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 Libav.
9  *
10  * Libav 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  * Libav 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 Libav; 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 
31 #define MAX_RLE_BULK 127
32 
33 #define MAX_RLE_REPEAT 128
34 
35 #define MAX_RLE_SKIP 254
36 
37 typedef struct QtrleEncContext {
42  unsigned int max_buf_size;
52  signed char *rlecode_table;
62 
64 {
65  QtrleEncContext *s = avctx->priv_data;
66 
67  if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
68  return -1;
69  }
70  s->avctx=avctx;
71 
72  switch (avctx->pix_fmt) {
74  s->pixel_size = 2;
75  break;
76  case AV_PIX_FMT_RGB24:
77  s->pixel_size = 3;
78  break;
79  case AV_PIX_FMT_ARGB:
80  s->pixel_size = 4;
81  break;
82  default:
83  av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
84  break;
85  }
86  avctx->bits_per_coded_sample = s->pixel_size*8;
87 
89  s->skip_table = av_mallocz(s->avctx->width);
90  s->length_table = av_mallocz((s->avctx->width + 1)*sizeof(int));
91  if (!s->skip_table || !s->length_table || !s->rlecode_table) {
92  av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
93  return -1;
94  }
95  if (avpicture_alloc(&s->previous_frame, avctx->pix_fmt, avctx->width, avctx->height) < 0) {
96  av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
97  return -1;
98  }
99 
100  s->max_buf_size = s->avctx->width*s->avctx->height*s->pixel_size*2 /* image base material */
101  + 15 /* header + footer */
102  + s->avctx->height*2 /* skip code+rle end */
103  + s->avctx->width/MAX_RLE_BULK + 1 /* rle codes */;
104  avctx->coded_frame = &s->frame;
105  return 0;
106 }
107 
111 static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)
112 {
113  int width=s->avctx->width;
114  int i;
115  signed char rlecode;
116 
117  /* We will use it to compute the best bulk copy sequence */
118  unsigned int bulkcount;
119  /* This will be the number of pixels equal to the preivous frame one's
120  * starting from the ith pixel */
121  unsigned int skipcount;
122  /* This will be the number of consecutive equal pixels in the current
123  * frame, starting from the ith one also */
124  unsigned int repeatcount;
125 
126  /* The cost of the three different possibilities */
127  int total_bulk_cost;
128  int total_skip_cost;
129  int total_repeat_cost;
130 
131  int temp_cost;
132  int j;
133 
134  uint8_t *this_line = p-> data[0] + line*p-> linesize[0] +
135  (width - 1)*s->pixel_size;
136  uint8_t *prev_line = s->previous_frame.data[0] + line*s->previous_frame.linesize[0] +
137  (width - 1)*s->pixel_size;
138 
139  s->length_table[width] = 0;
140  skipcount = 0;
141 
142  for (i = width - 1; i >= 0; i--) {
143 
144  if (!s->frame.key_frame && !memcmp(this_line, prev_line, s->pixel_size))
145  skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
146  else
147  skipcount = 0;
148 
149  total_skip_cost = s->length_table[i + skipcount] + 2;
150  s->skip_table[i] = skipcount;
151 
152 
153  if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
154  repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
155  else
156  repeatcount = 1;
157 
158  total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;
159 
160  /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
161  * so let's make it aware */
162  if (i == 0) {
163  total_skip_cost--;
164  total_repeat_cost++;
165  }
166 
167  if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
168  /* repeat is the best */
169  s->length_table[i] = total_repeat_cost;
170  s->rlecode_table[i] = -repeatcount;
171  }
172  else if (skipcount > 0) {
173  /* skip is the best choice here */
174  s->length_table[i] = total_skip_cost;
175  s->rlecode_table[i] = 0;
176  }
177  else {
178  /* We cannot do neither skip nor repeat
179  * thus we search for the best bulk copy to do */
180 
181  int limit = FFMIN(width - i, MAX_RLE_BULK);
182 
183  temp_cost = 1 + s->pixel_size + !i;
184  total_bulk_cost = INT_MAX;
185 
186  for (j = 1; j <= limit; j++) {
187  if (s->length_table[i + j] + temp_cost < total_bulk_cost) {
188  /* We have found a better bulk copy ... */
