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 static int msrle_decode_pal4(AVCodecContext *avctx, AVPicture *pic,
00034                              GetByteContext *gb)
00035 {
00036     unsigned char rle_code;
00037     unsigned char extra_byte, odd_pixel;
00038     unsigned char stream_byte;
00039     unsigned int pixel_ptr = 0;
00040     int row_dec = pic->linesize[0];
00041     int row_ptr = (avctx->height - 1) * row_dec;
00042     int frame_size = row_dec * avctx->height;
00043     int i;
00044 
00045     while (row_ptr >= 0) {
00046         if (bytestream2_get_bytes_left(gb) <= 0) {
00047             av_log(avctx, AV_LOG_ERROR,
00048                    "MS RLE: bytestream overrun, %d rows left\n",
00049                    row_ptr);
00050             return AVERROR_INVALIDDATA;
00051         }
00052         rle_code = stream_byte = bytestream2_get_byteu(gb);
00053         if (rle_code == 0) {
00054             /* fetch the next byte to see how to handle escape code */
00055             stream_byte = bytestream2_get_byte(gb);
00056             if (stream_byte == 0) {
00057                 /* line is done, goto the next one */
00058                 row_ptr -= row_dec;
00059                 pixel_ptr = 0;
00060             } else if (stream_byte == 1) {
00061                 /* decode is done */
00062                 return 0;
00063             } else if (stream_byte == 2) {
00064                 /* reposition frame decode coordinates */
00065                 stream_byte = bytestream2_get_byte(gb);
00066                 pixel_ptr += stream_byte;
00067                 stream_byte = bytestream2_get_byte(gb);
00068                 row_ptr -= stream_byte * row_dec;
00069             } else {
00070                 // copy pixels from encoded stream
00071                 odd_pixel =  stream_byte & 1;
00072                 rle_code = (stream_byte + 1) / 2;
00073                 extra_byte = rle_code & 0x01;
00074                 if (row_ptr + pixel_ptr + stream_byte > frame_size ||
00075                     bytestream2_get_bytes_left(gb) < rle_code) {
00076                     av_log(avctx, AV_LOG_ERROR,
00077                            "MS RLE: frame/stream ptr just went out of bounds (copy)\n");
00078                     return AVERROR_INVALIDDATA;
00079                 }
00080 
00081                 for (i = 0; i < rle_code; i++) {
00082                     if (pixel_ptr >= avctx->width)
00083                         break;
00084                     stream_byte = bytestream2_get_byteu(gb);
00085                     pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
00086                     pixel_ptr++;
00087                     if (i + 1 == rle_code && odd_pixel)
00088                         break;
00089                     if (pixel_ptr >= avctx->width)
00090                         break;
00091                     pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
00092                     pixel_ptr++;
00093                 }
00094 
00095                 // if the RLE code is odd, skip a byte in the stream
00096                 if (extra_byte)
00097                     bytestream2_skip(gb, 1);
00098             }
00099         } else {
00100             // decode a run of data
00101             if (row_ptr + pixel_ptr + stream_byte > frame_size) {
00102                 av_log(avctx, AV_LOG_ERROR,
00103                        "MS RLE: frame ptr just went out of bounds (run)\n");
00104                 return AVERROR_INVALIDDATA;
00105             }
00106             stream_byte = bytestream2_get_byte(gb);
00107             for (i = 0; i < rle_code; i++) {
00108                 if (pixel_ptr >= avctx->width)
00109                     break;
00110                 if ((i & 1) == 0)
00111                     pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
00112                 else
00113                     pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
00114                 pixel_ptr++;
00115             }
00116         }
00117     }
00118 
00119     /* one last sanity check on the way out */
00120     if (bytestream2_get_bytes_left(gb)) {
00121         av_log(avctx, AV_LOG_ERROR,
00122                "MS RLE: ended frame decode with %d bytes left over\n",
00123                bytestream2_get_bytes_left(gb));
00124         return AVERROR_INVALIDDATA;
00125     }
00126 
00127     return 0;
00128 }
00129 
00130 
00131 static int msrle_decode_8_16_24_32(AVCodecContext *avctx, AVPicture *pic,
00132                                    int depth, GetByteContext *gb)
00133 {
00134     uint8_t *output, *output_end;
00135     int p1, p2, line=avctx->height - 1, pos=0, i;
00136     uint16_t pix16;
00137     uint32_t pix32;
00138     unsigned int width= FFABS(pic->linesize[0]) / (depth >> 3);
00139 
00140     output     = pic->data[0] + (avctx->height - 1) * pic->linesize[0];
00141     output_end = pic->data[0] +  avctx->height      * pic->linesize[0];
00142     while (bytestream2_get_bytes_left(gb) > 0) {
00143         p1 = bytestream2_get_byteu(gb);
00144         if(p1 == 0) { //Escape code
