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escape130.c
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1 /*
2  * Escape 130 Video Decoder
3  * Copyright (C) 2008 Eli Friedman (eli.friedman <at> gmail.com)
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 #include "avcodec.h"
23 
24 #define BITSTREAM_READER_LE
25 #include "get_bits.h"
26 #include "internal.h"
27 
28 
29 typedef struct Escape130Context {
30  AVFrame frame;
31  uint8_t *bases;
32 } Escape130Context;
33 
34 /**
35  * Initialize the decoder
36  * @param avctx decoder context
37  * @return 0 success, negative on error
38  */
39 static av_cold int escape130_decode_init(AVCodecContext *avctx)
40 {
41  Escape130Context *s = avctx->priv_data;
42  avctx->pix_fmt = AV_PIX_FMT_YUV420P;
43 
44  if((avctx->width&1) || (avctx->height&1)){
45  av_log(avctx, AV_LOG_ERROR, "Dimensions are not a multiple of the block size\n");
46  return AVERROR(EINVAL);
47  }
48 
49  s->bases= av_malloc(avctx->width * avctx->height /4);
50 
51  return 0;
52 }
53 
54 static av_cold int escape130_decode_close(AVCodecContext *avctx)
55 {
56  Escape130Context *s = avctx->priv_data;
57 
58  if (s->frame.data[0])
59  avctx->release_buffer(avctx, &s->frame);
60 
61  av_freep(&s->bases);
62 
63  return 0;
64 }
65 
66 static unsigned decode_skip_count(GetBitContext* gb) {
67  unsigned value;
68  // This function reads a maximum of 27 bits,
69  // which is within the padding space
70  if (get_bits_left(gb) < 1+3)
71  return -1;
72 
73  value = get_bits1(gb);
74  if (value)
75  return 0;
76 
77  value = get_bits(gb, 3);
78  if (value)
79  return value;
80 
81  value = get_bits(gb, 8);
82  if (value)
83  return value + 7;
84 
85  value = get_bits(gb, 15);
86  if (value)
87  return value + 262;
88 
89  return -1;
90 }
91 
92 /**
93  * Decode a single frame
94  * @param avctx decoder context
95  * @param data decoded frame
96  * @param got_frame have decoded frame
97  * @param buf input buffer
98  * @param buf_size input buffer size
99  * @return 0 success, -1 on error
100  */
101 static int escape130_decode_frame(AVCodecContext *avctx,
102  void *data, int *got_frame,
103  AVPacket *avpkt)
104 {
105  const uint8_t *buf = avpkt->data;
106  int buf_size = avpkt->size;
107  Escape130Context *s = avctx->priv_data;
108 
109  GetBitContext gb;
110  unsigned i;
111 
112  uint8_t *old_y, *old_cb, *old_cr,
113  *new_y, *new_cb, *new_cr;
114  unsigned old_y_stride, old_cb_stride, old_cr_stride,
115  new_y_stride, new_cb_stride, new_cr_stride;
116  unsigned total_blocks = avctx->width * avctx->height / 4,
117  block_index, row_index = 0;
118  unsigned y[4] = {0}, cb = 16, cr = 16;
119  unsigned skip = -1;
120  unsigned y_base = 0;
121  uint8_t *yb= s->bases;
122 
123  AVFrame new_frame = { { 0 } };
124 
125  init_get_bits(&gb, buf, buf_size * 8);
126 
127  if (get_bits_left(&gb) < 128)
128  return -1;
129 
130  // Header; no useful information in here
131  skip_bits_long(&gb, 128);
132 
133  new_frame.reference = 3;
134  if (ff_get_buffer(avctx, &new_frame)) {
135  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
136  return -1;
137  }
138 
139  new_y = new_frame.data[0];
140  new_cb = new_frame.data[1];
141  new_cr = new_frame.data[2];
142  new_y_stride = new_frame.linesize[0];
143  new_cb_stride = new_frame.linesize[1];
144  new_cr_stride = new_frame.linesize[2];
145  old_y = s->frame.data[0];
146  old_cb = s->frame.data[1];
147  old_cr = s->frame.data[2];
148  old_y_stride = s->frame.linesize[0];
149  old_cb_stride = s->frame.linesize[1];
150  old_cr_stride = s->frame.linesize[2];
151 
152  av_log(avctx, AV_LOG_DEBUG,
153  "Strides: %i, %i\n",
154  new_y_stride, new_cb_stride);
155 
156  for (block_index = 0; block_index < total_blocks; block_index++) {
157  // Note that this call will make us skip the rest of the blocks
158  // if the frame prematurely ends
159  if (skip == -1)
160  skip = decode_skip_count(&gb);
161 
162  if (skip) {
163  if (old_y) {
164  y[0] = old_y[0] / 4;
165  y[1] = old_y[1] / 4;
