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
47typedef struct MmContext {
48    AVCodecContext *avctx;
49    AVFrame frame;
50    int palette[AVPALETTE_COUNT];
51} MmContext;
52
53static 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
73static 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
84static 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
119static 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
160static 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
192static 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
202AVCodec 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};
214