libavcodec/msrle.c

   1 /*
   2  * Micrsoft RLE Video Decoder
   3  * Copyright (C) 2003 the ffmpeg project
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 /**
  21  * @file msrle.c
  22  * MS RLE Video Decoder by Mike Melanson (melanson@pcisys.net)
  23  * For more information about the MS RLE format, visit:
  24  *   http://www.pcisys.net/~melanson/codecs/
  25  *
  26  * The MS RLE decoder outputs PAL8 colorspace data.
  27  *
  28  * Note that this decoder expects the palette colors from the end of the
  29  * BITMAPINFO header passed through palctrl.
  30  */
  31
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <unistd.h>
  36
  37 #include "common.h"
  38 #include "avcodec.h"
  39 #include "dsputil.h"
  40
  41 typedef struct MsrleContext {
  42     AVCodecContext *avctx;
  43     AVFrame frame;
  44     AVFrame prev_frame;
  45
  46     unsigned char *buf;
  47     int size;
  48
  49 } MsrleContext;
  50
  51 #define FETCH_NEXT_STREAM_BYTE() \
  52     if (stream_ptr >= s->size) \
  53     { \
  54       printf(" MS RLE: stream ptr just went out of bounds (1)\n"); \
  55       return; \
  56     } \
  57     stream_byte = s->buf[stream_ptr++];
  58
  59 static void msrle_decode_pal8(MsrleContext *s)
  60 {
  61     int stream_ptr = 0;
  62     unsigned char rle_code;
  63     unsigned char extra_byte;
  64     unsigned char stream_byte;
  65     int pixel_ptr = 0;
  66     int row_dec = s->frame.linesize[0];
  67     int row_ptr = (s->avctx->height - 1) * row_dec;
  68     int frame_size = row_dec * s->avctx->height;
  69
  70     while (row_ptr >= 0) {
  71         FETCH_NEXT_STREAM_BYTE();
  72         rle_code = stream_byte;
  73         if (rle_code == 0) {
  74             /* fetch the next byte to see how to handle escape code */
  75             FETCH_NEXT_STREAM_BYTE();
  76             if (stream_byte == 0) {
  77                 /* line is done, goto the next one */
  78                 row_ptr -= row_dec;
  79                 pixel_ptr = 0;
  80             } else if (stream_byte == 1) {
  81                 /* decode is done */
  82                 return;
  83             } else if (stream_byte == 2) {
  84                 /* reposition frame decode coordinates */
  85                 FETCH_NEXT_STREAM_BYTE();
  86                 pixel_ptr += stream_byte;
  87                 FETCH_NEXT_STREAM_BYTE();
  88                 row_ptr -= stream_byte * row_dec;
  89             } else {
  90                 /* copy pixels from encoded stream */
  91                 if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
  92                     (row_ptr < 0)) {
  93                     printf(" MS RLE: frame ptr just went out of bounds (1)\n");
  94                     return;
  95                 }
  96
  97                 rle_code = stream_byte;
  98                 extra_byte = stream_byte & 0x01;
  99                 if (stream_ptr + rle_code + extra_byte > s->size) {
 100                     printf(" MS RLE: stream ptr just went out of bounds (2)\n");
 101                     return;
 102                 }
 103
 104                 while (rle_code--) {
 105                     FETCH_NEXT_STREAM_BYTE();
 106                     s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
 107                     pixel_ptr++;
 108                 }
 109
 110                 /* if the RLE code is odd, skip a byte in the stream */
 111                 if (extra_byte)
 112                     stream_ptr++;
 113             }
 114         } else {
 115             /* decode a run of data */
 116             if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
 117                 (row_ptr < 0)) {
 118                 printf(" MS RLE: frame ptr just went out of bounds (2)\n");
 119                 return;
 120             }
 121
 122             FETCH_NEXT_STREAM_BYTE();
 123
 124             while(rle_code--) {
 125                 s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
 126                 pixel_ptr++;
 127             }
 128         }
 129     }
 130
 131     /* make the palette available */
 132     memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);
 133     if (s->avctx->palctrl->palette_changed) {
 134         s->frame.palette_has_changed = 1;
 135         s->avctx->palctrl->palette_changed = 0;
 136     }
 137
 138     /* one last sanity check on the way out */
 139     if (stream_ptr < s->size)
 140         printf(" MS RLE: ended frame decode with bytes left over (%d < %d)\n",
 141             stream_ptr, s->size);
 142 }
 143
 144 static int msrle_decode_init(AVCodecContext *avctx)
 145 {
 146     MsrleContext *s = (MsrleContext *)avctx->priv_data;
 147
 148     s->avctx = avctx;
 149
 150     avctx->pix_fmt = PIX_FMT_PAL8;
 151     avctx->has_b_frames = 0;
 152     s->frame.data[0] = s->prev_frame.data[0] = NULL;
 153
 154     return 0;
 155 }
 156
 157 static int msrle_decode_frame(AVCodecContext *avctx,
 158                               void *data, int *data_size,
 159                               uint8_t *buf, int buf_size)
 160 {
 161     MsrleContext *s = (MsrleContext *)avctx->priv_data;
 162
 163     s->buf = buf;
 164     s->size = buf_size;
 165
 166     s->frame.reference = 1;
 167     if (avctx->get_buffer(avctx, &s->frame)) {
 168         printf ("  MS RLE: get_buffer() failed\n");
 169         return -1;
 170     }
 171
 172     if (s->prev_frame.data[0] && (s->frame.linesize[0] != s->prev_frame.linesize[0]))
 173         printf ("  MS RLE: Buffer linesize changed: current %u, previous %u.\n"
 174                 "          Expect wrong image and/or crash!\n",
 175                 s->frame.linesize[0], s->prev_frame.linesize[0]);
 176
 177     /* grossly inefficient, but...oh well */
 178     if (s->prev_frame.data[0] != NULL)
 179         memcpy(s->frame.data[0], s->prev_frame.data[0],
 180         s->frame.linesize[0] * s->avctx->height);
 181
 182     msrle_decode_pal8(s);
 183
 184     if (s->prev_frame.data[0])
 185         avctx->release_buffer(avctx, &s->prev_frame);
 186
 187     /* shuffle frames */
 188     s->prev_frame = s->frame;
 189
 190     *data_size = sizeof(AVFrame);
 191     *(AVFrame*)data = s->frame;
 192
 193     /* report that the buffer was completely consumed */
 194     return buf_size;
 195 }
 196
 197 static int msrle_decode_end(AVCodecContext *avctx)
 198 {
 199     MsrleContext *s = (MsrleContext *)avctx->priv_data;
 200
 201     /* release the last frame */
 202     if (s->prev_frame.data[0])
 203         avctx->release_buffer(avctx, &s->prev_frame);
 204
 205     return 0;
 206 }
 207
 208 AVCodec msrle_decoder = {
 209     "msrle",
 210     CODEC_TYPE_VIDEO,
 211     CODEC_ID_MSRLE,
 212     sizeof(MsrleContext),
 213     msrle_decode_init,
 214     NULL,
 215     msrle_decode_end,
 216     msrle_decode_frame,
 217     CODEC_CAP_DR1,
 218 };