1 // Copyright 2010 Google Inc. All Rights Reserved.
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 // -----------------------------------------------------------------------------
8 // Main decoding functions for WEBP images.
10 // Author: Skal (pascal.massimino@gmail.com)
17 #include "../webp/mux_types.h" // ALPHA_FLAG
19 #if defined(__cplusplus) || defined(c_plusplus)
23 //------------------------------------------------------------------------------
26 // 0...3 "RIFF" 4-byte tag
27 // 4...7 size of image data (including metadata) starting at offset 8
28 // 8...11 "WEBP" our form-type signature
29 // The RIFF container (12 bytes) is followed by appropriate chunks:
30 // 12..15 "VP8 ": 4-bytes tags, signaling the use of VP8 video format
31 // 16..19 size of the raw VP8 image data, starting at offset 20
32 // 20.... the VP8 bytes
34 // 12..15 "VP8L": 4-bytes tags, signaling the use of VP8L lossless format
35 // 16..19 size of the raw VP8L image data, starting at offset 20
36 // 20.... the VP8L bytes
38 // 12..15 "VP8X": 4-bytes tags, describing the extended-VP8 chunk.
39 // 16..19 size of the VP8X chunk starting at offset 20.
40 // 20..23 VP8X flags bit-map corresponding to the chunk-types present.
41 // 24..26 Width of the Canvas Image.
42 // 27..29 Height of the Canvas Image.
43 // There can be extra chunks after the "VP8X" chunk (ICCP, FRGM, ANMF, VP8,
44 // VP8L, XMP, EXIF ...)
45 // All sizes are in little-endian order.
46 // Note: chunk data size must be padded to multiple of 2 when written.
48 static WEBP_INLINE uint32_t get_le24(const uint8_t* const data) {
49 return data[0] | (data[1] << 8) | (data[2] << 16);
52 static WEBP_INLINE uint32_t get_le32(const uint8_t* const data) {
53 return (uint32_t)get_le24(data) | (data[3] << 24);
56 // Validates the RIFF container (if detected) and skips over it.
57 // If a RIFF container is detected,
58 // Returns VP8_STATUS_BITSTREAM_ERROR for invalid header, and
59 // VP8_STATUS_OK otherwise.
60 // In case there are not enough bytes (partial RIFF container), return 0 for
61 // *riff_size. Else return the RIFF size extracted from the header.
62 static VP8StatusCode ParseRIFF(const uint8_t** const data,
63 size_t* const data_size,
64 size_t* const riff_size) {
66 assert(data_size != NULL);
67 assert(riff_size != NULL);
69 *riff_size = 0; // Default: no RIFF present.
70 if (*data_size >= RIFF_HEADER_SIZE && !memcmp(*data, "RIFF", TAG_SIZE)) {
71 if (memcmp(*data + 8, "WEBP", TAG_SIZE)) {
72 return VP8_STATUS_BITSTREAM_ERROR; // Wrong image file signature.
74 const uint32_t size = get_le32(*data + TAG_SIZE);
75 // Check that we have at least one chunk (i.e "WEBP" + "VP8?nnnn").
76 if (size < TAG_SIZE + CHUNK_HEADER_SIZE) {
77 return VP8_STATUS_BITSTREAM_ERROR;
79 if (size > MAX_CHUNK_PAYLOAD) {
80 return VP8_STATUS_BITSTREAM_ERROR;
82 // We have a RIFF container. Skip it.
84 *data += RIFF_HEADER_SIZE;
85 *data_size -= RIFF_HEADER_SIZE;
91 // Validates the VP8X header and skips over it.
92 // Returns VP8_STATUS_BITSTREAM_ERROR for invalid VP8X header,
93 // VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
94 // VP8_STATUS_OK otherwise.
95 // If a VP8X chunk is found, found_vp8x is set to true and *width_ptr,
96 // *height_ptr and *flags_ptr are set to the corresponding values extracted
97 // from the VP8X chunk.
98 static VP8StatusCode ParseVP8X(const uint8_t** const data,
99 size_t* const data_size,
100 int* const found_vp8x,
101 int* const width_ptr, int* const height_ptr,
102 uint32_t* const flags_ptr) {
103 const uint32_t vp8x_size = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
104 assert(data != NULL);
105 assert(data_size != NULL);
106 assert(found_vp8x != NULL);
110 if (*data_size < CHUNK_HEADER_SIZE) {
111 return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
114 if (!memcmp(*data, "VP8X", TAG_SIZE)) {
117 const uint32_t chunk_size = get_le32(*data + TAG_SIZE);
118 if (chunk_size != VP8X_CHUNK_SIZE) {
119 return VP8_STATUS_BITSTREAM_ERROR; // Wrong chunk size.
