1 // Copyright 2010 Google Inc. All Rights Reserved.
2 //
3 // This code is licensed under the same terms as WebM:
4 // Software License Agreement: http://www.webmproject.org/license/software/
5 // Additional IP Rights Grant: http://www.webmproject.org/license/additional/
6 // -----------------------------------------------------------------------------
7 //
8 // main entry for the decoder
9 //
10 // Author: Skal (pascal.massimino@gmail.com)
11
12 #include <stdlib.h>
13
14 #include "./vp8i.h"
15 #include "./vp8li.h"
16 #include "./webpi.h"
17 #include "../utils/bit_reader.h"
18
19 #if defined(__cplusplus) || defined(c_plusplus)
20 extern "C" {
21 #endif
22
23 //------------------------------------------------------------------------------
24
WebPGetDecoderVersion(void)25 int WebPGetDecoderVersion(void) {
26 return (DEC_MAJ_VERSION << 16) | (DEC_MIN_VERSION << 8) | DEC_REV_VERSION;
27 }
28
29 //------------------------------------------------------------------------------
30 // VP8Decoder
31
SetOk(VP8Decoder * const dec)32 static void SetOk(VP8Decoder* const dec) {
33 dec->status_ = VP8_STATUS_OK;
34 dec->error_msg_ = "OK";
35 }
36
VP8InitIoInternal(VP8Io * const io,int version)37 int VP8InitIoInternal(VP8Io* const io, int version) {
38 if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
39 return 0; // mismatch error
40 }
41 if (io != NULL) {
42 memset(io, 0, sizeof(*io));
43 }
44 return 1;
45 }
46
VP8New(void)47 VP8Decoder* VP8New(void) {
48 VP8Decoder* const dec = (VP8Decoder*)calloc(1, sizeof(*dec));
49 if (dec != NULL) {
50 SetOk(dec);
51 WebPWorkerInit(&dec->worker_);
52 dec->ready_ = 0;
53 dec->num_parts_ = 1;
54 }
55 return dec;
56 }
57
VP8Status(VP8Decoder * const dec)58 VP8StatusCode VP8Status(VP8Decoder* const dec) {
59 if (!dec) return VP8_STATUS_INVALID_PARAM;
60 return dec->status_;
61 }
62
VP8StatusMessage(VP8Decoder * const dec)63 const char* VP8StatusMessage(VP8Decoder* const dec) {
64 if (dec == NULL) return "no object";
65 if (!dec->error_msg_) return "OK";
66 return dec->error_msg_;
67 }
68
VP8Delete(VP8Decoder * const dec)69 void VP8Delete(VP8Decoder* const dec) {
70 if (dec != NULL) {
71 VP8Clear(dec);
72 free(dec);
73 }
74 }
75
VP8SetError(VP8Decoder * const dec,VP8StatusCode error,const char * const msg)76 int VP8SetError(VP8Decoder* const dec,
77 VP8StatusCode error, const char* const msg) {
78 // TODO This check would be unnecessary if alpha decompression was separated
79 // from VP8ProcessRow/FinishRow. This avoids setting 'dec->status_' to
80 // something other than VP8_STATUS_BITSTREAM_ERROR on alpha decompression
81 // failure.
82 if (dec->status_ == VP8_STATUS_OK) {
83 dec->status_ = error;
84 dec->error_msg_ = msg;
85 dec->ready_ = 0;
86 }
87 return 0;
88 }
89
90 //------------------------------------------------------------------------------
91
VP8CheckSignature(const uint8_t * const data,size_t data_size)92 int VP8CheckSignature(const uint8_t* const data, size_t data_size) {
93 return (data_size >= 3 &&
94 data[0] == 0x9d && data[1] == 0x01 && data[2] == 0x2a);
95 }
96
VP8GetInfo(const uint8_t * data,size_t data_size,size_t chunk_size,int * const width,int * const height)97 int VP8GetInfo(const uint8_t* data, size_t data_size, size_t chunk_size,
98 int* const width, int* const height) {
99 if (data == NULL || data_size < VP8_FRAME_HEADER_SIZE) {
100 return 0; // not enough data
101 }
102 // check signature
103 if (!VP8CheckSignature(data + 3, data_size - 3)) {
104 return 0; // Wrong signature.
