1 /*
2 * QuickTime RPZA Video Encoder
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file rpzaenc.c
23 * QT RPZA Video Encoder by Todd Kirby <doubleshot@pacbell.net> and David Adler
24 */
25
26 #include "libavutil/avassert.h"
27 #include "libavutil/common.h"
28 #include "libavutil/opt.h"
29
30 #include "avcodec.h"
31 #include "internal.h"
32 #include "put_bits.h"
33
34 typedef struct RpzaContext {
35 AVClass *avclass;
36
37 int skip_frame_thresh;
38 int start_one_color_thresh;
39 int continue_one_color_thresh;
40 int sixteen_color_thresh;
41
42 AVFrame *prev_frame; // buffer for previous source frame
43 PutBitContext pb; // buffer for encoded frame data.
44
45 int frame_width; // width in pixels of source frame
46 int frame_height; // height in pixesl of source frame
47
48 int first_frame; // flag set to one when the first frame is being processed
49 // so that comparisons with previous frame data in not attempted
50 } RpzaContext;
51
52 typedef enum channel_offset {
53 RED = 2,
54 GREEN = 1,
55 BLUE = 0,
56 } channel_offset;
57
58 typedef struct rgb {
59 uint8_t r;
60 uint8_t g;
61 uint8_t b;
62 } rgb;
63
64 #define SQR(x) ((x) * (x))
65
66 /* 15 bit components */
67 #define GET_CHAN(color, chan) (((color) >> ((chan) * 5) & 0x1F) * 8)
68 #define R(color) GET_CHAN(color, RED)
69 #define G(color) GET_CHAN(color, GREEN)
70 #define B(color) GET_CHAN(color, BLUE)
71
72 typedef struct BlockInfo {
73 int row;
74 int col;
75 int block_width;
76 int block_height;
77 int image_width;
78 int image_height;
79 int block_index;
80 uint16_t start;
81 int rowstride;
82 int blocks_per_row;
83 int total_blocks;
84 } BlockInfo;
85
get_colors(uint8_t * min,uint8_t * max,uint8_t color4[4][3])86 static void get_colors(uint8_t *min, uint8_t *max, uint8_t color4[4][3])
87 {
88 uint8_t step;
89
90 color4[0][0] = min[0];
91 color4[0][1] = min[1];
92 color4[0][2] = min[2];
93
94 color4[3][0] = max[0];
95 color4[3][1] = max[1];
96 color4[3][2] = max[2];
97
98 // red components
99 step = (color4[3][0] - color4[0][0] + 1) / 3;
100 color4[1][0] = color4[0][0] + step;
101 color4[2][0] = color4[3][0] - step;
102
103 // green components
104 step = (color4[3][1] - color4[0][1] + 1) / 3;
105 color4[1][1] = color4[0][1] + step;
106 color4[2][1] = color4[3][1] - step;
107
108 // blue components
109 step = (color4[3][2] - color4[0][2] + 1) / 3;
110 color4[1][2] = color4[0][2] + step;
111 color4[2][2] = color4[3][2] - step;
112 }
113
114 /* Fill BlockInfo struct with information about a 4x4 block of the image */
get_block_info(BlockInfo * bi,int block)115 static int get_block_info(BlockInfo *bi, int block)
116 {
117 bi->row = block / bi->blocks_per_row;
118 bi->col = block % bi->blocks_per_row;
119
120 // test for right edge block
121 if (bi->col == bi->blocks_per_row - 1 && (bi->image_width % 4) != 0) {
122 bi->block_width = bi->image_width % 4;
123 } else {
124 bi->block_width = 4;
125 }
126
127 // test for bottom edge block
128 if (bi->row == (bi->image_height / 4) && (bi->image_height % 4) != 0) {
