ba99fb91b89ddd09fdf70995be2fe421e4858439
[libav.git] / libavcodec / rl2.c
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
40 typedef 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 in 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 */
59 static 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 */
130 static 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 static int rl2_decode_frame(AVCodecContext *avctx,
173 void *data, int *data_size,
174 AVPacket *avpkt)
175 {
176 const uint8_t *buf = avpkt->data;
177 int buf_size = avpkt->size;
178 Rl2Context *s = avctx->priv_data;
179
180 if(s->frame.data[0])
181 avctx->release_buffer(avctx, &s->frame);
182
183 /** get buffer */
184 s->frame.reference= 0;
185 if(avctx->get_buffer(avctx, &s->frame)) {
186 av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
187 return -1;
188 }
189
190 /** run length decode */
191 rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
192
193 /** make the palette available on the way out */
194 memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
195
196 *data_size = sizeof(AVFrame);
197 *(AVFrame*)data = s->frame;
198
199 /** report that the buffer was completely consumed */
200 return buf_size;
201 }
202
203
204 /**
205 * Uninit decoder
206 * @param avctx decoder context
207 * @return 0 success, -1 on error
208 */
209 static av_cold int rl2_decode_end(AVCodecContext *avctx)
210 {
211 Rl2Context *s = avctx->priv_data;
212
213 if(s->frame.data[0])
214 avctx->release_buffer(avctx, &s->frame);
215
216 av_free(s->back_frame);
217
218 return 0;
219 }
220
221
222 AVCodec rl2_decoder = {
223 "rl2",
224 AVMEDIA_TYPE_VIDEO,
225 CODEC_ID_RL2,
226 sizeof(Rl2Context),
227 rl2_decode_init,
228 NULL,
229 rl2_decode_end,
230 rl2_decode_frame,
231 CODEC_CAP_DR1,
232 .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
233 };
234