FFmpeg: libavcodec/mmvideo.c Source File

FFmpeg
mmvideo.c
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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 {
50   AVCodecContext *avctx;
51   AVFrame *frame;
52   unsigned int palette[AVPALETTE_COUNT];
53   GetByteContext gb;
54 } MmContext;
55 
56  static av_cold int mm_decode_init(AVCodecContext *avctx)
57 {
58  MmContext *s = avctx->priv_data;
59 
60  s->avctx = avctx;
61 
62  avctx->pix_fmt = AV_PIX_FMT_PAL8;
63 
64  if (!avctx->width || !avctx->height ||
65  (avctx->width & 1) || (avctx->height & 1)) {
66  av_log(avctx, AV_LOG_ERROR, "Invalid video dimensions: %dx%d\n",
67  avctx->width, avctx->height);
68  return AVERROR(EINVAL);
69  }
70 
71  s->frame = av_frame_alloc();
72  if (!s->frame)
73  return AVERROR(ENOMEM);
74 
75  return 0;
76 }
77 
78  static void mm_decode_pal(MmContext *s)
79 {
80  int i;
81 
82  bytestream2_skip(&s->gb, 4);
83  for (i = 0; i < 128; i++) {
84  s->palette[i] = 0xFFU << 24 | bytestream2_get_be24(&s->gb);
85  s->palette[i+128] = s->palette[i]<<2;
86  }
87 }
88 
89 /**
90  * @param half_horiz Half horizontal resolution (0 or 1)
91  * @param half_vert Half vertical resolution (0 or 1)
92  */
93  static int mm_decode_intra(MmContext * s, int half_horiz, int half_vert)
94 {
95  int x = 0, y = 0;
96 
97  while (bytestream2_get_bytes_left(&s->gb) > 0) {
98  int run_length, color;
99 
100  if (y >= s->avctx->height)
101  return 0;
102 
103  color = bytestream2_get_byte(&s->gb);
104  if (color & 0x80) {
105  run_length = 1;
106  }else{
107  run_length = (color & 0x7f) + 2;
108  color = bytestream2_get_byte(&s->gb);
109  }
110 
111  if (half_horiz)
112  run_length *=2;
113 
114  if (run_length > s->avctx->width - x)
115  return AVERROR_INVALIDDATA;
116 
117  if (color) {
118  memset(s->frame->data[0] + y*s->frame->linesize[0] + x, color, run_length);
119  if (half_vert && y + half_vert < s->avctx->height)
120  memset(s->frame->data[0] + (y+1)*s->frame->linesize[0] + x, color, run_length);
121  }
122  x+= run_length;
123 
124  if (x >= s->avctx->width) {
125  x=0;
126  y += 1 + half_vert;
127  }
128  }
129 
130  return 0;
131 }
132 
133 /**
134  * @param half_horiz Half horizontal resolution (0 or 1)
135  * @param half_vert Half vertical resolution (0 or 1)
136  */
137  static int mm_decode_inter(MmContext * s, int half_horiz, int half_vert)
138 {
139  int data_off = bytestream2_get_le16(&s->gb);
140  int y = 0;
141  GetByteContext data_ptr;
142 
143  if (bytestream2_get_bytes_left(&s->gb) < data_off)
144  return AVERROR_INVALIDDATA;
145 
146  bytestream2_init(&data_ptr, s->gb.buffer + data_off, bytestream2_get_bytes_left(&s->gb) - data_off);
147  while (s->gb.buffer < data_ptr.buffer_start) {
148  int i, j;
149  int length = bytestream2_get_byte(&s->gb);
150  int x = bytestream2_get_byte(&s->gb) + ((length & 0x80) << 1);
151  length &= 0x7F;
152 
153  if (length==0) {
154  y += x;
155  continue;
156  }
157 
158  if (y + half_vert >= s->avctx->height)
159  return 0;
160 
161  for(i=0; i<length; i++) {
162  int replace_array = bytestream2_get_byte(&s->gb);
163  for(j=0; j<8; j++) {
164  int replace = (replace_array >> (7-j)) & 1;
165  if (x + half_horiz >= s->avctx->width)
166  return AVERROR_INVALIDDATA;
167  if (replace) {
168  int color = bytestream2_get_byte(&data_ptr);
169  s->frame->data[0][y*s->frame->linesize[0] + x] = color;
170  if (half_horiz)
171  s->frame->data[0][y*s->frame->linesize[0] + x + 1] = color;
172  if (half_vert) {
173  s->frame->data[0][(y+1)*s->frame->linesize[0] + x] = color;
174  if (half_horiz)
175  s->frame->data[0][(y+1)*s->frame->linesize[0] + x + 1] = color;
176  }
177  }
178  x += 1 + half_horiz;
179  }
180  }
181 
182  y += 1 + half_vert;
183  }
184 
185  return 0;
186 }
187 
188  static int mm_decode_frame(AVCodecContext *avctx,
189  void *data, int *got_frame,
190  AVPacket *avpkt)
191 {
192  const uint8_t *buf = avpkt->data;
193  int buf_size = avpkt->size;
194  MmContext *s = avctx->priv_data;
195  int type, res;
196 
197  if (buf_size < MM_PREAMBLE_SIZE)
198  return AVERROR_INVALIDDATA;
199  type = AV_RL16(&buf[0]);
200  buf += MM_PREAMBLE_SIZE;
201  buf_size -= MM_PREAMBLE_SIZE;
202  bytestream2_init(&s->gb, buf, buf_size);
203 
204  if ((res = ff_reget_buffer(avctx, s->frame)) < 0)
205  return res;
206 
207  switch(type) {
208  case MM_TYPE_PALETTE : mm_decode_pal(s); return avpkt->size;
209  case MM_TYPE_INTRA : res = mm_decode_intra(s, 0, 0); break;
210  case MM_TYPE_INTRA_HH : res = mm_decode_intra(s, 1, 0); break;
211  case MM_TYPE_INTRA_HHV : res = mm_decode_intra(s, 1, 1); break;
212  case MM_TYPE_INTER : res = mm_decode_inter(s, 0, 0); break;
213  case MM_TYPE_INTER_HH : res = mm_decode_inter(s, 1, 0); break;
214  case MM_TYPE_INTER_HHV : res = mm_decode_inter(s, 1, 1); break;
215  default:
216  res = AVERROR_INVALIDDATA;
217  break;
218  }
219  if (res < 0)
220  return res;
221 
222  memcpy(s->frame->data[1], s->palette, AVPALETTE_SIZE);
223 
224  if ((res = av_frame_ref(data, s->frame)) < 0)
225  return res;
226 
227  *got_frame = 1;
228 
229  return avpkt->size;
230 }
231 
232  static av_cold int mm_decode_end(AVCodecContext *avctx)
233 {
234  MmContext *s = avctx->priv_data;
235 
236  av_frame_free(&s->frame);
237 
238  return 0;
239 }
240 
241  AVCodec ff_mmvideo_decoder = {
242  .name = "mmvideo",
243  .long_name = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),
244  .type = AVMEDIA_TYPE_VIDEO,
245  .id = AV_CODEC_ID_MMVIDEO,
246  .priv_data_size = sizeof(MmContext),
247  .init = mm_decode_init,
248  .close = mm_decode_end,
249  .decode = mm_decode_frame,
250  .capabilities = CODEC_CAP_DR1,
251 };
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