129 bi->block_height = bi->image_height % 4;
130 } else {
131 bi->block_height = 4;
132 }
133
134 return block ? (bi->col * 4) + (bi->row * bi->rowstride * 4) : 0;
135 }
136
rgb24_to_rgb555(uint8_t * rgb24)137 static uint16_t rgb24_to_rgb555(uint8_t *rgb24)
138 {
139 uint16_t rgb555 = 0;
140 uint32_t r, g, b;
141
142 r = rgb24[0] >> 3;
143 g = rgb24[1] >> 3;
144 b = rgb24[2] >> 3;
145
146 rgb555 |= (r << 10);
147 rgb555 |= (g << 5);
148 rgb555 |= (b << 0);
149
150 return rgb555;
151 }
152
153 /*
154 * Returns the total difference between two 24 bit color values
155 */
diff_colors(uint8_t * colorA,uint8_t * colorB)156 static int diff_colors(uint8_t *colorA, uint8_t *colorB)
157 {
158 int tot;
159
160 tot = SQR(colorA[0] - colorB[0]);
161 tot += SQR(colorA[1] - colorB[1]);
162 tot += SQR(colorA[2] - colorB[2]);
163
164 return tot;
165 }
166
167 /*
168 * Returns the maximum channel difference
169 */
max_component_diff(uint16_t * colorA,uint16_t * colorB)170 static int max_component_diff(uint16_t *colorA, uint16_t *colorB)
171 {
172 int diff, max = 0;
173
174 diff = FFABS(R(colorA[0]) - R(colorB[0]));
175 if (diff > max) {
176 max = diff;
177 }
178 diff = FFABS(G(colorA[0]) - G(colorB[0]));
179 if (diff > max) {
180 max = diff;
181 }
182 diff = FFABS(B(colorA[0]) - B(colorB[0]));
183 if (diff > max) {
184 max = diff;
185 }
186 return max * 8;
187 }
188
189 /*
190 * Find the channel that has the largest difference between minimum and maximum
191 * color values. Put the minimum value in min, maximum in max and the channel
192 * in chan.
193 */
get_max_component_diff(BlockInfo * bi,uint16_t * block_ptr,uint8_t * min,uint8_t * max,channel_offset * chan)194 static void get_max_component_diff(BlockInfo *bi, uint16_t *block_ptr,
195 uint8_t *min, uint8_t *max, channel_offset *chan)
196 {
197 int x, y;
198 uint8_t min_r, max_r, min_g, max_g, min_b, max_b;
199 uint8_t r, g, b;
200
201 // fix warning about uninitialized vars
202 min_r = min_g = min_b = UINT8_MAX;
203 max_r = max_g = max_b = 0;
204
205 // loop thru and compare pixels
206 for (y = 0; y < bi->block_height; y++) {
207 for (x = 0; x < bi->block_width; x++) {
208 // TODO: optimize
209 min_r = FFMIN(R(block_ptr[x]), min_r);
210 min_g = FFMIN(G(block_ptr[x]), min_g);
211 min_b = FFMIN(B(block_ptr[x]), min_b);
212
213 max_r = FFMAX(R(block_ptr[x]), max_r);
214 max_g = FFMAX(G(block_ptr[x]), max_g);
215 max_b = FFMAX(B(block_ptr[x]), max_b);
216 }
217 block_ptr += bi->rowstride;
218 }
219
220 r = max_r - min_r;
221 g = max_g - min_g;
222 b = max_b - min_b;
223
224 if (r > g && r > b) {
225 *max = max_r;
226 *min = min_r;
227 *chan = RED;
228 } else if (g > b && g >= r) {
229 *max = max_g;
230 *min = min_g;
231 *chan = GREEN;
232 } else {
233 *max = max_b;
234 *min = min_b;
235 *chan = BLUE;
236 }
237 }
238
239 /*
240 * Compare two 4x4 blocks to determine if the total difference between the
241 * blocks is greater than the thresh parameter. Returns -1 if difference
242 * exceeds threshold or zero otherwise.