00145             p2 = bytestream2_get_byte(gb);
00146             if(p2 == 0) { //End-of-line
00147                 output = pic->data[0] + (--line) * pic->linesize[0];
00148                 if (line < 0) {
00149                     if (bytestream2_get_be16(gb) == 1) { // end-of-picture
00150                         return 0;
00151                     } else {
00152                         av_log(avctx, AV_LOG_ERROR,
00153                                "Next line is beyond picture bounds (%d bytes left)\n",
00154                                bytestream2_get_bytes_left(gb));
00155                         return AVERROR_INVALIDDATA;
00156                     }
00157                 }
00158                 pos = 0;
00159                 continue;
00160             } else if(p2 == 1) { //End-of-picture
00161                 return 0;
00162             } else if(p2 == 2) { //Skip
00163                 p1 = bytestream2_get_byte(gb);
00164                 p2 = bytestream2_get_byte(gb);
00165                 line -= p2;
00166                 pos += p1;
00167                 if (line < 0 || pos >= width){
00168                     av_log(avctx, AV_LOG_ERROR, "Skip beyond picture bounds\n");
00169                     return -1;
00170                 }
00171                 output = pic->data[0] + line * pic->linesize[0] + pos * (depth >> 3);
00172                 continue;
00173             }
00174             // Copy data
00175             if ((pic->linesize[0] > 0 && output + p2 * (depth >> 3) > output_end) ||
00176                 (pic->linesize[0] < 0 && output + p2 * (depth >> 3) < output_end)) {
00177                 bytestream2_skip(gb, 2 * (depth >> 3));
00178                 continue;
00179             } else if (bytestream2_get_bytes_left(gb) < p2 * (depth >> 3)) {
00180                 av_log(avctx, AV_LOG_ERROR, "bytestream overrun\n");
00181                 return AVERROR_INVALIDDATA;
00182             }
00183 
00184             if ((depth == 8) || (depth == 24)) {
00185                 for(i = 0; i < p2 * (depth >> 3); i++) {
00186                     *output++ = bytestream2_get_byteu(gb);
00187                 }
00188                 // RLE8 copy is actually padded - and runs are not!
00189                 if(depth == 8 && (p2 & 1)) {
00190                     bytestream2_skip(gb, 1);
00191                 }
00192             } else if (depth == 16) {
00193                 for(i = 0; i < p2; i++) {
00194                     *(uint16_t*)output = bytestream2_get_le16u(gb);
00195                     output += 2;
00196                 }
00197             } else if (depth == 32) {
00198                 for(i = 0; i < p2; i++) {
00199                     *(uint32_t*)output = bytestream2_get_le32u(gb);
00200                     output += 4;
00201                 }
00202             }
00203             pos += p2;
00204         } else { //run of pixels
00205             uint8_t pix[3]; //original pixel
00206             switch(depth){
00207             case  8: pix[0] = bytestream2_get_byte(gb);
00208                      break;
00209             case 16: pix16  = bytestream2_get_le16(gb);
00210                      break;
00211             case 24: pix[0] = bytestream2_get_byte(gb);
00212                      pix[1] = bytestream2_get_byte(gb);
00213                      pix[2] = bytestream2_get_byte(gb);
00214                      break;
00215             case 32: pix32  = bytestream2_get_le32(gb);
00216                      break;
00217             }
00218             if ((pic->linesize[0] > 0 && output + p1 * (depth >> 3) > output_end) ||
00219                 (pic->linesize[0] < 0 && output + p1 * (depth >> 3) < output_end))
00220                 continue;
00221             for(i = 0; i < p1; i++) {
00222                 switch(depth){
00223                 case  8: *output++ = pix[0];
00224                          break;
00225                 case 16: *(uint16_t*)output = pix16;
00226                          output += 2;
00227                          break;
00228                 case 24: *output++ = pix[0];
00229                          *output++ = pix[1];
00230                          *output++ = pix[2];
00231                          break;
00232                 case 32: *(uint32_t*)output = pix32;
00233                          output += 4;
00234                          break;
00235                 }
00236             }
00237             pos += p1;
00238         }
00239     }
00240 
00241     av_log(avctx, AV_LOG_WARNING, "MS RLE warning: no end-of-picture code\n");
00242     return 0;
00243 }
00244 
00245 
00246 int ff_msrle_decode(AVCodecContext *avctx, AVPicture *pic,
00247                     int depth, GetByteContext *gb)
00248 {
00249     switch(depth){
00250     case  4:
00251         return msrle_decode_pal4(avctx, pic, gb);
00252     case  8:
00253     case 16:
00254     case 24:
00255     case 32:
00256         return msrle_decode_8_16_24_32(avctx, pic, depth, gb);
00257     default:
00258         av_log(avctx, AV_LOG_ERROR, "Unknown depth %d\n", depth);
00259         return -1;
00260     }
00261 }