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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 {
42  unsigned int max_buf_size;
44  /**
45  * This array will contain at ith position the value of the best RLE code
46  * if the line started at pixel i
47  * There can be 3 values :
48  * skip (0) : skip as much as possible pixels because they are equal to the
49  * previous frame ones
50  * repeat (<-1) : repeat that pixel -rle_code times, still as much as
51  * possible
52  * copy (>0) : copy the raw next rle_code pixels */
53  signed char *rlecode_table;
54  /**
55  * This array will contain the length of the best rle encoding of the line
56  * starting at ith pixel */
58  /**
59  * Will contain at ith position the number of consecutive pixels equal to the previous
60  * frame starting from pixel i */
63 
65 {
66  QtrleEncContext *s = avctx->priv_data;
67  int ret;
68 
69  if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
70  return AVERROR(EINVAL);
71  }
72  s->avctx=avctx;
73  s->logical_width=avctx->width;
74 
75  switch (avctx->pix_fmt) {
76  case AV_PIX_FMT_GRAY8:
77  s->logical_width = avctx->width / 4;
78  s->pixel_size = 4;
79  break;
81  s->pixel_size = 2;
82  break;
83  case AV_PIX_FMT_RGB24:
84  s->pixel_size = 3;
85  break;
86  case AV_PIX_FMT_ARGB:
87  s->pixel_size = 4;
88  break;
89  default:
90  av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
91  break;
92  }
93  avctx->bits_per_coded_sample = avctx->pix_fmt == AV_PIX_FMT_GRAY8 ? 40 : s->pixel_size*8;
94 
97  s->length_table = av_mallocz((s->logical_width + 1)*sizeof(int));
98  if (!s->skip_table || !s->length_table || !s->rlecode_table) {
99  av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
100  return AVERROR(ENOMEM);
101  }
102  if ((ret = avpicture_alloc(&s->previous_frame, avctx->pix_fmt, avctx->width, avctx->height)) < 0) {
103  av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
104  return ret;
105  }
106 
107  s->max_buf_size = s->logical_width*s->avctx->height*s->pixel_size*2 /* image base material */
108  + 15 /* header + footer */
109  + s->avctx->height*2 /* skip code+rle end */
110  + s->logical_width/MAX_RLE_BULK + 1 /* rle codes */;
111  avctx->coded_frame = &s->frame;
112  return 0;
113 }
114 
115 /**
116  * Compute the best RLE sequence for a line
117  */
118 static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)
119 {
120  int width=s->logical_width;
121  int i;
122  signed char rlecode;
123 
124  /* This will be the number of pixels equal to the preivous frame one's
125  * starting from the ith pixel */
126  unsigned int skipcount;
127  /* This will be the number of consecutive equal pixels in the current
128  * frame, starting from the ith one also */
129  unsigned int av_uninit(repeatcount);
130 
131  /* The cost of the three different possibilities */
132  int total_skip_cost;
133  int total_repeat_cost;
134 
135  int base_bulk_cost;
136  int lowest_bulk_cost;
137  int lowest_bulk_cost_index;
138  int sec_lowest_bulk_cost;
139  int sec_lowest_bulk_cost_index;
140 
141  uint8_t *this_line = p-> data[0] + line*p-> linesize[0] +
142  (width - 1)*s->pixel_size;
143  uint8_t *prev_line = s->previous_frame.data[0] + line*s->previous_frame.linesize[0] +
144  (width - 1)*s->pixel_size;
145 
146  s->length_table[width] = 0;
147  skipcount = 0;
148 
149  /* Initial values */
150  lowest_bulk_cost = INT_MAX / 2;
151  lowest_bulk_cost_index = width;
152  sec_lowest_bulk_cost = INT_MAX / 2;
153  sec_lowest_bulk_cost_index = width;
154 
155  base_bulk_cost = 1 + s->pixel_size;
156 
157  for (i = width - 1; i >= 0; i--) {
158 
159  int prev_bulk_cost;
160 
161  /* If our lowest bulk cost index is too far away, replace it
162  * with the next lowest bulk cost */
163  if (FFMIN(width, i + MAX_RLE_BULK) < lowest_bulk_cost_index) {
164  lowest_bulk_cost = sec_lowest_bulk_cost;
165  lowest_bulk_cost_index = sec_lowest_bulk_cost_index;
