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rl2.c
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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  * @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/internal.h"
34 #include "libavutil/intreadwrite.h"
35 #include "libavutil/mem.h"
36 #include "avcodec.h"
37 #include "internal.h"
38 
39 
40 #define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
41 
42 typedef struct Rl2Context {
44 
45  uint16_t video_base; ///< initial drawing offset
46  uint32_t clr_count; ///< number of used colors (currently unused)
47  uint8_t *back_frame; ///< background frame
49 } Rl2Context;
50 
51 /**
52  * Run Length Decode a single 320x200 frame
53  * @param s rl2 context
54  * @param in input buffer
55  * @param size input buffer size
56  * @param out output buffer
57  * @param stride stride of the output buffer
58  * @param video_base offset of the rle data inside the frame
59  */
60 static void rl2_rle_decode(Rl2Context *s, const uint8_t *in, int size,
61  uint8_t *out, int stride, int video_base)
62 {
63  int base_x = video_base % s->avctx->width;
64  int base_y = video_base / s->avctx->width;
65  int stride_adj = stride - s->avctx->width;
66  int i;
67  const uint8_t *back_frame = s->back_frame;
68  const uint8_t *in_end = in + size;
69  const uint8_t *out_end = out + stride * s->avctx->height;
70  uint8_t *line_end;
71 
72  /** copy start of the background frame */
73  for (i = 0; i <= base_y; i++) {
74  if (s->back_frame)
75  memcpy(out, back_frame, s->avctx->width);
76  out += stride;
77  back_frame += s->avctx->width;
78  }
79  back_frame += base_x - s->avctx->width;
80  line_end = out - stride_adj;
81  out += base_x - stride;
82 
83  /** decode the variable part of the frame */
84  while (in < in_end) {
85  uint8_t val = *in++;
86  int len = 1;
87  if (val >= 0x80) {
88  if (in >= in_end)
89  break;
90  len = *in++;
91  if (!len)
92  break;
93  }
94 
95  if (len >= out_end - out)
96  break;
97 
98  if (s->back_frame)
99  val |= 0x80;
100  else
101  val &= ~0x80;
102 
103  while (len--) {
104  *out++ = (val == 0x80) ? *back_frame : val;
105  back_frame++;
106  if (out == line_end) {
107  out += stride_adj;
108  line_end += stride;
109  if (len >= out_end - out)
110  break;
111  }
112  }
113  }
114 
115  /** copy the rest from the background frame */
116  if (s->back_frame) {
117  while (out < out_end) {
118  memcpy(out, back_frame, line_end - out);
119  back_frame += line_end - out;
120  out = line_end + stride_adj;
121  line_end += stride;
122  }
123  }
124 }
125 
126 
127 /**
128  * Initialize the decoder
129  * @param avctx decoder context
130  * @return 0 success, -1 on error
131  */
133 {
134  Rl2Context *s = avctx->priv_data;
135  int back_size;
136  int i;
137 
138  s->avctx = avctx;
139  avctx->pix_fmt = AV_PIX_FMT_PAL8;
140 
141  /** parse extra data */
142  if (!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE) {
143  av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
144  return AVERROR(EINVAL);
145  }
146 
147  /** get frame_offset */
148  s->video_base = AV_RL16(&avctx->extradata[0]);
149  s->clr_count = AV_RL32(&avctx->extradata[2]);
150 
151  if (s->video_base >= avctx->width * avctx->height) {
152  av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
153  return AVERROR_INVALIDDATA;
154  }
155 
156  /** initialize palette */
157  for (i = 0; i < AVPALETTE_COUNT; i++)
158  s->palette[i] = 0xFFU << 24 | AV_RB24(&avctx->extradata[6 + i * 3]);
159 
160  /** decode background frame if present */
161  back_size = avctx->extradata_size - EXTRADATA1_SIZE;
162 
163  if (back_size > 0) {
164  uint8_t *back_frame = av_mallocz(avctx->width*avctx->height);
165  if (!back_frame)
166  return AVERROR(ENOMEM);
167  rl2_rle_decode(s, avctx->extradata + EXTRADATA1_SIZE, back_size,
168  back_frame, avctx->width, 0);
169  s->back_frame = back_frame;
170  }
171  return 0;
172 }
173 
174 
176  void *data, int *got_frame,
177  AVPacket *avpkt)
178 {
179  AVFrame *frame = data;
180  const uint8_t *buf = avpkt->data;
181  int ret, buf_size = avpkt->size;
182  Rl2Context *s = avctx->priv_data;
183 
184  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
185  return ret;
186 
187  /** run length decode */
188  rl2_rle_decode(s, buf, buf_size, frame->data[0], frame->linesize[0],
189  s->video_base);
190 
191  /** make the palette available on the way out */
192  memcpy(frame->data[1], s->palette, AVPALETTE_SIZE);
193 
194  *got_frame = 1;
195 
196  /** report that the buffer was completely consumed */
197  return buf_size;
198 }
199 
200 
201 /**
202  * Uninit decoder
203  * @param avctx decoder context
204  * @return 0 success, -1 on error
205  */
207 {
208  Rl2Context *s = avctx->priv_data;
209 
210  av_free(s->back_frame);
211 
212  return 0;
213 }
214 
215 
217  .name = "rl2",
218  .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
219  .type = AVMEDIA_TYPE_VIDEO,
220  .id = AV_CODEC_ID_RL2,
221  .priv_data_size = sizeof(Rl2Context),
225  .capabilities = CODEC_CAP_DR1,
226 };