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 // main entry for the decoder
11 //
12 // Author: Skal (pascal.massimino@gmail.com)
13
14 #include <stdlib.h>
15
16 #include "./vp8i.h"
17 #include "./vp8li.h"
18 #include "./webpi.h"
19 #include "../utils/bit_reader.h"
20
21 #if defined(__cplusplus) || defined(c_plusplus)
22 extern "C" {
23 #endif
24
25 //------------------------------------------------------------------------------
26
WebPGetDecoderVersion(void)27 int WebPGetDecoderVersion(void) {
28 return (DEC_MAJ_VERSION << 16) | (DEC_MIN_VERSION << 8) | DEC_REV_VERSION;
29 }
30
31 //------------------------------------------------------------------------------
32 // VP8Decoder
33
SetOk(VP8Decoder * const dec)34 static void SetOk(VP8Decoder* const dec) {
35 dec->status_ = VP8_STATUS_OK;
36 dec->error_msg_ = "OK";
37 }
38
VP8InitIoInternal(VP8Io * const io,int version)39 int VP8InitIoInternal(VP8Io* const io, int version) {
40 if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
41 return 0; // mismatch error
42 }
43 if (io != NULL) {
44 memset(io, 0, sizeof(*io));
45 }
46 return 1;
47 }
48
VP8New(void)49 VP8Decoder* VP8New(void) {
50 VP8Decoder* const dec = (VP8Decoder*)calloc(1, sizeof(*dec));
51 if (dec != NULL) {
52 SetOk(dec);
53 WebPWorkerInit(&dec->worker_);
54 dec->ready_ = 0;
55 dec->num_parts_ = 1;
56 }
57 return dec;
58 }
59
VP8Status(VP8Decoder * const dec)60 VP8StatusCode VP8Status(VP8Decoder* const dec) {
61 if (!dec) return VP8_STATUS_INVALID_PARAM;
62 return dec->status_;
63 }
64
VP8StatusMessage(VP8Decoder * const dec)65 const char* VP8StatusMessage(VP8Decoder* const dec) {
66 if (dec == NULL) return "no object";
67 if (!dec->error_msg_) return "OK";
68 return dec->error_msg_;
69 }
70
VP8Delete(VP8Decoder * const dec)71 void VP8Delete(VP8Decoder* const dec) {
72 if (dec != NULL) {
73 VP8Clear(dec);
74 free(dec);
75 }
76 }
77
VP8SetError(VP8Decoder * const dec,VP8StatusCode error,const char * const msg)78 int VP8SetError(VP8Decoder* const dec,
79 VP8StatusCode error, const char* const msg) {
80 // TODO This check would be unnecessary if alpha decompression was separated
81 // from VP8ProcessRow/FinishRow. This avoids setting 'dec->status_' to
82 // something other than VP8_STATUS_BITSTREAM_ERROR on alpha decompression
83 // failure.
84 if (dec->status_ == VP8_STATUS_OK) {
85 dec->status_ = error;
86 dec->error_msg_ = msg;
87 dec->ready_ = 0;
88 }
89 return 0;
90 }
91
92 //------------------------------------------------------------------------------
93
VP8CheckSignature(const uint8_t * const data,size_t data_size)94 int VP8CheckSignature(const uint8_t* const data, size_t data_size) {
95 return (data_size >= 3 &&
96 data[0] == 0x9d && data[1] == 0x01 && data[2] == 0x2a);
97 }
98
VP8GetInfo(const uint8_t * data,size_t data_size,size_t chunk_size,int * const width,int * const height)99 int VP8GetInfo(const uint8_t* data, size_t data_size, size_t chunk_size,
100 int* const width, int* const height) {
101 if (data == NULL || data_size < VP8_FRAME_HEADER_SIZE) {
102 return 0; // not enough data
103 }
104 // check signature
105 if (!VP8CheckSignature(data + 3, data_size - 3)) {
106 return 0; // Wrong signature.