105 } else {
106 const uint32_t bits = data[0] | (data[1] << 8) | (data[2] << 16);
107 const int key_frame = !(bits & 1);
108 const int w = ((data[7] << 8) | data[6]) & 0x3fff;
109 const int h = ((data[9] << 8) | data[8]) & 0x3fff;
110
111 if (!key_frame) { // Not a keyframe.
112 return 0;
113 }
114
115 if (((bits >> 1) & 7) > 3) {
116 return 0; // unknown profile
117 }
118 if (!((bits >> 4) & 1)) {
119 return 0; // first frame is invisible!
120 }
121 if (((bits >> 5)) >= chunk_size) { // partition_length
122 return 0; // inconsistent size information.
123 }
124
125 if (width) {
126 *width = w;
127 }
128 if (height) {
129 *height = h;
130 }
131
132 return 1;
133 }
134 }
135
136 //------------------------------------------------------------------------------
137 // Header parsing
138
ResetSegmentHeader(VP8SegmentHeader * const hdr)139 static void ResetSegmentHeader(VP8SegmentHeader* const hdr) {
140 assert(hdr != NULL);
141 hdr->use_segment_ = 0;
142 hdr->update_map_ = 0;
143 hdr->absolute_delta_ = 1;
144 memset(hdr->quantizer_, 0, sizeof(hdr->quantizer_));
145 memset(hdr->filter_strength_, 0, sizeof(hdr->filter_strength_));
146 }
147
148 // Paragraph 9.3
ParseSegmentHeader(VP8BitReader * br,VP8SegmentHeader * hdr,VP8Proba * proba)149 static int ParseSegmentHeader(VP8BitReader* br,
150 VP8SegmentHeader* hdr, VP8Proba* proba) {
151 assert(br != NULL);
152 assert(hdr != NULL);
153 hdr->use_segment_ = VP8Get(br);
154 if (hdr->use_segment_) {
155 hdr->update_map_ = VP8Get(br);
156 if (VP8Get(br)) { // update data
157 int s;
158 hdr->absolute_delta_ = VP8Get(br);
159 for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
160 hdr->quantizer_[s] = VP8Get(br) ? VP8GetSignedValue(br, 7) : 0;
161 }
162 for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
163 hdr->filter_strength_[s] = VP8Get(br) ? VP8GetSignedValue(br, 6) : 0;
164 }
165 }
166 if (hdr->update_map_) {
167 int s;
168 for (s = 0; s < MB_FEATURE_TREE_PROBS; ++s) {
169 proba->segments_[s] = VP8Get(br) ? VP8GetValue(br, 8) : 255u;
170 }
171 }
172 } else {
173 hdr->update_map_ = 0;
174 }
175 return !br->eof_;
176 }
177
178 // Paragraph 9.5
179 // This function returns VP8_STATUS_SUSPENDED if we don't have all the
180 // necessary data in 'buf'.
181 // This case is not necessarily an error (for incremental decoding).
182 // Still, no bitreader is ever initialized to make it possible to read
183 // unavailable memory.
184 // If we don't even have the partitions' sizes, than VP8_STATUS_NOT_ENOUGH_DATA
185 // is returned, and this is an unrecoverable error.
186 // If the partitions were positioned ok, VP8_STATUS_OK is returned.
ParsePartitions(VP8Decoder * const dec,const uint8_t * buf,size_t size)187 static VP8StatusCode ParsePartitions(VP8Decoder* const dec,
188 const uint8_t* buf, size_t size) {
189 VP8BitReader* const br = &dec->br_;
190 const uint8_t* sz = buf;
191 const uint8_t* buf_end = buf + size;
192 const uint8_t* part_start;
193 int last_part;
194 int p;
195
196 dec->num_parts_ = 1 << VP8GetValue(br, 2);
197 last_part = dec->num_parts_ - 1;
198 part_start = buf + last_part * 3;
199 if (buf_end < part_start) {
200 // we can't even read the sizes with sz[]! That's a failure.
