FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
mmvideo.c
Go to the documentation of this file.
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
24  * American Laser Games MM Video Decoder
25  * by Peter Ross (pross@xvid.org)
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 #include "bytestream.h"
37 #include "internal.h"
38 
39 #define MM_PREAMBLE_SIZE 6
40 
41 #define MM_TYPE_INTER 0x5
42 #define MM_TYPE_INTRA 0x8
43 #define MM_TYPE_INTRA_HH 0xc
44 #define MM_TYPE_INTER_HH 0xd
45 #define MM_TYPE_INTRA_HHV 0xe
46 #define MM_TYPE_INTER_HHV 0xf
47 #define MM_TYPE_PALETTE 0x31
48 
49 typedef struct MmContext {
52  unsigned int palette[AVPALETTE_COUNT];
54 } MmContext;
55 
57 {
58  MmContext *s = avctx->priv_data;
59 
60  s->avctx = avctx;
61 
62  avctx->pix_fmt = AV_PIX_FMT_PAL8;
63 
64  s->frame = av_frame_alloc();
65  if (!s->frame)
66  return AVERROR(ENOMEM);
67 
68  return 0;
69 }
70 
71 static void mm_decode_pal(MmContext *s)
72 {
73  int i;
74 
75  bytestream2_skip(&s->gb, 4);
76  for (i = 0; i < 128; i++) {
77  s->palette[i] = 0xFFU << 24 | bytestream2_get_be24(&s->gb);
78  s->palette[i+128] = s->palette[i]<<2;
79  }
80 }
81 
82 /**
83  * @param half_horiz Half horizontal resolution (0 or 1)
84  * @param half_vert Half vertical resolution (0 or 1)
85  */
86 static int mm_decode_intra(MmContext * s, int half_horiz, int half_vert)
87 {
88  int x = 0, y = 0;
89 
90  while (bytestream2_get_bytes_left(&s->gb) > 0) {
91  int run_length, color;
92 
93  if (y >= s->avctx->height)
94  return 0;
95 
96  color = bytestream2_get_byte(&s->gb);
97  if (color & 0x80) {
98  run_length = 1;
99  }else{
100  run_length = (color & 0x7f) + 2;
101  color = bytestream2_get_byte(&s->gb);
102  }
103 
104  if (half_horiz)
105  run_length *=2;
106 
107  if (run_length > s->avctx->width - x)
108  return AVERROR_INVALIDDATA;
109 
110  if (color) {
111  memset(s->frame->data[0] + y*s->frame->linesize[0] + x, color, run_length);
112  if (half_vert && y + half_vert < s->avctx->height)
113  memset(s->frame->data[0] + (y+1)*s->frame->linesize[0] + x, color, run_length);
114  }
115  x+= run_length;
116 
117  if (x >= s->avctx->width) {
118  x=0;
119  y += 1 + half_vert;
120  }
121  }
122 
123  return 0;
124 }
125 
126 /**
127  * @param half_horiz Half horizontal resolution (0 or 1)
128  * @param half_vert Half vertical resolution (0 or 1)
129  */
130 static int mm_decode_inter(MmContext * s, int half_horiz, int half_vert)
131 {
132  int data_off = bytestream2_get_le16(&s->gb);
133  int y = 0;
134  GetByteContext data_ptr;
135 
136  if (bytestream2_get_bytes_left(&s->gb) < data_off)
137  return AVERROR_INVALIDDATA;
138 
139  bytestream2_init(&data_ptr, s->gb.buffer + data_off, bytestream2_get_bytes_left(&s->gb) - data_off);
140  while (s->gb.buffer < data_ptr.buffer_start) {
141  int i, j;
142  int length = bytestream2_get_byte(&s->gb);
143  int x = bytestream2_get_byte(&s->gb) + ((length & 0x80) << 1);
144  length &= 0x7F;
145 
146  if (length==0) {
147  y += x;
148  continue;
149  }
150 
151  if (y + half_vert >= s->avctx->height)
152  return 0;
153 
154  for(i=0; i<length; i++) {
155  int replace_array = bytestream2_get_byte(&s->gb);
156  for(j=0; j<8; j++) {
157  int replace = (replace_array >> (7-j)) & 1;
158  if (x + half_horiz >= s->avctx->width)
159  return AVERROR_INVALIDDATA;
160  if (replace) {
161  int color = bytestream2_get_byte(&data_ptr);
162  s->frame->data[0][y*s->frame->linesize[0] + x] = color;
163  if (half_horiz)
164  s->frame->data[0][y*s->frame->linesize[0] + x + 1] = color;
165  if (half_vert) {
166  s->frame->data[0][(y+1)*s->frame->linesize[0] + x] = color;
167  if (half_horiz)
168  s->frame->data[0][(y+1)*s->frame->linesize[0] + x + 1] = color;
169  }
170  }
171  x += 1 + half_horiz;
172  }
173  }
174 
175  y += 1 + half_vert;
176  }
177 
178  return 0;
179 }
180 
181 static int mm_decode_frame(AVCodecContext *avctx,
182  void *data, int *got_frame,
183  AVPacket *avpkt)
184 {
185  const uint8_t *buf = avpkt->data;
186  int buf_size = avpkt->size;
187  MmContext *s = avctx->priv_data;
188  int type, res;
189 
190  if (buf_size < MM_PREAMBLE_SIZE)
191  return AVERROR_INVALIDDATA;
192  type = AV_RL16(&buf[0]);
193  buf += MM_PREAMBLE_SIZE;
194  buf_size -= MM_PREAMBLE_SIZE;
195  bytestream2_init(&s->gb, buf, buf_size);
196 
197  if ((res = ff_reget_buffer(avctx, s->frame)) < 0)
198  return res;
199 
200  switch(type) {
201  case MM_TYPE_PALETTE : mm_decode_pal(s); return avpkt->size;
202  case MM_TYPE_INTRA : res = mm_decode_intra(s, 0, 0); break;
203  case MM_TYPE_INTRA_HH : res = mm_decode_intra(s, 1, 0); break;
204  case MM_TYPE_INTRA_HHV : res = mm_decode_intra(s, 1, 1); break;
205  case MM_TYPE_INTER : res = mm_decode_inter(s, 0, 0); break;
206  case MM_TYPE_INTER_HH : res = mm_decode_inter(s, 1, 0); break;
207  case MM_TYPE_INTER_HHV : res = mm_decode_inter(s, 1, 1); break;
208  default:
209  res = AVERROR_INVALIDDATA;
210  break;
211  }
212  if (res < 0)
213  return res;
214 
215  memcpy(s->frame->data[1], s->palette, AVPALETTE_SIZE);
216 
217  if ((res = av_frame_ref(data, s->frame)) < 0)
218  return res;
219 
220  *got_frame = 1;
221 
222  return avpkt->size;
223 }
224 
226 {
227  MmContext *s = avctx->priv_data;
228 
229  av_frame_free(&s->frame);
230 
231  return 0;
232 }
233 
235  .name = "mmvideo",
236  .long_name = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),
237  .type = AVMEDIA_TYPE_VIDEO,
238  .id = AV_CODEC_ID_MMVIDEO,
239  .priv_data_size = sizeof(MmContext),
240  .init = mm_decode_init,
241  .close = mm_decode_end,
243  .capabilities = CODEC_CAP_DR1,
244 };