243 */
compare_blocks(uint16_t * block1,uint16_t * block2,BlockInfo * bi,int thresh)244 static int compare_blocks(uint16_t *block1, uint16_t *block2, BlockInfo *bi, int thresh)
245 {
246 int x, y, diff = 0;
247 for (y = 0; y < bi->block_height; y++) {
248 for (x = 0; x < bi->block_width; x++) {
249 diff = max_component_diff(&block1[x], &block2[x]);
250 if (diff >= thresh) {
251 return -1;
252 }
253 }
254 block1 += bi->rowstride;
255 block2 += bi->rowstride;
256 }
257 return 0;
258 }
259
260 /*
261 * Determine the fit of one channel to another within a 4x4 block. This
262 * is used to determine the best palette choices for 4-color encoding.
263 */
leastsquares(uint16_t * block_ptr,BlockInfo * bi,channel_offset xchannel,channel_offset ychannel,double * slope,double * y_intercept,double * correlation_coef)264 static int leastsquares(uint16_t *block_ptr, BlockInfo *bi,
265 channel_offset xchannel, channel_offset ychannel,
266 double *slope, double *y_intercept, double *correlation_coef)
267 {
268 double sumx = 0, sumy = 0, sumx2 = 0, sumy2 = 0, sumxy = 0,
269 sumx_sq = 0, sumy_sq = 0, tmp, tmp2;
270 int i, j, count;
271 uint8_t x, y;
272
273 count = bi->block_height * bi->block_width;
274
275 if (count < 2)
276 return -1;
277
278 for (i = 0; i < bi->block_height; i++) {
279 for (j = 0; j < bi->block_width; j++) {
280 x = GET_CHAN(block_ptr[j], xchannel);
281 y = GET_CHAN(block_ptr[j], ychannel);
282 sumx += x;
283 sumy += y;
284 sumx2 += x * x;
285 sumy2 += y * y;
286 sumxy += x * y;
287 }
288 block_ptr += bi->rowstride;
289 }
290
291 sumx_sq = sumx * sumx;
292 tmp = (count * sumx2 - sumx_sq);
293
294 // guard against div/0
295 if (tmp == 0)
296 return -2;
297
298 sumy_sq = sumy * sumy;
299
300 *slope = (sumx * sumy - sumxy) / tmp;
301 *y_intercept = (sumy - (*slope) * sumx) / count;
302
303 tmp2 = count * sumy2 - sumy_sq;
304 if (tmp2 == 0) {
305 *correlation_coef = 0.0;
306 } else {
307 *correlation_coef = (count * sumxy - sumx * sumy) /
308 sqrt(tmp * tmp2);
309 }
310
311 return 0; // success
312 }
313
314 /*
315 * Determine the amount of error in the leastsquares fit.
316 */
calc_lsq_max_fit_error(uint16_t * block_ptr,BlockInfo * bi,int min,int max,int tmp_min,int tmp_max,channel_offset xchannel,channel_offset ychannel)317 static int calc_lsq_max_fit_error(uint16_t *block_ptr, BlockInfo *bi,
318 int min, int max, int tmp_min, int tmp_max,
319 channel_offset xchannel, channel_offset ychannel)
320 {
321 int i, j, x, y;
322 int err;
323 int max_err = 0;
324
325 for (i = 0; i < bi->block_height; i++) {
326 for (j = 0; j < bi->block_width; j++) {
327 int x_inc, lin_y, lin_x;
328 x = GET_CHAN(block_ptr[j], xchannel);
329 y = GET_CHAN(block_ptr[j], ychannel);
330
331 /* calculate x_inc as the 4-color index (0..3) */
332 x_inc = floor( (x - min) * 3.0 / (max - min) + 0.5);
333 x_inc = FFMAX(FFMIN(3, x_inc), 0);
334
335 /* calculate lin_y corresponding to x_inc */
336 lin_y = (int)(tmp_min + (tmp_max - tmp_min) * x_inc / 3.0 + 0.5);
337
338 err = FFABS(lin_y - y);
339 if (err > max_err)
340 max_err = err;
341
342 /* calculate lin_x corresponding to x_inc */
343 lin_x = (int)(min + (max - min) * x_inc / 3.0 + 0.5);
344
345 err = FFABS(lin_x - x);
346 if (err > max_err)
347 max_err += err;
348 }
349 block_ptr += bi->rowstride;
