1// Copyright 2010 Google Inc. All Rights Reserved.
2//
3// Use of this source code is governed by a BSD-style license
4// that can be found in the COPYING file in the root of the source
5// tree. An additional intellectual property rights grant can be found
6// in the file PATENTS. All contributing project authors may
7// be found in the AUTHORS file in the root of the source tree.
8// -----------------------------------------------------------------------------
9//
10// Frame-reconstruction function. Memory allocation.
11//
12// Author: Skal (pascal.massimino@gmail.com)
13
14#include <stdlib.h>
15#include "src/dec/vp8i_dec.h"
16#include "src/utils/utils.h"
17
18//------------------------------------------------------------------------------
19// Main reconstruction function.
20
21static const uint16_t kScan[16] = {
22 0 + 0 * BPS, 4 + 0 * BPS, 8 + 0 * BPS, 12 + 0 * BPS,
23 0 + 4 * BPS, 4 + 4 * BPS, 8 + 4 * BPS, 12 + 4 * BPS,
24 0 + 8 * BPS, 4 + 8 * BPS, 8 + 8 * BPS, 12 + 8 * BPS,
25 0 + 12 * BPS, 4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS
26};
27
28static int CheckMode(int mb_x, int mb_y, int mode) {
29 if (mode == B_DC_PRED) {
30 if (mb_x == 0) {
31 return (mb_y == 0) ? B_DC_PRED_NOTOPLEFT : B_DC_PRED_NOLEFT;
32 } else {
33 return (mb_y == 0) ? B_DC_PRED_NOTOP : B_DC_PRED;
34 }
35 }
36 return mode;
37}
38
39static void Copy32b(uint8_t* const dst, const uint8_t* const src) {
40 memcpy(dst, src, 4);
41}
42
43static WEBP_INLINE void DoTransform(uint32_t bits, const int16_t* const src,
44 uint8_t* const dst) {
45 switch (bits >> 30) {
46 case 3:
47 VP8Transform(src, dst, 0);
48 break;
49 case 2:
50 VP8TransformAC3(src, dst);
51 break;
52 case 1:
53 VP8TransformDC(src, dst);
54 break;
55 default:
56 break;
57 }
58}
59
60static void DoUVTransform(uint32_t bits, const int16_t* const src,
61 uint8_t* const dst) {
62 if (bits & 0xff) { // any non-zero coeff at all?
63 if (bits & 0xaa) { // any non-zero AC coefficient?
64 VP8TransformUV(src, dst); // note we don't use the AC3 variant for U/V
65 } else {
66 VP8TransformDCUV(src, dst);
67 }
68 }
69}
70
71static void ReconstructRow(const VP8Decoder* const dec,
72 const VP8ThreadContext* ctx) {
73 int j;
74 int mb_x;
75 const int mb_y = ctx->mb_y_;
76 const int cache_id = ctx->id_;
77 uint8_t* const y_dst = dec->yuv_b_ + Y_OFF;
78 uint8_t* const u_dst = dec->yuv_b_ + U_OFF;
79 uint8_t* const v_dst = dec->yuv_b_ + V_OFF;
80
81 // Initialize left-most block.
82 for (j = 0; j < 16; ++j) {
83 y_dst[j * BPS - 1] = 129;
84 }
85 for (j = 0; j < 8; ++j) {
86 u_dst[j * BPS - 1] = 129;
87 v_dst[j * BPS - 1] = 129;
88 }
89
90 // Init top-left sample on left column too.
91 if (mb_y > 0) {
92 y_dst[-1 - BPS] = u_dst[-1 - BPS] = v_dst[-1 - BPS] = 129;
93 } else {
94 // we only need to do this init once at block (0,0).
95 // Afterward, it remains valid for the whole topmost row.
96 memset(y_dst - BPS - 1, 127, 16 + 4 + 1);
97 memset(u_dst - BPS - 1, 127, 8 + 1);
98 memset(v_dst - BPS - 1, 127, 8 + 1);
99 }
100
101 // Reconstruct one row.
102 for (mb_x = 0; mb_x < dec->mb_w_; ++mb_x) {
103 const VP8MBData* const block = ctx->mb_data_ + mb_x;
104
105 // Rotate in the left samples from previously decoded block. We move four
106 // pixels at a time for alignment reason, and because of in-loop filter.