166 
167  sec_lowest_bulk_cost = INT_MAX / 2;
168  sec_lowest_bulk_cost_index = width;
169  }
170 
171  /* Deal with the first pixel's bulk cost */
172  if (!i) {
173  base_bulk_cost++;
174  lowest_bulk_cost++;
175  sec_lowest_bulk_cost++;
176  }
177 
178  /* Look at the bulk cost of the previous loop and see if it is
179  * a new lower bulk cost */
180  prev_bulk_cost = s->length_table[i + 1] + base_bulk_cost;
181  if (prev_bulk_cost <= sec_lowest_bulk_cost) {
182  /* If it's lower than the 2nd lowest, then it may be lower
183  * than the lowest */
184  if (prev_bulk_cost <= lowest_bulk_cost) {
185 
186  /* If we have found a new lowest bulk cost,
187  * then the 2nd lowest bulk cost is now farther than the
188  * lowest bulk cost, and will never be used */
189  sec_lowest_bulk_cost = INT_MAX / 2;
190 
191  lowest_bulk_cost = prev_bulk_cost;
192  lowest_bulk_cost_index = i + 1;
193  } else {
194  /* Then it must be the 2nd lowest bulk cost */
195  sec_lowest_bulk_cost = prev_bulk_cost;
196  sec_lowest_bulk_cost_index = i + 1;
197  }
198  }
199 
200  if (!s->frame.key_frame && !memcmp(this_line, prev_line, s->pixel_size))
201  skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
202  else
203  skipcount = 0;
204 
205  total_skip_cost = s->length_table[i + skipcount] + 2;
206  s->skip_table[i] = skipcount;
207 
208 
209  if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
210  repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
211  else
212  repeatcount = 1;
213 
214  total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;
215 
216  /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
217  * so let's make it aware */
218  if (i == 0) {
219  total_skip_cost--;
220  total_repeat_cost++;
221  }
222 
223  if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
224  /* repeat is the best */
225  s->length_table[i] = total_repeat_cost;
226  s->rlecode_table[i] = -repeatcount;
227  }
228  else if (skipcount > 0) {
229  /* skip is the best choice here */
230  s->length_table[i] = total_skip_cost;
231  s->rlecode_table[i] = 0;
232  }
233  else {
234  /* We cannot do neither skip nor repeat
235  * thus we use the best bulk copy */
236 
237  s->length_table[i] = lowest_bulk_cost;
238  s->rlecode_table[i] = lowest_bulk_cost_index - i;
239 
240  }
241 
242  /* These bulk costs increase every iteration */
243  lowest_bulk_cost += s->pixel_size;
244  sec_lowest_bulk_cost += s->pixel_size;
245 
246  this_line -= s->pixel_size;
247  prev_line -= s->pixel_size;
248  }
249 
250  /* Good ! Now we have the best sequence for this line, let's output it */
251 
252  /* We do a special case for the first pixel so that we avoid testing it in
253  * the whole loop */
254 
255  i=0;
256  this_line = p-> data[0] + line*p->linesize[0];
257 
258  if (s->rlecode_table[0] == 0) {
259  bytestream_put_byte(buf, s->skip_table[0] + 1);
260  i += s->skip_table[0];
261  }
262  else bytestream_put_byte(buf, 1);
263 
264 
265  while (i < width) {
266  rlecode = s->rlecode_table[i];
267  bytestream_put_byte(buf, rlecode);
268  if (rlecode == 0) {
269  /* Write a skip sequence */
270  bytestream_put_byte(buf, s->skip_table[i] + 1);
271  i += s->skip_table[i];
272  }
273  else if (rlecode > 0) {
274  /* bulk copy */
275  if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
276  int j;
277  // QT grayscale colorspace has 0=white and 255=black, we will
278  // ignore the palette that is included in the AVFrame because
279  // AV_PIX_FMT_GRAY8 has defined color mapping
280  for (j = 0; j < rlecode*s->pixel_size; ++j)
281  bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
282  } else {
283  bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
284  }
285  i += rlecode;
286  }
287  else {
288  /* repeat the bits */
289  if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
290  int j;
291  // QT grayscale colorspace has 0=white and 255=black, ...