350 }
351
352 return max_err;
353 }
354
355 /*
356 * Find the closest match to a color within the 4-color palette
357 */
match_color(uint16_t * color,uint8_t colors[4][3])358 static int match_color(uint16_t *color, uint8_t colors[4][3])
359 {
360 int ret = 0;
361 int smallest_variance = INT_MAX;
362 uint8_t dithered_color[3];
363
364 for (int channel = 0; channel < 3; channel++) {
365 dithered_color[channel] = GET_CHAN(color[0], channel);
366 }
367
368 for (int palette_entry = 0; palette_entry < 4; palette_entry++) {
369 int variance = diff_colors(dithered_color, colors[palette_entry]);
370
371 if (variance < smallest_variance) {
372 smallest_variance = variance;
373 ret = palette_entry;
374 }
375 }
376
377 return ret;
378 }
379
380 /*
381 * Encode a block using the 4-color opcode and palette. return number of
382 * blocks encoded (until we implement multi-block 4 color runs this will
383 * always be 1)
384 */
encode_four_color_block(uint8_t * min_color,uint8_t * max_color,PutBitContext * pb,uint16_t * block_ptr,BlockInfo * bi)385 static int encode_four_color_block(uint8_t *min_color, uint8_t *max_color,
386 PutBitContext *pb, uint16_t *block_ptr, BlockInfo *bi)
387 {
388 int x, y, idx;
389 uint8_t color4[4][3];
390 uint16_t rounded_max, rounded_min;
391
392 // round min and max wider
393 rounded_min = rgb24_to_rgb555(min_color);
394 rounded_max = rgb24_to_rgb555(max_color);
395
396 // put a and b colors
397 // encode 4 colors = first 16 bit color with MSB zeroed and...
398 put_bits(pb, 16, rounded_max & ~0x8000);
399 // ...second 16 bit color with MSB on.
400 put_bits(pb, 16, rounded_min | 0x8000);
401
402 get_colors(min_color, max_color, color4);
403
404 for (y = 0; y < 4; y++) {
405 for (x = 0; x < 4; x++) {
406 idx = match_color(&block_ptr[x], color4);
407 put_bits(pb, 2, idx);
408 }
409 block_ptr += bi->rowstride;
410 }
411 return 1; // num blocks encoded
412 }
413
414 /*
415 * Copy a 4x4 block from the current frame buffer to the previous frame buffer.
416 */
update_block_in_prev_frame(const uint16_t * src_pixels,uint16_t * dest_pixels,const BlockInfo * bi,int block_counter)417 static void update_block_in_prev_frame(const uint16_t *src_pixels,
418 uint16_t *dest_pixels,
419 const BlockInfo *bi, int block_counter)
420 {
421 const int y_size = FFMIN(4, bi->image_height - bi->row * 4);
422
423 for (int y = 0; y < y_size; y++) {
424 memcpy(dest_pixels, src_pixels, 8);
425 dest_pixels += bi->rowstride;
426 src_pixels += bi->rowstride;
427 }
428 }
429
430 /*
431 * update statistics for the specified block. If first_block,
432 * it initializes the statistics. Otherwise it updates the statistics IF THIS
433 * BLOCK IS SUITABLE TO CONTINUE A 1-COLOR RUN. That is, it checks whether
434 * the range of colors (since the routine was called first_block != 0) are
435 * all close enough intensities to be represented by a single color.
436
437 * The routine returns 0 if this block is too different to be part of
438 * the same run of 1-color blocks. The routine returns 1 if this
439 * block can be part of the same 1-color block run.
440
441 * If the routine returns 1, it also updates its arguments to include
442 * the statistics of this block. Otherwise, the stats are unchanged
443 * and don't include the current block.