107 if (mb_x > 0) {
108 for (j = -1; j < 16; ++j) {
109 Copy32b(&y_dst[j * BPS - 4], &y_dst[j * BPS + 12]);
110 }
111 for (j = -1; j < 8; ++j) {
112 Copy32b(&u_dst[j * BPS - 4], &u_dst[j * BPS + 4]);
113 Copy32b(&v_dst[j * BPS - 4], &v_dst[j * BPS + 4]);
114 }
115 }
116 {
117 // bring top samples into the cache
118 VP8TopSamples* const top_yuv = dec->yuv_t_ + mb_x;
119 const int16_t* const coeffs = block->coeffs_;
120 uint32_t bits = block->non_zero_y_;
121 int n;
122
123 if (mb_y > 0) {
124 memcpy(y_dst - BPS, top_yuv[0].y, 16);
125 memcpy(u_dst - BPS, top_yuv[0].u, 8);
126 memcpy(v_dst - BPS, top_yuv[0].v, 8);
127 }
128
129 // predict and add residuals
130 if (block->is_i4x4_) { // 4x4
131 uint32_t* const top_right = (uint32_t*)(y_dst - BPS + 16);
132
133 if (mb_y > 0) {
134 if (mb_x >= dec->mb_w_ - 1) { // on rightmost border
135 memset(top_right, top_yuv[0].y[15], sizeof(*top_right));
136 } else {
137 memcpy(top_right, top_yuv[1].y, sizeof(*top_right));
138 }
139 }
140 // replicate the top-right pixels below
141 top_right[BPS] = top_right[2 * BPS] = top_right[3 * BPS] = top_right[0];
142
143 // predict and add residuals for all 4x4 blocks in turn.
144 for (n = 0; n < 16; ++n, bits <<= 2) {
145 uint8_t* const dst = y_dst + kScan[n];
146 VP8PredLuma4[block->imodes_[n]](dst);
147 DoTransform(bits, coeffs + n * 16, dst);
148 }
149 } else { // 16x16
150 const int pred_func = CheckMode(mb_x, mb_y, block->imodes_[0]);
151 VP8PredLuma16[pred_func](y_dst);
152 if (bits != 0) {
153 for (n = 0; n < 16; ++n, bits <<= 2) {
154 DoTransform(bits, coeffs + n * 16, y_dst + kScan[n]);
155 }
156 }
157 }
158 {
159 // Chroma
160 const uint32_t bits_uv = block->non_zero_uv_;
161 const int pred_func = CheckMode(mb_x, mb_y, block->uvmode_);
162 VP8PredChroma8[pred_func](u_dst);
163 VP8PredChroma8[pred_func](v_dst);
164 DoUVTransform(bits_uv >> 0, coeffs + 16 * 16, u_dst);
165 DoUVTransform(bits_uv >> 8, coeffs + 20 * 16, v_dst);
166 }
167
168 // stash away top samples for next block
169 if (mb_y < dec->mb_h_ - 1) {
170 memcpy(top_yuv[0].y, y_dst + 15 * BPS, 16);
171 memcpy(top_yuv[0].u, u_dst + 7 * BPS, 8);
172 memcpy(top_yuv[0].v, v_dst + 7 * BPS, 8);
173 }
174 }
175 // Transfer reconstructed samples from yuv_b_ cache to final destination.
176 {
177 const int y_offset = cache_id * 16 * dec->cache_y_stride_;
178 const int uv_offset = cache_id * 8 * dec->cache_uv_stride_;
179 uint8_t* const y_out = dec->cache_y_ + mb_x * 16 + y_offset;
180 uint8_t* const u_out = dec->cache_u_ + mb_x * 8 + uv_offset;
181 uint8_t* const v_out = dec->cache_v_ + mb_x * 8 + uv_offset;
182 for (j = 0; j < 16; ++j) {
183 memcpy(y_out + j * dec->cache_y_stride_, y_dst + j * BPS, 16);
184 }
185 for (j = 0; j < 8; ++j) {
186 memcpy(u_out + j * dec->cache_uv_stride_, u_dst + j * BPS, 8);
187 memcpy(v_out + j * dec->cache_uv_stride_, v_dst + j * BPS, 8);
188 }
189 }
190 }
191}
192
193//------------------------------------------------------------------------------
194// Filtering
195
196// kFilterExtraRows[] = How many extra lines are needed on the MB boundary
197// for caching, given a filtering level.
198// Simple filter: up to 2 luma samples are read and 1 is written.
199// Complex filter: up to 4 luma samples are read and 3 are written. Same for
200// U/V, so it's 8 samples total (because of the 2x upsampling).
