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 extradata.
  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     unsigned int palette[256];
  50 } MsrleContext;
  51
  52 #define FETCH_NEXT_STREAM_BYTE() \
  53     if (stream_ptr >= s->size) \
  54     { \
  55       printf(" MS RLE: stream ptr just went out of bounds (1)\n"); \
  56       return; \
  57     } \
  58     stream_byte = s->buf[stream_ptr++];
  59
  60 static void msrle_decode_pal8(MsrleContext *s)
  61 {
  62     int stream_ptr = 0;
  63     unsigned char rle_code;
  64     unsigned char extra_byte;
  65     unsigned char stream_byte;
  66     int pixel_ptr = 0;
  67     int row_dec = s->frame.linesize[0];
  68     int row_ptr = (s->avctx->height - 1) * row_dec;
  69     int frame_size = row_dec * s->avctx->height;
  70
  71     while (row_ptr >= 0) {
  72         FETCH_NEXT_STREAM_BYTE();
  73         rle_code = stream_byte;
  74         if (rle_code == 0) {
  75             /* fetch the next byte to see how to handle escape code */
  76             FETCH_NEXT_STREAM_BYTE();
  77             if (stream_byte == 0) {
  78                 /* line is done, goto the next one */
  79                 row_ptr -= row_dec;
  80                 pixel_ptr = 0;
  81             } else if (stream_byte == 1) {
  82                 /* decode is done */
  83                 return;
  84             } else if (stream_byte == 2) {
  85                 /* reposition frame decode coordinates */
  86                 FETCH_NEXT_STREAM_BYTE();
  87                 pixel_ptr += stream_byte;
  88                 FETCH_NEXT_STREAM_BYTE();
  89                 row_ptr -= stream_byte * row_dec;
  90             } else {
  91                 /* copy pixels from encoded stream */
  92                 if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
  93                     (row_ptr < 0)) {
  94                     printf(" MS RLE: frame ptr just went out of bounds (1)\n");
  95                     return;
  96                 }
  97
  98                 rle_code = stream_byte;
  99                 extra_byte = stream_byte & 0x01;
 100                 if (stream_ptr + rle_code + extra_byte > s->size) {
 101                     printf(" MS RLE: stream ptr just went out of bounds (2)\n");
 102                     return;
 103                 }
 104
 105                 while (rle_code--) {
 106                     FETCH_NEXT_STREAM_BYTE();
 107                     s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
 108                     pixel_ptr++;
 109                 }
 110
 111                 /* if the RLE code is odd, skip a byte in the stream */
 112                 if (extra_byte)
 113                     stream_ptr++;
 114             }
 115         } else {
 116             /* decode a run of data */
 117             if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
 118                 (row_ptr < 0)) {
 119                 printf(" MS RLE: frame ptr just went out of bounds (2)\n");
 120                 return;
 121             }
 122
 123             FETCH_NEXT_STREAM_BYTE();
 124
 125             while(rle_code--) {
 126                 s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
 127                 pixel_ptr++;
 128             }
 129         }
 130     }
 131
 132     /* make the palette available */
 133     memcpy(s->frame.data[1], s->palette, 256 * 4);
 134
 135     /* one last sanity check on the way out */
 136     if (stream_ptr < s->size)
 137         printf(" MS RLE: ended frame decode with bytes left over (%d < %d)\n",
 138             stream_ptr, s->size);
 139 }
 140
 141 static int msrle_decode_init(AVCodecContext *avctx)
 142 {
 143     MsrleContext *s = (MsrleContext *)avctx->priv_data;
 144     int i, j;
 145     unsigned char *palette;
 146
 147     s->avctx = avctx;
 148
 149     avctx->pix_fmt = PIX_FMT_PAL8;
 150     avctx->has_b_frames = 0;
 151     s->frame.data[0] = s->prev_frame.data[0] = NULL;
 152
 153     /* convert palette */
 154     palette = (unsigned char *)s->avctx->extradata;
 155     memset (s->palette, 0, 256 * 4);
 156     for (i = 0, j = 0; i < s->avctx->extradata_size / 4; i++, j += 4)
 157         s->palette[i] =
 158             (palette[j + 2] << 16) |
 159             (palette[j + 1] <<  8) |
 160             (palette[j + 0] <<  0);
 161
 162     return 0;
 163 }
 164
 165 static int msrle_decode_frame(AVCodecContext *avctx,
 166                               void *data, int *data_size,
 167                               uint8_t *buf, int buf_size)
 168 {
 169     MsrleContext *s = (MsrleContext *)avctx->priv_data;
 170
 171     s->buf = buf;
 172     s->size = buf_size;
 173
 174     if (avctx->get_buffer(avctx, &s->frame)) {
 175         printf ("  MS RLE: get_buffer() failed\n");
 176         return -1;
 177     }
 178
 179     /* grossly inefficient, but...oh well */
 180     if (s->prev_frame.data[0] != NULL)
 181         memcpy(s->frame.data[0], s->prev_frame.data[0],
 182         s->frame.linesize[0] * s->avctx->height);
 183
 184     msrle_decode_pal8(s);
 185
 186     if (s->frame.data[0])
 187         avctx->release_buffer(avctx, &s->frame);
 188
 189     /* shuffle frames */
 190     s->prev_frame = s->frame;
 191
 192     *data_size = sizeof(AVFrame);
 193     *(AVFrame*)data = s->frame;
 194
 195     /* report that the buffer was completely consumed */
 196     return buf_size;
 197 }
 198
 199 static int msrle_decode_end(AVCodecContext *avctx)
 200 {
 201     MsrleContext *s = (MsrleContext *)avctx->priv_data;
 202
 203     /* release the last frame */
 204     if (s->prev_frame.data[0])
 205         avctx->release_buffer(avctx, &s->prev_frame);
 206
 207     return 0;
 208 }
 209
 210 AVCodec msrle_decoder = {
 211     "msrle",
 212     CODEC_TYPE_VIDEO,
 213     CODEC_ID_MSRLE,
 214     sizeof(MsrleContext),
 215     msrle_decode_init,
 216     NULL,
 217     msrle_decode_end,
 218     msrle_decode_frame,
 219     CODEC_CAP_DR1,
 220 };