444 */
update_block_stats(RpzaContext * s,BlockInfo * bi,uint16_t * block,uint8_t min_color[3],uint8_t max_color[3],int * total_rgb,int * total_pixels,uint8_t avg_color[3],int first_block)445 static int update_block_stats(RpzaContext *s, BlockInfo *bi, uint16_t *block,
446 uint8_t min_color[3], uint8_t max_color[3],
447 int *total_rgb, int *total_pixels,
448 uint8_t avg_color[3], int first_block)
449 {
450 int x, y;
451 int is_in_range;
452 int total_pixels_blk;
453 int threshold;
454
455 uint8_t min_color_blk[3], max_color_blk[3];
456 int total_rgb_blk[3];
457 uint8_t avg_color_blk[3];
458
459 if (first_block) {
460 min_color[0] = UINT8_MAX;
461 min_color[1] = UINT8_MAX;
462 min_color[2] = UINT8_MAX;
463 max_color[0] = 0;
464 max_color[1] = 0;
465 max_color[2] = 0;
466 total_rgb[0] = 0;
467 total_rgb[1] = 0;
468 total_rgb[2] = 0;
469 *total_pixels = 0;
470 threshold = s->start_one_color_thresh;
471 } else {
472 threshold = s->continue_one_color_thresh;
473 }
474
475 /*
476 The *_blk variables will include the current block.
477 Initialize them based on the blocks so far.
478 */
479 min_color_blk[0] = min_color[0];
480 min_color_blk[1] = min_color[1];
481 min_color_blk[2] = min_color[2];
482 max_color_blk[0] = max_color[0];
483 max_color_blk[1] = max_color[1];
484 max_color_blk[2] = max_color[2];
485 total_rgb_blk[0] = total_rgb[0];
486 total_rgb_blk[1] = total_rgb[1];
487 total_rgb_blk[2] = total_rgb[2];
488 total_pixels_blk = *total_pixels + bi->block_height * bi->block_width;
489
490 /*
491 Update stats for this block's pixels
492 */
493 for (y = 0; y < bi->block_height; y++) {
494 for (x = 0; x < bi->block_width; x++) {
495 total_rgb_blk[0] += R(block[x]);
496 total_rgb_blk[1] += G(block[x]);
497 total_rgb_blk[2] += B(block[x]);
498
499 min_color_blk[0] = FFMIN(R(block[x]), min_color_blk[0]);
500 min_color_blk[1] = FFMIN(G(block[x]), min_color_blk[1]);
501 min_color_blk[2] = FFMIN(B(block[x]), min_color_blk[2]);
502
503 max_color_blk[0] = FFMAX(R(block[x]), max_color_blk[0]);
504 max_color_blk[1] = FFMAX(G(block[x]), max_color_blk[1]);
505 max_color_blk[2] = FFMAX(B(block[x]), max_color_blk[2]);
506 }
507 block += bi->rowstride;
508 }
509
510 /*
511 Calculate average color including current block.
512 */
513 avg_color_blk[0] = total_rgb_blk[0] / total_pixels_blk;
514 avg_color_blk[1] = total_rgb_blk[1] / total_pixels_blk;
515 avg_color_blk[2] = total_rgb_blk[2] / total_pixels_blk;
516
517 /*
518 Are all the pixels within threshold of the average color?
519 */
520 is_in_range = (max_color_blk[0] - avg_color_blk[0] <= threshold &&
521 max_color_blk[1] - avg_color_blk[1] <= threshold &&
522 max_color_blk[2] - avg_color_blk[2] <= threshold &&
523 avg_color_blk[0] - min_color_blk[0] <= threshold &&
524 avg_color_blk[1] - min_color_blk[1] <= threshold &&
525 avg_color_blk[2] - min_color_blk[2] <= threshold);