107 } else {
108 const uint32_t bits = data[0] | (data[1] << 8) | (data[2] << 16);
109 const int key_frame = !(bits & 1);
110 const int w = ((data[7] << 8) | data[6]) & 0x3fff;
111 const int h = ((data[9] << 8) | data[8]) & 0x3fff;
112
113 if (!key_frame) { // Not a keyframe.
114 return 0;
115 }
116
117 if (((bits >> 1) & 7) > 3) {
118 return 0; // unknown profile
119 }
120 if (!((bits >> 4) & 1)) {
121 return 0; // first frame is invisible!
122 }
123 if (((bits >> 5)) >= chunk_size) { // partition_length
124 return 0; // inconsistent size information.
125 }
126
127 if (width) {
128 *width = w;
129 }
130 if (height) {
131 *height = h;
132 }
133
134 return 1;
135 }
136 }
137
138 //------------------------------------------------------------------------------
139 // Header parsing
140
ResetSegmentHeader(VP8SegmentHeader * const hdr)141 static void ResetSegmentHeader(VP8SegmentHeader* const hdr) {
142 assert(hdr != NULL);
143 hdr->use_segment_ = 0;
144 hdr->update_map_ = 0;
145 hdr->absolute_delta_ = 1;
146 memset(hdr->quantizer_, 0, sizeof(hdr->quantizer_));
147 memset(hdr->filter_strength_, 0, sizeof(hdr->filter_strength_));
148 }
149
150 // Paragraph 9.3
ParseSegmentHeader(VP8BitReader * br,VP8SegmentHeader * hdr,VP8Proba * proba)151 static int ParseSegmentHeader(VP8BitReader* br,
152 VP8SegmentHeader* hdr, VP8Proba* proba) {
153 assert(br != NULL);
154 assert(hdr != NULL);
155 hdr->use_segment_ = VP8Get(br);
156 if (hdr->use_segment_) {
157 hdr->update_map_ = VP8Get(br);
158 if (VP8Get(br)) { // update data
159 int s;
160 hdr->absolute_delta_ = VP8Get(br);
161 for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
162 hdr->quantizer_[s] = VP8Get(br) ? VP8GetSignedValue(br, 7) : 0;
163 }
164 for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
165 hdr->filter_strength_[s] = VP8Get(br) ? VP8GetSignedValue(br, 6) : 0;
166 }
167 }
168 if (hdr->update_map_) {
169 int s;
170 for (s = 0; s < MB_FEATURE_TREE_PROBS; ++s) {
171 proba->segments_[s] = VP8Get(br) ? VP8GetValue(br, 8) : 255u;
172 }
173 }
174 } else {
175 hdr->update_map_ = 0;
176 }
177 return !br->eof_;
178 }
179
180 // Paragraph 9.5
181 // This function returns VP8_STATUS_SUSPENDED if we don't have all the
182 // necessary data in 'buf'.
183 // This case is not necessarily an error (for incremental decoding).
184 // Still, no bitreader is ever initialized to make it possible to read
185 // unavailable memory.
186 // If we don't even have the partitions' sizes, than VP8_STATUS_NOT_ENOUGH_DATA
187 // is returned, and this is an unrecoverable error.
188 // If the partitions were positioned ok, VP8_STATUS_OK is returned.
ParsePartitions(VP8Decoder * const dec,const uint8_t * buf,size_t size)189 static VP8StatusCode ParsePartitions(VP8Decoder* const dec,
190 const uint8_t* buf, size_t size) {
191 VP8BitReader* const br = &dec->br_;
192 const uint8_t* sz = buf;
193 const uint8_t* buf_end = buf + size;
194 const uint8_t* part_start;
195 int last_part;
196 int p;
197
198 dec->num_parts_ = 1 << VP8GetValue(br, 2);
199 last_part = dec->num_parts_ - 1;
200 part_start = buf + last_part * 3;
201 if (buf_end < part_start) {
202 // we can't even read the sizes with sz[]! That's a failure.