201static const uint8_t kFilterExtraRows[3] = { 0, 2, 8 };
202
203static void DoFilter(const VP8Decoder* const dec, int mb_x, int mb_y) {
204 const VP8ThreadContext* const ctx = &dec->thread_ctx_;
205 const int cache_id = ctx->id_;
206 const int y_bps = dec->cache_y_stride_;
207 const VP8FInfo* const f_info = ctx->f_info_ + mb_x;
208 uint8_t* const y_dst = dec->cache_y_ + cache_id * 16 * y_bps + mb_x * 16;
209 const int ilevel = f_info->f_ilevel_;
210 const int limit = f_info->f_limit_;
211 if (limit == 0) {
212 return;
213 }
214 assert(limit >= 3);
215 if (dec->filter_type_ == 1) { // simple
216 if (mb_x > 0) {
217 VP8SimpleHFilter16(y_dst, y_bps, limit + 4);
218 }
219 if (f_info->f_inner_) {
220 VP8SimpleHFilter16i(y_dst, y_bps, limit);
221 }
222 if (mb_y > 0) {
223 VP8SimpleVFilter16(y_dst, y_bps, limit + 4);
224 }
225 if (f_info->f_inner_) {
226 VP8SimpleVFilter16i(y_dst, y_bps, limit);
227 }
228 } else { // complex
229 const int uv_bps = dec->cache_uv_stride_;
230 uint8_t* const u_dst = dec->cache_u_ + cache_id * 8 * uv_bps + mb_x * 8;
231 uint8_t* const v_dst = dec->cache_v_ + cache_id * 8 * uv_bps + mb_x * 8;
232 const int hev_thresh = f_info->hev_thresh_;
233 if (mb_x > 0) {
234 VP8HFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh);
235 VP8HFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh);
236 }
237 if (f_info->f_inner_) {
238 VP8HFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh);
239 VP8HFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh);
240 }
241 if (mb_y > 0) {
242 VP8VFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh);
243 VP8VFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh);
244 }
245 if (f_info->f_inner_) {
246 VP8VFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh);
247 VP8VFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh);
248 }
249 }
250}
251
252// Filter the decoded macroblock row (if needed)
253static void FilterRow(const VP8Decoder* const dec) {
254 int mb_x;
255 const int mb_y = dec->thread_ctx_.mb_y_;
256 assert(dec->thread_ctx_.filter_row_);
257 for (mb_x = dec->tl_mb_x_; mb_x < dec->br_mb_x_; ++mb_x) {
258 DoFilter(dec, mb_x, mb_y);
259 }
260}
261
262//------------------------------------------------------------------------------
263// Precompute the filtering strength for each segment and each i4x4/i16x16 mode.
264
265static void PrecomputeFilterStrengths(VP8Decoder* const dec) {
266 if (dec->filter_type_ > 0) {
267 int s;
268 const VP8FilterHeader* const hdr = &dec->filter_hdr_;
269 for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
270 int i4x4;
271 // First, compute the initial level
272 int base_level;
273 if (dec->segment_hdr_.use_segment_) {
274 base_level = dec->segment_hdr_.filter_strength_[s];
275 if (!dec->segment_hdr_.absolute_delta_) {
276 base_level += hdr->level_;
277 }
278 } else {
279 base_level = hdr->level_;
280 }
281 for (i4x4 = 0; i4x4 <= 1; ++i4x4) {
282 VP8FInfo* const info = &dec->fstrengths_[s][i4x4];
283 int level = base_level;
284 if (hdr->use_lf_delta_) {
285 level += hdr->ref_lf_delta_[0];
286 if (i4x4) {
287 level += hdr->mode_lf_delta_[0];
288 }
289 }
290 level = (level < 0) ? 0 : (level > 63) ? 63 : level;
291 if (level > 0) {
292 int ilevel = level;
293 if (hdr->sharpness_ > 0) {
294 if (hdr->sharpness_ > 4) {
295 ilevel >>= 2;
296 } else {
297 ilevel >>= 1;
298 }
299 if (ilevel > 9 - hdr->sharpness_) {
300 ilevel = 9 - hdr->sharpness_;
301 }
302 }
303 if (ilevel < 1) ilevel = 1;
304 info->f_ilevel_ = ilevel;
305 info->f_limit_ = 2 * level + ilevel;
