1/*
2 * RL2 Video Decoder
3 * Copyright (C) 2008 Sascha Sommer (saschasommer@freenet.de)
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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 * RL2 Video Decoder
25 * @author Sascha Sommer (saschasommer@freenet.de)
26 * @see http://wiki.multimedia.cx/index.php?title=RL2
27 */
28
29#include <stdio.h>
30#include <stdlib.h>
31#include <string.h>
32
33#include "libavutil/intreadwrite.h"
34#include "avcodec.h"
35
36
37#define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
38
39typedef struct Rl2Context {
40    AVCodecContext *avctx;
41    AVFrame frame;
42
43    unsigned short video_base; ///< initial drawing offset
44    unsigned int clr_count;    ///< number of used colors (currently unused)
45    unsigned char* back_frame; ///< background frame
46    unsigned int palette[AVPALETTE_COUNT];
47} Rl2Context;
48
49/**
50 * Run Length Decode a single 320x200 frame
51 * @param s rl2 context
52 * @param in input buffer
53 * @param size input buffer size
54 * @param out ouput buffer
55 * @param stride stride of the output buffer
56 * @param video_base offset of the rle data inside the frame
57 */
58static void rl2_rle_decode(Rl2Context *s,const unsigned char* in,int size,
59                               unsigned char* out,int stride,int video_base){
60    int base_x = video_base % s->avctx->width;
61    int base_y = video_base / s->avctx->width;
62    int stride_adj = stride - s->avctx->width;
63    int i;
64    const unsigned char* back_frame = s->back_frame;
65    const unsigned char* in_end = in + size;
66    const unsigned char* out_end = out + stride * s->avctx->height;
67    unsigned char* line_end = out + s->avctx->width;
68
69    /** copy start of the background frame */
70    for(i=0;i<=base_y;i++){
71        if(s->back_frame)
72            memcpy(out,back_frame,s->avctx->width);
73        out += stride;
74        back_frame += s->avctx->width;
75    }
76    back_frame += base_x - s->avctx->width;
77    line_end = out - stride_adj;
78    out += base_x - stride;
79
80    /** decode the variable part of the frame */
81    while(in < in_end){
82        unsigned char val = *in++;
83        int len = 1;
84        if(val >= 0x80){
85            if(in >= in_end)
86                break;
87            len = *in++;
88            if(!len)
89                break;
90        }
91
92        if(len >= out_end - out)
93            break;
94
95        if(s->back_frame)
96            val |= 0x80;
97        else
98            val &= ~0x80;
99
100        while(len--){
101            *out++ = (val == 0x80)? *back_frame:val;
102            back_frame++;
103            if(out == line_end){
104                 out += stride_adj;
105                 line_end += stride;
106                 if(len >= out_end - out)
107                     break;
108            }
109        }
110    }
111
112    /** copy the rest from the background frame */
113    if(s->back_frame){
114        while(out < out_end){
115            memcpy(out, back_frame, line_end - out);
116            back_frame += line_end - out;
117            out = line_end + stride_adj;
118            line_end += stride;
119        }
120    }
121}
122
123
124/**
125 * Initialize the decoder
126 * @param avctx decoder context
127 * @return 0 success, -1 on error
128 */
129static av_cold int rl2_decode_init(AVCodecContext *avctx)
130{
131    Rl2Context *s = avctx->priv_data;
132    int back_size;
133    int i;
134    s->avctx = avctx;
135    avctx->pix_fmt = PIX_FMT_PAL8;
136
137    /** parse extra data */
138    if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
139        av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
140        return -1;
141    }
142
143    /** get frame_offset */
144    s->video_base = AV_RL16(&avctx->extradata[0]);
145    s->clr_count = AV_RL32(&avctx->extradata[2]);
146
147    if(s->video_base >= avctx->width * avctx->height){
148        av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
149        return -1;
150    }
151
152    /** initialize palette */
153    for(i=0;i<AVPALETTE_COUNT;i++)
154        s->palette[i] = AV_RB24(&avctx->extradata[6 + i * 3]);
155
156    /** decode background frame if present */
157    back_size = avctx->extradata_size - EXTRADATA1_SIZE;
158
159    if(back_size > 0){
160        unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
161        if(!back_frame)
162            return -1;
163        rl2_rle_decode(s,avctx->extradata + EXTRADATA1_SIZE,back_size,
164                           back_frame,avctx->width,0);
165        s->back_frame = back_frame;
166    }
167    return 0;
168}
169
170
171static int rl2_decode_frame(AVCodecContext *avctx,
172                              void *data, int *data_size,
173                              AVPacket *avpkt)
174{
175    const uint8_t *buf = avpkt->data;
176    int buf_size = avpkt->size;
177    Rl2Context *s = avctx->priv_data;
178
179    if(s->frame.data[0])
180        avctx->release_buffer(avctx, &s->frame);
181
182    /** get buffer */
183    s->frame.reference= 0;
184    if(avctx->get_buffer(avctx, &s->frame)) {
185        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
186        return -1;
187    }
188
189    /** run length decode */
190    rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
191
192    /** make the palette available on the way out */
193    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
194
195    *data_size = sizeof(AVFrame);
196    *(AVFrame*)data = s->frame;
197
198    /** report that the buffer was completely consumed */
199    return buf_size;
200}
201
202
203/**
204 * Uninit decoder
205 * @param avctx decoder context
206 * @return 0 success, -1 on error
207 */
208static av_cold int rl2_decode_end(AVCodecContext *avctx)
209{
210    Rl2Context *s = avctx->priv_data;
211
212    if(s->frame.data[0])
213        avctx->release_buffer(avctx, &s->frame);
214
215    av_free(s->back_frame);
216
217    return 0;
218}
219
220
221AVCodec ff_rl2_decoder = {
222    .name           = "rl2",
223    .type           = AVMEDIA_TYPE_VIDEO,
224    .id             = CODEC_ID_RL2,
225    .priv_data_size = sizeof(Rl2Context),
226    .init           = rl2_decode_init,
227    .close          = rl2_decode_end,
228    .decode         = rl2_decode_frame,
229    .capabilities   = CODEC_CAP_DR1,
230    .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
231};
232
233