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qtrleenc.c
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1 /*
2  * Quicktime Animation (RLE) Video Encoder
3  * Copyright (C) 2007 Clemens Fruhwirth
4  * Copyright (C) 2007 Alexis Ballier
5  *
6  * This file is based on flashsvenc.c.
7  *
8  * This file is part of FFmpeg.
9  *
10  * FFmpeg is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * FFmpeg is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with FFmpeg; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 #include "libavutil/imgutils.h"
26 #include "avcodec.h"
27 #include "bytestream.h"
28 #include "internal.h"
29 
30 /** Maximum RLE code for bulk copy */
31 #define MAX_RLE_BULK 127
32 /** Maximum RLE code for repeat */
33 #define MAX_RLE_REPEAT 128
34 /** Maximum RLE code for skip */
35 #define MAX_RLE_SKIP 254
36 
37 typedef struct QtrleEncContext {
41  unsigned int max_buf_size;
43  /**
44  * This array will contain at ith position the value of the best RLE code
45  * if the line started at pixel i
46  * There can be 3 values :
47  * skip (0) : skip as much as possible pixels because they are equal to the
48  * previous frame ones
49  * repeat (<-1) : repeat that pixel -rle_code times, still as much as
50  * possible
51  * copy (>0) : copy the raw next rle_code pixels */
52  signed char *rlecode_table;
53  /**
54  * This array will contain the length of the best rle encoding of the line
55  * starting at ith pixel */
57  /**
58  * Will contain at ith position the number of consecutive pixels equal to the previous
59  * frame starting from pixel i */
62 
64 {
65  QtrleEncContext *s = avctx->priv_data;
66 
67  av_frame_free(&avctx->coded_frame);
68 
72  av_free(s->skip_table);
73  return 0;
74 }
75 
77 {
78  QtrleEncContext *s = avctx->priv_data;
79  int ret;
80 
81  if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
82  return AVERROR(EINVAL);
83  }
84  s->avctx=avctx;
85  s->logical_width=avctx->width;
86 
87  switch (avctx->pix_fmt) {
88  case AV_PIX_FMT_GRAY8:
89  if (avctx->width % 4) {
90  av_log(avctx, AV_LOG_ERROR, "Width not being a multiple of 4 is not supported\n");
91  return AVERROR(EINVAL);
92  }
93  s->logical_width = avctx->width / 4;
94  s->pixel_size = 4;
95  break;
97  s->pixel_size = 2;
98  break;
99  case AV_PIX_FMT_RGB24:
100  s->pixel_size = 3;
101  break;
102  case AV_PIX_FMT_ARGB:
103  s->pixel_size = 4;
104  break;
105  default:
106  av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
107  break;
108  }
109  avctx->bits_per_coded_sample = avctx->pix_fmt == AV_PIX_FMT_GRAY8 ? 40 : s->pixel_size*8;
110 
113  s->length_table = av_mallocz_array(s->logical_width + 1, sizeof(int));
114  if (!s->skip_table || !s->length_table || !s->rlecode_table) {
115  av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
116  return AVERROR(ENOMEM);
117  }
118  if ((ret = avpicture_alloc(&s->previous_frame, avctx->pix_fmt, avctx->width, avctx->height)) < 0) {
119  av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
120  return ret;
121  }
122 
123  s->max_buf_size = s->logical_width*s->avctx->height*s->pixel_size*2 /* image base material */
124  + 15 /* header + footer */
125  + s->avctx->height*2 /* skip code+rle end */
126  + s->logical_width/MAX_RLE_BULK + 1 /* rle codes */;
127 
128  avctx->coded_frame = av_frame_alloc();
129  if (!avctx->coded_frame) {
130  qtrle_encode_end(avctx);
131  return AVERROR(ENOMEM);
132  }
133 
134  return 0;
135 }
136 
137 /**
138  * Compute the best RLE sequence for a line
139  */
140 static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)
141 {
142  int width=s->logical_width;
143  int i;
144  signed char rlecode;
145 
146  /* This will be the number of pixels equal to the preivous frame one's
147  * starting from the ith pixel */
148  unsigned int skipcount;
149  /* This will be the number of consecutive equal pixels in the current
150  * frame, starting from the ith one also */
151  unsigned int av_uninit(repeatcount);
152 
153  /* The cost of the three different possibilities */
154  int total_skip_cost;
155  int total_repeat_cost;
156 
157  int base_bulk_cost;
158  int lowest_bulk_cost;
159  int lowest_bulk_cost_index;
160  int sec_lowest_bulk_cost;
161  int sec_lowest_bulk_cost_index;
162 
163  uint8_t *this_line = p-> data[0] + line*p-> linesize[0] +
164  (width - 1)*s->pixel_size;
165  uint8_t *prev_line = s->previous_frame.data[0] + line*s->previous_frame.linesize[0] +
166  (width - 1)*s->pixel_size;
167 
168  s->length_table[width] = 0;
