 * (depth >> 3) < output_end)) {
00173                 src += p2 * (depth >> 3);
00174                 continue;
00175             }
00176             if ((depth == 8) || (depth == 24)) {
00177                 for(i = 0; i < p2 * (depth >> 3); i++) {
00178                     *output++ = *src++;
00179                 }
00180                 // RLE8 copy is actually padded - and runs are not!
00181                 if(depth == 8 && (p2 & 1)) {
00182                     src++;
00183                 }
00184             } else if (depth == 16) {
00185                 for(i = 0; i < p2; i++) {
00186                     pix16 = AV_RL16(src);
00187                     src += 2;
00188                     *(uint16_t*)output = pix16;
00189                     output += 2;
00190                 }
00191             } else if (depth == 32) {
00192                 for(i = 0; i < p2; i++) {
00193                     pix32 = AV_RL32(src);
00194                     src += 4;
00195                     *(uint32_t*)output = pix32;
00196                     output += 4;
00197                 }
00198             }
00199             pos += p2;
00200         } else { //run of pixels
00201             uint8_t pix[3]; //original pixel
00202             switch(depth){
00203             case  8: pix[0] = *src++;
00204                      break;
00205             case 16: pix16 = AV_RL16(src);
00206                      src += 2;
00207                      break;
00208             case 24: pix[0] = *src++;
00209                      pix[1] = *src++;
00210                      pix[2] = *src++;
00211                      break;
00212             case 32: pix32 = AV_RL32(src);
00213                      src += 4;
00214                      break;
00215             }
00216             if ((pic->linesize[0] > 0 && output + p1 * (depth >> 3) > output_end)
00217               ||(pic->linesize[0] < 0 && output + p1 * (depth >> 3) < output_end))
00218                 continue;
00219             for(i = 0; i < p1; i++) {
00220                 switch(depth){
00221                 case  8: *output++ = pix[0];
00222                          break;
00223                 case 16: *(uint16_t*)output = pix16;
00224                          output += 2;
00225                          break;
00226                 case 24: *output++ = pix[0];
00227                          *output++ = pix[1];
00228                          *output++ = pix[2];
00229                          break;
00230                 case 32: *(uint32_t*)output = pix32;
00231                          output += 4;
00232                          break;
00233                 }
00234             }
00235             pos += p1;
00236         }
00237     }
00238 
00239     av_log(avctx, AV_LOG_WARNING, "MS RLE warning: no end-of-picture code\n");
00240     return 0;
00241 }
00242 
00243 
00244 int ff_msrle_decode(AVCodecContext *avctx, AVPicture *pic, int depth,
00245                     const uint8_t* data, int data_size)
00246 {
00247     switch(depth){
00248     case  4:
00249         return msrle_decode_pal4(avctx, pic, data, data_size);
00250     case  8:
00251     case 16:
00252     case 24:
00253     case 32:
00254         return msrle_decode_8_16_24_32(avctx, pic, depth, data, data_size);
00255     default:
00256         av_log(avctx, AV_LOG_ERROR, "Unknown depth %d\n", depth);
00257         return -1;
00258     }
00259 }
00260 

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