FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/rpzaenc.c
Date: 2021-09-26 18:22:30
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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 "encode.h"
32 #include "internal.h"
33 #include "put_bits.h"
34
35 typedef struct RpzaContext {
36 AVClass *avclass;
37
38 int skip_frame_thresh;
39 int start_one_color_thresh;
40 int continue_one_color_thresh;
41 int sixteen_color_thresh;
42
43 AVFrame *prev_frame; // buffer for previous source frame
44 PutBitContext pb; // buffer for encoded frame data.
45
46 int frame_width; // width in pixels of source frame
47 int frame_height; // height in pixesl of source frame
48
49 int first_frame; // flag set to one when the first frame is being processed
50 // so that comparisons with previous frame data in not attempted
51 } RpzaContext;
52
53 typedef enum channel_offset {
54 RED = 2,
55 GREEN = 1,
56 BLUE = 0,
57 } channel_offset;
58
59 typedef struct rgb {
60 uint8_t r;
61 uint8_t g;
62 uint8_t b;
63 } rgb;
64
65 #define SQR(x) ((x) * (x))
66
67 /* 15 bit components */
68 #define GET_CHAN(color, chan) (((color) >> ((chan) * 5) & 0x1F) * 8)
69 #define R(color) GET_CHAN(color, RED)
70 #define G(color) GET_CHAN(color, GREEN)
71 #define B(color) GET_CHAN(color, BLUE)
72
73 typedef struct BlockInfo {
74 int row;
75 int col;
76 int block_width;
77 int block_height;
78 int image_width;
79 int image_height;
80 int block_index;
81 uint16_t start;
82 int rowstride;
83 int blocks_per_row;
84 int total_blocks;
85 } BlockInfo;
86
87 static void get_colors(uint8_t *min, uint8_t *max, uint8_t color4[4][3])
88 {
89 uint8_t step;
90
91 color4[0][0] = min[0];
92 color4[0][1] = min[1];
93 color4[0][2] = min[2];
94
95 color4[3][0] = max[0];
96 color4[3][1] = max[1];
97 color4[3][2] = max[2];
98
99 // red components
100 step = (color4[3][0] - color4[0][0] + 1) / 3;
101 color4[1][0] = color4[0][0] + step;
102 color4[2][0] = color4[3][0] - step;
103
104 // green components
105 step = (color4[3][1] - color4[0][1] + 1) / 3;
106 color4[1][1] = color4[0][1] + step;
107 color4[2][1] = color4[3][1] - step;
108
109 // blue components
110 step = (color4[3][2] - color4[0][2] + 1) / 3;
111 color4[1][2] = color4[0][2] + step;
112 color4[2][2] = color4[3][2] - step;
113 }
114
115 /* Fill BlockInfo struct with information about a 4x4 block of the image */
116 static int get_block_info(BlockInfo *bi, int block)
117 {
118 bi->row = block / bi->blocks_per_row;
119 bi->col = block % bi->blocks_per_row;
120
121 // test for right edge block
122 if (bi->col == bi->blocks_per_row - 1 && (bi->image_width % 4) != 0) {
123 bi->block_width = bi->image_width % 4;
124 } else {
125 bi->block_width = 4;
126 }
127
128 // test for bottom edge block
129 if (bi->row == (bi->image_height / 4) && (bi->image_height % 4) != 0) {
130 bi->block_height = bi->image_height % 4;
131 } else {
132 bi->block_height = 4;
133 }
134
135 return block ? (bi->col * 4) + (bi->row * bi->rowstride * 4) : 0;
136 }
137
138 static uint16_t rgb24_to_rgb555(uint8_t *rgb24)
139 {
140 uint16_t rgb555 = 0;
141 uint32_t r, g, b;
142
143 r = rgb24[0] >> 3;
144 g = rgb24[1] >> 3;
145 b = rgb24[2] >> 3;
146
147 rgb555 |= (r << 10);
148 rgb555 |= (g << 5);
149 rgb555 |= (b << 0);
150
151 return rgb555;
152 }
153
154 /*
155 * Returns the total difference between two 24 bit color values
156 */
157 static int diff_colors(uint8_t *colorA, uint8_t *colorB)
158 {
159 int tot;
160
161 tot = SQR(colorA[0] - colorB[0]);
162 tot += SQR(colorA[1] - colorB[1]);
163 tot += SQR(colorA[2] - colorB[2]);
164
165 return tot;
166 }
167
168 /*
169 * Returns the maximum channel difference
170 */
171 static int max_component_diff(uint16_t *colorA, uint16_t *colorB)
172 {
173 int diff, max = 0;
174
175 diff = FFABS(R(colorA[0]) - R(colorB[0]));
176 if (diff > max) {
177 max = diff;
178 }
179 diff = FFABS(G(colorA[0]) - G(colorB[0]));
180 if (diff > max) {
181 max = diff;
182 }
183 diff = FFABS(B(colorA[0]) - B(colorB[0]));
184 if (diff > max) {
185 max = diff;
186 }
187 return max * 8;
188 }
189
190 /*
191 * Find the channel that has the largest difference between minimum and maximum
192 * color values. Put the minimum value in min, maximum in max and the channel
193 * in chan.