203 return VP8_STATUS_NOT_ENOUGH_DATA;
204 }
205 for (p = 0; p < last_part; ++p) {
206 const uint32_t psize = sz[0] | (sz[1] << 8) | (sz[2] << 16);
207 const uint8_t* part_end = part_start + psize;
208 if (part_end > buf_end) part_end = buf_end;
209 VP8InitBitReader(dec->parts_ + p, part_start, part_end);
210 part_start = part_end;
211 sz += 3;
212 }
213 VP8InitBitReader(dec->parts_ + last_part, part_start, buf_end);
214 return (part_start < buf_end) ? VP8_STATUS_OK :
215 VP8_STATUS_SUSPENDED; // Init is ok, but there's not enough data
216 }
217
218 // Paragraph 9.4
ParseFilterHeader(VP8BitReader * br,VP8Decoder * const dec)219 static int ParseFilterHeader(VP8BitReader* br, VP8Decoder* const dec) {
220 VP8FilterHeader* const hdr = &dec->filter_hdr_;
221 hdr->simple_ = VP8Get(br);
222 hdr->level_ = VP8GetValue(br, 6);
223 hdr->sharpness_ = VP8GetValue(br, 3);
224 hdr->use_lf_delta_ = VP8Get(br);
225 if (hdr->use_lf_delta_) {
226 if (VP8Get(br)) { // update lf-delta?
227 int i;
228 for (i = 0; i < NUM_REF_LF_DELTAS; ++i) {
229 if (VP8Get(br)) {
230 hdr->ref_lf_delta_[i] = VP8GetSignedValue(br, 6);
231 }
232 }
233 for (i = 0; i < NUM_MODE_LF_DELTAS; ++i) {
234 if (VP8Get(br)) {
235 hdr->mode_lf_delta_[i] = VP8GetSignedValue(br, 6);
236 }
237 }
238 }
239 }
240 dec->filter_type_ = (hdr->level_ == 0) ? 0 : hdr->simple_ ? 1 : 2;
241 return !br->eof_;
242 }
243
244 // Topmost call
VP8GetHeaders(VP8Decoder * const dec,VP8Io * const io)245 int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io) {
246 const uint8_t* buf;
247 size_t buf_size;
248 VP8FrameHeader* frm_hdr;
249 VP8PictureHeader* pic_hdr;
250 VP8BitReader* br;
251 VP8StatusCode status;
252 WebPHeaderStructure headers;
253
254 if (dec == NULL) {
255 return 0;
256 }
257 SetOk(dec);
258 if (io == NULL) {
259 return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
260 "null VP8Io passed to VP8GetHeaders()");
261 }
262
263 // Process Pre-VP8 chunks.
264 headers.data = io->data;
265 headers.data_size = io->data_size;
266 status = WebPParseHeaders(&headers);
267 if (status != VP8_STATUS_OK) {
268 return VP8SetError(dec, status, "Incorrect/incomplete header.");
269 }
270 if (headers.is_lossless) {
271 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
272 "Unexpected lossless format encountered.");
273 }
274
275 if (dec->alpha_data_ == NULL) {
276 assert(dec->alpha_data_size_ == 0);
277 // We have NOT set alpha data yet. Set it now.
278 // (This is to ensure that dec->alpha_data_ is NOT reset to NULL if
279 // WebPParseHeaders() is called more than once, as in incremental decoding
280 // case.)
281 dec->alpha_data_ = headers.alpha_data;
282 dec->alpha_data_size_ = headers.alpha_data_size;
283 }
284
285 // Process the VP8 frame header.