526
527 if (is_in_range) {
528 /*
529 Set the output variables to include this block.
530 */
531 min_color[0] = min_color_blk[0];
532 min_color[1] = min_color_blk[1];
533 min_color[2] = min_color_blk[2];
534 max_color[0] = max_color_blk[0];
535 max_color[1] = max_color_blk[1];
536 max_color[2] = max_color_blk[2];
537 total_rgb[0] = total_rgb_blk[0];
538 total_rgb[1] = total_rgb_blk[1];
539 total_rgb[2] = total_rgb_blk[2];
540 *total_pixels = total_pixels_blk;
541 avg_color[0] = avg_color_blk[0];
542 avg_color[1] = avg_color_blk[1];
543 avg_color[2] = avg_color_blk[2];
544 }
545
546 return is_in_range;
547 }
548
rpza_encode_stream(RpzaContext * s,const AVFrame * pict)549 static void rpza_encode_stream(RpzaContext *s, const AVFrame *pict)
550 {
551 BlockInfo bi;
552 int block_counter = 0;
553 int n_blocks;
554 int total_blocks;
555 int prev_block_offset;
556 int block_offset = 0;
557 uint8_t min = 0, max = 0;
558 channel_offset chan;
559 int i;
560 int tmp_min, tmp_max;
561 int total_rgb[3];
562 uint8_t avg_color[3];
563 int pixel_count;
564 uint8_t min_color[3], max_color[3];
565 double slope, y_intercept, correlation_coef;
566 uint16_t *src_pixels = (uint16_t *)pict->data[0];
567 uint16_t *prev_pixels = (uint16_t *)s->prev_frame->data[0];
568
569 /* Number of 4x4 blocks in frame. */
570 total_blocks = ((s->frame_width + 3) / 4) * ((s->frame_height + 3) / 4);
571
572 bi.image_width = s->frame_width;
573 bi.image_height = s->frame_height;
574 bi.rowstride = pict->linesize[0] / 2;
575
576 bi.blocks_per_row = (s->frame_width + 3) / 4;
577
578 while (block_counter < total_blocks) {
579 // SKIP CHECK
580 // make sure we have a valid previous frame and we're not writing
581 // a key frame
582 if (!s->first_frame) {
583 n_blocks = 0;
584 prev_block_offset = 0;
585
586 while (n_blocks < 32 && block_counter + n_blocks < total_blocks) {
587
588 block_offset = get_block_info(&bi, block_counter + n_blocks);
589
590 // multi-block opcodes cannot span multiple rows.
591 // If we're starting a new row, break out and write the opcode
592 /* TODO: Should eventually use bi.row here to determine when a
593 row break occurs, but that is currently breaking the
594 quicktime player. This is probably due to a bug in the
595 way I'm calculating the current row.
596 */
597 if (prev_block_offset && block_offset - prev_block_offset > 12) {
598 break;
599 }
600
601 prev_block_offset = block_offset;
602
603 if (compare_blocks(&prev_pixels[block_offset],
604 &src_pixels[block_offset], &bi, s->skip_frame_thresh) != 0) {
605 // write out skipable blocks
606 if (n_blocks) {
607
608 // write skip opcode
609 put_bits(&s->pb, 8, 0x80 | (n_blocks - 1));
610 block_counter += n_blocks;
611
612 goto post_skip;
613 }
614 break;
615 }
616
617 /*
618 * NOTE: we don't update skipped blocks in the previous frame buffer
619 * since skipped needs always to be compared against the first skipped
620 * block to avoid artifacts during gradual fade in/outs.
621 */
622
623 // update_block_in_prev_frame(&src_pixels[block_offset],
624 // &prev_pixels[block_offset], &bi, block_counter + n_blocks);
625
626 n_blocks++;
627 }
628
629 // we're either at the end of the frame or we've reached the maximum
630 // of 32 blocks in a run. Write out the run.
631 if (n_blocks) {
632 // write skip opcode
633 put_bits(&s->pb, 8, 0x80 | (n_blocks - 1));
634 block_counter += n_blocks;
635
636 continue;
637 }
638
639 } else {
640 block_offset = get_block_info(&bi, block_counter);
641 }
642 post_skip :
643
644 // ONE COLOR CHECK
645 if (update_block_stats(s, &bi, &src_pixels[block_offset],
646 min_color, max_color,
647 total_rgb, &pixel_count, avg_color, 1)) {
648 prev_block_offset = block_offset;
649
650 n_blocks = 1;
651
652 /* update this block in the previous frame buffer */
653 update_block_in_prev_frame(&src_pixels[block_offset],
654 &prev_pixels[block_offset], &bi, block_counter + n_blocks);
655
656 // check for subsequent blocks with the same color
657 while (n_blocks < 32 && block_counter + n_blocks < total_blocks) {
658 block_offset = get_block_info(&bi, block_counter + n_blocks);
659
660 // multi-block opcodes cannot span multiple rows.