169  skipcount = 0;
170 
171  /* Initial values */
172  lowest_bulk_cost = INT_MAX / 2;
173  lowest_bulk_cost_index = width;
174  sec_lowest_bulk_cost = INT_MAX / 2;
175  sec_lowest_bulk_cost_index = width;
176 
177  base_bulk_cost = 1 + s->pixel_size;
178 
179  for (i = width - 1; i >= 0; i--) {
180 
181  int prev_bulk_cost;
182 
183  /* If our lowest bulk cost index is too far away, replace it
184  * with the next lowest bulk cost */
185  if (FFMIN(width, i + MAX_RLE_BULK) < lowest_bulk_cost_index) {
186  lowest_bulk_cost = sec_lowest_bulk_cost;
187  lowest_bulk_cost_index = sec_lowest_bulk_cost_index;
188 
189  sec_lowest_bulk_cost = INT_MAX / 2;
190  sec_lowest_bulk_cost_index = width;
191  }
192 
193  /* Deal with the first pixel's bulk cost */
194  if (!i) {
195  base_bulk_cost++;
196  lowest_bulk_cost++;
197  sec_lowest_bulk_cost++;
198  }
199 
200  /* Look at the bulk cost of the previous loop and see if it is
201  * a new lower bulk cost */
202  prev_bulk_cost = s->length_table[i + 1] + base_bulk_cost;
203  if (prev_bulk_cost <= sec_lowest_bulk_cost) {
204  /* If it's lower than the 2nd lowest, then it may be lower
205  * than the lowest */
206  if (prev_bulk_cost <= lowest_bulk_cost) {
207 
208  /* If we have found a new lowest bulk cost,
209  * then the 2nd lowest bulk cost is now farther than the
210  * lowest bulk cost, and will never be used */
211  sec_lowest_bulk_cost = INT_MAX / 2;
212 
213  lowest_bulk_cost = prev_bulk_cost;
214  lowest_bulk_cost_index = i + 1;
215  } else {
216  /* Then it must be the 2nd lowest bulk cost */
217  sec_lowest_bulk_cost = prev_bulk_cost;
218  sec_lowest_bulk_cost_index = i + 1;
219  }
220  }
221 
222  if (!s->avctx->coded_frame->key_frame && !memcmp(this_line, prev_line, s->pixel_size))
223  skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
224  else
225  skipcount = 0;
226 
227  total_skip_cost = s->length_table[i + skipcount] + 2;
228  s->skip_table[i] = skipcount;
229 
230 
231  if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
232  repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
233  else
234  repeatcount = 1;
235 
236  total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;
237 
238  /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
239  * so let's make it aware */
240  if (i == 0) {
241  total_skip_cost--;
242  total_repeat_cost++;
243  }
244 
245  if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
246  /* repeat is the best */
247  s->length_table[i] = total_repeat_cost;
248  s->rlecode_table[i] = -repeatcount;
249  }
250  else if (skipcount > 0) {
251  /* skip is the best choice here */
252  s->length_table[i] = total_skip_cost;
253  s->rlecode_table[i] = 0;
254  }
255  else {
256  /* We cannot do neither skip nor repeat
257  * thus we use the best bulk copy */
258 
259  s->length_table[i] = lowest_bulk_cost;
260  s->rlecode_table[i] = lowest_bulk_cost_index - i;
261 
262  }
263 
264  /* These bulk costs increase every iteration */
265  lowest_bulk_cost += s->pixel_size;
266  sec_lowest_bulk_cost += s->pixel_size;
267 
268  this_line -= s->pixel_size;
269  prev_line -= s->pixel_size;
270  }
271 
272  /* Good ! Now we have the best sequence for this line, let's output it */
273 
274  /* We do a special case for the first pixel so that we avoid testing it in
275  * the whole loop */
276 
277  i=0;
278  this_line = p-> data[0] + line*p->linesize[0];
279 
280  if (s->rlecode_table[0] == 0) {
281  bytestream_put_byte(buf, s->skip_table[0] + 1);
282  i += s->skip_table[0];
283  }
284  else bytestream_put_byte(buf, 1);
285 
286 
287  while (i < width) {
288  rlecode = s->rlecode_table[i];
289  bytestream_put_byte(buf, rlecode);
290  if (rlecode == 0) {
291  /* Write a skip sequence */
292  bytestream_put_byte(buf, s->skip_table[i] + 1);
293  i += s->skip_table[i];
294  }
295  else if (rlecode > 0) {
296  /* bulk copy */
297  if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
298  int j;
299  // QT grayscale colorspace has 0=white and 255=black, we will
300  // ignore the palette that is included in the AVFrame because
301  // AV_PIX_FMT_GRAY8 has defined color mapping
302  for (j = 0; j < rlecode*s->pixel_size; ++j)
303  bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
304  } else {
305  bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
306  }
307  i += rlecode;
308  }
309  else {
310  /* repeat the bits */
311  if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
312  int j;
313  // QT grayscale colorspace has 0=white and 255=black, ...
