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
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    s->frame.reference = 1;
62    if (avctx->get_buffer(avctx, &s->frame)) {
63        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
64        return -1;
65    }
66
67    return 0;
68}
69
70static void mm_decode_pal(MmContext *s, const uint8_t *buf, const uint8_t *buf_end)
71{
72    int i;
73    buf += 4;
74    for (i=0; i<128 && buf+2<buf_end; i++) {
75        s->palette[i] = AV_RB24(buf);
76        s->palette[i+128] = s->palette[i]<<2;
77        buf += 3;
78    }
79}
80
81static void mm_decode_intra(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
82{
83    int i, x, y;
84    i=0; x=0; y=0;
85
86    while(i<buf_size) {
87        int run_length, color;
88
89        if (buf[i] & 0x80) {
90            run_length = 1;
91            color = buf[i];
92            i++;
93        }else{
94            run_length = (buf[i] & 0x7f) + 2;
95            color = buf[i+1];
96            i+=2;
97        }
98
99        if (half_horiz)
100            run_length *=2;
101
102        if (color) {
103            memset(s->frame.data[0] + y*s->frame.linesize[0] + x, color, run_length);
104            if (half_vert)
105                memset(s->frame.data[0] + (y+1)*s->frame.linesize[0] + x, color, run_length);
106        }
107        x+= run_length;
108
109        if (x >= s->avctx->width) {
110            x=0;
111            y += half_vert ? 2 : 1;
112        }
113    }
114}
115
116static void mm_decode_inter(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
117{
118    const int data_ptr = 2 + AV_RL16(&buf[0]);
119    int d, r, y;
120    d = data_ptr; r = 2; y = 0;
121
122    while(r < data_ptr) {
123        int i, j;
124        int length = buf[r] & 0x7f;
125        int x = buf[r+1] + ((buf[r] & 0x80) << 1);
126        r += 2;
127
128        if (length==0) {
129            y += x;
130            continue;
131        }
132
133        for(i=0; i<length; i++) {
134            for(j=0; j<8; j++) {
135                int replace = (buf[r+i] >> (7-j)) & 1;
136                if (replace) {
137                    int color = buf[d];
138                    s->frame.data[0][y*s->frame.linesize[0] + x] = color;
139                    if (half_horiz)
140                        s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;
141                    if (half_vert) {
142                        s->frame.data[0][(y+1)*s->frame.linesize[0] + x] = color;
143                        if (half_horiz)
144                            s->frame.data[0][(y+1)*s->frame.linesize[0] + x + 1] = color;
145                    }
146                    d++;
147                }
148                x += half_horiz ? 2 : 1;
149            }
150        }
151
152        r += length;
153        y += half_vert ? 2 : 1;
154    }
155}
156
157static int mm_decode_frame(AVCodecContext *avctx,
158                            void *data, int *data_size,
159                            AVPacket *avpkt)
160{
161    const uint8_t *buf = avpkt->data;
162    int buf_size = avpkt->size;
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
191static 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
201AVCodec mmvideo_decoder = {
202    "mmvideo",
203    AVMEDIA_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};
213