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 "./vp8i_dec.h"
16#include "../utils/utils.h"
17
18//------------------------------------------------------------------------------
19// Main reconstruction function.
20
21static const int 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 int 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 // TODO(skal): should we specially dither more for uv_quant_ < 0?
342 const int idx = (dqm->uv_quant_ < 0) ? 0 : dqm->uv_quant_;
343 dqm->dither_ = (f * kQuantToDitherAmp[idx]) >> 3;
344 }
345 all_amp |= dqm->dither_;
346 }
347 if (all_amp != 0) {
348 VP8InitRandom(&dec->dithering_rg_, 1.0f);
349 dec->dither_ = 1;
350 }
351 }
352 // potentially allow alpha dithering
353 dec->alpha_dithering_ = options->alpha_dithering_strength;
354 if (dec->alpha_dithering_ > 100) {
355 dec->alpha_dithering_ = 100;
356 } else if (dec->alpha_dithering_ < 0) {
357 dec->alpha_dithering_ = 0;
358 }
359 }
360}
361
362// Convert to range: [-2,2] for dither=50, [-4,4] for dither=100
363static void Dither8x8(VP8Random* const rg, uint8_t* dst, int bps, int amp) {
364 uint8_t dither[64];
365 int i;
366 for (i = 0; i < 8 * 8; ++i) {
367 dither[i] = VP8RandomBits2(rg, VP8_DITHER_AMP_BITS + 1, amp);
368 }
369 VP8DitherCombine8x8(dither, dst, bps);
370}
371
372static void DitherRow(VP8Decoder* const dec) {
373 int mb_x;
374 assert(dec->dither_);
375 for (mb_x = dec->tl_mb_x_; mb_x < dec->br_mb_x_; ++mb_x) {
376 const VP8ThreadContext* const ctx = &dec->thread_ctx_;
377 const VP8MBData* const data = ctx->mb_data_ + mb_x;
378 const int cache_id = ctx->id_;
379 const int uv_bps = dec->cache_uv_stride_;
380 if (data->dither_ >= MIN_DITHER_AMP) {
381 uint8_t* const u_dst = dec->cache_u_ + cache_id * 8 * uv_bps + mb_x * 8;
382 uint8_t* const v_dst = dec->cache_v_ + cache_id * 8 * uv_bps + mb_x * 8;
383 Dither8x8(&dec->dithering_rg_, u_dst, uv_bps, data->dither_);
384 Dither8x8(&dec->dithering_rg_, v_dst, uv_bps, data->dither_);
385 }
386 }
387}
388
389//------------------------------------------------------------------------------
390// This function is called after a row of macroblocks is finished decoding.
391// It also takes into account the following restrictions:
392// * In case of in-loop filtering, we must hold off sending some of the bottom
393// pixels as they are yet unfiltered. They will be when the next macroblock
394// row is decoded. Meanwhile, we must preserve them by rotating them in the
395// cache area. This doesn't hold for the very bottom row of the uncropped
396// picture of course.
397// * we must clip the remaining pixels against the cropping area. The VP8Io
398// struct must have the following fields set correctly before calling put():
399
400#define MACROBLOCK_VPOS(mb_y) ((mb_y) * 16) // vertical position of a MB
401
402// Finalize and transmit a complete row. Return false in case of user-abort.
403static int FinishRow(VP8Decoder* const dec, VP8Io* const io) {
404 int ok = 1;
405 const VP8ThreadContext* const ctx = &dec->thread_ctx_;
406 const int cache_id = ctx->id_;
407 const int extra_y_rows = kFilterExtraRows[dec->filter_type_];
408 const int ysize = extra_y_rows * dec->cache_y_stride_;
409 const int uvsize = (extra_y_rows / 2) * dec->cache_uv_stride_;
410 const int y_offset = cache_id * 16 * dec->cache_y_stride_;
411 const int uv_offset = cache_id * 8 * dec->cache_uv_stride_;
412 uint8_t* const ydst = dec->cache_y_ - ysize + y_offset;
413 uint8_t* const udst = dec->cache_u_ - uvsize + uv_offset;
414 uint8_t* const vdst = dec->cache_v_ - uvsize + uv_offset;
415 const int mb_y = ctx->mb_y_;
416 const int is_first_row = (mb_y == 0);
417 const int is_last_row = (mb_y >= dec->br_mb_y_ - 1);
418
419 if (dec->mt_method_ == 2) {
420 ReconstructRow(dec, ctx);
421 }
422
423 if (ctx->filter_row_) {
424 FilterRow(dec);
425 }
426
427 if (dec->dither_) {
428 DitherRow(dec);
429 }
430
431 if (io->put != NULL) {
432 int y_start = MACROBLOCK_VPOS(mb_y);
433 int y_end = MACROBLOCK_VPOS(mb_y + 1);
434 if (!is_first_row) {
435 y_start -= extra_y_rows;
436 io->y = ydst;
437 io->u = udst;
438 io->v = vdst;
439 } else {
440 io->y = dec->cache_y_ + y_offset;
441 io->u = dec->cache_u_ + uv_offset;
442 io->v = dec->cache_v_ + uv_offset;
443 }
444
445 if (!is_last_row) {
446 y_end -= extra_y_rows;
447 }
448 if (y_end > io->crop_bottom) {
449 y_end = io->crop_bottom; // make sure we don't overflow on last row.
