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 decoding functions for WEBP images.
11//
12// Author: Skal (pascal.massimino@gmail.com)
13
14#include <stdlib.h>
15
16#include "src/dec/vp8i_dec.h"
17#include "src/dec/vp8li_dec.h"
18#include "src/dec/webpi_dec.h"
19#include "src/utils/utils.h"
20#include "src/webp/mux_types.h" // ALPHA_FLAG
21
22//------------------------------------------------------------------------------
23// RIFF layout is:
24// Offset tag
25// 0...3 "RIFF" 4-byte tag
26// 4...7 size of image data (including metadata) starting at offset 8
27// 8...11 "WEBP" our form-type signature
28// The RIFF container (12 bytes) is followed by appropriate chunks:
29// 12..15 "VP8 ": 4-bytes tags, signaling the use of VP8 video format
30// 16..19 size of the raw VP8 image data, starting at offset 20
31// 20.... the VP8 bytes
32// Or,
33// 12..15 "VP8L": 4-bytes tags, signaling the use of VP8L lossless format
34// 16..19 size of the raw VP8L image data, starting at offset 20
35// 20.... the VP8L bytes
36// Or,
37// 12..15 "VP8X": 4-bytes tags, describing the extended-VP8 chunk.
38// 16..19 size of the VP8X chunk starting at offset 20.
39// 20..23 VP8X flags bit-map corresponding to the chunk-types present.
40// 24..26 Width of the Canvas Image.
41// 27..29 Height of the Canvas Image.
42// There can be extra chunks after the "VP8X" chunk (ICCP, ANMF, VP8, VP8L,
43// XMP, EXIF ...)
44// All sizes are in little-endian order.
45// Note: chunk data size must be padded to multiple of 2 when written.
46
47// Validates the RIFF container (if detected) and skips over it.
48// If a RIFF container is detected, returns:
49// VP8_STATUS_BITSTREAM_ERROR for invalid header,
50// VP8_STATUS_NOT_ENOUGH_DATA for truncated data if have_all_data is true,
51// and VP8_STATUS_OK otherwise.
52// In case there are not enough bytes (partial RIFF container), return 0 for
53// *riff_size. Else return the RIFF size extracted from the header.
54static VP8StatusCode ParseRIFF(const uint8_t** const data,
55 size_t* const data_size, int have_all_data,
56 size_t* const riff_size) {
57 assert(data != NULL);
58 assert(data_size != NULL);
59 assert(riff_size != NULL);
60
61 *riff_size = 0; // Default: no RIFF present.
62 if (*data_size >= RIFF_HEADER_SIZE && !memcmp(*data, "RIFF", TAG_SIZE)) {
63 if (memcmp(*data + 8, "WEBP", TAG_SIZE)) {
64 return VP8_STATUS_BITSTREAM_ERROR; // Wrong image file signature.
65 } else {
66 const uint32_t size = GetLE32(*data + TAG_SIZE);
67 // Check that we have at least one chunk (i.e "WEBP" + "VP8?nnnn").
68 if (size < TAG_SIZE + CHUNK_HEADER_SIZE) {
69 return VP8_STATUS_BITSTREAM_ERROR;
70 }
71 if (size > MAX_CHUNK_PAYLOAD) {
72 return VP8_STATUS_BITSTREAM_ERROR;
73 }
74 if (have_all_data && (size > *data_size - CHUNK_HEADER_SIZE)) {
75 return VP8_STATUS_NOT_ENOUGH_DATA; // Truncated bitstream.
76 }
77 // We have a RIFF container. Skip it.
78 *riff_size = size;
79 *data += RIFF_HEADER_SIZE;
80 *data_size -= RIFF_HEADER_SIZE;
81 }
82 }
83 return VP8_STATUS_OK;
84}
85
86// Validates the VP8X header and skips over it.
87// Returns VP8_STATUS_BITSTREAM_ERROR for invalid VP8X header,
88// VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
89// VP8_STATUS_OK otherwise.
90// If a VP8X chunk is found, found_vp8x is set to true and *width_ptr,
91// *height_ptr and *flags_ptr are set to the corresponding values extracted
92// from the VP8X chunk.