306 info->hev_thresh_ = (level >= 40) ? 2 : (level >= 15) ? 1 : 0;
307 } else {
308 info->f_limit_ = 0; // no filtering
309 }
310 info->f_inner_ = i4x4;
311 }
312 }
313 }
314}
315
316//------------------------------------------------------------------------------
317// Dithering
318
319// minimal amp that will provide a non-zero dithering effect
320#define MIN_DITHER_AMP 4
321
322#define DITHER_AMP_TAB_SIZE 12
323static const uint8_t kQuantToDitherAmp[DITHER_AMP_TAB_SIZE] = {
324 // roughly, it's dqm->uv_mat_[1]
325 8, 7, 6, 4, 4, 2, 2, 2, 1, 1, 1, 1
326};
327
328void VP8InitDithering(const WebPDecoderOptions* const options,
329 VP8Decoder* const dec) {
330 assert(dec != NULL);
331 if (options != NULL) {
332 const int d = options->dithering_strength;
333 const int max_amp = (1 << VP8_RANDOM_DITHER_FIX) - 1;
334 const int f = (d < 0) ? 0 : (d > 100) ? max_amp : (d * max_amp / 100);
335 if (f > 0) {
336 int s;
337 int all_amp = 0;
338 for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
339 VP8QuantMatrix* const dqm = &dec->dqm_[s];
340 if (dqm->uv_quant_ < DITHER_AMP_TAB_SIZE) {
341 const int idx = (dqm->uv_quant_ < 0) ? 0 : dqm->uv_quant_;
342 dqm->dither_ = (f * kQuantToDitherAmp[idx]) >> 3;
343 }
344 all_amp |= dqm->dither_;
345 }
346 if (all_amp != 0) {
347 VP8InitRandom(&dec->dithering_rg_, 1.0f);
348 dec->dither_ = 1;
349 }
350 }
351 // potentially allow alpha dithering
352 dec->alpha_dithering_ = options->alpha_dithering_strength;
353 if (dec->alpha_dithering_ > 100) {
354 dec->alpha_dithering_ = 100;
355 } else if (dec->alpha_dithering_ < 0) {
356 dec->alpha_dithering_ = 0;
357 }
358 }
359}
360
361// Convert to range: [-2,2] for dither=50, [-4,4] for dither=100
362static void Dither8x8(VP8Random* const rg, uint8_t* dst, int bps, int amp) {
363 uint8_t dither[64];
364 int i;
365 for (i = 0; i < 8 * 8; ++i) {
366 dither[i] = VP8RandomBits2(rg, VP8_DITHER_AMP_BITS + 1, amp);
367 }
368 VP8DitherCombine8x8(dither, dst, bps);
369}
370
371static void DitherRow(VP8Decoder* const dec) {
372 int mb_x;
373 assert(dec->dither_);
374 for (mb_x = dec->tl_mb_x_; mb_x < dec->br_mb_x_; ++mb_x) {
375 const VP8ThreadContext* const ctx = &dec->thread_ctx_;
376 const VP8MBData* const data = ctx->mb_data_ + mb_x;
377 const int cache_id = ctx->id_;
378 const int uv_bps = dec->cache_uv_stride_;
379 if (data->dither_ >= MIN_DITHER_AMP) {
380 uint8_t* const u_dst = dec->cache_u_ + cache_id * 8 * uv_bps + mb_x * 8;
381 uint8_t* const v_dst = dec->cache_v_ + cache_id * 8 * uv_bps + mb_x * 8;
382 Dither8x8(&dec->dithering_rg_, u_dst, uv_bps, data->dither_);
383 Dither8x8(&dec->dithering_rg_, v_dst, uv_bps, data->dither_);
384 }
385 }
386}
387
388//------------------------------------------------------------------------------
389// This function is called after a row of macroblocks is finished decoding.
390// It also takes into account the following restrictions:
391// * In case of in-loop filtering, we must hold off sending some of the bottom
392// pixels as they are yet unfiltered. They will be when the next macroblock
393// row is decoded. Meanwhile, we must preserve them by rotating them in the
394// cache area. This doesn't hold for the very bottom row of the uncropped
395// picture of course.
396// * we must clip the remaining pixels against the cropping area. The VP8Io
397// struct must have the following fields set correctly before calling put():
398
399#define MACROBLOCK_VPOS(mb_y) ((mb_y) * 16) // vertical position of a MB
400
401// Finalize and transmit a complete row. Return false in case of user-abort.