450 }
451 io->a = NULL;
452 if (dec->alpha_data_ != NULL && y_start < y_end) {
453 // TODO(skal): testing presence of alpha with dec->alpha_data_ is not a
454 // good idea.
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 // TODO(skal): filter type / strength / sharpness forcing
562
563 // Define the area where we can skip in-loop filtering, in case of cropping.
564 //
565 // 'Simple' filter reads two luma samples outside of the macroblock
566 // and filters one. It doesn't filter the chroma samples. Hence, we can
567 // avoid doing the in-loop filtering before crop_top/crop_left position.
568 // For the 'Complex' filter, 3 samples are read and up to 3 are filtered.
569 // Means: there's a dependency chain that goes all the way up to the
570 // top-left corner of the picture (MB #0). We must filter all the previous
571 // macroblocks.
572 // TODO(skal): add an 'approximate_decoding' option, that won't produce
573 // a 1:1 bit-exactness for complex filtering?
574 {
575 const int extra_pixels = kFilterExtraRows[dec->filter_type_];
576 if (dec->filter_type_ == 2) {
577 // For complex filter, we need to preserve the dependency chain.
578 dec->tl_mb_x_ = 0;
579 dec->tl_mb_y_ = 0;
580 } else {
581 // For simple filter, we can filter only the cropped region.
582 // We include 'extra_pixels' on the other side of the boundary, since
583 // vertical or horizontal filtering of the previous macroblock can
584 // modify some abutting pixels.
585 dec->tl_mb_x_ = (io->crop_left - extra_pixels) >> 4;
586 dec->tl_mb_y_ = (io->crop_top - extra_pixels) >> 4;
587 if (dec->tl_mb_x_ < 0) dec->tl_mb_x_ = 0;
588 if (dec->tl_mb_y_ < 0) dec->tl_mb_y_ = 0;
589 }
590 // We need some 'extra' pixels on the right/bottom.
591 dec->br_mb_y_ = (io->crop_bottom + 15 + extra_pixels) >> 4;
592 dec->br_mb_x_ = (io->crop_right + 15 + extra_pixels) >> 4;
593 if (dec->br_mb_x_ > dec->mb_w_) {
594 dec->br_mb_x_ = dec->mb_w_;
595 }
596 if (dec->br_mb_y_ > dec->mb_h_) {
597 dec->br_mb_y_ = dec->mb_h_;
598 }
599 }
600 PrecomputeFilterStrengths(dec);
601 return VP8_STATUS_OK;
602}
603
604int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io) {
605 int ok = 1;
606 if (dec->mt_method_ > 0) {
607 ok = WebPGetWorkerInterface()->Sync(&dec->worker_);
608 }
609
610 if (io->teardown != NULL) {
611 io->teardown(io);
612 }
613 return ok;
614}
615
616//------------------------------------------------------------------------------
617// For multi-threaded decoding we need to use 3 rows of 16 pixels as delay line.
618//
619// Reason is: the deblocking filter cannot deblock the bottom horizontal edges
620// immediately, and needs to wait for first few rows of the next macroblock to
621// be decoded. Hence, deblocking is lagging behind by 4 or 8 pixels (depending
622// on strength).
623// With two threads, the vertical positions of the rows being decoded are:
624// Decode: [ 0..15][16..31][32..47][48..63][64..79][...