194 */
195 static void get_max_component_diff(BlockInfo *bi, uint16_t *block_ptr,
196 uint8_t *min, uint8_t *max, channel_offset *chan)
197 {
198 int x, y;
199 uint8_t min_r, max_r, min_g, max_g, min_b, max_b;
200 uint8_t r, g, b;
201
202 // fix warning about uninitialized vars
203 min_r = min_g = min_b = UINT8_MAX;
204 max_r = max_g = max_b = 0;
205
206 // loop thru and compare pixels
207 for (y = 0; y < bi->block_height; y++) {
208 for (x = 0; x < bi->block_width; x++){
209 // TODO: optimize
210 min_r = FFMIN(R(block_ptr[x]), min_r);
211 min_g = FFMIN(G(block_ptr[x]), min_g);
212 min_b = FFMIN(B(block_ptr[x]), min_b);
213
214 max_r = FFMAX(R(block_ptr[x]), max_r);
215 max_g = FFMAX(G(block_ptr[x]), max_g);
216 max_b = FFMAX(B(block_ptr[x]), max_b);
217 }
218 block_ptr += bi->rowstride;
219 }
220
221 r = max_r - min_r;
222 g = max_g - min_g;
223 b = max_b - min_b;
224
225 if (r > g && r > b) {
226 *max = max_r;
227 *min = min_r;
228 *chan = RED;
229 } else if (g > b && g >= r) {
230 *max = max_g;
231 *min = min_g;
232 *chan = GREEN;
233 } else {
234 *max = max_b;
235 *min = min_b;
236 *chan = BLUE;
237 }
238 }
239
240 /*
241 * Compare two 4x4 blocks to determine if the total difference between the
242 * blocks is greater than the thresh parameter. Returns -1 if difference
243 * exceeds threshold or zero otherwise.
244 */
245 static int compare_blocks(uint16_t *block1, uint16_t *block2, BlockInfo *bi, int thresh)
246 {
247 int x, y, diff = 0;
248 for (y = 0; y < bi->block_height; y++) {
249 for (x = 0; x < bi->block_width; x++) {
250 diff = max_component_diff(&block1[x], &block2[x]);
251 if (diff >= thresh) {
252 return -1;
253 }
254 }
255 block1 += bi->rowstride;
256 block2 += bi->rowstride;
257 }
258 return 0;
259 }
260
261 /*
262 * Determine the fit of one channel to another within a 4x4 block. This
263 * is used to determine the best palette choices for 4-color encoding.