93static VP8StatusCode ParseVP8X(const uint8_t** const data,
94 size_t* const data_size,
95 int* const found_vp8x,
96 int* const width_ptr, int* const height_ptr,
97 uint32_t* const flags_ptr) {
98 const uint32_t vp8x_size = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
99 assert(data != NULL);
100 assert(data_size != NULL);
101 assert(found_vp8x != NULL);
102
103 *found_vp8x = 0;
104
105 if (*data_size < CHUNK_HEADER_SIZE) {
106 return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
107 }
108
109 if (!memcmp(*data, "VP8X", TAG_SIZE)) {
110 int width, height;
111 uint32_t flags;
112 const uint32_t chunk_size = GetLE32(*data + TAG_SIZE);
113 if (chunk_size != VP8X_CHUNK_SIZE) {
114 return VP8_STATUS_BITSTREAM_ERROR; // Wrong chunk size.
115 }
116
117 // Verify if enough data is available to validate the VP8X chunk.
118 if (*data_size < vp8x_size) {
119 return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
120 }
121 flags = GetLE32(*data + 8);
122 width = 1 + GetLE24(*data + 12);
123 height = 1 + GetLE24(*data + 15);
124 if (width * (uint64_t)height >= MAX_IMAGE_AREA) {
125 return VP8_STATUS_BITSTREAM_ERROR; // image is too large
126 }
127
128 if (flags_ptr != NULL) *flags_ptr = flags;
129 if (width_ptr != NULL) *width_ptr = width;
130 if (height_ptr != NULL) *height_ptr = height;
131 // Skip over VP8X header bytes.
132 *data += vp8x_size;
133 *data_size -= vp8x_size;
134 *found_vp8x = 1;
135 }
136 return VP8_STATUS_OK;
137}
138
139// Skips to the next VP8/VP8L chunk header in the data given the size of the
140// RIFF chunk 'riff_size'.
141// Returns VP8_STATUS_BITSTREAM_ERROR if any invalid chunk size is encountered,
142// VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
143// VP8_STATUS_OK otherwise.
144// If an alpha chunk is found, *alpha_data and *alpha_size are set
145// appropriately.
146static VP8StatusCode ParseOptionalChunks(const uint8_t** const data,
147 size_t* const data_size,
148 size_t const riff_size,
149 const uint8_t** const alpha_data,
150 size_t* const alpha_size) {
151 const uint8_t* buf;
152 size_t buf_size;
153 uint32_t total_size = TAG_SIZE + // "WEBP".
154 CHUNK_HEADER_SIZE + // "VP8Xnnnn".
155 VP8X_CHUNK_SIZE; // data.
156 assert(data != NULL);
157 assert(data_size != NULL);
158 buf = *data;
159 buf_size = *data_size;
160
161 assert(alpha_data != NULL);
162 assert(alpha_size != NULL);
163 *alpha_data = NULL;
164 *alpha_size = 0;
165
166 while (1) {
167 uint32_t chunk_size;
168 uint32_t disk_chunk_size; // chunk_size with padding
169
170 *data = buf;
171 *data_size = buf_size;
172
173 if (buf_size < CHUNK_HEADER_SIZE) { // Insufficient data.
174 return VP8_STATUS_NOT_ENOUGH_DATA;
175 }
176
177 chunk_size = GetLE32(buf + TAG_SIZE);
178 if (chunk_size > MAX_CHUNK_PAYLOAD) {
179 return VP8_STATUS_BITSTREAM_ERROR; // Not a valid chunk size.
180 }
181 // For odd-sized chunk-payload, there's one byte padding at the end.
182 disk_chunk_size = (CHUNK_HEADER_SIZE + chunk_size + 1) & ~1u;
183 total_size += disk_chunk_size;
184
185 // Check that total bytes skipped so far does not exceed riff_size.
186 if (riff_size > 0 && (total_size > riff_size)) {
187 return VP8_STATUS_BITSTREAM_ERROR; // Not a valid chunk size.
188 }
189
190 // Start of a (possibly incomplete) VP8/VP8L chunk implies that we have
191 // parsed all the optional chunks.
192 // Note: This check must occur before the check 'buf_size < disk_chunk_size'
193 // below to allow incomplete VP8/VP8L chunks.
194 if (!memcmp(buf, "VP8 ", TAG_SIZE) ||
195 !memcmp(buf, "VP8L", TAG_SIZE)) {
196 return VP8_STATUS_OK;
197 }
198
199 if (buf_size < disk_chunk_size) { // Insufficient data.