402static int FinishRow(void* arg1, void* arg2) {
403 VP8Decoder* const dec = (VP8Decoder*)arg1;
404 VP8Io* const io = (VP8Io*)arg2;
405 int ok = 1;
406 const VP8ThreadContext* const ctx = &dec->thread_ctx_;
407 const int cache_id = ctx->id_;
408 const int extra_y_rows = kFilterExtraRows[dec->filter_type_];
409 const int ysize = extra_y_rows * dec->cache_y_stride_;
410 const int uvsize = (extra_y_rows / 2) * dec->cache_uv_stride_;
411 const int y_offset = cache_id * 16 * dec->cache_y_stride_;
412 const int uv_offset = cache_id * 8 * dec->cache_uv_stride_;
413 uint8_t* const ydst = dec->cache_y_ - ysize + y_offset;
414 uint8_t* const udst = dec->cache_u_ - uvsize + uv_offset;
415 uint8_t* const vdst = dec->cache_v_ - uvsize + uv_offset;
416 const int mb_y = ctx->mb_y_;
417 const int is_first_row = (mb_y == 0);
418 const int is_last_row = (mb_y >= dec->br_mb_y_ - 1);
419
420 if (dec->mt_method_ == 2) {
421 ReconstructRow(dec, ctx);
422 }
423
424 if (ctx->filter_row_) {
425 FilterRow(dec);
426 }
427
428 if (dec->dither_) {
429 DitherRow(dec);
430 }
431
432 if (io->put != NULL) {
433 int y_start = MACROBLOCK_VPOS(mb_y);
434 int y_end = MACROBLOCK_VPOS(mb_y + 1);
435 if (!is_first_row) {
436 y_start -= extra_y_rows;
437 io->y = ydst;
438 io->u = udst;
439 io->v = vdst;
440 } else {
441 io->y = dec->cache_y_ + y_offset;
442 io->u = dec->cache_u_ + uv_offset;
443 io->v = dec->cache_v_ + uv_offset;
444 }
445
446 if (!is_last_row) {
447 y_end -= extra_y_rows;
448 }
449 if (y_end > io->crop_bottom) {
450 y_end = io->crop_bottom; // make sure we don't overflow on last row.
451 }
452 // If dec->alpha_data_ is not NULL, we have some alpha plane present.
453 io->a = NULL;
454 if (dec->alpha_data_ != NULL && y_start < y_end) {
455 io->a = VP8DecompressAlphaRows(dec, io, y_start, y_end - y_start);
456 if (io->a == NULL) {
457 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
458 "Could not decode alpha data.");
459 }
460 }
461 if (y_start < io->crop_top) {
462 const int delta_y = io->crop_top - y_start;
463 y_start = io->crop_top;
464 assert(!(delta_y & 1));
465 io->y += dec->cache_y_stride_ * delta_y;
466 io->u += dec->cache_uv_stride_ * (delta_y >> 1);
467 io->v += dec->cache_uv_stride_ * (delta_y >> 1);
468 if (io->a != NULL) {
469 io->a += io->width * delta_y;
470 }
471 }
472 if (y_start < y_end) {
473 io->y += io->crop_left;
474 io->u += io->crop_left >> 1;
475 io->v += io->crop_left >> 1;
476 if (io->a != NULL) {
477 io->a += io->crop_left;
478 }
479 io->mb_y = y_start - io->crop_top;
480 io->mb_w = io->crop_right - io->crop_left;
481 io->mb_h = y_end - y_start;
482 ok = io->put(io);
483 }
484 }
485 // rotate top samples if needed
486 if (cache_id + 1 == dec->num_caches_) {
487 if (!is_last_row) {
488 memcpy(dec->cache_y_ - ysize, ydst + 16 * dec->cache_y_stride_, ysize);
489 memcpy(dec->cache_u_ - uvsize, udst + 8 * dec->cache_uv_stride_, uvsize);
490 memcpy(dec->cache_v_ - uvsize, vdst + 8 * dec->cache_uv_stride_, uvsize);
491 }
492 }
493
494 return ok;
495}
496
497#undef MACROBLOCK_VPOS
498
499//------------------------------------------------------------------------------
500
501int VP8ProcessRow(VP8Decoder* const dec, VP8Io* const io) {
502 int ok = 1;
503 VP8ThreadContext* const ctx = &dec->thread_ctx_;
504 const int filter_row =
505 (dec->filter_type_ > 0) &&
506 (dec->mb_y_ >= dec->tl_mb_y_) && (dec->mb_y_ <= dec->br_mb_y_);
507 if (dec->mt_method_ == 0) {
508 // ctx->id_ and ctx->f_info_ are already set
509 ctx->mb_y_ = dec->mb_y_;
510 ctx->filter_row_ = filter_row;
511 ReconstructRow(dec, ctx);
512 ok = FinishRow(dec, io);
513 } else {
514 WebPWorker* const worker = &dec->worker_;