264 */
265 static int leastsquares(uint16_t *block_ptr, BlockInfo *bi,
266 channel_offset xchannel, channel_offset ychannel,
267 double *slope, double *y_intercept, double *correlation_coef)
268 {
269 double sumx = 0, sumy = 0, sumx2 = 0, sumy2 = 0, sumxy = 0,
270 sumx_sq = 0, sumy_sq = 0, tmp, tmp2;
271 int i, j, count;
272 uint8_t x, y;
273
274 count = bi->block_height * bi->block_width;
275
276 if (count < 2)
277 return -1;
278
279 for (i = 0; i < bi->block_height; i++) {
280 for (j = 0; j < bi->block_width; j++){
281 x = GET_CHAN(block_ptr[j], xchannel);
282 y = GET_CHAN(block_ptr[j], ychannel);
283 sumx += x;
284 sumy += y;
285 sumx2 += x * x;
286 sumy2 += y * y;
287 sumxy += x * y;
288 }
289 block_ptr += bi->rowstride;
290 }
291
292 sumx_sq = sumx * sumx;
293 tmp = (count * sumx2 - sumx_sq);
294
295 // guard against div/0
296 if (tmp == 0)
297 return -2;
298
299 sumy_sq = sumy * sumy;
300
301 *slope = (sumx * sumy - sumxy) / tmp;
302 *y_intercept = (sumy - (*slope) * sumx) / count;
303
304 tmp2 = count * sumy2 - sumy_sq;
305 if (tmp2 == 0) {
306 *correlation_coef = 0.0;
307 } else {
308 *correlation_coef = (count * sumxy - sumx * sumy) /
309 sqrt(tmp * tmp2);
310 }
311
312 return 0; // success
313 }
314
315 /*
316 * Determine the amount of error in the leastsquares fit.
317 */
318 static int calc_lsq_max_fit_error(uint16_t *block_ptr, BlockInfo *bi,
319 int min, int max, int tmp_min, int tmp_max,
320 channel_offset xchannel, channel_offset ychannel)
321 {
322 int i, j, x, y;
323 int err;
324 int max_err = 0;
325
326 for (i = 0; i < bi->block_height; i++) {
327 for (j = 0; j < bi->block_width; j++){
328 int x_inc, lin_y, lin_x;
329 x = GET_CHAN(block_ptr[j], xchannel);
330 y = GET_CHAN(block_ptr[j], ychannel);
331
332 /* calculate x_inc as the 4-color index (0..3) */
333 x_inc = floor( (x - min) * 3.0 / (max - min) + 0.5);
334 x_inc = FFMAX(FFMIN(3, x_inc), 0);
335
336 /* calculate lin_y corresponding to x_inc */
337 lin_y = (int)(tmp_min + (tmp_max - tmp_min) * x_inc / 3.0 + 0.5);
338
339 err = FFABS(lin_y - y);
340 if (err > max_err)
341 max_err = err;
342
343 /* calculate lin_x corresponding to x_inc */
344 lin_x = (int)(min + (max - min) * x_inc / 3.0 + 0.5);
345
346 err = FFABS(lin_x - x);
347 if (err > max_err)
348 max_err += err;
349 }
350 block_ptr += bi->rowstride;
351 }
352
353 return max_err;
354 }
355
356 /*
357 * Find the closest match to a color within the 4-color palette
358 */
359 static int match_color(uint16_t *color, uint8_t colors[4][3])
360 {
361 int ret = 0;
362 int smallest_variance = INT_MAX;
363 uint8_t dithered_color[3];
364
365 for (int channel = 0; channel < 3; channel++) {
366 dithered_color[channel] = GET_CHAN(color[0], channel);
367 }
368
369 for (int palette_entry = 0; palette_entry < 4; palette_entry++) {
370 int variance = diff_colors(dithered_color, colors[palette_entry]);
371
372 if (variance < smallest_variance) {
373 smallest_variance = variance;
374 ret = palette_entry;
375 }
376 }
377
378 return ret;
379 }
380
381 /*
382 * Encode a block using the 4-color opcode and palette. return number of
383 * blocks encoded (until we implement multi-block 4 color runs this will
384 * always be 1)
385 */
386 static int encode_four_color_block(uint8_t *min_color, uint8_t *max_color,
387 PutBitContext *pb, uint16_t *block_ptr, BlockInfo *bi)
388 {
389 int x, y, idx;
390 uint8_t color4[4][3];
391 uint16_t rounded_max, rounded_min;
392
393 // round min and max wider
394 rounded_min = rgb24_to_rgb555(min_color);
395 rounded_max = rgb24_to_rgb555(max_color);
396
397 // put a and b colors
398 // encode 4 colors = first 16 bit color with MSB zeroed and...
399 put_bits(pb, 16, rounded_max & ~0x8000);
400 // ...second 16 bit color with MSB on.
