summaryrefslogtreecommitdiff
path: root/libavcodec/rl2.c
blob: 7eebddff6f4557f14f88b2500599628b891c9685 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
/*
 * RL2 Video Decoder
 * Copyright (C) 2008 Sascha Sommer (saschasommer@freenet.de)
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * RL2 Video Decoder
 * @author Sascha Sommer (saschasommer@freenet.de)
 * @see http://wiki.multimedia.cx/index.php?title=RL2
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "libavutil/intreadwrite.h"
#include "avcodec.h"


#define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette

typedef struct Rl2Context {
    AVCodecContext *avctx;
    AVFrame frame;

    unsigned short video_base; ///< initial drawing offset
    unsigned int clr_count;    ///< number of used colors (currently unused)
    unsigned char* back_frame; ///< background frame
    unsigned int palette[AVPALETTE_COUNT];
} Rl2Context;

/**
 * Run Length Decode a single 320x200 frame
 * @param s rl2 context
 * @param in input buffer
 * @param size input buffer size
 * @param out output buffer
 * @param stride stride of the output buffer
 * @param video_base offset of the rle data inside the frame
 */
static void rl2_rle_decode(Rl2Context *s,const unsigned char* in,int size,
                               unsigned char* out,int stride,int video_base){
    int base_x = video_base % s->avctx->width;
    int base_y = video_base / s->avctx->width;
    int stride_adj = stride - s->avctx->width;
    int i;
    const unsigned char* back_frame = s->back_frame;
    const unsigned char* in_end = in + size;
    const unsigned char* out_end = out + stride * s->avctx->height;
    unsigned char* line_end = out + s->avctx->width;

    /** copy start of the background frame */
    for(i=0;i<=base_y;i++){
        if(s->back_frame)
            memcpy(out,back_frame,s->avctx->width);
        out += stride;
        back_frame += s->avctx->width;
    }
    back_frame += base_x - s->avctx->width;
    line_end = out - stride_adj;
    out += base_x - stride;

    /** decode the variable part of the frame */
    while(in < in_end){
        unsigned char val = *in++;
        int len = 1;
        if(val >= 0x80){
            if(in >= in_end)
                break;
            len = *in++;
            if(!len)
                break;
        }

        if(len >= out_end - out)
            break;

        if(s->back_frame)
            val |= 0x80;
        else
            val &= ~0x80;

        while(len--){
            *out++ = (val == 0x80)? *back_frame:val;
            back_frame++;
            if(out == line_end){
                 out += stride_adj;
                 line_end += stride;
                 if(len >= out_end - out)
                     break;
            }
        }
    }

    /** copy the rest from the background frame */
    if(s->back_frame){
        while(out < out_end){
            memcpy(out, back_frame, line_end - out);
            back_frame += line_end - out;
            out = line_end + stride_adj;
            line_end += stride;
        }
    }
}


/**
 * Initialize the decoder
 * @param avctx decoder context
 * @return 0 success, -1 on error
 */
static av_cold int rl2_decode_init(AVCodecContext *avctx)
{
    Rl2Context *s = avctx->priv_data;
    int back_size;
    int i;
    s->avctx = avctx;
    avctx->pix_fmt = PIX_FMT_PAL8;
    avcodec_get_frame_defaults(&s->frame);

    /** parse extra data */
    if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
        av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
        return -1;
    }

    /** get frame_offset */
    s->video_base = AV_RL16(&avctx->extradata[0]);
    s->clr_count = AV_RL32(&avctx->extradata[2]);

    if(s->video_base >= avctx->width * avctx->height){
        av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
        return -1;
    }

    /** initialize palette */
    for(i=0;i<AVPALETTE_COUNT;i++)
        s->palette[i] = 0xFF << 24 | AV_RB24(&avctx->extradata[6 + i * 3]);

    /** decode background frame if present */
    back_size = avctx->extradata_size - EXTRADATA1_SIZE;

    if(back_size > 0){
        unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
        if(!back_frame)
            return -1;
        rl2_rle_decode(s,avctx->extradata + EXTRADATA1_SIZE,back_size,
                           back_frame,avctx->width,0);
        s->back_frame = back_frame;
    }
    return 0;
}


static int rl2_decode_frame(AVCodecContext *avctx,
                              void *data, int *data_size,
                              AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    Rl2Context *s = avctx->priv_data;

    if(s->frame.data[0])
        avctx->release_buffer(avctx, &s->frame);

    /** get buffer */
    s->frame.reference= 0;
    if(avctx->get_buffer(avctx, &s->frame)) {
        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return -1;
    }

    /** run length decode */
    rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);

    /** make the palette available on the way out */
    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);

    *data_size = sizeof(AVFrame);
    *(AVFrame*)data = s->frame;

    /** report that the buffer was completely consumed */
    return buf_size;
}


/**
 * Uninit decoder
 * @param avctx decoder context
 * @return 0 success, -1 on error
 */
static av_cold int rl2_decode_end(AVCodecContext *avctx)
{
    Rl2Context *s = avctx->priv_data;

    if(s->frame.data[0])
        avctx->release_buffer(avctx, &s->frame);

    av_free(s->back_frame);

    return 0;
}


AVCodec ff_rl2_decoder = {
    .name           = "rl2",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_RL2,
    .priv_data_size = sizeof(Rl2Context),
    .init           = rl2_decode_init,
    .close          = rl2_decode_end,
    .decode         = rl2_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
    .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
};