200 return VP8_STATUS_NOT_ENOUGH_DATA;
201 }
202
203 if (!memcmp(buf, "ALPH", TAG_SIZE)) { // A valid ALPH header.
204 *alpha_data = buf + CHUNK_HEADER_SIZE;
205 *alpha_size = chunk_size;
206 }
207
208 // We have a full and valid chunk; skip it.
209 buf += disk_chunk_size;
210 buf_size -= disk_chunk_size;
211 }
212}
213
214// Validates the VP8/VP8L Header ("VP8 nnnn" or "VP8L nnnn") and skips over it.
215// Returns VP8_STATUS_BITSTREAM_ERROR for invalid (chunk larger than
216// riff_size) VP8/VP8L header,
217// VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
218// VP8_STATUS_OK otherwise.
219// If a VP8/VP8L chunk is found, *chunk_size is set to the total number of bytes
220// extracted from the VP8/VP8L chunk header.
221// The flag '*is_lossless' is set to 1 in case of VP8L chunk / raw VP8L data.
222static VP8StatusCode ParseVP8Header(const uint8_t** const data_ptr,
223 size_t* const data_size, int have_all_data,
224 size_t riff_size, size_t* const chunk_size,
225 int* const is_lossless) {
226 const uint8_t* const data = *data_ptr;
227 const int is_vp8 = !memcmp(data, "VP8 ", TAG_SIZE);
228 const int is_vp8l = !memcmp(data, "VP8L", TAG_SIZE);
229 const uint32_t minimal_size =
230 TAG_SIZE + CHUNK_HEADER_SIZE; // "WEBP" + "VP8 nnnn" OR
231 // "WEBP" + "VP8Lnnnn"
232 assert(data != NULL);
233 assert(data_size != NULL);
234 assert(chunk_size != NULL);
235 assert(is_lossless != NULL);
236
237 if (*data_size < CHUNK_HEADER_SIZE) {
238 return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
239 }
240
241 if (is_vp8 || is_vp8l) {
242 // Bitstream contains VP8/VP8L header.
243 const uint32_t size = GetLE32(data + TAG_SIZE);
244 if ((riff_size >= minimal_size) && (size > riff_size - minimal_size)) {
245 return VP8_STATUS_BITSTREAM_ERROR; // Inconsistent size information.
246 }
247 if (have_all_data && (size > *data_size - CHUNK_HEADER_SIZE)) {
248 return VP8_STATUS_NOT_ENOUGH_DATA; // Truncated bitstream.
249 }
250 // Skip over CHUNK_HEADER_SIZE bytes from VP8/VP8L Header.
251 *chunk_size = size;
252 *data_ptr += CHUNK_HEADER_SIZE;
253 *data_size -= CHUNK_HEADER_SIZE;
254 *is_lossless = is_vp8l;
255 } else {
256 // Raw VP8/VP8L bitstream (no header).
257 *is_lossless = VP8LCheckSignature(data, *data_size);
258 *chunk_size = *data_size;
259 }
260
261 return VP8_STATUS_OK;
262}
263
264//------------------------------------------------------------------------------
265
266// Fetch '*width', '*height', '*has_alpha' and fill out 'headers' based on
267// 'data'. All the output parameters may be NULL. If 'headers' is NULL only the
268// minimal amount will be read to fetch the remaining parameters.
269// If 'headers' is non-NULL this function will attempt to locate both alpha
270// data (with or without a VP8X chunk) and the bitstream chunk (VP8/VP8L).
271// Note: The following chunk sequences (before the raw VP8/VP8L data) are
272// considered valid by this function:
273// RIFF + VP8(L)
274// RIFF + VP8X + (optional chunks) + VP8(L)
275// ALPH + VP8 <-- Not a valid WebP format: only allowed for internal purpose.
276// VP8(L) <-- Not a valid WebP format: only allowed for internal purpose.
