libavcodec/aasc.c

   1 /*
   2  * Autodesc RLE Decoder
   3  * Copyright (C) 2005 the ffmpeg project
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file aasc.c
  24  * Autodesc RLE Video Decoder by Konstantin Shishkov
  25  */
  26
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30
  31 #include "avcodec.h"
  32 #include "dsputil.h"
  33
  34 typedef struct AascContext {
  35     AVCodecContext *avctx;
  36     AVFrame frame;
  37 } AascContext;
  38
  39 #define FETCH_NEXT_STREAM_BYTE() \
  40     if (stream_ptr >= buf_size) \
  41     { \
  42       av_log(s->avctx, AV_LOG_ERROR, " AASC: stream ptr just went out of bounds (fetch)\n"); \
  43       break; \
  44     } \
  45     stream_byte = buf[stream_ptr++];
  46
  47 static av_cold int aasc_decode_init(AVCodecContext *avctx)
  48 {
  49     AascContext *s = avctx->priv_data;
  50
  51     s->avctx = avctx;
  52
  53     avctx->pix_fmt = PIX_FMT_BGR24;
  54     s->frame.data[0] = NULL;
  55
  56     return 0;
  57 }
  58
  59 static int aasc_decode_frame(AVCodecContext *avctx,
  60                               void *data, int *data_size,
  61                               const uint8_t *buf, int buf_size)
  62 {
  63     AascContext *s = avctx->priv_data;
  64     int stream_ptr = 4;
  65     unsigned char rle_code;
  66     unsigned char stream_byte;
  67     int pixel_ptr = 0;
  68     int row_dec, row_ptr;
  69     int frame_size;
  70     int i;
  71
  72     s->frame.reference = 1;
  73     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
  74     if (avctx->reget_buffer(avctx, &s->frame)) {
  75         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
  76         return -1;
  77     }
  78
  79     row_dec = s->frame.linesize[0];
  80     row_ptr = (s->avctx->height - 1) * row_dec;
  81     frame_size = row_dec * s->avctx->height;
  82
  83     while (row_ptr >= 0) {
  84         FETCH_NEXT_STREAM_BYTE();
  85         rle_code = stream_byte;
  86         if (rle_code == 0) {
  87             /* fetch the next byte to see how to handle escape code */
  88             FETCH_NEXT_STREAM_BYTE();
  89             if (stream_byte == 0) {
  90                 /* line is done, goto the next one */
  91                 row_ptr -= row_dec;
  92                 pixel_ptr = 0;
  93             } else if (stream_byte == 1) {
  94                 /* decode is done */
  95                 break;
  96             } else if (stream_byte == 2) {
  97                 /* reposition frame decode coordinates */
  98                 FETCH_NEXT_STREAM_BYTE();
  99                 pixel_ptr += stream_byte;
 100                 FETCH_NEXT_STREAM_BYTE();
 101                 row_ptr -= stream_byte * row_dec;
 102             } else {
 103                 /* copy pixels from encoded stream */
 104                 if ((pixel_ptr + stream_byte > avctx->width * 3) ||
 105                     (row_ptr < 0)) {
 106                     av_log(s->avctx, AV_LOG_ERROR, " AASC: frame ptr just went out of bounds (copy1)\n");
 107                     break;
 108                 }
 109
 110                 rle_code = stream_byte;
 111                 if (stream_ptr + rle_code > buf_size) {
 112                     av_log(s->avctx, AV_LOG_ERROR, " AASC: stream ptr just went out of bounds (copy2)\n");
 113                     break;
 114                 }
 115
 116                 for (i = 0; i < rle_code; i++) {
 117                     FETCH_NEXT_STREAM_BYTE();
 118                     s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
 119                     pixel_ptr++;
 120                 }
 121                 if (rle_code & 1)
 122                     stream_ptr++;
 123             }
 124         } else {
 125             /* decode a run of data */
 126             if ((pixel_ptr + rle_code > avctx->width * 3) ||
 127                 (row_ptr < 0)) {
 128                 av_log(s->avctx, AV_LOG_ERROR, " AASC: frame ptr just went out of bounds (run1)\n");
 129                 break;
 130             }
 131
 132             FETCH_NEXT_STREAM_BYTE();
 133
 134             while(rle_code--) {
 135                 s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
 136                 pixel_ptr++;
 137             }
 138         }
 139     }
 140
 141     /* one last sanity check on the way out */
 142     if (stream_ptr < buf_size)
 143         av_log(s->avctx, AV_LOG_ERROR, " AASC: ended frame decode with bytes left over (%d < %d)\n",
 144             stream_ptr, buf_size);
 145
 146     *data_size = sizeof(AVFrame);
 147     *(AVFrame*)data = s->frame;
 148
 149     /* report that the buffer was completely consumed */
 150     return buf_size;
 151 }
 152
 153 static av_cold int aasc_decode_end(AVCodecContext *avctx)
 154 {
 155     AascContext *s = avctx->priv_data;
 156
 157     /* release the last frame */
 158     if (s->frame.data[0])
 159         avctx->release_buffer(avctx, &s->frame);
 160
 161     return 0;
 162 }
 163
 164 AVCodec aasc_decoder = {
 165     "aasc",
 166     CODEC_TYPE_VIDEO,
 167     CODEC_ID_AASC,
 168     sizeof(AascContext),
 169     aasc_decode_init,
 170     NULL,
 171     aasc_decode_end,
 172     aasc_decode_frame,
 173     CODEC_CAP_DR1,
 174 };