189  total_bulk_cost = s->length_table[i + j] + temp_cost;
190  bulkcount = j;
191  }
192  temp_cost += s->pixel_size;
193  }
194 
195  s->length_table[i] = total_bulk_cost;
196  s->rlecode_table[i] = bulkcount;
197  }
198 
199  this_line -= s->pixel_size;
200  prev_line -= s->pixel_size;
201  }
202 
203  /* Good ! Now we have the best sequence for this line, let's ouput it */
204 
205  /* We do a special case for the first pixel so that we avoid testing it in
206  * the whole loop */
207 
208  i=0;
209  this_line = p-> data[0] + line*p->linesize[0];
210 
211  if (s->rlecode_table[0] == 0) {
212  bytestream_put_byte(buf, s->skip_table[0] + 1);
213  i += s->skip_table[0];
214  }
215  else bytestream_put_byte(buf, 1);
216 
217 
218  while (i < width) {
219  rlecode = s->rlecode_table[i];
220  bytestream_put_byte(buf, rlecode);
221  if (rlecode == 0) {
222  /* Write a skip sequence */
223  bytestream_put_byte(buf, s->skip_table[i] + 1);
224  i += s->skip_table[i];
225  }
226  else if (rlecode > 0) {
227  /* bulk copy */
228  bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
229  i += rlecode;
230  }
231  else {
232  /* repeat the bits */
233  bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
234  i -= rlecode;
235  }
236  }
237  bytestream_put_byte(buf, -1); // end RLE line
238 }
239 
241 static int encode_frame(QtrleEncContext *s, const AVFrame *p, uint8_t *buf)
242 {
243  int i;
244  int start_line = 0;
245  int end_line = s->avctx->height;
246  uint8_t *orig_buf = buf;
247 
248  if (!s->frame.key_frame) {
249  unsigned line_size = s->avctx->width * s->pixel_size;
250  for (start_line = 0; start_line < s->avctx->height; start_line++)
251  if (memcmp(p->data[0] + start_line*p->linesize[0],
252  s->previous_frame.data[0] + start_line*s->previous_frame.linesize[0],
253  line_size))
254  break;
255 
256  for (end_line=s->avctx->height; end_line > start_line; end_line--)
257  if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
258  s->previous_frame.data[0] + (end_line - 1)*s->previous_frame.linesize[0],
259  line_size))
260  break;
261  }
262 
263  bytestream_put_be32(&buf, 0); // CHUNK SIZE, patched later
264 
265  if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
266  bytestream_put_be16(&buf, 0); // header
267  else {
268  bytestream_put_be16(&buf, 8); // header
269  bytestream_put_be16(&buf, start_line); // starting line
270  bytestream_put_be16(&buf, 0); // unknown
271  bytestream_put_be16(&buf, end_line - start_line); // lines to update
272  bytestream_put_be16(&buf, 0); // unknown
273  }
274  for (i = start_line; i < end_line; i++)
275  qtrle_encode_line(s, p, i, &buf);
276 
277  bytestream_put_byte(&buf, 0); // zero skip code = frame finished
278  AV_WB32(orig_buf, buf - orig_buf); // patch the chunk size
279  return buf - orig_buf;
280 }
281 
283  const AVFrame *pict, int *got_packet)
284 {
285  QtrleEncContext * const s = avctx->priv_data;
286  AVFrame * const p = &s->frame;
287  int ret;
288 
289  *p = *pict;
290 
291  if ((ret = ff_alloc_packet(pkt, s->max_buf_size)) < 0) {
292  /* Upper bound check for compressed data */
293  av_log(avctx, AV_LOG_ERROR, "Error getting output packet of size %d.\n", s->max_buf_size);
294  return ret;
295  }
296 
297  if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {
298  /* I-Frame */
300  p->key_frame = 1;
301  } else {
302  /* P-Frame */
304  p->key_frame = 0;
305  }
306 
307  pkt->size = encode_frame(s, pict, pkt->data);
308 
309  /* save the current frame */
310  av_picture_copy(&s->previous_frame, (AVPicture *)p, avctx->pix_fmt, avctx->width, avctx->height);
311 
312  if (p->key_frame)
313  pkt->flags |= AV_PKT_FLAG_KEY;
314  *got_packet = 1;
315 
316  return 0;
317 }
318 
320 {
321  QtrleEncContext *s = avctx->priv_data;
322 
325  av_free(s->length_table);
326  av_free(s->skip_table);
327  return 0;
328 }
329 
331  .name = "qtrle",
332  .type = AVMEDIA_TYPE_VIDEO,
333  .id = AV_CODEC_ID_QTRLE,
334  .priv_data_size = sizeof(QtrleEncContext),
336  .encode2 = qtrle_encode_frame,
338  .pix_fmts = (const enum AVPixelFormat[]){
340  },
341  .long_name = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
342 };