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