201 return VP8_STATUS_NOT_ENOUGH_DATA;
202 }
203 for (p = 0; p < last_part; ++p) {
204 const uint32_t psize = sz[0] | (sz[1] << 8) | (sz[2] << 16);
205 const uint8_t* part_end = part_start + psize;
206 if (part_end > buf_end) part_end = buf_end;
207 VP8InitBitReader(dec->parts_ + p, part_start, part_end);
208 part_start = part_end;
209 sz += 3;
210 }
211 VP8InitBitReader(dec->parts_ + last_part, part_start, buf_end);
212 return (part_start < buf_end) ? VP8_STATUS_OK :
213 VP8_STATUS_SUSPENDED; // Init is ok, but there's not enough data
214 }
215
216 // Paragraph 9.4
ParseFilterHeader(VP8BitReader * br,VP8Decoder * const dec)217 static int ParseFilterHeader(VP8BitReader* br, VP8Decoder* const dec) {
218 VP8FilterHeader* const hdr = &dec->filter_hdr_;
219 hdr->simple_ = VP8Get(br);
220 hdr->level_ = VP8GetValue(br, 6);
221 hdr->sharpness_ = VP8GetValue(br, 3);
222 hdr->use_lf_delta_ = VP8Get(br);
223 if (hdr->use_lf_delta_) {
224 if (VP8Get(br)) { // update lf-delta?
225 int i;
226 for (i = 0; i < NUM_REF_LF_DELTAS; ++i) {
227 if (VP8Get(br)) {
228 hdr->ref_lf_delta_[i] = VP8GetSignedValue(br, 6);
229 }
230 }
231 for (i = 0; i < NUM_MODE_LF_DELTAS; ++i) {
232 if (VP8Get(br)) {
233 hdr->mode_lf_delta_[i] = VP8GetSignedValue(br, 6);
234 }
235 }
236 }
237 }
238 dec->filter_type_ = (hdr->level_ == 0) ? 0 : hdr->simple_ ? 1 : 2;
239 if (dec->filter_type_ > 0) { // precompute filter levels per segment
240 if (dec->segment_hdr_.use_segment_) {
241 int s;
242 for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
243 int strength = dec->segment_hdr_.filter_strength_[s];
244 if (!dec->segment_hdr_.absolute_delta_) {
245 strength += hdr->level_;
246 }
247 dec->filter_levels_[s] = strength;
248 }
249 } else {
250 dec->filter_levels_[0] = hdr->level_;
251 }
252 }
253 return !br->eof_;
254 }
255
256 // Topmost call
VP8GetHeaders(VP8Decoder * const dec,VP8Io * const io)257 int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io) {
258 const uint8_t* buf;
259 size_t buf_size;
260 VP8FrameHeader* frm_hdr;
261 VP8PictureHeader* pic_hdr;
262 VP8BitReader* br;
263 VP8StatusCode status;
264 WebPHeaderStructure headers;
265
266 if (dec == NULL) {
267 return 0;
268 }
269 SetOk(dec);
270 if (io == NULL) {
271 return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
272 "null VP8Io passed to VP8GetHeaders()");
273 }
274
275 // Process Pre-VP8 chunks.
276 headers.data = io->data;
277 headers.data_size = io->data_size;
278 status = WebPParseHeaders(&headers);
279 if (status != VP8_STATUS_OK) {
280 return VP8SetError(dec, status, "Incorrect/incomplete header.");
281 }
282 if (headers.is_lossless) {
283 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
284 "Unexpected lossless format encountered.");
285 }
286
287 if (dec->alpha_data_ == NULL) {
288 assert(dec->alpha_data_size_ == 0);
289 // We have NOT set alpha data yet. Set it now.
290 // (This is to ensure that dec->alpha_data_ is NOT reset to NULL if
291 // WebPParseHeaders() is called more than once, as in incremental decoding
292 // case.)
