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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 {
45 
46  uint16_t video_base; ///< initial drawing offset
47  uint32_t clr_count; ///< number of used colors (currently unused)
48  uint8_t *back_frame; ///< background frame
50 } Rl2Context;
51 
52 /**
53  * Run Length Decode a single 320x200 frame
54  * @param s rl2 context
55  * @param in input buffer
56  * @param size input buffer size
57  * @param out output buffer
58  * @param stride stride of the output buffer
59  * @param video_base offset of the rle data inside the frame
60  */
61 static void rl2_rle_decode(Rl2Context *s, const uint8_t *in, int size,
62  uint8_t *out, int stride, int video_base)
63 {
64  int base_x = video_base % s->avctx->width;
65  int base_y = video_base / s->avctx->width;
66  int stride_adj = stride - s->avctx->width;
67  int i;
68  const uint8_t *back_frame = s->back_frame;
69  const uint8_t *in_end = in + size;
70  const uint8_t *out_end = out + stride * s->avctx->height;
71  uint8_t *line_end;
72 
73  /** copy start of the background frame */
74  for (i = 0; i <= base_y; i++) {
75  if (s->back_frame)
76  memcpy(out, back_frame, s->avctx->width);
77  out += stride;
78  back_frame += s->avctx->width;
79  }
80  back_frame += base_x - s->avctx->width;
81  line_end = out - stride_adj;
82  out += base_x - stride;
83 
84  /** decode the variable part of the frame */
85  while (in < in_end) {
86  uint8_t val = *in++;
87  int len = 1;
88  if (val >= 0x80) {
89  if (in >= in_end)
90  break;
91  len = *in++;
92  if (!len)
93  break;
94  }
95 
96  if (len >= out_end - out)
97  break;
98 
99  if (s->back_frame)
100  val |= 0x80;
101  else
102  val &= ~0x80;
103 
104  while (len--) {
105  *out++ = (val == 0x80) ? *back_frame : val;
106  back_frame++;
107  if (out == line_end) {
108  out += stride_adj;
109  line_end += stride;
110  if (len >= out_end - out)
111  break;
112  }
113  }
114  }
115 
116  /** copy the rest from the background frame */
117  if (s->back_frame) {
118  while (out < out_end) {
119  memcpy(out, back_frame, line_end - out);
120  back_frame += line_end - out;
121  out = line_end + stride_adj;
122  line_end += stride;
123  }
124  }
125 }
126 
127 
128 /**
129  * Initialize the decoder
130  * @param avctx decoder context
131  * @return 0 success, -1 on error
132  */
134 {
135  Rl2Context *s = avctx->priv_data;
136  int back_size;
137  int i;
138 
139  s->avctx = avctx;
140  avctx->pix_fmt = AV_PIX_FMT_PAL8;
142 
143  /** parse extra data */
144  if (!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE) {
145  av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
146  return AVERROR(EINVAL);
147  }
148 
149  /** get frame_offset */
150  s->video_base = AV_RL16(&avctx->extradata[0]);
151  s->clr_count = AV_RL32(&avctx->extradata[2]);
152 
153  if (s->video_base >= avctx->width * avctx->height) {
154  av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
155  return AVERROR_INVALIDDATA;
156  }
157 
158  /** initialize palette */
159  for (i = 0; i < AVPALETTE_COUNT; i++)
160  s->palette[i] = 0xFFU << 24 | AV_RB24(&avctx->extradata[6 + i * 3]);
161 
162  /** decode background frame if present */
163  back_size = avctx->extradata_size - EXTRADATA1_SIZE;
164 
165  if (back_size > 0) {
166  uint8_t *back_frame = av_mallocz(avctx->width*avctx->height);
167  if (!back_frame)
168  return AVERROR(ENOMEM);
169  rl2_rle_decode(s, avctx->extradata + EXTRADATA1_SIZE, back_size,
170  back_frame, avctx->width, 0);
171  s->back_frame = back_frame;
172  }
173  return 0;
174 }
175 
176 
178  void *data, int *got_frame,
179  AVPacket *avpkt)
180 {
181  const uint8_t *buf = avpkt->data;
182  int ret, buf_size = avpkt->size;
183  Rl2Context *s = avctx->priv_data;
184 
185  if (s->frame.data[0])
186  avctx->release_buffer(avctx, &s->frame);
187 
188  /** get buffer */
189  s->frame.reference = 0;
190  if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
191  av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
192  return ret;
193  }
194 
195  /** run length decode */
196  rl2_rle_decode(s, buf, buf_size, s->frame.data[0], s->frame.linesize[0],
197  s->video_base);
198 
199  /** make the palette available on the way out */
200  memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
201 
202  *got_frame = 1;
203  *(AVFrame*)data = s->frame;
204 
205  /** report that the buffer was completely consumed */
206  return buf_size;
207 }
208 
209 
210 /**
211  * Uninit decoder
212  * @param avctx decoder context
213  * @return 0 success, -1 on error
214  */
216 {
217  Rl2Context *s = avctx->priv_data;
218 
219  if (s->frame.data[0])
220  avctx->release_buffer(avctx, &s->frame);
221 
222  av_free(s->back_frame);
223 
224  return 0;
225 }
226 
227 
229  .name = "rl2",
230  .type = AVMEDIA_TYPE_VIDEO,
231  .id = AV_CODEC_ID_RL2,
232  .priv_data_size = sizeof(Rl2Context),
236  .capabilities = CODEC_CAP_DR1,
237  .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
238 };