286 buf = headers.data + headers.offset;
287 buf_size = headers.data_size - headers.offset;
288 assert(headers.data_size >= headers.offset); // WebPParseHeaders' guarantee
289 if (buf_size < 4) {
290 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
291 "Truncated header.");
292 }
293
294 // Paragraph 9.1
295 {
296 const uint32_t bits = buf[0] | (buf[1] << 8) | (buf[2] << 16);
297 frm_hdr = &dec->frm_hdr_;
298 frm_hdr->key_frame_ = !(bits & 1);
299 frm_hdr->profile_ = (bits >> 1) & 7;
300 frm_hdr->show_ = (bits >> 4) & 1;
301 frm_hdr->partition_length_ = (bits >> 5);
302 if (frm_hdr->profile_ > 3)
303 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
304 "Incorrect keyframe parameters.");
305 if (!frm_hdr->show_)
306 return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
307 "Frame not displayable.");
308 buf += 3;
309 buf_size -= 3;
310 }
311
312 pic_hdr = &dec->pic_hdr_;
313 if (frm_hdr->key_frame_) {
314 // Paragraph 9.2
315 if (buf_size < 7) {
316 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
317 "cannot parse picture header");
318 }
319 if (!VP8CheckSignature(buf, buf_size)) {
320 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
321 "Bad code word");
322 }
323 pic_hdr->width_ = ((buf[4] << 8) | buf[3]) & 0x3fff;
324 pic_hdr->xscale_ = buf[4] >> 6; // ratio: 1, 5/4 5/3 or 2
325 pic_hdr->height_ = ((buf[6] << 8) | buf[5]) & 0x3fff;
326 pic_hdr->yscale_ = buf[6] >> 6;
327 buf += 7;
328 buf_size -= 7;
329
330 dec->mb_w_ = (pic_hdr->width_ + 15) >> 4;
331 dec->mb_h_ = (pic_hdr->height_ + 15) >> 4;
332 // Setup default output area (can be later modified during io->setup())
333 io->width = pic_hdr->width_;
334 io->height = pic_hdr->height_;
335 io->use_scaling = 0;
336 io->use_cropping = 0;
337 io->crop_top = 0;
338 io->crop_left = 0;
339 io->crop_right = io->width;
340 io->crop_bottom = io->height;
341 io->mb_w = io->width; // sanity check
342 io->mb_h = io->height; // ditto
343
344 VP8ResetProba(&dec->proba_);
345 ResetSegmentHeader(&dec->segment_hdr_);
346 dec->segment_ = 0; // default for intra
347 }
348
349 // Check if we have all the partition #0 available, and initialize dec->br_
350 // to read this partition (and this partition only).
351 if (frm_hdr->partition_length_ > buf_size) {
352 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
353 "bad partition length");
354 }
355
356 br = &dec->br_;
357 VP8InitBitReader(br, buf, buf + frm_hdr->partition_length_);
358 buf += frm_hdr->partition_length_;
359 buf_size -= frm_hdr->partition_length_;
360
361 if (frm_hdr->key_frame_) {
362 pic_hdr->colorspace_ = VP8Get(br);
363 pic_hdr->clamp_type_ = VP8Get(br);
364 }
365 if (!ParseSegmentHeader(br, &dec->segment_hdr_, &dec->proba_)) {
366 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
367 "cannot parse segment header");
368 }
369 // Filter specs
370 if (!ParseFilterHeader(br, dec)) {
371 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
372 "cannot parse filter header");
373 }
374 status = ParsePartitions(dec, buf, buf_size);
375 if (status != VP8_STATUS_OK) {
376 return VP8SetError(dec, status, "cannot parse partitions");
377 }
378
379 // quantizer change
380 VP8ParseQuant(dec);
381
382 // Frame buffer marking
383 if (!frm_hdr->key_frame_) {
384 // Paragraph 9.7
385 #ifndef ONLY_KEYFRAME_CODE
386 dec->buffer_flags_ = VP8Get(br) << 0; // update golden
387 dec->buffer_flags_ |= VP8Get(br) << 1; // update alt ref
388 if (!(dec->buffer_flags_ & 1)) {
389 dec->buffer_flags_ |= VP8GetValue(br, 2) << 2;
390 }
391 if (!(dec->buffer_flags_ & 2)) {
392 dec->buffer_flags_ |= VP8GetValue(br, 2) << 4;
393 }