277static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
278 size_t data_size,
279 int* const width,
280 int* const height,
281 int* const has_alpha,
282 int* const has_animation,
283 int* const format,
284 WebPHeaderStructure* const headers) {
285 int canvas_width = 0;
286 int canvas_height = 0;
287 int image_width = 0;
288 int image_height = 0;
289 int found_riff = 0;
290 int found_vp8x = 0;
291 int animation_present = 0;
292 const int have_all_data = (headers != NULL) ? headers->have_all_data : 0;
293
294 VP8StatusCode status;
295 WebPHeaderStructure hdrs;
296
297 if (data == NULL || data_size < RIFF_HEADER_SIZE) {
298 return VP8_STATUS_NOT_ENOUGH_DATA;
299 }
300 memset(&hdrs, 0, sizeof(hdrs));
301 hdrs.data = data;
302 hdrs.data_size = data_size;
303
304 // Skip over RIFF header.
305 status = ParseRIFF(&data, &data_size, have_all_data, &hdrs.riff_size);
306 if (status != VP8_STATUS_OK) {
307 return status; // Wrong RIFF header / insufficient data.
308 }
309 found_riff = (hdrs.riff_size > 0);
310
311 // Skip over VP8X.
312 {
313 uint32_t flags = 0;
314 status = ParseVP8X(&data, &data_size, &found_vp8x,
315 &canvas_width, &canvas_height, &flags);
316 if (status != VP8_STATUS_OK) {
317 return status; // Wrong VP8X / insufficient data.
318 }
319 animation_present = !!(flags & ANIMATION_FLAG);
320 if (!found_riff && found_vp8x) {
321 // Note: This restriction may be removed in the future, if it becomes
322 // necessary to send VP8X chunk to the decoder.
323 return VP8_STATUS_BITSTREAM_ERROR;
324 }
325 if (has_alpha != NULL) *has_alpha = !!(flags & ALPHA_FLAG);
326 if (has_animation != NULL) *has_animation = animation_present;
327 if (format != NULL) *format = 0; // default = undefined
328
329 image_width = canvas_width;
330 image_height = canvas_height;
331 if (found_vp8x && animation_present && headers == NULL) {
332 status = VP8_STATUS_OK;
333 goto ReturnWidthHeight; // Just return features from VP8X header.
334 }
335 }
336
337 if (data_size < TAG_SIZE) {
338 status = VP8_STATUS_NOT_ENOUGH_DATA;
339 goto ReturnWidthHeight;
340 }
341
342 // Skip over optional chunks if data started with "RIFF + VP8X" or "ALPH".
343 if ((found_riff && found_vp8x) ||
344 (!found_riff && !found_vp8x && !memcmp(data, "ALPH", TAG_SIZE))) {
345 status = ParseOptionalChunks(&data, &data_size, hdrs.riff_size,
346 &hdrs.alpha_data, &hdrs.alpha_data_size);
347 if (status != VP8_STATUS_OK) {
348 goto ReturnWidthHeight; // Invalid chunk size / insufficient data.
349 }
350 }
351
352 // Skip over VP8/VP8L header.
353 status = ParseVP8Header(&data, &data_size, have_all_data, hdrs.riff_size,
354 &hdrs.compressed_size, &hdrs.is_lossless);
355 if (status != VP8_STATUS_OK) {
356 goto ReturnWidthHeight; // Wrong VP8/VP8L chunk-header / insufficient data.
357 }
358 if (hdrs.compressed_size > MAX_CHUNK_PAYLOAD) {
359 return VP8_STATUS_BITSTREAM_ERROR;
360 }
361
362 if (format != NULL && !animation_present) {
363 *format = hdrs.is_lossless ? 2 : 1;
364 }
365
366 if (!hdrs.is_lossless) {
367 if (data_size < VP8_FRAME_HEADER_SIZE) {
368 status = VP8_STATUS_NOT_ENOUGH_DATA;
369 goto ReturnWidthHeight;
370 }
371 // Validates raw VP8 data.
372 if (!VP8GetInfo(data, data_size, (uint32_t)hdrs.compressed_size,
373 &image_width, &image_height)) {
374 return VP8_STATUS_BITSTREAM_ERROR;
375 }
376 } else {
377 if (data_size < VP8L_FRAME_HEADER_SIZE) {
378 status = VP8_STATUS_NOT_ENOUGH_DATA;
379 goto ReturnWidthHeight;
380 }
381 // Validates raw VP8L data.
382 if (!VP8LGetInfo(data, data_size, &image_width, &image_height, has_alpha)) {
383 return VP8_STATUS_BITSTREAM_ERROR;
384 }
385 }
386 // Validates image size coherency.