122 // Verify if enough data is available to validate the VP8X chunk.
123 if (*data_size < vp8x_size) {
124 return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
126 flags = get_le32(*data + 8);
127 width = 1 + get_le24(*data + 12);
128 height = 1 + get_le24(*data + 15);
129 if (width * (uint64_t)height >= MAX_IMAGE_AREA) {
130 return VP8_STATUS_BITSTREAM_ERROR; // image is too large
133 if (flags_ptr != NULL) *flags_ptr = flags;
134 if (width_ptr != NULL) *width_ptr = width;
135 if (height_ptr != NULL) *height_ptr = height;
136 // Skip over VP8X header bytes.
138 *data_size -= vp8x_size;
141 return VP8_STATUS_OK;
144 // Skips to the next VP8/VP8L chunk header in the data given the size of the
145 // RIFF chunk 'riff_size'.
146 // Returns VP8_STATUS_BITSTREAM_ERROR if any invalid chunk size is encountered,
147 // VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
148 // VP8_STATUS_OK otherwise.
149 // If an alpha chunk is found, *alpha_data and *alpha_size are set
151 static VP8StatusCode ParseOptionalChunks(const uint8_t** const data,
152 size_t* const data_size,
153 size_t const riff_size,
154 const uint8_t** const alpha_data,
155 size_t* const alpha_size) {
158 uint32_t total_size = TAG_SIZE + // "WEBP".
159 CHUNK_HEADER_SIZE + // "VP8Xnnnn".
160 VP8X_CHUNK_SIZE; // data.
161 assert(data != NULL);
162 assert(data_size != NULL);
164 buf_size = *data_size;
166 assert(alpha_data != NULL);
167 assert(alpha_size != NULL);
173 uint32_t disk_chunk_size; // chunk_size with padding
176 *data_size = buf_size;
178 if (buf_size < CHUNK_HEADER_SIZE) { // Insufficient data.
179 return VP8_STATUS_NOT_ENOUGH_DATA;
182 chunk_size = get_le32(buf + TAG_SIZE);
183 if (chunk_size > MAX_CHUNK_PAYLOAD) {
184 return VP8_STATUS_BITSTREAM_ERROR; // Not a valid chunk size.
186 // For odd-sized chunk-payload, there's one byte padding at the end.
187 disk_chunk_size = (CHUNK_HEADER_SIZE + chunk_size + 1) & ~1;
188 total_size += disk_chunk_size;
190 // Check that total bytes skipped so far does not exceed riff_size.
191 if (riff_size > 0 && (total_size > riff_size)) {
192 return VP8_STATUS_BITSTREAM_ERROR; // Not a valid chunk size.
195 // Start of a (possibly incomplete) VP8/VP8L chunk implies that we have
196 // parsed all the optional chunks.
197 // Note: This check must occur before the check 'buf_size < disk_chunk_size'
198 // below to allow incomplete VP8/VP8L chunks.
199 if (!memcmp(buf, "VP8 ", TAG_SIZE) ||
200 !memcmp(buf, "VP8L", TAG_SIZE)) {
201 return VP8_STATUS_OK;
204 if (buf_size < disk_chunk_size) { // Insufficient data.
205 return VP8_STATUS_NOT_ENOUGH_DATA;
208 if (!memcmp(buf, "ALPH", TAG_SIZE)) { // A valid ALPH header.
209 *alpha_data = buf + CHUNK_HEADER_SIZE;
210 *alpha_size = chunk_size;
213 // We have a full and valid chunk; skip it.
214 buf += disk_chunk_size;
215 buf_size -= disk_chunk_size;
219 // Validates the VP8/VP8L Header ("VP8 nnnn" or "VP8L nnnn") and skips over it.
220 // Returns VP8_STATUS_BITSTREAM_ERROR for invalid (chunk larger than
221 // riff_size) VP8/VP8L header,
222 // VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
223 // VP8_STATUS_OK otherwise.
224 // If a VP8/VP8L chunk is found, *chunk_size is set to the total number of bytes
225 // extracted from the VP8/VP8L chunk header.
226 // The flag '*is_lossless' is set to 1 in case of VP8L chunk / raw VP8L data.