166  y[2] = old_y[old_y_stride] / 4;
167  y[3] = old_y[old_y_stride+1] / 4;
168  y_base= yb[0];
169  cb = old_cb[0] / 8;
170  cr = old_cr[0] / 8;
171  } else {
172  y_base=y[0] = y[1] = y[2] = y[3] = 0;
173  cb = cr = 16;
174  }
175  } else {
176  if (get_bits1(&gb)) {
177  static const uint8_t offset_table[] = {2, 4, 10, 20};
178  static const int8_t sign_table[64][4] =
179  { {0, 0, 0, 0},
180  {-1, 1, 0, 0},
181  {1, -1, 0, 0},
182  {-1, 0, 1, 0},
183  {-1, 1, 1, 0},
184  {0, -1, 1, 0},
185  {1, -1, 1, 0},
186  {-1, -1, 1, 0},
187  {1, 0, -1, 0},
188  {0, 1, -1, 0},
189  {1, 1, -1, 0},
190  {-1, 1, -1, 0},
191  {1, -1, -1, 0},
192  {-1, 0, 0, 1},
193  {-1, 1, 0, 1},
194  {0, -1, 0, 1},
195 
196  {0, 0, 0, 0},
197  {1, -1, 0, 1},
198  {-1, -1, 0, 1},
199  {-1, 0, 1, 1},
200  {-1, 1, 1, 1},
201  {0, -1, 1, 1},
202  {1, -1, 1, 1},
203  {-1, -1, 1, 1},
204  {0, 0, -1, 1},
205  {1, 0, -1, 1},
206  {-1, 0, -1, 1},
207  {0, 1, -1, 1},
208  {1, 1, -1, 1},
209  {-1, 1, -1, 1},
210  {0, -1, -1, 1},
211  {1, -1, -1, 1},
212 
213  {0, 0, 0, 0},
214  {-1, -1, -1, 1},
215  {1, 0, 0, -1},
216  {0, 1, 0, -1},
217  {1, 1, 0, -1},
218  {-1, 1, 0, -1},
219  {1, -1, 0, -1},
220  {0, 0, 1, -1},
221  {1, 0, 1, -1},
222  {-1, 0, 1, -1},
223  {0, 1, 1, -1},
224  {1, 1, 1, -1},
225  {-1, 1, 1, -1},
226  {0, -1, 1, -1},
227  {1, -1, 1, -1},
228  {-1, -1, 1, -1},
229 
230  {0, 0, 0, 0},
231  {1, 0, -1, -1},
232  {0, 1, -1, -1},
233  {1, 1, -1, -1},
234  {-1, 1, -1, -1},
235  {1, -1, -1, -1} };
236  unsigned sign_selector = get_bits(&gb, 6);
237  unsigned difference_selector = get_bits(&gb, 2);
238  y_base = 2 * get_bits(&gb, 5);
239  for (i = 0; i < 4; i++) {
240  y[i] = av_clip((int)y_base + offset_table[difference_selector] *
241  sign_table[sign_selector][i], 0, 63);
242  }
243  } else if (get_bits1(&gb)) {
244  if (get_bits1(&gb)) {
245  y_base = get_bits(&gb, 6);
246  } else {
247  unsigned adjust_index = get_bits(&gb, 3);
248  static const int8_t adjust[] = {-4, -3, -2, -1, 1, 2, 3, 4};
249  y_base = (y_base + adjust[adjust_index]) & 63;
250  }
251  for (i = 0; i < 4; i++)
252  y[i] = y_base;
253  }
254 
255  if (get_bits1(&gb)) {
256  if (get_bits1(&gb)) {
257  cb = get_bits(&gb, 5);
258  cr = get_bits(&gb, 5);
259  } else {
260  unsigned adjust_index = get_bits(&gb, 3);
261  static const int8_t adjust[2][8] =
262  { { 1, 1, 0, -1, -1, -1, 0, 1 },
263  { 0, 1, 1, 1, 0, -1, -1, -1 } };
264  cb = (cb + adjust[0][adjust_index]) & 31;
265  cr = (cr + adjust[1][adjust_index]) & 31;
266  }
267  }
268  }
269  *yb++= y_base;
270 
271  new_y[0] = y[0] * 4;
272  new_y[1] = y[1] * 4;
273  new_y[new_y_stride] = y[2] * 4;
274  new_y[new_y_stride + 1] = y[3] * 4;
275  *new_cb = cb * 8;
276  *new_cr = cr * 8;
277 
278  if (old_y)
279  old_y += 2, old_cb++, old_cr++;
280  new_y += 2, new_cb++, new_cr++;
281  row_index++;
282  if (avctx->width / 2 == row_index) {
283  row_index = 0;
284  if (old_y) {
285  old_y += old_y_stride * 2 - avctx->width;
286  old_cb += old_cb_stride - avctx->width / 2;
287  old_cr += old_cr_stride - avctx->width / 2;
288  }
289  new_y += new_y_stride * 2 - avctx->width;
290  new_cb += new_cb_stride - avctx->width / 2;
291  new_cr += new_cr_stride - avctx->width / 2;
292  }
293 
294  skip--;
295  }
296 
297  av_log(avctx, AV_LOG_DEBUG,
298  "Escape sizes: %i, %i\n",
299  buf_size, get_bits_count(&gb) / 8);
300 
301  if (s->frame.data[0])
302  avctx->release_buffer(avctx, &s->frame);
303 
304  *(AVFrame*)data = s->frame = new_frame;
305  *got_frame = 1;
306 
307  return buf_size;
308 }
309 
310 
311 AVCodec ff_escape130_decoder = {
312  .name = "escape130",
313  .type = AVMEDIA_TYPE_VIDEO,
314  .id = AV_CODEC_ID_ESCAPE130,
315  .priv_data_size = sizeof(Escape130Context),
316  .init = escape130_decode_init,
317  .close = escape130_decode_close,
318  .decode = escape130_decode_frame,
319  .capabilities = CODEC_CAP_DR1,
320  .long_name = NULL_IF_CONFIG_SMALL("Escape 130"),
321 };
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