293 dec->alpha_data_ = headers.alpha_data;
294 dec->alpha_data_size_ = headers.alpha_data_size;
295 }
296
297 // Process the VP8 frame header.
298 buf = headers.data + headers.offset;
299 buf_size = headers.data_size - headers.offset;
300 assert(headers.data_size >= headers.offset); // WebPParseHeaders' guarantee
301 if (buf_size < 4) {
302 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
303 "Truncated header.");
304 }
305
306 // Paragraph 9.1
307 {
308 const uint32_t bits = buf[0] | (buf[1] << 8) | (buf[2] << 16);
309 frm_hdr = &dec->frm_hdr_;
310 frm_hdr->key_frame_ = !(bits & 1);
311 frm_hdr->profile_ = (bits >> 1) & 7;
312 frm_hdr->show_ = (bits >> 4) & 1;
313 frm_hdr->partition_length_ = (bits >> 5);
314 if (frm_hdr->profile_ > 3)
315 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
316 "Incorrect keyframe parameters.");
317 if (!frm_hdr->show_)
318 return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
319 "Frame not displayable.");
320 buf += 3;
321 buf_size -= 3;
322 }
323
324 pic_hdr = &dec->pic_hdr_;
325 if (frm_hdr->key_frame_) {
326 // Paragraph 9.2
327 if (buf_size < 7) {
328 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
329 "cannot parse picture header");
330 }
331 if (!VP8CheckSignature(buf, buf_size)) {
332 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
333 "Bad code word");
334 }
335 pic_hdr->width_ = ((buf[4] << 8) | buf[3]) & 0x3fff;
336 pic_hdr->xscale_ = buf[4] >> 6; // ratio: 1, 5/4 5/3 or 2
337 pic_hdr->height_ = ((buf[6] << 8) | buf[5]) & 0x3fff;
338 pic_hdr->yscale_ = buf[6] >> 6;
339 buf += 7;
340 buf_size -= 7;
341
342 dec->mb_w_ = (pic_hdr->width_ + 15) >> 4;
343 dec->mb_h_ = (pic_hdr->height_ + 15) >> 4;
344 // Setup default output area (can be later modified during io->setup())
345 io->width = pic_hdr->width_;
346 io->height = pic_hdr->height_;
347 io->use_scaling = 0;
348 io->use_cropping = 0;
349 io->crop_top = 0;
350 io->crop_left = 0;
351 io->crop_right = io->width;
352 io->crop_bottom = io->height;
353 io->mb_w = io->width; // sanity check
354 io->mb_h = io->height; // ditto
355
356 VP8ResetProba(&dec->proba_);
357 ResetSegmentHeader(&dec->segment_hdr_);
358 dec->segment_ = 0; // default for intra
359 }
360
361 // Check if we have all the partition #0 available, and initialize dec->br_
362 // to read this partition (and this partition only).
363 if (frm_hdr->partition_length_ > buf_size) {
364 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
365 "bad partition length");
366 }
367
368 br = &dec->br_;
369 VP8InitBitReader(br, buf, buf + frm_hdr->partition_length_);
370 buf += frm_hdr->partition_length_;
371 buf_size -= frm_hdr->partition_length_;
372
373 if (frm_hdr->key_frame_) {
374 pic_hdr->colorspace_ = VP8Get(br);
375 pic_hdr->clamp_type_ = VP8Get(br);
376 }
377 if (!ParseSegmentHeader(br, &dec->segment_hdr_, &dec->proba_)) {
378 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
379 "cannot parse segment header");
380 }
381 // Filter specs
382 if (!ParseFilterHeader(br, dec)) {
383 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
384 "cannot parse filter header");
385 }
386 status = ParsePartitions(dec, buf, buf_size);
387 if (status != VP8_STATUS_OK) {
388 return VP8SetError(dec, status, "cannot parse partitions");