515 // Finish previous job *before* updating context
516 ok &= WebPGetWorkerInterface()->Sync(worker);
517 assert(worker->status_ == OK);
518 if (ok) { // spawn a new deblocking/output job
519 ctx->io_ = *io;
520 ctx->id_ = dec->cache_id_;
521 ctx->mb_y_ = dec->mb_y_;
522 ctx->filter_row_ = filter_row;
523 if (dec->mt_method_ == 2) { // swap macroblock data
524 VP8MBData* const tmp = ctx->mb_data_;
525 ctx->mb_data_ = dec->mb_data_;
526 dec->mb_data_ = tmp;
527 } else {
528 // perform reconstruction directly in main thread
529 ReconstructRow(dec, ctx);
530 }
531 if (filter_row) { // swap filter info
532 VP8FInfo* const tmp = ctx->f_info_;
533 ctx->f_info_ = dec->f_info_;
534 dec->f_info_ = tmp;
535 }
536 // (reconstruct)+filter in parallel
537 WebPGetWorkerInterface()->Launch(worker);
538 if (++dec->cache_id_ == dec->num_caches_) {
539 dec->cache_id_ = 0;
540 }
541 }
542 }
543 return ok;
544}
545
546//------------------------------------------------------------------------------
547// Finish setting up the decoding parameter once user's setup() is called.
548
549VP8StatusCode VP8EnterCritical(VP8Decoder* const dec, VP8Io* const io) {
550 // Call setup() first. This may trigger additional decoding features on 'io'.
551 // Note: Afterward, we must call teardown() no matter what.
552 if (io->setup != NULL && !io->setup(io)) {
553 VP8SetError(dec, VP8_STATUS_USER_ABORT, "Frame setup failed");
554 return dec->status_;
555 }
556
557 // Disable filtering per user request
558 if (io->bypass_filtering) {
559 dec->filter_type_ = 0;
560 }
561
562 // Define the area where we can skip in-loop filtering, in case of cropping.
563 //
564 // 'Simple' filter reads two luma samples outside of the macroblock
565 // and filters one. It doesn't filter the chroma samples. Hence, we can
566 // avoid doing the in-loop filtering before crop_top/crop_left position.
567 // For the 'Complex' filter, 3 samples are read and up to 3 are filtered.
568 // Means: there's a dependency chain that goes all the way up to the
569 // top-left corner of the picture (MB #0). We must filter all the previous
570 // macroblocks.
571 {
572 const int extra_pixels = kFilterExtraRows[dec->filter_type_];
573 if (dec->filter_type_ == 2) {
574 // For complex filter, we need to preserve the dependency chain.
575 dec->tl_mb_x_ = 0;
576 dec->tl_mb_y_ = 0;
577 } else {
578 // For simple filter, we can filter only the cropped region.
579 // We include 'extra_pixels' on the other side of the boundary, since
580 // vertical or horizontal filtering of the previous macroblock can
581 // modify some abutting pixels.
582 dec->tl_mb_x_ = (io->crop_left - extra_pixels) >> 4;
583 dec->tl_mb_y_ = (io->crop_top - extra_pixels) >> 4;
584 if (dec->tl_mb_x_ < 0) dec->tl_mb_x_ = 0;
585 if (dec->tl_mb_y_ < 0) dec->tl_mb_y_ = 0;
586 }
587 // We need some 'extra' pixels on the right/bottom.
588 dec->br_mb_y_ = (io->crop_bottom + 15 + extra_pixels) >> 4;
589 dec->br_mb_x_ = (io->crop_right + 15 + extra_pixels) >> 4;
590 if (dec->br_mb_x_ > dec->mb_w_) {
591 dec->br_mb_x_ = dec->mb_w_;
592 }
593 if (dec->br_mb_y_ > dec->mb_h_) {
594 dec->br_mb_y_ = dec->mb_h_;
595 }
596 }
597 PrecomputeFilterStrengths(dec);
598 return VP8_STATUS_OK;
599}
600
601int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io) {
602 int ok = 1;
603 if (dec->mt_method_ > 0) {
604 ok = WebPGetWorkerInterface()->Sync(&dec->worker_);
605 }
606
607 if (io->teardown != NULL) {
608 io->teardown(io);
609 }
610 return ok;
611}
612
613//------------------------------------------------------------------------------
614// For multi-threaded decoding we need to use 3 rows of 16 pixels as delay line.