394 dec->buffer_flags_ |= VP8Get(br) << 6; // sign bias golden
395 dec->buffer_flags_ |= VP8Get(br) << 7; // sign bias alt ref
396 #else
397 return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
398 "Not a key frame.");
399 #endif
400 } else {
401 dec->buffer_flags_ = 0x003 | 0x100;
402 }
403
404 // Paragraph 9.8
405 #ifndef ONLY_KEYFRAME_CODE
406 dec->update_proba_ = VP8Get(br);
407 if (!dec->update_proba_) { // save for later restore
408 dec->proba_saved_ = dec->proba_;
409 }
410 dec->buffer_flags_ &= 1 << 8;
411 dec->buffer_flags_ |=
412 (frm_hdr->key_frame_ || VP8Get(br)) << 8; // refresh last frame
413 #else
414 VP8Get(br); // just ignore the value of update_proba_
415 #endif
416
417 VP8ParseProba(br, dec);
418
419 #ifdef WEBP_EXPERIMENTAL_FEATURES
420 // Extensions
421 if (dec->pic_hdr_.colorspace_) {
422 const size_t kTrailerSize = 8;
423 const uint8_t kTrailerMarker = 0x01;
424 const uint8_t* ext_buf = buf - kTrailerSize;
425 size_t size;
426
427 if (frm_hdr->partition_length_ < kTrailerSize ||
428 ext_buf[kTrailerSize - 1] != kTrailerMarker) {
429 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
430 "RIFF: Inconsistent extra information.");
431 }
432
433 // Layer
434 size = (ext_buf[0] << 0) | (ext_buf[1] << 8) | (ext_buf[2] << 16);
435 dec->layer_data_size_ = size;
436 dec->layer_data_ = NULL; // will be set later
437 dec->layer_colorspace_ = ext_buf[3];
438 }
439 #endif
440
441 // sanitized state
442 dec->ready_ = 1;
443 return 1;
444 }
445
446 //------------------------------------------------------------------------------
447 // Residual decoding (Paragraph 13.2 / 13.3)
448
449 static const int kBands[16 + 1] = {
450 0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
451 0 // extra entry as sentinel
452 };
453
454 static const uint8_t kCat3[] = { 173, 148, 140, 0 };
455 static const uint8_t kCat4[] = { 176, 155, 140, 135, 0 };
456 static const uint8_t kCat5[] = { 180, 157, 141, 134, 130, 0 };
457 static const uint8_t kCat6[] =
458 { 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0 };
459 static const uint8_t* const kCat3456[] = { kCat3, kCat4, kCat5, kCat6 };
460 static const uint8_t kZigzag[16] = {
461 0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
462 };
463
464 typedef const uint8_t (*ProbaArray)[NUM_CTX][NUM_PROBAS]; // for const-casting
465 typedef const uint8_t (*ProbaCtxArray)[NUM_PROBAS];
466
467 // See section 13-2: http://tools.ietf.org/html/rfc6386#section-13.2
GetLargeValue(VP8BitReader * const br,const uint8_t * const p)468 static int GetLargeValue(VP8BitReader* const br, const uint8_t* const p) {
469 int v;
470 if (!VP8GetBit(br, p[3])) {
471 if (!VP8GetBit(br, p[4])) {
472 v = 2;
473 } else {
474 v = 3 + VP8GetBit(br, p[5]);
475 }
476 } else {
477 if (!VP8GetBit(br, p[6])) {
478 if (!VP8GetBit(br, p[7])) {
479 v = 5 + VP8GetBit(br, 159);
480 } else {
481 v = 7 + 2 * VP8GetBit(br, 165);
482 v += VP8GetBit(br, 145);
483 }
484 } else {
485 const uint8_t* tab;
486 const int bit1 = VP8GetBit(br, p[8]);
487 const int bit0 = VP8GetBit(br, p[9 + bit1]);
488 const int cat = 2 * bit1 + bit0;
489 v = 0;
490 for (tab = kCat3456[cat]; *tab; ++tab) {
491 v += v + VP8GetBit(br, *tab);
492 }
493 v += 3 + (8 << cat);
494 }
495 }
496 return v;
497 }
498
499 // Returns the position of the last non-zero coeff plus one
500 // (and 0 if there's no coeff at all)
GetCoeffs(VP8BitReader * const br,ProbaArray prob,int ctx,const quant_t dq,int n,int16_t * out)501 static int GetCoeffs(VP8BitReader* const br, ProbaArray prob,
502 int ctx, const quant_t dq, int n, int16_t* out) {
503 // n is either 0 or 1 here. kBands[n] is not necessary for extracting '*p'.