389 }
390
391 // quantizer change
392 VP8ParseQuant(dec);
393
394 // Frame buffer marking
395 if (!frm_hdr->key_frame_) {
396 // Paragraph 9.7
397 #ifndef ONLY_KEYFRAME_CODE
398 dec->buffer_flags_ = VP8Get(br) << 0; // update golden
399 dec->buffer_flags_ |= VP8Get(br) << 1; // update alt ref
400 if (!(dec->buffer_flags_ & 1)) {
401 dec->buffer_flags_ |= VP8GetValue(br, 2) << 2;
402 }
403 if (!(dec->buffer_flags_ & 2)) {
404 dec->buffer_flags_ |= VP8GetValue(br, 2) << 4;
405 }
406 dec->buffer_flags_ |= VP8Get(br) << 6; // sign bias golden
407 dec->buffer_flags_ |= VP8Get(br) << 7; // sign bias alt ref
408 #else
409 return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
410 "Not a key frame.");
411 #endif
412 } else {
413 dec->buffer_flags_ = 0x003 | 0x100;
414 }
415
416 // Paragraph 9.8
417 #ifndef ONLY_KEYFRAME_CODE
418 dec->update_proba_ = VP8Get(br);
419 if (!dec->update_proba_) { // save for later restore
420 dec->proba_saved_ = dec->proba_;
421 }
422 dec->buffer_flags_ &= 1 << 8;
423 dec->buffer_flags_ |=
424 (frm_hdr->key_frame_ || VP8Get(br)) << 8; // refresh last frame
425 #else
426 VP8Get(br); // just ignore the value of update_proba_
427 #endif
428
429 VP8ParseProba(br, dec);
430
431 #ifdef WEBP_EXPERIMENTAL_FEATURES
432 // Extensions
433 if (dec->pic_hdr_.colorspace_) {
434 const size_t kTrailerSize = 8;
435 const uint8_t kTrailerMarker = 0x01;
436 const uint8_t* ext_buf = buf - kTrailerSize;
437 size_t size;
438
439 if (frm_hdr->partition_length_ < kTrailerSize ||
440 ext_buf[kTrailerSize - 1] != kTrailerMarker) {
441 return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
442 "RIFF: Inconsistent extra information.");
443 }
444
445 // Layer
446 size = (ext_buf[0] << 0) | (ext_buf[1] << 8) | (ext_buf[2] << 16);
447 dec->layer_data_size_ = size;
448 dec->layer_data_ = NULL; // will be set later
449 dec->layer_colorspace_ = ext_buf[3];
450 }
451 #endif
452
453 // sanitized state
454 dec->ready_ = 1;
455 return 1;
456 }
457
458 //------------------------------------------------------------------------------
459 // Residual decoding (Paragraph 13.2 / 13.3)
460
461 static const uint8_t kBands[16 + 1] = {
462 0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
463 0 // extra entry as sentinel
464 };
465
466 static const uint8_t kCat3[] = { 173, 148, 140, 0 };
467 static const uint8_t kCat4[] = { 176, 155, 140, 135, 0 };
468 static const uint8_t kCat5[] = { 180, 157, 141, 134, 130, 0 };
469 static const uint8_t kCat6[] =
470 { 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0 };
471 static const uint8_t* const kCat3456[] = { kCat3, kCat4, kCat5, kCat6 };
472 static const uint8_t kZigzag[16] = {
473 0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
474 };
475
476 typedef const uint8_t (*ProbaArray)[NUM_CTX][NUM_PROBAS]; // for const-casting
477
478 // Returns the position of the last non-zero coeff plus one
479 // (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)480 static int GetCoeffs(VP8BitReader* const br, ProbaArray prob,
481 int ctx, const quant_t dq, int n, int16_t* out) {
482 // n is either 0 or 1 here. kBands[n] is not necessary for extracting '*p'.
483 const uint8_t* p = prob[n][ctx];
484 if (!VP8GetBit(br, p[0])) { // first EOB is more a 'CBP' bit.
