FFmpeg: libavcodec/msrledec.c Source File

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     unsigned 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                     av_log(avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
00080                     return -1;
00081                 }
00082 
00083                 for (i = 0; i < rle_code; i++) {
00084                     if (pixel_ptr >= avctx->width)
00085                         break;
00086                     FETCH_NEXT_STREAM_BYTE();
00087                     pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
00088                     pixel_ptr++;
00089                     if (i + 1 == rle_code && odd_pixel)
00090                         break;
00091                     if (pixel_ptr >= avctx->width)
00092                         break;
00093                     pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
00094                     pixel_ptr++;
00095                 }
00096 
00097                 // if the RLE code is odd, skip a byte in the stream
00098                 if (extra_byte)
00099                     stream_ptr++;
00100             }
00101         } else {
00102             // decode a run of data
00103             if (row_ptr + pixel_ptr + stream_byte > frame_size) {
00104                 av_log(avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
00105                 return -1;
00106             }
00107             FETCH_NEXT_STREAM_BYTE();
00108             for (i = 0; i < rle_code; i++) {
00109                 if (pixel_ptr >= avctx->width)
00110                     break;
00111                 if ((i & 1) == 0)
00112                     pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
00113                 else
00114                     pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
00115                 pixel_ptr++;
00116             }
00117         }
00118     }
00119 
00120     /* one last sanity check on the way out */
00121     if (stream_ptr < data_size) {
00122         av_log(avctx, AV_LOG_ERROR, " MS RLE: ended frame decode with bytes left over (%d < %d)\n",
00123             stream_ptr, data_size);
00124         return -1;
00125     }
00126 
00127     return 0;
00128 }
00129 
00130 
00131 static int msrle_decode_8_16_24_32(AVCodecContext *avctx, AVPicture *pic, int depth,
00132                                     const uint8_t *data, int srcsize)
00133 {
00134     uint8_t *output, *output_end;
00135     const uint8_t* src = data;
00136     int p1, p2, line=avctx->height - 1, pos=0, i;
00137     uint16_t av_uninit(pix16);
00138     uint32_t av_uninit(pix32);
00139     unsigned int width= FFABS(pic->linesize[0]) / (depth >> 3);
00140 
00141     output = pic->data[0] + (avctx->height - 1) * pic->linesize[0];
00142     output_end = pic->data[0] + (avctx->height) * pic->linesize[0];
00143     while(src < data + srcsize) {
00144         p1 = *src++;
00145         if(p1 == 0) { //Escape code
00146             p2 = *src++;
00147             if(p2 == 0) { //End-of-line
00148                 output = pic->data[0] + (--line) * pic->linesize[0];
00149                 if (line < 0 && !(src+1 < data + srcsize && AV_RB16(src) == 1)) {
00150                     av_log(avctx, AV_LOG_ERROR, "Next line is beyond picture bounds\n");
00151                     return -1;
00152                 }
00153                 pos = 0;
00154                 continue;
00155             } else if(p2 == 1) { //End-of-picture
00156                 return 0;
00157             } else if(p2 == 2) { //Skip
00158                 p1 = *src++;
00159                 p2 = *src++;
00160                 line -= p2;
00161                 pos += p1;
00162                 if (line < 0 || pos >= width){
00163                     av_log(avctx, AV_LOG_ERROR, "Skip beyond picture bounds\n");
00164                     return -1;
00165                 }
00166                 output = pic->data[0] + line * pic->linesize[0] + pos * (depth >> 3);
00167                 continue;
00168             }
00169             // Copy data
00170             if ((pic->linesize[0] > 0 && output + p2 * (depth >> 3) > output_end)
00171               ||(pic->linesize[0] < 0 && output + p2 * (depth >> 3) < output_end)) {
00172                 src += p2 * (depth >> 3);
00173                 continue;
00174             }
00175             if ((depth == 8) || (depth == 24)) {
00176                 for(i = 0; i < p2 * (depth >> 3); i++) {
00177                     *output++ = *src++;
00178                 }
00179                 // RLE8 copy is actually padded - and runs are not!
00180                 if(depth == 8 && (p2 & 1)) {
00181                     src++;
00182                 }
00183             } else if (depth == 16) {
00184                 for(i = 0; i < p2; i++) {
00185                     pix16 = AV_RL16(src);
00186                     src += 2;
00187                     *(uint16_t*)output = pix16;
00188                     output += 2;
00189                 }
00190             } else if (depth == 32) {
00191                 for(i = 0; i < p2; i++) {
00192                     pix32 = AV_RL32(src);
00193                     src += 4;
00194                     *(uint32_t*)output = pix32;
00195                     output += 4;
00196                 }
00197             }
00198             pos += p2;
00199         } else { //run of pixels
00200             uint8_t pix[3]; //original pixel
00201             switch(depth){
00202             case  8: pix[0] = *src++;
00203                      break;
00204             case 16: pix16 = AV_RL16(src);
00205                      src += 2;
00206                      break;
00207             case 24: pix[0] = *src++;
00208                      pix[1] = *src++;
00209                      pix[2] = *src++;
00210                      break;
00211             case 32: pix32 = AV_RL32(src);
00212                      src += 4;
00213                      break;
00214             }
00215             if ((pic->linesize[0] > 0 && output + p1 * (depth >> 3) > output_end)
00216               ||(pic->linesize[0] < 0 && output + p1 * (depth >> 3) < output_end))
00217                 continue;
00218             for(i = 0; i < p1; i++) {
00219                 switch(depth){
00220                 case  8: *output++ = pix[0];
00221                          break;
00222                 case 16: *(uint16_t*)output = pix16;
00223                          output += 2;
00224                          break;
00225                 case 24: *output++ = pix[0];
00226                          *output++ = pix[1];
00227                          *output++ = pix[2];
00228                          break;
00229                 case 32: *(uint32_t*)output = pix32;
00230                          output += 4;
00231                          break;
00232                 }
00233             }
00234             pos += p1;
00235         }
00236     }
00237 
00238     av_log(avctx, AV_LOG_WARNING, "MS RLE warning: no end-of-picture code\n");
00239     return 0;
00240 }
00241 
00242 
00243 int ff_msrle_decode(AVCodecContext *avctx, AVPicture *pic, int depth,
00244                     const uint8_t* data, int data_size)
00245 {
00246     switch(depth){
00247     case  4:
00248         return msrle_decode_pal4(avctx, pic, data, data_size);
00249     case  8:
00250     case 16:
00251     case 24:
00252     case 32:
00253         return msrle_decode_8_16_24_32(avctx, pic, depth, data, data_size);
00254     default:
00255         av_log(avctx, AV_LOG_ERROR, "Unknown depth %d\n", depth);
00256         return -1;
00257     }
00258 }
00259