504 const uint8_t* p = prob[n][ctx];
505 if (!VP8GetBit(br, p[0])) { // first EOB is more a 'CBP' bit.
506 return 0;
507 }
508 for (; n < 16; ++n) {
509 const ProbaCtxArray p_ctx = prob[kBands[n + 1]];
510 if (!VP8GetBit(br, p[1])) {
511 p = p_ctx[0];
512 } else { // non zero coeff
513 int v;
514 if (!VP8GetBit(br, p[2])) {
515 v = 1;
516 p = p_ctx[1];
517 } else {
518 v = GetLargeValue(br, p);
519 p = p_ctx[2];
520 }
521 out[kZigzag[n]] = VP8GetSigned(br, v) * dq[n > 0];
522 if (n < 15 && !VP8GetBit(br, p[0])) { // EOB
523 return n + 1;
524 }
525 }
526 }
527 return 16;
528 }
529
530 // Alias-safe way of converting 4bytes to 32bits.
531 typedef union {
532 uint8_t i8[4];
533 uint32_t i32;
534 } PackedNz;
535
536 // Table to unpack four bits into four bytes
537 static const PackedNz kUnpackTab[16] = {
538 {{0, 0, 0, 0}}, {{1, 0, 0, 0}}, {{0, 1, 0, 0}}, {{1, 1, 0, 0}},
539 {{0, 0, 1, 0}}, {{1, 0, 1, 0}}, {{0, 1, 1, 0}}, {{1, 1, 1, 0}},
540 {{0, 0, 0, 1}}, {{1, 0, 0, 1}}, {{0, 1, 0, 1}}, {{1, 1, 0, 1}},
541 {{0, 0, 1, 1}}, {{1, 0, 1, 1}}, {{0, 1, 1, 1}}, {{1, 1, 1, 1}} };
542
543 // Macro to pack four LSB of four bytes into four bits.
544 #if defined(__PPC__) || defined(_M_PPC) || defined(_ARCH_PPC) || \
545 defined(__BIG_ENDIAN__)
546 #define PACK_CST 0x08040201U
547 #else
548 #define PACK_CST 0x01020408U
549 #endif
550 #define PACK(X, S) ((((X).i32 * PACK_CST) & 0xff000000) >> (S))
551
ParseResiduals(VP8Decoder * const dec,VP8MB * const mb,VP8BitReader * const token_br)552 static void ParseResiduals(VP8Decoder* const dec,
553 VP8MB* const mb, VP8BitReader* const token_br) {
554 int out_t_nz, out_l_nz, first;
555 ProbaArray ac_prob;
556 const VP8QuantMatrix* q = &dec->dqm_[dec->segment_];
557 int16_t* dst = dec->coeffs_;
558 VP8MB* const left_mb = dec->mb_info_ - 1;
559 PackedNz nz_ac, nz_dc;
560 PackedNz tnz, lnz;
561 uint32_t non_zero_ac = 0;
562 uint32_t non_zero_dc = 0;
563 int x, y, ch;
564
565 nz_dc.i32 = nz_ac.i32 = 0;
566 memset(dst, 0, 384 * sizeof(*dst));
567 if (!dec->is_i4x4_) { // parse DC
568 int16_t dc[16] = { 0 };
569 const int ctx = mb->dc_nz_ + left_mb->dc_nz_;
570 mb->dc_nz_ = left_mb->dc_nz_ =
571 (GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[1],
572 ctx, q->y2_mat_, 0, dc) > 0);