485 return 0;
486 }
487 while (1) {
488 ++n;
489 if (!VP8GetBit(br, p[1])) {
490 p = prob[kBands[n]][0];
491 } else { // non zero coeff
492 int v, j;
493 if (!VP8GetBit(br, p[2])) {
494 p = prob[kBands[n]][1];
495 v = 1;
496 } else {
497 if (!VP8GetBit(br, p[3])) {
498 if (!VP8GetBit(br, p[4])) {
499 v = 2;
500 } else {
501 v = 3 + VP8GetBit(br, p[5]);
502 }
503 } else {
504 if (!VP8GetBit(br, p[6])) {
505 if (!VP8GetBit(br, p[7])) {
506 v = 5 + VP8GetBit(br, 159);
507 } else {
508 v = 7 + 2 * VP8GetBit(br, 165);
509 v += VP8GetBit(br, 145);
510 }
511 } else {
512 const uint8_t* tab;
513 const int bit1 = VP8GetBit(br, p[8]);
514 const int bit0 = VP8GetBit(br, p[9 + bit1]);
515 const int cat = 2 * bit1 + bit0;
516 v = 0;
517 for (tab = kCat3456[cat]; *tab; ++tab) {
518 v += v + VP8GetBit(br, *tab);
519 }
520 v += 3 + (8 << cat);
521 }
522 }
523 p = prob[kBands[n]][2];
524 }
525 j = kZigzag[n - 1];
526 out[j] = VP8GetSigned(br, v) * dq[j > 0];
527 if (n == 16 || !VP8GetBit(br, p[0])) { // EOB
528 return n;
529 }
530 }
531 if (n == 16) {
532 return 16;
533 }
534 }
535 }
536
537 // Alias-safe way of converting 4bytes to 32bits.
538 typedef union {
539 uint8_t i8[4];
540 uint32_t i32;
541 } PackedNz;
542
543 // Table to unpack four bits into four bytes
544 static const PackedNz kUnpackTab[16] = {
545 {{0, 0, 0, 0}}, {{1, 0, 0, 0}}, {{0, 1, 0, 0}}, {{1, 1, 0, 0}},
546 {{0, 0, 1, 0}}, {{1, 0, 1, 0}}, {{0, 1, 1, 0}}, {{1, 1, 1, 0}},
547 {{0, 0, 0, 1}}, {{1, 0, 0, 1}}, {{0, 1, 0, 1}}, {{1, 1, 0, 1}},
548 {{0, 0, 1, 1}}, {{1, 0, 1, 1}}, {{0, 1, 1, 1}}, {{1, 1, 1, 1}} };
549
550 // Macro to pack four LSB of four bytes into four bits.
551 #if defined(__PPC__) || defined(_M_PPC) || defined(_ARCH_PPC) || \
552 defined(__BIG_ENDIAN__)
553 #define PACK_CST 0x08040201U
554 #else
555 #define PACK_CST 0x01020408U
556 #endif
557 #define PACK(X, S) ((((X).i32 * PACK_CST) & 0xff000000) >> (S))
558
ParseResiduals(VP8Decoder * const dec,VP8MB * const mb,VP8BitReader * const token_br)559 static void ParseResiduals(VP8Decoder* const dec,
560 VP8MB* const mb, VP8BitReader* const token_br) {
561 int out_t_nz, out_l_nz, first;
562 ProbaArray ac_prob;
563 const VP8QuantMatrix* q = &dec->dqm_[dec->segment_];
564 int16_t* dst = dec->coeffs_;
565 VP8MB* const left_mb = dec->mb_info_ - 1;
566 PackedNz nz_ac, nz_dc;
567 PackedNz tnz, lnz;
568 uint32_t non_zero_ac = 0;
569 uint32_t non_zero_dc = 0;
570 int x, y, ch;
571
572 nz_dc.i32 = nz_ac.i32 = 0;
573 memset(dst, 0, 384 * sizeof(*dst));