401 put_bits(pb, 16, rounded_min | 0x8000);
402
403 get_colors(min_color, max_color, color4);
404
405 for (y = 0; y < 4; y++) {
406 for (x = 0; x < 4; x++) {
407 idx = match_color(&block_ptr[x], color4);
408 put_bits(pb, 2, idx);
409 }
410 block_ptr += bi->rowstride;
411 }
412 return 1; // num blocks encoded
413 }
414
415 /*
416 * Copy a 4x4 block from the current frame buffer to the previous frame buffer.
417 */
418 static void update_block_in_prev_frame(const uint16_t *src_pixels,
419 uint16_t *dest_pixels,
420 const BlockInfo *bi, int block_counter)
421 {
422 for (int y = 0; y < 4; y++) {
423 memcpy(dest_pixels, src_pixels, 8);
424 dest_pixels += bi->rowstride;
425 src_pixels += bi->rowstride;
426 }
427 }
428
429 /*
430 * update statistics for the specified block. If first_block,
431 * it initializes the statistics. Otherwise it updates the statistics IF THIS
432 * BLOCK IS SUITABLE TO CONTINUE A 1-COLOR RUN. That is, it checks whether
433 * the range of colors (since the routine was called first_block != 0) are
434 * all close enough intensities to be represented by a single color.
435
436 * The routine returns 0 if this block is too different to be part of
437 * the same run of 1-color blocks. The routine returns 1 if this
438 * block can be part of the same 1-color block run.
439
440 * If the routine returns 1, it also updates its arguments to include
441 * the statistics of this block. Otherwise, the stats are unchanged
442 * and don't include the current block.
443 */
444 static int update_block_stats(RpzaContext *s, BlockInfo *bi, uint16_t *block,
445 uint8_t min_color[3], uint8_t max_color[3],
446 int *total_rgb, int *total_pixels,
447 uint8_t avg_color[3], int first_block)
448 {
449 int x, y;
450 int is_in_range;
451 int total_pixels_blk;
452 int threshold;
453
454 uint8_t min_color_blk[3], max_color_blk[3];
455 int total_rgb_blk[3];
456 uint8_t avg_color_blk[3];
457
458 if (first_block) {
459 min_color[0] = UINT8_MAX;
460 min_color[1] = UINT8_MAX;
461 min_color[2] = UINT8_MAX;
462 max_color[0] = 0;
463 max_color[1] = 0;
464 max_color[2] = 0;
465 total_rgb[0] = 0;
466 total_rgb[1] = 0;
467 total_rgb[2] = 0;
468 *total_pixels = 0;
469 threshold = s->start_one_color_thresh;
470 } else {
471 threshold = s->continue_one_color_thresh;
472 }
473
474 /*
475 The *_blk variables will include the current block.
476 Initialize them based on the blocks so far.
477 */
478 min_color_blk[0] = min_color[0];
479 min_color_blk[1] = min_color[1];
480 min_color_blk[2] = min_color[2];
481 max_color_blk[0] = max_color[0];
482 max_color_blk[1] = max_color[1];
483 max_color_blk[2] = max_color[2];
484 total_rgb_blk[0] = total_rgb[0];
485 total_rgb_blk[1] = total_rgb[1];
486 total_rgb_blk[2] = total_rgb[2];
487 total_pixels_blk = *total_pixels + bi->block_height * bi->block_width;
488
489 /*
490 Update stats for this block's pixels
491 */
492 for (y = 0; y < bi->block_height; y++) {
493 for (x = 0; x < bi->block_width; x++) {
494 total_rgb_blk[0] += R(block[x]);
495 total_rgb_blk[1] += G(block[x]);
496 total_rgb_blk[2] += B(block[x]);
497
498 min_color_blk[0] = FFMIN(R(block[x]), min_color_blk[0]);
499 min_color_blk[1] = FFMIN(G(block[x]), min_color_blk[1]);
500 min_color_blk[2] = FFMIN(B(block[x]), min_color_blk[2]);
501
502 max_color_blk[0] = FFMAX(R(block[x]), max_color_blk[0]);
503 max_color_blk[1] = FFMAX(G(block[x]), max_color_blk[1]);
504 max_color_blk[2] = FFMAX(B(block[x]), max_color_blk[2]);
505 }
506 block += bi->rowstride;