573 first = 1;
574 ac_prob = (ProbaArray)dec->proba_.coeffs_[0];
575 VP8TransformWHT(dc, dst);
576 } else {
577 first = 0;
578 ac_prob = (ProbaArray)dec->proba_.coeffs_[3];
579 }
580
581 tnz = kUnpackTab[mb->nz_ & 0xf];
582 lnz = kUnpackTab[left_mb->nz_ & 0xf];
583 for (y = 0; y < 4; ++y) {
584 int l = lnz.i8[y];
585 for (x = 0; x < 4; ++x) {
586 const int ctx = l + tnz.i8[x];
587 const int nz = GetCoeffs(token_br, ac_prob, ctx,
588 q->y1_mat_, first, dst);
589 tnz.i8[x] = l = (nz > 0);
590 nz_dc.i8[x] = (dst[0] != 0);
591 nz_ac.i8[x] = (nz > 1);
592 dst += 16;
593 }
594 lnz.i8[y] = l;
595 non_zero_dc |= PACK(nz_dc, 24 - y * 4);
596 non_zero_ac |= PACK(nz_ac, 24 - y * 4);
597 }
598 out_t_nz = PACK(tnz, 24);
599 out_l_nz = PACK(lnz, 24);
600
601 tnz = kUnpackTab[mb->nz_ >> 4];
602 lnz = kUnpackTab[left_mb->nz_ >> 4];
603 for (ch = 0; ch < 4; ch += 2) {
604 for (y = 0; y < 2; ++y) {
605 int l = lnz.i8[ch + y];
606 for (x = 0; x < 2; ++x) {
607 const int ctx = l + tnz.i8[ch + x];
608 const int nz =
609 GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[2],
610 ctx, q->uv_mat_, 0, dst);
611 tnz.i8[ch + x] = l = (nz > 0);
612 nz_dc.i8[y * 2 + x] = (dst[0] != 0);
613 nz_ac.i8[y * 2 + x] = (nz > 1);
614 dst += 16;
615 }
616 lnz.i8[ch + y] = l;
617 }
618 non_zero_dc |= PACK(nz_dc, 8 - ch * 2);
619 non_zero_ac |= PACK(nz_ac, 8 - ch * 2);
620 }
621 out_t_nz |= PACK(tnz, 20);
622 out_l_nz |= PACK(lnz, 20);
623 mb->nz_ = out_t_nz;
624 left_mb->nz_ = out_l_nz;
625
626 dec->non_zero_ac_ = non_zero_ac;
627 dec->non_zero_ = non_zero_ac | non_zero_dc;
628 mb->skip_ = !dec->non_zero_;
629 }
630 #undef PACK
631
632 //------------------------------------------------------------------------------
633 // Main loop
634
VP8DecodeMB(VP8Decoder * const dec,VP8BitReader * const token_br)635 int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br) {
636 VP8BitReader* const br = &dec->br_;
637 VP8MB* const left = dec->mb_info_ - 1;
638 VP8MB* const info = dec->mb_info_ + dec->mb_x_;
639
640 // Note: we don't save segment map (yet), as we don't expect
641 // to decode more than 1 keyframe.
642 if (dec->segment_hdr_.update_map_) {
643 // Hardcoded tree parsing
644 dec->segment_ = !VP8GetBit(br, dec->proba_.segments_[0]) ?