615//
616// Reason is: the deblocking filter cannot deblock the bottom horizontal edges
617// immediately, and needs to wait for first few rows of the next macroblock to
618// be decoded. Hence, deblocking is lagging behind by 4 or 8 pixels (depending
619// on strength).
620// With two threads, the vertical positions of the rows being decoded are:
621// Decode: [ 0..15][16..31][32..47][48..63][64..79][...
622// Deblock: [ 0..11][12..27][28..43][44..59][...
623// If we use two threads and two caches of 16 pixels, the sequence would be:
624// Decode: [ 0..15][16..31][ 0..15!!][16..31][ 0..15][...
625// Deblock: [ 0..11][12..27!!][-4..11][12..27][...
626// The problem occurs during row [12..15!!] that both the decoding and
627// deblocking threads are writing simultaneously.
628// With 3 cache lines, one get a safe write pattern:
629// Decode: [ 0..15][16..31][32..47][ 0..15][16..31][32..47][0..
630// Deblock: [ 0..11][12..27][28..43][-4..11][12..27][28...
631// Note that multi-threaded output _without_ deblocking can make use of two
632// cache lines of 16 pixels only, since there's no lagging behind. The decoding
633// and output process have non-concurrent writing:
634// Decode: [ 0..15][16..31][ 0..15][16..31][...
635// io->put: [ 0..15][16..31][ 0..15][...
636
637#define MT_CACHE_LINES 3
638#define ST_CACHE_LINES 1 // 1 cache row only for single-threaded case
639
640// Initialize multi/single-thread worker
641static int InitThreadContext(VP8Decoder* const dec) {
642 dec->cache_id_ = 0;
643 if (dec->mt_method_ > 0) {
644 WebPWorker* const worker = &dec->worker_;
645 if (!WebPGetWorkerInterface()->Reset(worker)) {
646 return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY,
647 "thread initialization failed.");
648 }
649 worker->data1 = dec;
650 worker->data2 = (void*)&dec->thread_ctx_.io_;
651 worker->hook = FinishRow;
652 dec->num_caches_ =
653 (dec->filter_type_ > 0) ? MT_CACHE_LINES : MT_CACHE_LINES - 1;
654 } else {
655 dec->num_caches_ = ST_CACHE_LINES;
656 }
657 return 1;
658}
659
660int VP8GetThreadMethod(const WebPDecoderOptions* const options,
661 const WebPHeaderStructure* const headers,
662 int width, int height) {
663 if (options == NULL || options->use_threads == 0) {
664 return 0;
665 }
666 (void)headers;
667 (void)width;
668 (void)height;
669 assert(headers == NULL || !headers->is_lossless);
670#if defined(WEBP_USE_THREAD)
671 if (width >= MIN_WIDTH_FOR_THREADS) return 2;
672#endif
673 return 0;
674}
675
676#undef MT_CACHE_LINES
677#undef ST_CACHE_LINES
678
679//------------------------------------------------------------------------------
680// Memory setup
681
682static int AllocateMemory(VP8Decoder* const dec) {
683 const int num_caches = dec->num_caches_;
684 const int mb_w = dec->mb_w_;
685 // Note: we use 'size_t' when there's no overflow risk, uint64_t otherwise.
686 const size_t intra_pred_mode_size = 4 * mb_w * sizeof(uint8_t);
687 const size_t top_size = sizeof(VP8TopSamples) * mb_w;
688 const size_t mb_info_size = (mb_w + 1) * sizeof(VP8MB);
689 const size_t f_info_size =
690 (dec->filter_type_ > 0) ?
691 mb_w * (dec->mt_method_ > 0 ? 2 : 1) * sizeof(VP8FInfo)
692 : 0;
693 const size_t yuv_size = YUV_SIZE * sizeof(*dec->yuv_b_);
694 const size_t mb_data_size =
695 (dec->mt_method_ == 2 ? 2 : 1) * mb_w * sizeof(*dec->mb_data_);
696 const size_t cache_height = (16 * num_caches
697 + kFilterExtraRows[dec->filter_type_]) * 3 / 2;
698 const size_t cache_size = top_size * cache_height;
699 // alpha_size is the only one that scales as width x height.
700 const uint64_t alpha_size = (dec->alpha_data_ != NULL) ?