507 }
508
509 /*
510 Calculate average color including current block.
511 */
512 avg_color_blk[0] = total_rgb_blk[0] / total_pixels_blk;
513 avg_color_blk[1] = total_rgb_blk[1] / total_pixels_blk;
514 avg_color_blk[2] = total_rgb_blk[2] / total_pixels_blk;
515
516 /*
517 Are all the pixels within threshold of the average color?
518 */
519 is_in_range = (max_color_blk[0] - avg_color_blk[0] <= threshold &&
520 max_color_blk[1] - avg_color_blk[1] <= threshold &&
521 max_color_blk[2] - avg_color_blk[2] <= threshold &&
522 avg_color_blk[0] - min_color_blk[0] <= threshold &&
523 avg_color_blk[1] - min_color_blk[1] <= threshold &&
524 avg_color_blk[2] - min_color_blk[2] <= threshold);
525
526 if (is_in_range) {
527 /*
528 Set the output variables to include this block.
529 */
530 min_color[0] = min_color_blk[0];
531 min_color[1] = min_color_blk[1];
532 min_color[2] = min_color_blk[2];
533 max_color[0] = max_color_blk[0];
534 max_color[1] = max_color_blk[1];
535 max_color[2] = max_color_blk[2];
536 total_rgb[0] = total_rgb_blk[0];
537 total_rgb[1] = total_rgb_blk[1];
538 total_rgb[2] = total_rgb_blk[2];
539 *total_pixels = total_pixels_blk;
540 avg_color[0] = avg_color_blk[0];
541 avg_color[1] = avg_color_blk[1];
542 avg_color[2] = avg_color_blk[2];
543 }
544
545 return is_in_range;
546 }
547
548 static void rpza_encode_stream(RpzaContext *s, const AVFrame *pict)
549 {
550 BlockInfo bi;
551 int block_counter = 0;
552 int n_blocks;
553 int total_blocks;
554 int prev_block_offset;
555 int block_offset = 0;
556 uint8_t min = 0, max = 0;
557 channel_offset chan;
558 int i;
559 int tmp_min, tmp_max;
560 int total_rgb[3];
561 uint8_t avg_color[3];
562 int pixel_count;
563 uint8_t min_color[3], max_color[3];
564 double slope, y_intercept, correlation_coef;
565 uint16_t *src_pixels = (uint16_t *)pict->data[0];
566 uint16_t *prev_pixels = (uint16_t *)s->prev_frame->data[0];
567
568 /* Number of 4x4 blocks in frame. */
569 total_blocks = ((s->frame_width + 3) / 4) * ((s->frame_height + 3) / 4);
570
571 bi.image_width = s->frame_width;
572 bi.image_height = s->frame_height;
573 bi.rowstride = pict->linesize[0] / 2;
574
575 bi.blocks_per_row = (s->frame_width + 3) / 4;
576
577 while (block_counter < total_blocks) {
578 // SKIP CHECK
579 // make sure we have a valid previous frame and we're not writing
580 // a key frame
581 if (!s->first_frame) {
582 n_blocks = 0;
583 prev_block_offset = 0;
584
585 while (n_blocks < 32 && block_counter + n_blocks < total_blocks) {
586
587 block_offset = get_block_info(&bi, block_counter + n_blocks);
588
589 // multi-block opcodes cannot span multiple rows.
590 // If we're starting a new row, break out and write the opcode
591 /* TODO: Should eventually use bi.row here to determine when a
592 row break occurs, but that is currently breaking the
593 quicktime player. This is probably due to a bug in the
594 way I'm calculating the current row.
595 */
596 if (prev_block_offset && block_offset - prev_block_offset > 12) {
597 break;
598 }
599
600 prev_block_offset = block_offset;
601
602 if (compare_blocks(&prev_pixels[block_offset],
603 &src_pixels[block_offset], &bi, s->skip_frame_thresh) != 0) {
604 // write out skipable blocks
605 if (n_blocks) {
606
607 // write skip opcode
608 put_bits(&s->pb, 8, 0x80 | (n_blocks - 1));
609 block_counter += n_blocks;
610
611 goto post_skip;
612 }
613 break;
614 }
615
616 /*
617 * NOTE: we don't update skipped blocks in the previous frame buffer
618 * since skipped needs always to be compared against the first skipped
619 * block to avoid artifacts during gradual fade in/outs.