661 // If we've hit end of a row, break out and write the opcode
662 if (block_offset - prev_block_offset > 12) {
663 break;
664 }
665
666 if (!update_block_stats(s, &bi, &src_pixels[block_offset],
667 min_color, max_color,
668 total_rgb, &pixel_count, avg_color, 0)) {
669 break;
670 }
671
672 prev_block_offset = block_offset;
673
674 /* update this block in the previous frame buffer */
675 update_block_in_prev_frame(&src_pixels[block_offset],
676 &prev_pixels[block_offset], &bi, block_counter + n_blocks);
677
678 n_blocks++;
679 }
680
681 // write one color opcode.
682 put_bits(&s->pb, 8, 0xa0 | (n_blocks - 1));
683 // write color to encode.
684 put_bits(&s->pb, 16, rgb24_to_rgb555(avg_color));
685 // skip past the blocks we've just encoded.
686 block_counter += n_blocks;
687 } else { // FOUR COLOR CHECK
688 int err = 0;
689
690 // get max component diff for block
691 get_max_component_diff(&bi, &src_pixels[block_offset], &min, &max, &chan);
692
693 min_color[0] = 0;
694 max_color[0] = 0;
695 min_color[1] = 0;
696 max_color[1] = 0;
697 min_color[2] = 0;
698 max_color[2] = 0;
699
700 // run least squares against other two components
701 for (i = 0; i < 3; i++) {
702 if (i == chan) {
703 min_color[i] = min;
704 max_color[i] = max;
705 continue;
706 }
707
708 slope = y_intercept = correlation_coef = 0;
709
710 if (leastsquares(&src_pixels[block_offset], &bi, chan, i,
711 &slope, &y_intercept, &correlation_coef)) {
712 min_color[i] = GET_CHAN(src_pixels[block_offset], i);
713 max_color[i] = GET_CHAN(src_pixels[block_offset], i);
714 } else {
715 tmp_min = (int)(0.5 + min * slope + y_intercept);
716 tmp_max = (int)(0.5 + max * slope + y_intercept);
717
718 av_assert0(tmp_min <= tmp_max);
719 // clamp min and max color values
720 tmp_min = av_clip_uint8(tmp_min);
721 tmp_max = av_clip_uint8(tmp_max);
722
723 err = FFMAX(calc_lsq_max_fit_error(&src_pixels[block_offset], &bi,
724 min, max, tmp_min, tmp_max, chan, i), err);
725
726 min_color[i] = tmp_min;
727 max_color[i] = tmp_max;
728 }
729 }
730
731 if (err > s->sixteen_color_thresh) { // DO SIXTEEN COLOR BLOCK
732 uint16_t *row_ptr;
733 int y_size, rgb555;
734
735 block_offset = get_block_info(&bi, block_counter);
736
737 row_ptr = &src_pixels[block_offset];
738 y_size = FFMIN(4, bi.image_height - bi.row * 4);
739
740 for (int y = 0; y < y_size; y++) {
741 for (int x = 0; x < 4; x++) {
742 rgb555 = row_ptr[x] & ~0x8000;
743
744 put_bits(&s->pb, 16, rgb555);
745 }
746 row_ptr += bi.rowstride;
747 }
748
749 for (int y = y_size; y < 4; y++) {
750 for (int x = 0; x < 4; x++)
751 put_bits(&s->pb, 16, 0);
752 }
753
754 block_counter++;
755 } else { // FOUR COLOR BLOCK
756 block_counter += encode_four_color_block(min_color, max_color,
757 &s->pb, &src_pixels[block_offset], &bi);
758 }
759
760 /* update this block in the previous frame buffer */
761 update_block_in_prev_frame(&src_pixels[block_offset],
762 &prev_pixels[block_offset], &bi, block_counter);
763 }
764 }
765 }
766
rpza_encode_init(AVCodecContext * avctx)767 static int rpza_encode_init(AVCodecContext *avctx)