292  for (j = 0; j < s->pixel_size; ++j)
293  bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
294  } else {
295  bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
296  }
297  i -= rlecode;
298  }
299  }
300  bytestream_put_byte(buf, -1); // end RLE line
301 }
302 
303 /** Encode frame including header */
304 static int encode_frame(QtrleEncContext *s, const AVFrame *p, uint8_t *buf)
305 {
306  int i;
307  int start_line = 0;
308  int end_line = s->avctx->height;
309  uint8_t *orig_buf = buf;
310 
311  if (!s->frame.key_frame) {
312  unsigned line_size = s->logical_width * s->pixel_size;
313  for (start_line = 0; start_line < s->avctx->height; start_line++)
314  if (memcmp(p->data[0] + start_line*p->linesize[0],
315  s->previous_frame.data[0] + start_line*s->previous_frame.linesize[0],
316  line_size))
317  break;
318 
319  for (end_line=s->avctx->height; end_line > start_line; end_line--)
320  if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
321  s->previous_frame.data[0] + (end_line - 1)*s->previous_frame.linesize[0],
322  line_size))
323  break;
324  }
325 
326  bytestream_put_be32(&buf, 0); // CHUNK SIZE, patched later
327 
328  if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
329  bytestream_put_be16(&buf, 0); // header
330  else {
331  bytestream_put_be16(&buf, 8); // header
332  bytestream_put_be16(&buf, start_line); // starting line
333  bytestream_put_be16(&buf, 0); // unknown
334  bytestream_put_be16(&buf, end_line - start_line); // lines to update
335  bytestream_put_be16(&buf, 0); // unknown
336  }
337  for (i = start_line; i < end_line; i++)
338  qtrle_encode_line(s, p, i, &buf);
339 
340  bytestream_put_byte(&buf, 0); // zero skip code = frame finished
341  AV_WB32(orig_buf, buf - orig_buf); // patch the chunk size
342  return buf - orig_buf;
343 }
344 
346  const AVFrame *pict, int *got_packet)
347 {
348  QtrleEncContext * const s = avctx->priv_data;
349  AVFrame * const p = &s->frame;
350  int ret;
351 
352  *p = *pict;
353 
354  if ((ret = ff_alloc_packet2(avctx, pkt, s->max_buf_size)) < 0)
355  return ret;
356 
357  if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {
358  /* I-Frame */
360  p->key_frame = 1;
361  } else {
362  /* P-Frame */
364  p->key_frame = 0;
365  }
366 
367  pkt->size = encode_frame(s, pict, pkt->data);
368 
369  /* save the current frame */
370  av_picture_copy(&s->previous_frame, (AVPicture *)p, avctx->pix_fmt, avctx->width, avctx->height);
371 
372  if (p->key_frame)
373  pkt->flags |= AV_PKT_FLAG_KEY;
374  *got_packet = 1;
375 
376  return 0;
377 }
378 
380 {
381  QtrleEncContext *s = avctx->priv_data;
382 
385  av_free(s->length_table);
386  av_free(s->skip_table);
387  return 0;
388 }
389 
391  .name = "qtrle",
392  .type = AVMEDIA_TYPE_VIDEO,
393  .id = AV_CODEC_ID_QTRLE,
394  .priv_data_size = sizeof(QtrleEncContext),
396  .encode2 = qtrle_encode_frame,
398  .pix_fmts = (const enum AVPixelFormat[]){
400  },
401  .long_name = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
402 };