complete American Laser Games MM playback system, courtesy of Peter Ross
[libav.git] / libavcodec / mmvideo.c
1 /*
2 * American Laser Games MM Video Decoder
3 * Copyright (c) 2006 Peter Ross
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20 /**
21 * @file mm.c
22 * American Laser Games MM Video Decoder
23 * by Peter Ross (suxen_drol at hotmail dot com)
24 *
25 * The MM format was used by IBM-PC ports of ALG's "arcade shooter" games,
26 * including Mad Dog McCree and Crime Patrol.
27 *
28 * Technical details here:
29 * http://wiki.multimedia.cx/index.php?title=American_Laser_Games_MM
30 */
31
32 #include "avcodec.h"
33
34 #define MM_PREAMBLE_SIZE 6
35
36 #define MM_TYPE_INTER 0x5
37 #define MM_TYPE_INTRA 0x8
38 #define MM_TYPE_INTRA_HH 0xc
39 #define MM_TYPE_INTER_HH 0xd
40 #define MM_TYPE_INTRA_HHV 0xe
41 #define MM_TYPE_INTER_HHV 0xf
42
43 typedef struct MmContext {
44 AVCodecContext *avctx;
45 AVFrame frame;
46 } MmContext;
47
48 static int mm_decode_init(AVCodecContext *avctx)
49 {
50 MmContext *s = avctx->priv_data;
51
52 s->avctx = avctx;
53
54 if (s->avctx->palctrl == NULL) {
55 av_log(avctx, AV_LOG_ERROR, "mmvideo: palette expected.\n");
56 return -1;
57 }
58
59 avctx->pix_fmt = PIX_FMT_PAL8;
60 avctx->has_b_frames = 0;
61
62 if (avcodec_check_dimensions(avctx, avctx->width, avctx->height))
63 return -1;
64
65 s->frame.reference = 1;
66 if (avctx->get_buffer(avctx, &s->frame)) {
67 av_log(s->avctx, AV_LOG_ERROR, "mmvideo: get_buffer() failed\n");
68 return -1;
69 }
70
71 return 0;
72 }
73
74 static void mm_decode_intra(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
75 {
76 int i, x, y;
77 i=0; x=0; y=0;
78
79 while(i<buf_size) {
80 int run_length, color;
81
82 if (buf[i] & 0x80) {
83 run_length = 1;
84 color = buf[i];
85 i++;
86 }else{
87 run_length = (buf[i] & 0x7f) + 2;
88 color = buf[i+1];
89 i+=2;
90 }
91
92 if (half_horiz)
93 run_length *=2;
94
95 if (color) {
96 memset(s->frame.data[0] + y*s->frame.linesize[0] + x, color, run_length);
97 if (half_vert)
98 memset(s->frame.data[0] + (y+1)*s->frame.linesize[0] + x, color, run_length);
99 }
100 x+= run_length;
101
102 if (x >= s->avctx->width) {
103 x=0;
104 y += half_vert ? 2 : 1;
105 }
106 }
107 }
108
109 static void mm_decode_inter(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
110 {
111 const int data_ptr = 2 + LE_16(&buf[0]);
112 int d, r, y;
113 d = data_ptr; r = 2; y = 0;
114
115 while(r < data_ptr) {
116 int i, j;
117 int length = buf[r] & 0x7f;
118 int x = buf[r+1] + ((buf[r] & 0x80) << 1);
119 r += 2;
120
121 if (length==0) {
122 y += x;
123 continue;
124 }
125
126 for(i=0; i<length; i++) {
127 for(j=0; j<8; j++) {
128 int replace = (buf[r+i] >> (7-j)) & 1;
129 if (replace) {
130 int color = buf[d];
131 s->frame.data[0][y*s->frame.linesize[0] + x] = color;
132 if (half_horiz)
133 s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;
134 if (half_vert) {
135 s->frame.data[0][(y+1)*s->frame.linesize[0] + x] = color;
136 if (half_horiz)
137 s->frame.data[0][(y+1)*s->frame.linesize[0] + x + 1] = color;
138 }
139 d++;
140 }
141 x += half_horiz ? 2 : 1;
142 }
143 }
144
145 r += length;
146 y += half_vert ? 2 : 1;
147 }
148 }
149
150 static int mm_decode_frame(AVCodecContext *avctx,
151 void *data, int *data_size,
152 uint8_t *buf, int buf_size)
153 {
154 MmContext *s = avctx->priv_data;
155 AVPaletteControl *palette_control = avctx->palctrl;
156 int type;
157
158 if (palette_control->palette_changed) {
159 memcpy(s->frame.data[1], palette_control->palette, AVPALETTE_SIZE);
160 palette_control->palette_changed = 0;
161 }
162
163 type = LE_16(&buf[0]);
164 buf += MM_PREAMBLE_SIZE;
165 buf_size -= MM_PREAMBLE_SIZE;
166
167 switch(type) {
168 case MM_TYPE_INTRA : mm_decode_intra(s, 0, 0, buf, buf_size); break;
169 case MM_TYPE_INTRA_HH : mm_decode_intra(s, 1, 0, buf, buf_size); break;
170 case MM_TYPE_INTRA_HHV : mm_decode_intra(s, 1, 1, buf, buf_size); break;
171 case MM_TYPE_INTER : mm_decode_inter(s, 0, 0, buf, buf_size); break;
172 case MM_TYPE_INTER_HH : mm_decode_inter(s, 1, 0, buf, buf_size); break;
173 case MM_TYPE_INTER_HHV : mm_decode_inter(s, 1, 1, buf, buf_size); break;
174 default :
175 return -1;
176 }
177
178 *data_size = sizeof(AVFrame);
179 *(AVFrame*)data = s->frame;
180
181 return buf_size;
182 }
183
184 static int mm_decode_end(AVCodecContext *avctx)
185 {
186 MmContext *s = avctx->priv_data;
187
188 if(s->frame.data[0])
189 avctx->release_buffer(avctx, &s->frame);
190
191 return 0;
192 }
193
194 AVCodec mmvideo_decoder = {
195 "mmvideo",
196 CODEC_TYPE_VIDEO,
197 CODEC_ID_MMVIDEO,
198 sizeof(MmContext),
199 mm_decode_init,
200 NULL,
201 mm_decode_end,
202 mm_decode_frame,
203 CODEC_CAP_DR1,
204 };