387 if (found_vp8x) {
388 if (canvas_width != image_width || canvas_height != image_height) {
389 return VP8_STATUS_BITSTREAM_ERROR;
390 }
391 }
392 if (headers != NULL) {
393 *headers = hdrs;
394 headers->offset = data - headers->data;
395 assert((uint64_t)(data - headers->data) < MAX_CHUNK_PAYLOAD);
396 assert(headers->offset == headers->data_size - data_size);
397 }
398 ReturnWidthHeight:
399 if (status == VP8_STATUS_OK ||
400 (status == VP8_STATUS_NOT_ENOUGH_DATA && found_vp8x && headers == NULL)) {
401 if (has_alpha != NULL) {
402 // If the data did not contain a VP8X/VP8L chunk the only definitive way
403 // to set this is by looking for alpha data (from an ALPH chunk).
404 *has_alpha |= (hdrs.alpha_data != NULL);
405 }
406 if (width != NULL) *width = image_width;
407 if (height != NULL) *height = image_height;
408 return VP8_STATUS_OK;
409 } else {
410 return status;
411 }
412}
413
414VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers) {
415 // status is marked volatile as a workaround for a clang-3.8 (aarch64) bug
416 volatile VP8StatusCode status;
417 int has_animation = 0;
418 assert(headers != NULL);
419 // fill out headers, ignore width/height/has_alpha.
420 status = ParseHeadersInternal(headers->data, headers->data_size,
421 NULL, NULL, NULL, &has_animation,
422 NULL, headers);
423 if (status == VP8_STATUS_OK || status == VP8_STATUS_NOT_ENOUGH_DATA) {
424 // The WebPDemux API + libwebp can be used to decode individual
425 // uncomposited frames or the WebPAnimDecoder can be used to fully
426 // reconstruct them (see webp/demux.h).
427 if (has_animation) {
428 status = VP8_STATUS_UNSUPPORTED_FEATURE;
429 }
430 }
431 return status;
432}
433
434//------------------------------------------------------------------------------
435// WebPDecParams
436
437void WebPResetDecParams(WebPDecParams* const params) {
438 if (params != NULL) {
439 memset(params, 0, sizeof(*params));
440 }
441}
442
443//------------------------------------------------------------------------------
444// "Into" decoding variants
445
446// Main flow
447static VP8StatusCode DecodeInto(const uint8_t* const data, size_t data_size,
448 WebPDecParams* const params) {
449 VP8StatusCode status;
450 VP8Io io;
451 WebPHeaderStructure headers;
452
453 headers.data = data;
454 headers.data_size = data_size;
455 headers.have_all_data = 1;
456 status = WebPParseHeaders(&headers); // Process Pre-VP8 chunks.
457 if (status != VP8_STATUS_OK) {
458 return status;
459 }
460
461 assert(params != NULL);
462 VP8InitIo(&io);
463 io.data = headers.data + headers.offset;
464 io.data_size = headers.data_size - headers.offset;
465 WebPInitCustomIo(params, &io); // Plug the I/O functions.
466
467 if (!headers.is_lossless) {
468 VP8Decoder* const dec = VP8New();
469 if (dec == NULL) {
470 return VP8_STATUS_OUT_OF_MEMORY;
471 }
472 dec->alpha_data_ = headers.alpha_data;
473 dec->alpha_data_size_ = headers.alpha_data_size;
474
475 // Decode bitstream header, update io->width/io->height.
476 if (!VP8GetHeaders(dec, &io)) {
477 status = dec->status_; // An error occurred. Grab error status.
478 } else {
479 // Allocate/check output buffers.
480 status = WebPAllocateDecBuffer(io.width, io.height, params->options,
481 params->output);
482 if (status == VP8_STATUS_OK) { // Decode
483 // This change must be done before calling VP8Decode()
484 dec->mt_method_ = VP8GetThreadMethod(params->options, &headers,
485 io.width, io.height);
486 VP8InitDithering(params->options, dec);
487 if (!VP8Decode(dec, &io)) {
488 status = dec->status_;
489 }
490 }
491 }
492 VP8Delete(dec);
493 } else {
494 VP8LDecoder* const dec = VP8LNew();
495 if (dec == NULL) {
496 return VP8_STATUS_OUT_OF_MEMORY;
497 }
498 if (!VP8LDecodeHeader(dec, &io)) {
499 status = dec->status_; // An error occurred. Grab error status.