625// Deblock: [ 0..11][12..27][28..43][44..59][...
626// If we use two threads and two caches of 16 pixels, the sequence would be:
627// Decode: [ 0..15][16..31][ 0..15!!][16..31][ 0..15][...
628// Deblock: [ 0..11][12..27!!][-4..11][12..27][...
629// The problem occurs during row [12..15!!] that both the decoding and
630// deblocking threads are writing simultaneously.
631// With 3 cache lines, one get a safe write pattern:
632// Decode: [ 0..15][16..31][32..47][ 0..15][16..31][32..47][0..
633// Deblock: [ 0..11][12..27][28..43][-4..11][12..27][28...
634// Note that multi-threaded output _without_ deblocking can make use of two
635// cache lines of 16 pixels only, since there's no lagging behind. The decoding
636// and output process have non-concurrent writing:
637// Decode: [ 0..15][16..31][ 0..15][16..31][...
638// io->put: [ 0..15][16..31][ 0..15][...
639
640#define MT_CACHE_LINES 3
641#define ST_CACHE_LINES 1 // 1 cache row only for single-threaded case
642
643// Initialize multi/single-thread worker
644static int InitThreadContext(VP8Decoder* const dec) {
645 dec->cache_id_ = 0;
646 if (dec->mt_method_ > 0) {
647 WebPWorker* const worker = &dec->worker_;
648 if (!WebPGetWorkerInterface()->Reset(worker)) {
649 return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY,
650 "thread initialization failed.");
651 }
652 worker->data1 = dec;
653 worker->data2 = (void*)&dec->thread_ctx_.io_;
654 worker->hook = (WebPWorkerHook)FinishRow;
655 dec->num_caches_ =
656 (dec->filter_type_ > 0) ? MT_CACHE_LINES : MT_CACHE_LINES - 1;
657 } else {
658 dec->num_caches_ = ST_CACHE_LINES;
659 }
660 return 1;
661}
662
663int VP8GetThreadMethod(const WebPDecoderOptions* const options,
664 const WebPHeaderStructure* const headers,
665 int width, int height) {
666 if (options == NULL || options->use_threads == 0) {
667 return 0;
668 }
669 (void)headers;
670 (void)width;
671 (void)height;
672 assert(headers == NULL || !headers->is_lossless);
673#if defined(WEBP_USE_THREAD)
674 if (width < MIN_WIDTH_FOR_THREADS) return 0;
675 // TODO(skal): tune the heuristic further
676#if 0
677 if (height < 2 * width) return 2;
678#endif
679 return 2;
680#else // !WEBP_USE_THREAD
681 return 0;
682#endif
683}
684
685#undef MT_CACHE_LINES
686#undef ST_CACHE_LINES
687
688//------------------------------------------------------------------------------
689// Memory setup
690
691static int AllocateMemory(VP8Decoder* const dec) {
692 const int num_caches = dec->num_caches_;
693 const int mb_w = dec->mb_w_;
694 // Note: we use 'size_t' when there's no overflow risk, uint64_t otherwise.
695 const size_t intra_pred_mode_size = 4 * mb_w * sizeof(uint8_t);
696 const size_t top_size = sizeof(VP8TopSamples) * mb_w;
697 const size_t mb_info_size = (mb_w + 1) * sizeof(VP8MB);
698 const size_t f_info_size =
699 (dec->filter_type_ > 0) ?
700 mb_w * (dec->mt_method_ > 0 ? 2 : 1) * sizeof(VP8FInfo)
701 : 0;
702 const size_t yuv_size = YUV_SIZE * sizeof(*dec->yuv_b_);
703 const size_t mb_data_size =
704 (dec->mt_method_ == 2 ? 2 : 1) * mb_w * sizeof(*dec->mb_data_);
705 const size_t cache_height = (16 * num_caches
706 + kFilterExtraRows[dec->filter_type_]) * 3 / 2;
707 const size_t cache_size = top_size * cache_height;
708 // alpha_size is the only one that scales as width x height.
709 const uint64_t alpha_size = (dec->alpha_data_ != NULL) ?