620 */
621
622 // update_block_in_prev_frame(&src_pixels[block_offset],
623 // &prev_pixels[block_offset], &bi, block_counter + n_blocks);
624
625 n_blocks++;
626 }
627
628 // we're either at the end of the frame or we've reached the maximum
629 // of 32 blocks in a run. Write out the run.
630 if (n_blocks) {
631 // write skip opcode
632 put_bits(&s->pb, 8, 0x80 | (n_blocks - 1));
633 block_counter += n_blocks;
634
635 continue;
636 }
637
638 } else {
639 block_offset = get_block_info(&bi, block_counter);
640 }
641 post_skip :
642
643 // ONE COLOR CHECK
644 if (update_block_stats(s, &bi, &src_pixels[block_offset],
645 min_color, max_color,
646 total_rgb, &pixel_count, avg_color, 1)) {
647 prev_block_offset = block_offset;
648
649 n_blocks = 1;
650
651 /* update this block in the previous frame buffer */
652 update_block_in_prev_frame(&src_pixels[block_offset],
653 &prev_pixels[block_offset], &bi, block_counter + n_blocks);
654
655 // check for subsequent blocks with the same color
656 while (n_blocks < 32 && block_counter + n_blocks < total_blocks) {
657 block_offset = get_block_info(&bi, block_counter + n_blocks);
658
659 // multi-block opcodes cannot span multiple rows.
660 // If we've hit end of a row, break out and write the opcode
661 if (block_offset - prev_block_offset > 12) {
662 break;
663 }
664
665 if (!update_block_stats(s, &bi, &src_pixels[block_offset],
666 min_color, max_color,
667 total_rgb, &pixel_count, avg_color, 0)) {
668 break;
669 }
670
671 prev_block_offset = block_offset;
672
673 /* update this block in the previous frame buffer */
674 update_block_in_prev_frame(&src_pixels[block_offset],
675 &prev_pixels[block_offset], &bi, block_counter + n_blocks);
676
677 n_blocks++;
678 }
679
680 // write one color opcode.
681 put_bits(&s->pb, 8, 0xa0 | (n_blocks - 1));
682 // write color to encode.
683 put_bits(&s->pb, 16, rgb24_to_rgb555(avg_color));
684 // skip past the blocks we've just encoded.
685 block_counter += n_blocks;
686 } else { // FOUR COLOR CHECK
687 int err = 0;
688
689 // get max component diff for block
690 get_max_component_diff(&bi, &src_pixels[block_offset], &min, &max, &chan);
691
692 min_color[0] = 0;
693 max_color[0] = 0;
694 min_color[1] = 0;
695 max_color[1] = 0;
696 min_color[2] = 0;
697 max_color[2] = 0;
698
699 // run least squares against other two components
700 for (i = 0; i < 3; i++) {
701 if (i == chan) {
702 min_color[i] = min;
703 max_color[i] = max;
704 continue;
705 }
706
707 slope = y_intercept = correlation_coef = 0;
708
709 if (leastsquares(&src_pixels[block_offset], &bi, chan, i,
710 &slope, &y_intercept, &correlation_coef)) {
711 min_color[i] = GET_CHAN(src_pixels[block_offset], i);
712 max_color[i] = GET_CHAN(src_pixels[block_offset], i);
713 } else {
714 tmp_min = (int)(0.5 + min * slope + y_intercept);
715 tmp_max = (int)(0.5 + max * slope + y_intercept);
716
717 av_assert0(tmp_min <= tmp_max);
718 // clamp min and max color values
719 tmp_min = av_clip_uint8(tmp_min);
720 tmp_max = av_clip_uint8(tmp_max);
721
722 err = FFMAX(calc_lsq_max_fit_error(&src_pixels[block_offset], &bi,
723 min, max, tmp_min, tmp_max, chan, i), err);
724
725 min_color[i] = tmp_min;
726 max_color[i] = tmp_max;
727 }
728 }
729
730 if (err > s->sixteen_color_thresh) { // DO SIXTEEN COLOR BLOCK
731 uint16_t *row_ptr;
732 int rgb555;
733
734 block_offset = get_block_info(&bi, block_counter);
735
736 row_ptr = &src_pixels[block_offset];
737