500 } else {
501 // Allocate/check output buffers.
502 status = WebPAllocateDecBuffer(io.width, io.height, params->options,
503 params->output);
504 if (status == VP8_STATUS_OK) { // Decode
505 if (!VP8LDecodeImage(dec)) {
506 status = dec->status_;
507 }
508 }
509 }
510 VP8LDelete(dec);
511 }
512
513 if (status != VP8_STATUS_OK) {
514 WebPFreeDecBuffer(params->output);
515 } else {
516 if (params->options != NULL && params->options->flip) {
517 // This restores the original stride values if options->flip was used
518 // during the call to WebPAllocateDecBuffer above.
519 status = WebPFlipBuffer(params->output);
520 }
521 }
522 return status;
523}
524
525// Helpers
526static uint8_t* DecodeIntoRGBABuffer(WEBP_CSP_MODE colorspace,
527 const uint8_t* const data,
528 size_t data_size,
529 uint8_t* const rgba,
530 int stride, size_t size) {
531 WebPDecParams params;
532 WebPDecBuffer buf;
533 if (rgba == NULL) {
534 return NULL;
535 }
536 WebPInitDecBuffer(&buf);
537 WebPResetDecParams(&params);
538 params.output = &buf;
539 buf.colorspace = colorspace;
540 buf.u.RGBA.rgba = rgba;
541 buf.u.RGBA.stride = stride;
542 buf.u.RGBA.size = size;
543 buf.is_external_memory = 1;
544 if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
545 return NULL;
546 }
547 return rgba;
548}
549
550uint8_t* WebPDecodeRGBInto(const uint8_t* data, size_t data_size,
551 uint8_t* output, size_t size, int stride) {
552 return DecodeIntoRGBABuffer(MODE_RGB, data, data_size, output, stride, size);
553}
554
555uint8_t* WebPDecodeRGBAInto(const uint8_t* data, size_t data_size,
556 uint8_t* output, size_t size, int stride) {
557 return DecodeIntoRGBABuffer(MODE_RGBA, data, data_size, output, stride, size);
558}
559
560uint8_t* WebPDecodeARGBInto(const uint8_t* data, size_t data_size,
561 uint8_t* output, size_t size, int stride) {
562 return DecodeIntoRGBABuffer(MODE_ARGB, data, data_size, output, stride, size);
563}
564
565uint8_t* WebPDecodeBGRInto(const uint8_t* data, size_t data_size,
566 uint8_t* output, size_t size, int stride) {
567 return DecodeIntoRGBABuffer(MODE_BGR, data, data_size, output, stride, size);
568}
569
570uint8_t* WebPDecodeBGRAInto(const uint8_t* data, size_t data_size,
571 uint8_t* output, size_t size, int stride) {
572 return DecodeIntoRGBABuffer(MODE_BGRA, data, data_size, output, stride, size);
573}
574
575uint8_t* WebPDecodeYUVInto(const uint8_t* data, size_t data_size,
576 uint8_t* luma, size_t luma_size, int luma_stride,
577 uint8_t* u, size_t u_size, int u_stride,
578 uint8_t* v, size_t v_size, int v_stride) {
579 WebPDecParams params;
580 WebPDecBuffer output;
581 if (luma == NULL) return NULL;
582 WebPInitDecBuffer(&output);
583 WebPResetDecParams(&params);
584 params.output = &output;
585 output.colorspace = MODE_YUV;
586 output.u.YUVA.y = luma;
587 output.u.YUVA.y_stride = luma_stride;
588 output.u.YUVA.y_size = luma_size;
589 output.u.YUVA.u = u;
590 output.u.YUVA.u_stride = u_stride;
591 output.u.YUVA.u_size = u_size;
592 output.u.YUVA.v = v;
593 output.u.YUVA.v_stride = v_stride;
594 output.u.YUVA.v_size = v_size;
595 output.is_external_memory = 1;
596 if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
597 return NULL;
598 }
599 return luma;
600}
601
602//------------------------------------------------------------------------------
603
604static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* const data,
605 size_t data_size, int* const width, int* const height,
606 WebPDecBuffer* const keep_info) {
607 WebPDecParams params;
608 WebPDecBuffer output;
609
610 WebPInitDecBuffer(&output);
611 WebPResetDecParams(&params);
612 params.output = &output;
613 output.colorspace = mode;
614
615 // Retrieve (and report back) the required dimensions from bitstream.