574 if (!dec->is_i4x4_) { // parse DC
575 int16_t dc[16] = { 0 };
576 const int ctx = mb->dc_nz_ + left_mb->dc_nz_;
577 mb->dc_nz_ = left_mb->dc_nz_ =
578 (GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[1],
579 ctx, q->y2_mat_, 0, dc) > 0);
580 first = 1;
581 ac_prob = (ProbaArray)dec->proba_.coeffs_[0];
582 VP8TransformWHT(dc, dst);
583 } else {
584 first = 0;
585 ac_prob = (ProbaArray)dec->proba_.coeffs_[3];
586 }
587
588 tnz = kUnpackTab[mb->nz_ & 0xf];
589 lnz = kUnpackTab[left_mb->nz_ & 0xf];
590 for (y = 0; y < 4; ++y) {
591 int l = lnz.i8[y];
592 for (x = 0; x < 4; ++x) {
593 const int ctx = l + tnz.i8[x];
594 const int nz = GetCoeffs(token_br, ac_prob, ctx,
595 q->y1_mat_, first, dst);
596 tnz.i8[x] = l = (nz > 0);
597 nz_dc.i8[x] = (dst[0] != 0);
598 nz_ac.i8[x] = (nz > 1);
599 dst += 16;
600 }
601 lnz.i8[y] = l;
602 non_zero_dc |= PACK(nz_dc, 24 - y * 4);
603 non_zero_ac |= PACK(nz_ac, 24 - y * 4);
604 }
605 out_t_nz = PACK(tnz, 24);
606 out_l_nz = PACK(lnz, 24);
607
608 tnz = kUnpackTab[mb->nz_ >> 4];
609 lnz = kUnpackTab[left_mb->nz_ >> 4];
610 for (ch = 0; ch < 4; ch += 2) {
611 for (y = 0; y < 2; ++y) {
612 int l = lnz.i8[ch + y];
613 for (x = 0; x < 2; ++x) {
614 const int ctx = l + tnz.i8[ch + x];
615 const int nz =
616 GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[2],
617 ctx, q->uv_mat_, 0, dst);
618 tnz.i8[ch + x] = l = (nz > 0);
619 nz_dc.i8[y * 2 + x] = (dst[0] != 0);
620 nz_ac.i8[y * 2 + x] = (nz > 1);
621 dst += 16;
622 }
623 lnz.i8[ch + y] = l;
624 }
625 non_zero_dc |= PACK(nz_dc, 8 - ch * 2);
626 non_zero_ac |= PACK(nz_ac, 8 - ch * 2);
627 }
628 out_t_nz |= PACK(tnz, 20);
629 out_l_nz |= PACK(lnz, 20);
630 mb->nz_ = out_t_nz;
631 left_mb->nz_ = out_l_nz;
632
633 dec->non_zero_ac_ = non_zero_ac;
634 dec->non_zero_ = non_zero_ac | non_zero_dc;
635 mb->skip_ = !dec->non_zero_;
636 }
637 #undef PACK
638
639 //------------------------------------------------------------------------------
640 // Main loop
641
VP8DecodeMB(VP8Decoder * const dec,VP8BitReader * const token_br)642 int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br) {
643 VP8BitReader* const br = &dec->br_;
644 VP8MB* const left = dec->mb_info_ - 1;
645 VP8MB* const info = dec->mb_info_ + dec->mb_x_;
646
647 // Note: we don't save segment map (yet), as we don't expect
648 // to decode more than 1 keyframe.
649 if (dec->segment_hdr_.update_map_) {
650 // Hardcoded tree parsing
651 dec->segment_ = !VP8GetBit(br, dec->proba_.segments_[0]) ?