645 VP8GetBit(br, dec->proba_.segments_[1]) :
646 2 + VP8GetBit(br, dec->proba_.segments_[2]);
647 }
648 info->skip_ = dec->use_skip_proba_ ? VP8GetBit(br, dec->skip_p_) : 0;
649
650 VP8ParseIntraMode(br, dec);
651 if (br->eof_) {
652 return 0;
653 }
654
655 if (!info->skip_) {
656 ParseResiduals(dec, info, token_br);
657 } else {
658 left->nz_ = info->nz_ = 0;
659 if (!dec->is_i4x4_) {
660 left->dc_nz_ = info->dc_nz_ = 0;
661 }
662 dec->non_zero_ = 0;
663 dec->non_zero_ac_ = 0;
664 }
665
666 if (dec->filter_type_ > 0) { // store filter info
667 VP8FInfo* const finfo = dec->f_info_ + dec->mb_x_;
668 *finfo = dec->fstrengths_[dec->segment_][dec->is_i4x4_];
669 finfo->f_inner_ = (!info->skip_ || dec->is_i4x4_);
670 }
671
672 return (!token_br->eof_);
673 }
674
VP8InitScanline(VP8Decoder * const dec)675 void VP8InitScanline(VP8Decoder* const dec) {
676 VP8MB* const left = dec->mb_info_ - 1;
677 left->nz_ = 0;
678 left->dc_nz_ = 0;
679 memset(dec->intra_l_, B_DC_PRED, sizeof(dec->intra_l_));
680 dec->filter_row_ =
681 (dec->filter_type_ > 0) &&
682 (dec->mb_y_ >= dec->tl_mb_y_) && (dec->mb_y_ <= dec->br_mb_y_);
683 }
684
ParseFrame(VP8Decoder * const dec,VP8Io * io)685 static int ParseFrame(VP8Decoder* const dec, VP8Io* io) {
686 for (dec->mb_y_ = 0; dec->mb_y_ < dec->br_mb_y_; ++dec->mb_y_) {
687 VP8BitReader* const token_br =
688 &dec->parts_[dec->mb_y_ & (dec->num_parts_ - 1)];
689 VP8InitScanline(dec);
690 for (dec->mb_x_ = 0; dec->mb_x_ < dec->mb_w_; dec->mb_x_++) {
691 if (!VP8DecodeMB(dec, token_br)) {
692 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
693 "Premature end-of-file encountered.");
694 }
695 // Reconstruct and emit samples.
696 VP8ReconstructBlock(dec);
697 }
698 if (!VP8ProcessRow(dec, io)) {
699 return VP8SetError(dec, VP8_STATUS_USER_ABORT, "Output aborted.");
700 }
701 }
702 if (dec->use_threads_ && !WebPWorkerSync(&dec->worker_)) {
703 return 0;
704 }
705
706 // Finish
707 #ifndef ONLY_KEYFRAME_CODE
708 if (!dec->update_proba_) {
709 dec->proba_ = dec->proba_saved_;
710 }
711 #endif
712
713 #ifdef WEBP_EXPERIMENTAL_FEATURES
714 if (dec->layer_data_size_ > 0) {
715 if (!VP8DecodeLayer(dec)) {
716 return 0;
717 }
718 }
719 #endif
720
721 return 1;
722 }
723
724 // Main entry point
VP8Decode(VP8Decoder * const dec,VP8Io * const io)725 int VP8Decode(VP8Decoder* const dec, VP8Io* const io) {
726 int ok = 0;
727 if (dec == NULL) {
728 return 0;
729 }
730 if (io == NULL) {
731 return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
732 "NULL VP8Io parameter in VP8Decode().");
733 }
734
735 if (!dec->ready_) {
736 if (!VP8GetHeaders(dec, io)) {
737 return 0;
738 }
739 }
740 assert(dec->ready_);
741
742 // Finish setting up the decoding parameter. Will call io->setup().
743 ok = (VP8EnterCritical(dec, io) == VP8_STATUS_OK);
744 if (ok) { // good to go.
745 // Will allocate memory and prepare everything.
746 if (ok) ok = VP8InitFrame(dec, io);
747
748 // Main decoding loop
749 if (ok) ok = ParseFrame(dec, io);
750
751 // Exit.
752 ok &= VP8ExitCritical(dec, io);
753 }
754
755 if (!ok) {
756 VP8Clear(dec);
757 return 0;
758 }
759
760 dec->ready_ = 0;
761 return ok;
762 }
763
VP8Clear(VP8Decoder * const dec)764 void VP8Clear(VP8Decoder* const dec) {
765 if (dec == NULL) {
766 return;
767 }
768 if (dec->use_threads_) {
769 WebPWorkerEnd(&dec->worker_);
770 }
771 if (dec->mem_) {
772 free(dec->mem_);
773 }
774 dec->mem_ = NULL;
775 dec->mem_size_ = 0;
776 memset(&dec->br_, 0, sizeof(dec->br_));
777 dec->ready_ = 0;
778 }
779
780 //------------------------------------------------------------------------------
781
782 #if defined(__cplusplus) || defined(c_plusplus)
783 } // extern "C"
784 #endif
785