768 {
769 RpzaContext *s = avctx->priv_data;
770
771 s->frame_width = avctx->width;
772 s->frame_height = avctx->height;
773
774 s->prev_frame = av_frame_alloc();
775 if (!s->prev_frame)
776 return AVERROR(ENOMEM);
777
778 return 0;
779 }
780
rpza_encode_frame(AVCodecContext * avctx,AVPacket * pkt,const AVFrame * frame,int * got_packet)781 static int rpza_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
782 const AVFrame *frame, int *got_packet)
783 {
784 RpzaContext *s = avctx->priv_data;
785 const AVFrame *pict = frame;
786 uint8_t *buf;
787 int ret;
788
789 if ((ret = ff_alloc_packet2(avctx, pkt, 6LL * avctx->height * avctx->width, 0)) < 0)
790 return ret;
791
792 init_put_bits(&s->pb, pkt->data, pkt->size);
793
794 // skip 4 byte header, write it later once the size of the chunk is known
795 put_bits32(&s->pb, 0x00);
796
797 if (!s->prev_frame->data[0]) {
798 s->first_frame = 1;
799 s->prev_frame->format = pict->format;
800 s->prev_frame->width = pict->width;
801 s->prev_frame->height = pict->height;
802 ret = av_frame_get_buffer(s->prev_frame, 0);
803 if (ret < 0)
804 return ret;
805 } else {
806 s->first_frame = 0;
807 }
808
809 rpza_encode_stream(s, pict);
810
811 flush_put_bits(&s->pb);
812
813 av_shrink_packet(pkt, put_bits_count(&s->pb) >> 3);
814 buf = pkt->data;
815
816 // write header opcode
817 buf[0] = 0xe1; // chunk opcode
818
819 // write chunk length
820 AV_WB24(buf + 1, pkt->size);
821
822 *got_packet = 1;
823
824 return 0;
825 }
826
rpza_encode_end(AVCodecContext * avctx)827 static int rpza_encode_end(AVCodecContext *avctx)
828 {
829 RpzaContext *s = (RpzaContext *)avctx->priv_data;
830
831 av_frame_free(&s->prev_frame);
832
833 return 0;
834 }
835
836 #define OFFSET(x) offsetof(RpzaContext, x)
837 #define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
838 static const AVOption options[] = {
839 { "skip_frame_thresh", NULL, OFFSET(skip_frame_thresh), AV_OPT_TYPE_INT, {.i64=1}, 0, 24, VE},
840 { "start_one_color_thresh", NULL, OFFSET(start_one_color_thresh), AV_OPT_TYPE_INT, {.i64=1}, 0, 24, VE},
841 { "continue_one_color_thresh", NULL, OFFSET(continue_one_color_thresh), AV_OPT_TYPE_INT, {.i64=0}, 0, 24, VE},
842 { "sixteen_color_thresh", NULL, OFFSET(sixteen_color_thresh), AV_OPT_TYPE_INT, {.i64=1}, 0, 24, VE},
843 { NULL },
844 };
845
846 static const AVClass rpza_class = {
847 .class_name = "rpza",
848 .item_name = av_default_item_name,
849 .option = options,
850 .version = LIBAVUTIL_VERSION_INT,
851 };
852
853 AVCodec ff_rpza_encoder = {
854 .name = "rpza",
855 .long_name = NULL_IF_CONFIG_SMALL("QuickTime video (RPZA)"),
856 .type = AVMEDIA_TYPE_VIDEO,
857 .id = AV_CODEC_ID_RPZA,
858 .priv_data_size = sizeof(RpzaContext),
859 .priv_class = &rpza_class,
860 .init = rpza_encode_init,
861 .encode2 = rpza_encode_frame,
862 .close = rpza_encode_end,
863 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
864 .pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_RGB555,
865 AV_PIX_FMT_NONE},
866 };
867