227 static VP8StatusCode ParseVP8Header(const uint8_t** const data_ptr,
228 size_t* const data_size,
230 size_t* const chunk_size,
231 int* const is_lossless) {
232 const uint8_t* const data = *data_ptr;
233 const int is_vp8 = !memcmp(data, "VP8 ", TAG_SIZE);
234 const int is_vp8l = !memcmp(data, "VP8L", TAG_SIZE);
235 const uint32_t minimal_size =
236 TAG_SIZE + CHUNK_HEADER_SIZE; // "WEBP" + "VP8 nnnn" OR
237 // "WEBP" + "VP8Lnnnn"
238 assert(data != NULL);
239 assert(data_size != NULL);
240 assert(chunk_size != NULL);
241 assert(is_lossless != NULL);
243 if (*data_size < CHUNK_HEADER_SIZE) {
244 return VP8_STATUS_NOT_ENOUGH_DATA; // Insufficient data.
247 if (is_vp8 || is_vp8l) {
248 // Bitstream contains VP8/VP8L header.
249 const uint32_t size = get_le32(data + TAG_SIZE);
250 if ((riff_size >= minimal_size) && (size > riff_size - minimal_size)) {
251 return VP8_STATUS_BITSTREAM_ERROR; // Inconsistent size information.
253 // Skip over CHUNK_HEADER_SIZE bytes from VP8/VP8L Header.
255 *data_ptr += CHUNK_HEADER_SIZE;
256 *data_size -= CHUNK_HEADER_SIZE;
257 *is_lossless = is_vp8l;
259 // Raw VP8/VP8L bitstream (no header).
260 *is_lossless = VP8LCheckSignature(data, *data_size);
261 *chunk_size = *data_size;
264 return VP8_STATUS_OK;
267 //------------------------------------------------------------------------------
269 // Fetch '*width', '*height', '*has_alpha' and fill out 'headers' based on
270 // 'data'. All the output parameters may be NULL. If 'headers' is NULL only the
271 // minimal amount will be read to fetch the remaining parameters.
272 // If 'headers' is non-NULL this function will attempt to locate both alpha
273 // data (with or without a VP8X chunk) and the bitstream chunk (VP8/VP8L).
274 // Note: The following chunk sequences (before the raw VP8/VP8L data) are
275 // considered valid by this function:
277 // RIFF + VP8X + (optional chunks) + VP8(L)
278 // ALPH + VP8 <-- Not a valid WebP format: only allowed for internal purpose.
279 // VP8(L) <-- Not a valid WebP format: only allowed for internal purpose.
280 static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
284 int* const has_alpha,
285 int* const has_animation,
286 WebPHeaderStructure* const headers) {
289 VP8StatusCode status;
290 WebPHeaderStructure hdrs;
292 if (data == NULL || data_size < RIFF_HEADER_SIZE) {
293 return VP8_STATUS_NOT_ENOUGH_DATA;
295 memset(&hdrs, 0, sizeof(hdrs));
297 hdrs.data_size = data_size;
299 // Skip over RIFF header.
300 status = ParseRIFF(&data, &data_size, &hdrs.riff_size);
301 if (status != VP8_STATUS_OK) {
302 return status; // Wrong RIFF header / insufficient data.
304 found_riff = (hdrs.riff_size > 0);
309 status = ParseVP8X(&data, &data_size, &found_vp8x, width, height, &flags);
310 if (status != VP8_STATUS_OK) {
311 return status; // Wrong VP8X / insufficient data.
313 if (!found_riff && found_vp8x) {
314 // Note: This restriction may be removed in the future, if it becomes
315 // necessary to send VP8X chunk to the decoder.
316 return VP8_STATUS_BITSTREAM_ERROR;
318 if (has_alpha != NULL) *has_alpha = !!(flags & ALPHA_FLAG);
319 if (has_animation != NULL) *has_animation = !!(flags & ANIMATION_FLAG);
320 if (found_vp8x && headers == NULL) {
321 return VP8_STATUS_OK; // Return features from VP8X header.
325 if (data_size < TAG_SIZE) return VP8_STATUS_NOT_ENOUGH_DATA;
327 // Skip over optional chunks if data started with "RIFF + VP8X" or "ALPH".
328 if ((found_riff && found_vp8x) ||
329 (!found_riff && !found_vp8x && !memcmp(data, "ALPH", TAG_SIZE))) {
330 status = ParseOptionalChunks(&data, &data_size, hdrs.riff_size,
331 &hdrs.alpha_data, &hdrs.alpha_data_size);
332 if (status != VP8_STATUS_OK) {
333 return status; // Found an invalid chunk size / insufficient data.