738 for (int y = 0; y < 4; y++) {
739 for (int x = 0; x < 4; x++){
740 rgb555 = row_ptr[x] & ~0x8000;
741
742 put_bits(&s->pb, 16, rgb555);
743 }
744 row_ptr += bi.rowstride;
745 }
746
747 block_counter++;
748 } else { // FOUR COLOR BLOCK
749 block_counter += encode_four_color_block(min_color, max_color,
750 &s->pb, &src_pixels[block_offset], &bi);
751 }
752
753 /* update this block in the previous frame buffer */
754 update_block_in_prev_frame(&src_pixels[block_offset],
755 &prev_pixels[block_offset], &bi, block_counter);
756 }
757 }
758 }
759
760 static int rpza_encode_init(AVCodecContext *avctx)
761 {
762 RpzaContext *s = avctx->priv_data;
763
764 s->frame_width = avctx->width;
765 s->frame_height = avctx->height;
766
767 s->prev_frame = av_frame_alloc();
768 if (!s->prev_frame)
769 return AVERROR(ENOMEM);
770
771 return 0;
772 }
773
774 static int rpza_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
775 const AVFrame *frame, int *got_packet)
776 {
777 RpzaContext *s = avctx->priv_data;
778 const AVFrame *pict = frame;
779 uint8_t *buf;
780 int ret = ff_alloc_packet(avctx, pkt, 6LL * avctx->height * avctx->width);
781
782 if (ret < 0)
783 return ret;
784
785 init_put_bits(&s->pb, pkt->data, pkt->size);
786
787 // skip 4 byte header, write it later once the size of the chunk is known
788 put_bits32(&s->pb, 0x00);
789
790 if (!s->prev_frame->data[0]) {
791 s->first_frame = 1;
792 s->prev_frame->format = pict->format;
793 s->prev_frame->width = pict->width;
794 s->prev_frame->height = pict->height;
795 ret = av_frame_get_buffer(s->prev_frame, 0);
796 if (ret < 0)
797 return ret;
798 } else {
799 s->first_frame = 0;
800 }
801
802 rpza_encode_stream(s, pict);
803
804 flush_put_bits(&s->pb);
805
806 av_shrink_packet(pkt, put_bytes_output(&s->pb));
807 buf = pkt->data;
808
809 // write header opcode
810 buf[0] = 0xe1; // chunk opcode
811
812 // write chunk length
813 AV_WB24(buf + 1, pkt->size);
814
815 *got_packet = 1;
816
817 return 0;
818 }
819
820 static int rpza_encode_end(AVCodecContext *avctx)
821 {
822 RpzaContext *s = (RpzaContext *)avctx->priv_data;
823
824 av_frame_free(&s->prev_frame);
825
826 return 0;
827 }
828
829 #define OFFSET(x) offsetof(RpzaContext, x)
830 #define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
831 static const AVOption options[] = {
832 { "skip_frame_thresh", NULL, OFFSET(skip_frame_thresh), AV_OPT_TYPE_INT, {.i64=1}, 0, 24, VE},
833 { "start_one_color_thresh", NULL, OFFSET(start_one_color_thresh), AV_OPT_TYPE_INT, {.i64=1}, 0, 24, VE},
834 { "continue_one_color_thresh", NULL, OFFSET(continue_one_color_thresh), AV_OPT_TYPE_INT, {.i64=0}, 0, 24, VE},
835 { "sixteen_color_thresh", NULL, OFFSET(sixteen_color_thresh), AV_OPT_TYPE_INT, {.i64=1}, 0, 24, VE},
836 { NULL },
837 };
838
839 static const AVClass rpza_class = {
840 .class_name = "rpza",
841 .item_name = av_default_item_name,
842 .option = options,
843 .version = LIBAVUTIL_VERSION_INT,
844 };
845
846 const AVCodec ff_rpza_encoder = {
847 .name = "rpza",
848 .long_name = NULL_IF_CONFIG_SMALL("QuickTime video (RPZA)"),
849 .type = AVMEDIA_TYPE_VIDEO,
850 .id = AV_CODEC_ID_RPZA,
851 .priv_data_size = sizeof(RpzaContext),
852 .priv_class = &rpza_class,
853 .init = rpza_encode_init,
854 .encode2 = rpza_encode_frame,
855 .close = rpza_encode_end,
856 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
857 .pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_RGB555,
858 AV_PIX_FMT_NONE},
859 };
860