1/*
2 * RL2 Video Decoder
3 * Copyright (C) 2008 Sascha Sommer (saschasommer@freenet.de)
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 * RL2 Video Decoder
24 * @file
25 * @author Sascha Sommer (saschasommer@freenet.de)
26 * For more information about the RL2 format, visit:
27 *   http://wiki.multimedia.cx/index.php?title=RL2
28 */
29
30#include <stdio.h>
31#include <stdlib.h>
32#include <string.h>
33
34#include "libavutil/intreadwrite.h"
35#include "avcodec.h"
36
37
38#define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
39
40typedef struct Rl2Context {
41    AVCodecContext *avctx;
42    AVFrame frame;
43
44    unsigned short video_base; ///< initial drawing offset
45    unsigned int clr_count;    ///< number of used colors (currently unused)
46    unsigned char* back_frame; ///< background frame
47    unsigned int palette[AVPALETTE_COUNT];
48} Rl2Context;
49
50/**
51 * Run Length Decode a single 320x200 frame
52 * @param s rl2 context
53 * @param buf input buffer
54 * @param size input buffer size
55 * @param out ouput buffer
56 * @param stride stride of the output buffer
57 * @param video_base offset of the rle data inside the frame
58 */
59static void rl2_rle_decode(Rl2Context *s,const unsigned char* in,int size,
60                               unsigned char* out,int stride,int video_base){
61    int base_x = video_base % s->avctx->width;
62    int base_y = video_base / s->avctx->width;
63    int stride_adj = stride - s->avctx->width;
64    int i;
65    const unsigned char* back_frame = s->back_frame;
66    const unsigned char* in_end = in + size;
67    const unsigned char* out_end = out + stride * s->avctx->height;
68    unsigned char* line_end = out + s->avctx->width;
69
70    /** copy start of the background frame */
71    for(i=0;i<=base_y;i++){
72        if(s->back_frame)
73            memcpy(out,back_frame,s->avctx->width);
74        out += stride;
75        back_frame += s->avctx->width;
76    }
77    back_frame += base_x - s->avctx->width;
78    line_end = out - stride_adj;
79    out += base_x - stride;
80
81    /** decode the variable part of the frame */
82    while(in < in_end){
83        unsigned char val = *in++;
84        int len = 1;
85        if(val >= 0x80){
86            if(in >= in_end)
87                break;
88            len = *in++;
89            if(!len)
90                break;
91        }
92
93        if(len >= out_end - out)
94            break;
95
96        if(s->back_frame)
97            val |= 0x80;
98        else
99            val &= ~0x80;
100
101        while(len--){
102            *out++ = (val == 0x80)? *back_frame:val;
103            back_frame++;
104            if(out == line_end){
105                 out += stride_adj;
106                 line_end += stride;
107                 if(len >= out_end - out)
108                     break;
109            }
110        }
111    }
112
113    /** copy the rest from the background frame */
114    if(s->back_frame){
115        while(out < out_end){
116            memcpy(out, back_frame, line_end - out);
117            back_frame += line_end - out;
118            out = line_end + stride_adj;
119            line_end += stride;
120        }
121    }
122}
123
124
125/**
126 * Initialize the decoder
127 * @param avctx decoder context
128 * @return 0 success, -1 on error
129 */
130static av_cold int rl2_decode_init(AVCodecContext *avctx)
131{
132    Rl2Context *s = avctx->priv_data;
133    int back_size;
134    int i;
135    s->avctx = avctx;
136    avctx->pix_fmt = PIX_FMT_PAL8;
137
138    /** parse extra data */
139    if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
140        av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
141        return -1;
142    }
143
144    /** get frame_offset */
145    s->video_base = AV_RL16(&avctx->extradata[0]);
146    s->clr_count = AV_RL32(&avctx->extradata[2]);
147
148    if(s->video_base >= avctx->width * avctx->height){
149        av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
150        return -1;
151    }
152
153    /** initialize palette */
154    for(i=0;i<AVPALETTE_COUNT;i++)
155        s->palette[i] = AV_RB24(&avctx->extradata[6 + i * 3]);
156
157    /** decode background frame if present */
158    back_size = avctx->extradata_size - EXTRADATA1_SIZE;
159
160    if(back_size > 0){
161        unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
162        if(!back_frame)
163            return -1;
164        rl2_rle_decode(s,avctx->extradata + EXTRADATA1_SIZE,back_size,
165                           back_frame,avctx->width,0);
166        s->back_frame = back_frame;
167    }
168    return 0;
169}
170
171
172/**
173 * Decode a single frame
174 * @param avctx decoder context
175 * @param data decoded frame
176 * @param data_size size of the decoded frame
177 * @param buf input buffer
178 * @param buf_size input buffer size
179 * @return 0 success, -1 on error
180 */
181static int rl2_decode_frame(AVCodecContext *avctx,
182                              void *data, int *data_size,
183                              AVPacket *avpkt)
184{
185    const uint8_t *buf = avpkt->data;
186    int buf_size = avpkt->size;
187    Rl2Context *s = avctx->priv_data;
188
189    if(s->frame.data[0])
190        avctx->release_buffer(avctx, &s->frame);
191
192    /** get buffer */
193    s->frame.reference= 0;
194    if(avctx->get_buffer(avctx, &s->frame)) {
195        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
196        return -1;
197    }
198
199    /** run length decode */
200    rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
201
202    /** make the palette available on the way out */
203    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
204
205    *data_size = sizeof(AVFrame);
206    *(AVFrame*)data = s->frame;
207
208    /** report that the buffer was completely consumed */
209    return buf_size;
210}
211
212
213/**
214 * Uninit decoder
215 * @param avctx decoder context
216 * @return 0 success, -1 on error
217 */
218static av_cold int rl2_decode_end(AVCodecContext *avctx)
219{
220    Rl2Context *s = avctx->priv_data;
221
222    if(s->frame.data[0])
223        avctx->release_buffer(avctx, &s->frame);
224
225    av_free(s->back_frame);
226
227    return 0;
228}
229
230
231AVCodec rl2_decoder = {
232    "rl2",
233    AVMEDIA_TYPE_VIDEO,
234    CODEC_ID_RL2,
235    sizeof(Rl2Context),
236    rl2_decode_init,
237    NULL,
238    rl2_decode_end,
239    rl2_decode_frame,
240    CODEC_CAP_DR1,
241    .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
242};
243
244