314  for (j = 0; j < s->pixel_size; ++j)
315  bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
316  } else {
317  bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
318  }
319  i -= rlecode;
320  }
321  }
322  bytestream_put_byte(buf, -1); // end RLE line
323 }
324 
325 /** Encode frame including header */
327 {
328  int i;
329  int start_line = 0;
330  int end_line = s->avctx->height;
331  uint8_t *orig_buf = buf;
332 
333  if (!s->avctx->coded_frame->key_frame) {
334  unsigned line_size = s->logical_width * s->pixel_size;
335  for (start_line = 0; start_line < s->avctx->height; start_line++)
336  if (memcmp(p->data[0] + start_line*p->linesize[0],
337  s->previous_frame.data[0] + start_line*s->previous_frame.linesize[0],
338  line_size))
339  break;
340 
341  for (end_line=s->avctx->height; end_line > start_line; end_line--)
342  if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
343  s->previous_frame.data[0] + (end_line - 1)*s->previous_frame.linesize[0],
344  line_size))
345  break;
346  }
347 
348  bytestream_put_be32(&buf, 0); // CHUNK SIZE, patched later
349 
350  if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
351  bytestream_put_be16(&buf, 0); // header
352  else {
353  bytestream_put_be16(&buf, 8); // header
354  bytestream_put_be16(&buf, start_line); // starting line
355  bytestream_put_be16(&buf, 0); // unknown
356  bytestream_put_be16(&buf, end_line - start_line); // lines to update
357  bytestream_put_be16(&buf, 0); // unknown
358  }
359  for (i = start_line; i < end_line; i++)
360  qtrle_encode_line(s, p, i, &buf);
361 
362  bytestream_put_byte(&buf, 0); // zero skip code = frame finished
363  AV_WB32(orig_buf, buf - orig_buf); // patch the chunk size
364  return buf - orig_buf;
365 }
366 
368  const AVFrame *pict, int *got_packet)
369 {
370  QtrleEncContext * const s = avctx->priv_data;
371  AVFrame * const p = avctx->coded_frame;
372  int ret;
373 
374  if ((ret = ff_alloc_packet2(avctx, pkt, s->max_buf_size)) < 0)
375  return ret;
376 
377  if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {
378  /* I-Frame */
380  p->key_frame = 1;
381  } else {
382  /* P-Frame */
384  p->key_frame = 0;
385  }
386 
387  pkt->size = encode_frame(s, pict, pkt->data);
388 
389  /* save the current frame */
390  av_picture_copy(&s->previous_frame, (const AVPicture *)pict,
391  avctx->pix_fmt, avctx->width, avctx->height);
392 
393  if (p->key_frame)
394  pkt->flags |= AV_PKT_FLAG_KEY;
395  *got_packet = 1;
396 
397  return 0;
398 }
399 
401  .name = "qtrle",
402  .long_name = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
403  .type = AVMEDIA_TYPE_VIDEO,
404  .id = AV_CODEC_ID_QTRLE,
405  .priv_data_size = sizeof(QtrleEncContext),
407  .encode2 = qtrle_encode_frame,
409  .pix_fmts = (const enum AVPixelFormat[]){
411  },
412 };