libavcodec/mmvideo.c

   1 /*
   2  * American Laser Games MM Video Decoder
   3  * Copyright (c) 2006,2008 Peter Ross
   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 libavcodec/mmvideo.c
  24  * American Laser Games MM Video Decoder
  25  * by Peter Ross (suxen_drol at hotmail dot com)
  26  *
  27  * The MM format was used by IBM-PC ports of ALG's "arcade shooter" games,
  28  * including Mad Dog McCree and Crime Patrol.
  29  *
  30  * Technical details here:
  31  *  http://wiki.multimedia.cx/index.php?title=American_Laser_Games_MM
  32  */
  33
  34 #include "libavutil/intreadwrite.h"
  35 #include "avcodec.h"
  36
  37 #define MM_PREAMBLE_SIZE    6
  38
  39 #define MM_TYPE_INTER       0x5
  40 #define MM_TYPE_INTRA       0x8
  41 #define MM_TYPE_INTRA_HH    0xc
  42 #define MM_TYPE_INTER_HH    0xd
  43 #define MM_TYPE_INTRA_HHV   0xe
  44 #define MM_TYPE_INTER_HHV   0xf
  45 #define MM_TYPE_PALETTE     0x31
  46
  47 typedef struct MmContext {
  48     AVCodecContext *avctx;
  49     AVFrame frame;
  50     int palette[AVPALETTE_COUNT];
  51 } MmContext;
  52
  53 static av_cold int mm_decode_init(AVCodecContext *avctx)
  54 {
  55     MmContext *s = avctx->priv_data;
  56
  57     s->avctx = avctx;
  58
  59     avctx->pix_fmt = PIX_FMT_PAL8;
  60
  61     if (avcodec_check_dimensions(avctx, avctx->width, avctx->height))
  62         return -1;
  63
  64     s->frame.reference = 1;
  65     if (avctx->get_buffer(avctx, &s->frame)) {
  66         av_log(s->avctx, AV_LOG_ERROR, "mmvideo: get_buffer() failed\n");
  67         return -1;
  68     }
  69
  70     return 0;
  71 }
  72
  73 static void mm_decode_pal(MmContext *s, const uint8_t *buf, const uint8_t *buf_end)
  74 {
  75     int i;
  76     buf += 4;
  77     for (i=0; i<128 && buf+2<buf_end; i++) {
  78         s->palette[i] = AV_RB24(buf);
  79         s->palette[i+128] = s->palette[i]<<2;
  80         buf += 3;
  81     }
  82 }
  83
  84 static void mm_decode_intra(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
  85 {
  86     int i, x, y;
  87     i=0; x=0; y=0;
  88
  89     while(i<buf_size) {
  90         int run_length, color;
  91
  92         if (buf[i] & 0x80) {
  93             run_length = 1;
  94             color = buf[i];
  95             i++;
  96         }else{
  97             run_length = (buf[i] & 0x7f) + 2;
  98             color = buf[i+1];
  99             i+=2;
 100         }
 101
 102         if (half_horiz)
 103             run_length *=2;
 104
 105         if (color) {
 106             memset(s->frame.data[0] + y*s->frame.linesize[0] + x, color, run_length);
 107             if (half_vert)
 108                 memset(s->frame.data[0] + (y+1)*s->frame.linesize[0] + x, color, run_length);
 109         }
 110         x+= run_length;
 111
 112         if (x >= s->avctx->width) {
 113             x=0;
 114             y += half_vert ? 2 : 1;
 115         }
 116     }
 117 }
 118
 119 static void mm_decode_inter(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
 120 {
 121     const int data_ptr = 2 + AV_RL16(&buf[0]);
 122     int d, r, y;
 123     d = data_ptr; r = 2; y = 0;
 124
 125     while(r < data_ptr) {
 126         int i, j;
 127         int length = buf[r] & 0x7f;
 128         int x = buf[r+1] + ((buf[r] & 0x80) << 1);
 129         r += 2;
 130
 131         if (length==0) {
 132             y += x;
 133             continue;
 134         }
 135
 136         for(i=0; i<length; i++) {
 137             for(j=0; j<8; j++) {
 138                 int replace = (buf[r+i] >> (7-j)) & 1;
 139                 if (replace) {
 140                     int color = buf[d];
 141                     s->frame.data[0][y*s->frame.linesize[0] + x] = color;
 142                     if (half_horiz)
 143                         s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;
 144                     if (half_vert) {
 145                         s->frame.data[0][(y+1)*s->frame.linesize[0] + x] = color;
 146                         if (half_horiz)
 147                             s->frame.data[0][(y+1)*s->frame.linesize[0] + x + 1] = color;
 148                     }
 149                     d++;
 150                 }
 151                 x += half_horiz ? 2 : 1;
 152             }
 153         }
 154
 155         r += length;
 156         y += half_vert ? 2 : 1;
 157     }
 158 }
 159
 160 static int mm_decode_frame(AVCodecContext *avctx,
 161                             void *data, int *data_size,
 162                             const uint8_t *buf, int buf_size)
 163 {
 164     MmContext *s = avctx->priv_data;
 165     const uint8_t *buf_end = buf+buf_size;
 166     int type;
 167
 168     type = AV_RL16(&buf[0]);
 169     buf += MM_PREAMBLE_SIZE;
 170     buf_size -= MM_PREAMBLE_SIZE;
 171
 172     switch(type) {
 173     case MM_TYPE_PALETTE   : mm_decode_pal(s, buf, buf_end); return buf_size;
 174     case MM_TYPE_INTRA     : mm_decode_intra(s, 0, 0, buf, buf_size); break;
 175     case MM_TYPE_INTRA_HH  : mm_decode_intra(s, 1, 0, buf, buf_size); break;
 176     case MM_TYPE_INTRA_HHV : mm_decode_intra(s, 1, 1, buf, buf_size); break;
 177     case MM_TYPE_INTER     : mm_decode_inter(s, 0, 0, buf, buf_size); break;
 178     case MM_TYPE_INTER_HH  : mm_decode_inter(s, 1, 0, buf, buf_size); break;
 179     case MM_TYPE_INTER_HHV : mm_decode_inter(s, 1, 1, buf, buf_size); break;
 180     default :
 181         return -1;
 182     }
 183
 184     memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
 185
 186     *data_size = sizeof(AVFrame);
 187     *(AVFrame*)data = s->frame;
 188
 189     return buf_size;
 190 }
 191
 192 static av_cold int mm_decode_end(AVCodecContext *avctx)
 193 {
 194     MmContext *s = avctx->priv_data;
 195
 196     if(s->frame.data[0])
 197         avctx->release_buffer(avctx, &s->frame);
 198
 199     return 0;
 200 }
 201
 202 AVCodec mmvideo_decoder = {
 203     "mmvideo",
 204     CODEC_TYPE_VIDEO,
 205     CODEC_ID_MMVIDEO,
 206     sizeof(MmContext),
 207     mm_decode_init,
 208     NULL,
 209     mm_decode_end,
 210     mm_decode_frame,
 211     CODEC_CAP_DR1,
 212     .long_name = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),
 213 };