652 VP8GetBit(br, dec->proba_.segments_[1]) :
653 2 + VP8GetBit(br, dec->proba_.segments_[2]);
654 }
655 info->skip_ = dec->use_skip_proba_ ? VP8GetBit(br, dec->skip_p_) : 0;
656
657 VP8ParseIntraMode(br, dec);
658 if (br->eof_) {
659 return 0;
660 }
661
662 if (!info->skip_) {
663 ParseResiduals(dec, info, token_br);
664 } else {
665 left->nz_ = info->nz_ = 0;
666 if (!dec->is_i4x4_) {
667 left->dc_nz_ = info->dc_nz_ = 0;
668 }
669 dec->non_zero_ = 0;
670 dec->non_zero_ac_ = 0;
671 }
672
673 return (!token_br->eof_);
674 }
675
VP8InitScanline(VP8Decoder * const dec)676 void VP8InitScanline(VP8Decoder* const dec) {
677 VP8MB* const left = dec->mb_info_ - 1;
678 left->nz_ = 0;
679 left->dc_nz_ = 0;
680 memset(dec->intra_l_, B_DC_PRED, sizeof(dec->intra_l_));
681 dec->filter_row_ =
682 (dec->filter_type_ > 0) &&
683 (dec->mb_y_ >= dec->tl_mb_y_) && (dec->mb_y_ <= dec->br_mb_y_);
684 }
685
ParseFrame(VP8Decoder * const dec,VP8Io * io)686 static int ParseFrame(VP8Decoder* const dec, VP8Io* io) {
687 for (dec->mb_y_ = 0; dec->mb_y_ < dec->br_mb_y_; ++dec->mb_y_) {
688 VP8BitReader* const token_br =
689 &dec->parts_[dec->mb_y_ & (dec->num_parts_ - 1)];
690 VP8InitScanline(dec);
691 for (dec->mb_x_ = 0; dec->mb_x_ < dec->mb_w_; dec->mb_x_++) {
692 if (!VP8DecodeMB(dec, token_br)) {
693 return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
694 "Premature end-of-file encountered.");
695 }
696 VP8ReconstructBlock(dec);
697
698 // Store data and save block's filtering params
699 VP8StoreBlock(dec);
700 }
701 if (!VP8ProcessRow(dec, io)) {
702 return VP8SetError(dec, VP8_STATUS_USER_ABORT, "Output aborted.");
703 }
704 }
705 if (dec->use_threads_ && !WebPWorkerSync(&dec->worker_)) {
706 return 0;
707 }
708
709 // Finish
710 #ifndef ONLY_KEYFRAME_CODE
711 if (!dec->update_proba_) {
712 dec->proba_ = dec->proba_saved_;
713 }
714 #endif
715
716 #ifdef WEBP_EXPERIMENTAL_FEATURES
717 if (dec->layer_data_size_ > 0) {
718 if (!VP8DecodeLayer(dec)) {
719 return 0;
720 }
721 }
722 #endif
723
724 return 1;
725 }
726
727 // Main entry point
VP8Decode(VP8Decoder * const dec,VP8Io * const io)728 int VP8Decode(VP8Decoder* const dec, VP8Io* const io) {
729 int ok = 0;
730 if (dec == NULL) {
731 return 0;
732 }
733 if (io == NULL) {
734 return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
735 "NULL VP8Io parameter in VP8Decode().");
736 }
737
738 if (!dec->ready_) {
739 if (!VP8GetHeaders(dec, io)) {
740 return 0;
741 }
742 }
743 assert(dec->ready_);
744
745 // Finish setting up the decoding parameter. Will call io->setup().
746 ok = (VP8EnterCritical(dec, io) == VP8_STATUS_OK);
747 if (ok) { // good to go.
748 // Will allocate memory and prepare everything.
749 if (ok) ok = VP8InitFrame(dec, io);
750
751 // Main decoding loop
752 if (ok) ok = ParseFrame(dec, io);
753
754 // Exit.
755 ok &= VP8ExitCritical(dec, io);
756 }
757
758 if (!ok) {
759 VP8Clear(dec);
760 return 0;
761 }
762
763 dec->ready_ = 0;
764 return ok;
765 }
766
VP8Clear(VP8Decoder * const dec)767 void VP8Clear(VP8Decoder* const dec) {
768 if (dec == NULL) {
769 return;
770 }
771 if (dec->use_threads_) {
772 WebPWorkerEnd(&dec->worker_);
773 }
774 if (dec->mem_) {
775 free(dec->mem_);
776 }
777 dec->mem_ = NULL;
778 dec->mem_size_ = 0;
779 memset(&dec->br_, 0, sizeof(dec->br_));
780 dec->ready_ = 0;
781 }
782
783 //------------------------------------------------------------------------------
784
785 #if defined(__cplusplus) || defined(c_plusplus)
786 } // extern "C"
787 #endif
788