701 (uint64_t)dec->pic_hdr_.width_ * dec->pic_hdr_.height_ : 0ULL;
702 const uint64_t needed = (uint64_t)intra_pred_mode_size
703 + top_size + mb_info_size + f_info_size
704 + yuv_size + mb_data_size
705 + cache_size + alpha_size + WEBP_ALIGN_CST;
706 uint8_t* mem;
707
708 if (!CheckSizeOverflow(needed)) return 0; // check for overflow
709 if (needed > dec->mem_size_) {
710 WebPSafeFree(dec->mem_);
711 dec->mem_size_ = 0;
712 dec->mem_ = WebPSafeMalloc(needed, sizeof(uint8_t));
713 if (dec->mem_ == NULL) {
714 return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY,
715 "no memory during frame initialization.");
716 }
717 // down-cast is ok, thanks to WebPSafeMalloc() above.
718 dec->mem_size_ = (size_t)needed;
719 }
720
721 mem = (uint8_t*)dec->mem_;
722 dec->intra_t_ = mem;
723 mem += intra_pred_mode_size;
724
725 dec->yuv_t_ = (VP8TopSamples*)mem;
726 mem += top_size;
727
728 dec->mb_info_ = ((VP8MB*)mem) + 1;
729 mem += mb_info_size;
730
731 dec->f_info_ = f_info_size ? (VP8FInfo*)mem : NULL;
732 mem += f_info_size;
733 dec->thread_ctx_.id_ = 0;
734 dec->thread_ctx_.f_info_ = dec->f_info_;
735 if (dec->filter_type_ > 0 && dec->mt_method_ > 0) {
736 // secondary cache line. The deblocking process need to make use of the
737 // filtering strength from previous macroblock row, while the new ones
738 // are being decoded in parallel. We'll just swap the pointers.
739 dec->thread_ctx_.f_info_ += mb_w;
740 }
741
742 mem = (uint8_t*)WEBP_ALIGN(mem);
743 assert((yuv_size & WEBP_ALIGN_CST) == 0);
744 dec->yuv_b_ = mem;
745 mem += yuv_size;
746
747 dec->mb_data_ = (VP8MBData*)mem;
748 dec->thread_ctx_.mb_data_ = (VP8MBData*)mem;
749 if (dec->mt_method_ == 2) {
750 dec->thread_ctx_.mb_data_ += mb_w;
751 }
752 mem += mb_data_size;
753
754 dec->cache_y_stride_ = 16 * mb_w;
755 dec->cache_uv_stride_ = 8 * mb_w;
756 {
757 const int extra_rows = kFilterExtraRows[dec->filter_type_];
758 const int extra_y = extra_rows * dec->cache_y_stride_;
759 const int extra_uv = (extra_rows / 2) * dec->cache_uv_stride_;
760 dec->cache_y_ = mem + extra_y;
761 dec->cache_u_ = dec->cache_y_
762 + 16 * num_caches * dec->cache_y_stride_ + extra_uv;
763 dec->cache_v_ = dec->cache_u_
764 + 8 * num_caches * dec->cache_uv_stride_ + extra_uv;
765 dec->cache_id_ = 0;
766 }
767 mem += cache_size;
768
769 // alpha plane
770 dec->alpha_plane_ = alpha_size ? mem : NULL;
771 mem += alpha_size;
772 assert(mem <= (uint8_t*)dec->mem_ + dec->mem_size_);
773
774 // note: left/top-info is initialized once for all.
775 memset(dec->mb_info_ - 1, 0, mb_info_size);
776 VP8InitScanline(dec); // initialize left too.
777
778 // initialize top
779 memset(dec->intra_t_, B_DC_PRED, intra_pred_mode_size);
780
781 return 1;
782}
783
784static void InitIo(VP8Decoder* const dec, VP8Io* io) {
785 // prepare 'io'
786 io->mb_y = 0;
787 io->y = dec->cache_y_;
788 io->u = dec->cache_u_;
789 io->v = dec->cache_v_;
790 io->y_stride = dec->cache_y_stride_;
791 io->uv_stride = dec->cache_uv_stride_;
792 io->a = NULL;
793}
794
795int VP8InitFrame(VP8Decoder* const dec, VP8Io* const io) {
796 if (!InitThreadContext(dec)) return 0; // call first. Sets dec->num_caches_.
797 if (!AllocateMemory(dec)) return 0;
798 InitIo(dec, io);
799 VP8DspInit(); // Init critical function pointers and look-up tables.
800 return 1;
801}
802
803//------------------------------------------------------------------------------
804