616 if (!WebPGetInfo(data, data_size, &output.width, &output.height)) {
617 return NULL;
618 }
619 if (width != NULL) *width = output.width;
620 if (height != NULL) *height = output.height;
621
622 // Decode
623 if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
624 return NULL;
625 }
626 if (keep_info != NULL) { // keep track of the side-info
627 WebPCopyDecBuffer(&output, keep_info);
628 }
629 // return decoded samples (don't clear 'output'!)
630 return WebPIsRGBMode(mode) ? output.u.RGBA.rgba : output.u.YUVA.y;
631}
632
633uint8_t* WebPDecodeRGB(const uint8_t* data, size_t data_size,
634 int* width, int* height) {
635 return Decode(MODE_RGB, data, data_size, width, height, NULL);
636}
637
638uint8_t* WebPDecodeRGBA(const uint8_t* data, size_t data_size,
639 int* width, int* height) {
640 return Decode(MODE_RGBA, data, data_size, width, height, NULL);
641}
642
643uint8_t* WebPDecodeARGB(const uint8_t* data, size_t data_size,
644 int* width, int* height) {
645 return Decode(MODE_ARGB, data, data_size, width, height, NULL);
646}
647
648uint8_t* WebPDecodeBGR(const uint8_t* data, size_t data_size,
649 int* width, int* height) {
650 return Decode(MODE_BGR, data, data_size, width, height, NULL);
651}
652
653uint8_t* WebPDecodeBGRA(const uint8_t* data, size_t data_size,
654 int* width, int* height) {
655 return Decode(MODE_BGRA, data, data_size, width, height, NULL);
656}
657
658uint8_t* WebPDecodeYUV(const uint8_t* data, size_t data_size,
659 int* width, int* height, uint8_t** u, uint8_t** v,
660 int* stride, int* uv_stride) {
661 // data, width and height are checked by Decode().
662 if (u == NULL || v == NULL || stride == NULL || uv_stride == NULL) {
663 return NULL;
664 }
665
666 {
667 WebPDecBuffer output; // only to preserve the side-infos
668 uint8_t* const out = Decode(MODE_YUV, data, data_size,
669 width, height, &output);
670
671 if (out != NULL) {
672 const WebPYUVABuffer* const buf = &output.u.YUVA;
673 *u = buf->u;
674 *v = buf->v;
675 *stride = buf->y_stride;
676 *uv_stride = buf->u_stride;
677 assert(buf->u_stride == buf->v_stride);
678 }
679 return out;
680 }
681}
682
683static void DefaultFeatures(WebPBitstreamFeatures* const features) {
684 assert(features != NULL);
685 memset(features, 0, sizeof(*features));
686}
687
688static VP8StatusCode GetFeatures(const uint8_t* const data, size_t data_size,
689 WebPBitstreamFeatures* const features) {
690 if (features == NULL || data == NULL) {
691 return VP8_STATUS_INVALID_PARAM;
692 }
693 DefaultFeatures(features);
694
695 // Only parse enough of the data to retrieve the features.
696 return ParseHeadersInternal(data, data_size,
697 &features->width, &features->height,
698 &features->has_alpha, &features->has_animation,
699 &features->format, NULL);
700}
701
702//------------------------------------------------------------------------------
703// WebPGetInfo()
704
705int WebPGetInfo(const uint8_t* data, size_t data_size,
706 int* width, int* height) {
707 WebPBitstreamFeatures features;
708
709 if (GetFeatures(data, data_size, &features) != VP8_STATUS_OK) {
710 return 0;
711 }
712
713 if (width != NULL) {
714 *width = features.width;
715 }
716 if (height != NULL) {
717 *height = features.height;
718 }
719
720 return 1;
721}
722
723//------------------------------------------------------------------------------
724// Advance decoding API
725
726int WebPInitDecoderConfigInternal(WebPDecoderConfig* config,
727 int version) {
728 if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
729 return 0; // version mismatch
730 }
731 if (config == NULL) {
732 return 0;
733 }
734 memset(config, 0, sizeof(*config));
735 DefaultFeatures(&config->input);
736 WebPInitDecBuffer(&config->output);
737 return 1;
738}
739
740VP8StatusCode WebPGetFeaturesInternal(const uint8_t* data, size_t data_size,
741 WebPBitstreamFeatures* features,
742 int version) {
743 if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
744 return VP8_STATUS_INVALID_PARAM; // version mismatch
745 }
746 if (features == NULL) {
747 return VP8_STATUS_INVALID_PARAM;
748 }
749 return GetFeatures(data, data_size, features);
750}
751
752VP8StatusCode WebPDecode(const uint8_t* data, size_t data_size,
753 WebPDecoderConfig* config) {
754 WebPDecParams params;
755 VP8StatusCode status;
756
757 if (config == NULL) {
758 return VP8_STATUS_INVALID_PARAM;
759 }
760
761 status = GetFeatures(data, data_size, &config->input);
762 if (status != VP8_STATUS_OK) {
763 if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
764 return VP8_STATUS_BITSTREAM_ERROR; // Not-enough-data treated as error.