710 (uint64_t)dec->pic_hdr_.width_ * dec->pic_hdr_.height_ : 0ULL;
711 const uint64_t needed = (uint64_t)intra_pred_mode_size
712 + top_size + mb_info_size + f_info_size
713 + yuv_size + mb_data_size
714 + cache_size + alpha_size + WEBP_ALIGN_CST;
715 uint8_t* mem;
716
717 if (needed != (size_t)needed) return 0; // check for overflow
718 if (needed > dec->mem_size_) {
719 WebPSafeFree(dec->mem_);
720 dec->mem_size_ = 0;
721 dec->mem_ = WebPSafeMalloc(needed, sizeof(uint8_t));
722 if (dec->mem_ == NULL) {
723 return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY,
724 "no memory during frame initialization.");
725 }
726 // down-cast is ok, thanks to WebPSafeMalloc() above.
727 dec->mem_size_ = (size_t)needed;
728 }
729
730 mem = (uint8_t*)dec->mem_;
731 dec->intra_t_ = (uint8_t*)mem;
732 mem += intra_pred_mode_size;
733
734 dec->yuv_t_ = (VP8TopSamples*)mem;
735 mem += top_size;
736
737 dec->mb_info_ = ((VP8MB*)mem) + 1;
738 mem += mb_info_size;
739
740 dec->f_info_ = f_info_size ? (VP8FInfo*)mem : NULL;
741 mem += f_info_size;
742 dec->thread_ctx_.id_ = 0;
743 dec->thread_ctx_.f_info_ = dec->f_info_;
744 if (dec->mt_method_ > 0) {
745 // secondary cache line. The deblocking process need to make use of the
746 // filtering strength from previous macroblock row, while the new ones
747 // are being decoded in parallel. We'll just swap the pointers.
748 dec->thread_ctx_.f_info_ += mb_w;
749 }
750
751 mem = (uint8_t*)WEBP_ALIGN(mem);
752 assert((yuv_size & WEBP_ALIGN_CST) == 0);
753 dec->yuv_b_ = (uint8_t*)mem;
754 mem += yuv_size;
755
756 dec->mb_data_ = (VP8MBData*)mem;
757 dec->thread_ctx_.mb_data_ = (VP8MBData*)mem;
758 if (dec->mt_method_ == 2) {
759 dec->thread_ctx_.mb_data_ += mb_w;
760 }
761 mem += mb_data_size;
762
763 dec->cache_y_stride_ = 16 * mb_w;
764 dec->cache_uv_stride_ = 8 * mb_w;
765 {
766 const int extra_rows = kFilterExtraRows[dec->filter_type_];
767 const int extra_y = extra_rows * dec->cache_y_stride_;
768 const int extra_uv = (extra_rows / 2) * dec->cache_uv_stride_;
769 dec->cache_y_ = ((uint8_t*)mem) + extra_y;
770 dec->cache_u_ = dec->cache_y_
771 + 16 * num_caches * dec->cache_y_stride_ + extra_uv;
772 dec->cache_v_ = dec->cache_u_
773 + 8 * num_caches * dec->cache_uv_stride_ + extra_uv;
774 dec->cache_id_ = 0;
775 }
776 mem += cache_size;
777
778 // alpha plane
779 dec->alpha_plane_ = alpha_size ? (uint8_t*)mem : NULL;
780 mem += alpha_size;
781 assert(mem <= (uint8_t*)dec->mem_ + dec->mem_size_);
782
783 // note: left/top-info is initialized once for all.
784 memset(dec->mb_info_ - 1, 0, mb_info_size);
785 VP8InitScanline(dec); // initialize left too.
786
787 // initialize top
788 memset(dec->intra_t_, B_DC_PRED, intra_pred_mode_size);
789
790 return 1;
791}
792
793static void InitIo(VP8Decoder* const dec, VP8Io* io) {
794 // prepare 'io'
795 io->mb_y = 0;
796 io->y = dec->cache_y_;
797 io->u = dec->cache_u_;
798 io->v = dec->cache_v_;
799 io->y_stride = dec->cache_y_stride_;
800 io->uv_stride = dec->cache_uv_stride_;
801 io->a = NULL;
802}
803
804int VP8InitFrame(VP8Decoder* const dec, VP8Io* const io) {
805 if (!InitThreadContext(dec)) return 0; // call first. Sets dec->num_caches_.
806 if (!AllocateMemory(dec)) return 0;
807 InitIo(dec, io);
808 VP8DspInit(); // Init critical function pointers and look-up tables.
809 return 1;
810}
811
812//------------------------------------------------------------------------------
813