765 }
766 return status;
767 }
768
769 WebPResetDecParams(&params);
770 params.options = &config->options;
771 params.output = &config->output;
772 if (WebPAvoidSlowMemory(params.output, &config->input)) {
773 // decoding to slow memory: use a temporary in-mem buffer to decode into.
774 WebPDecBuffer in_mem_buffer;
775 WebPInitDecBuffer(&in_mem_buffer);
776 in_mem_buffer.colorspace = config->output.colorspace;
777 in_mem_buffer.width = config->input.width;
778 in_mem_buffer.height = config->input.height;
779 params.output = &in_mem_buffer;
780 status = DecodeInto(data, data_size, &params);
781 if (status == VP8_STATUS_OK) { // do the slow-copy
782 status = WebPCopyDecBufferPixels(&in_mem_buffer, &config->output);
783 }
784 WebPFreeDecBuffer(&in_mem_buffer);
785 } else {
786 status = DecodeInto(data, data_size, &params);
787 }
788
789 return status;
790}
791
792//------------------------------------------------------------------------------
793// Cropping and rescaling.
794
795int WebPCheckCropDimensions(int image_width, int image_height,
796 int x, int y, int w, int h) {
797 return !(x < 0 || y < 0 || w <= 0 || h <= 0 ||
798 x >= image_width || w > image_width || w > image_width - x ||
799 y >= image_height || h > image_height || h > image_height - y);
800}
801
802int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
803 VP8Io* const io, WEBP_CSP_MODE src_colorspace) {
804 const int W = io->width;
805 const int H = io->height;
806 int x = 0, y = 0, w = W, h = H;
807
808 // Cropping
809 io->use_cropping = (options != NULL) && options->use_cropping;
810 if (io->use_cropping) {
811 w = options->crop_width;
812 h = options->crop_height;
813 x = options->crop_left;
814 y = options->crop_top;
815 if (!WebPIsRGBMode(src_colorspace)) { // only snap for YUV420
816 x &= ~1;
817 y &= ~1;
818 }
819 if (!WebPCheckCropDimensions(W, H, x, y, w, h)) {
820 return 0; // out of frame boundary error
821 }
822 }
823 io->crop_left = x;
824 io->crop_top = y;
825 io->crop_right = x + w;
826 io->crop_bottom = y + h;
827 io->mb_w = w;
828 io->mb_h = h;
829
830 // Scaling
831 io->use_scaling = (options != NULL) && options->use_scaling;
832 if (io->use_scaling) {
833 int scaled_width = options->scaled_width;
834 int scaled_height = options->scaled_height;
835 if (!WebPRescalerGetScaledDimensions(w, h, &scaled_width, &scaled_height)) {
836 return 0;
837 }
838 io->scaled_width = scaled_width;
839 io->scaled_height = scaled_height;
840 }
841
842 // Filter
843 io->bypass_filtering = (options != NULL) && options->bypass_filtering;
844
845 // Fancy upsampler
846#ifdef FANCY_UPSAMPLING
847 io->fancy_upsampling = (options == NULL) || (!options->no_fancy_upsampling);
848#endif
849
850 if (io->use_scaling) {
851 // disable filter (only for large downscaling ratio).
852 io->bypass_filtering |= (io->scaled_width < W * 3 / 4) &&
853 (io->scaled_height < H * 3 / 4);
854 io->fancy_upsampling = 0;
855 }
856 return 1;
857}
858
859//------------------------------------------------------------------------------
860