337 // Skip over VP8/VP8L header.
338 status = ParseVP8Header(&data, &data_size, hdrs.riff_size,
339 &hdrs.compressed_size, &hdrs.is_lossless);
340 if (status != VP8_STATUS_OK) {
341 return status; // Wrong VP8/VP8L chunk-header / insufficient data.
343 if (hdrs.compressed_size > MAX_CHUNK_PAYLOAD) {
344 return VP8_STATUS_BITSTREAM_ERROR;
347 if (!hdrs.is_lossless) {
348 if (data_size < VP8_FRAME_HEADER_SIZE) {
349 return VP8_STATUS_NOT_ENOUGH_DATA;
351 // Validates raw VP8 data.
352 if (!VP8GetInfo(data, data_size,
353 (uint32_t)hdrs.compressed_size, width, height)) {
354 return VP8_STATUS_BITSTREAM_ERROR;
357 if (data_size < VP8L_FRAME_HEADER_SIZE) {
358 return VP8_STATUS_NOT_ENOUGH_DATA;
360 // Validates raw VP8L data.
361 if (!VP8LGetInfo(data, data_size, width, height, has_alpha)) {
362 return VP8_STATUS_BITSTREAM_ERROR;
366 if (has_alpha != NULL) {
367 // If the data did not contain a VP8X/VP8L chunk the only definitive way
368 // to set this is by looking for alpha data (from an ALPH chunk).
369 *has_alpha |= (hdrs.alpha_data != NULL);
371 if (headers != NULL) {
373 headers->offset = data - headers->data;
374 assert((uint64_t)(data - headers->data) < MAX_CHUNK_PAYLOAD);
375 assert(headers->offset == headers->data_size - data_size);
377 return VP8_STATUS_OK; // Return features from VP8 header.
380 VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers) {
381 VP8StatusCode status;
382 int has_animation = 0;
383 assert(headers != NULL);
384 // fill out headers, ignore width/height/has_alpha.
385 status = ParseHeadersInternal(headers->data, headers->data_size,
386 NULL, NULL, NULL, &has_animation, headers);
387 if (status == VP8_STATUS_OK || status == VP8_STATUS_NOT_ENOUGH_DATA) {
388 // TODO(jzern): full support of animation frames will require API additions.
390 status = VP8_STATUS_UNSUPPORTED_FEATURE;
396 //------------------------------------------------------------------------------
399 void WebPResetDecParams(WebPDecParams* const params) {
400 if (params != NULL) {
401 memset(params, 0, sizeof(*params));
405 //------------------------------------------------------------------------------
406 // "Into" decoding variants
409 static VP8StatusCode DecodeInto(const uint8_t* const data, size_t data_size,
410 WebPDecParams* const params) {
411 VP8StatusCode status;
413 WebPHeaderStructure headers;
416 headers.data_size = data_size;
417 status = WebPParseHeaders(&headers); // Process Pre-VP8 chunks.
418 if (status != VP8_STATUS_OK) {
422 assert(params != NULL);
424 io.data = headers.data + headers.offset;
425 io.data_size = headers.data_size - headers.offset;
426 WebPInitCustomIo(params, &io); // Plug the I/O functions.
428 if (!headers.is_lossless) {
429 VP8Decoder* const dec = VP8New();
431 return VP8_STATUS_OUT_OF_MEMORY;
433 #ifdef WEBP_USE_THREAD
434 dec->use_threads_ = params->options && (params->options->use_threads > 0);
436 dec->use_threads_ = 0;
438 dec->alpha_data_ = headers.alpha_data;
439 dec->alpha_data_size_ = headers.alpha_data_size;
441 // Decode bitstream header, update io->width/io->height.
442 if (!VP8GetHeaders(dec, &io)) {
443 status = dec->status_; // An error occurred. Grab error status.
445 // Allocate/check output buffers.
446 status = WebPAllocateDecBuffer(io.width, io.height, params->options,
448 if (status == VP8_STATUS_OK) { // Decode
449 if (!VP8Decode(dec, &io)) {
450 status = dec->status_;
456 VP8LDecoder* const dec = VP8LNew();
458 return VP8_STATUS_OUT_OF_MEMORY;
460 if (!VP8LDecodeHeader(dec, &io)) {
461 status = dec->status_; // An error occurred. Grab error status.
463 // Allocate/check output buffers.
464 status = WebPAllocateDecBuffer(io.width, io.height, params->options,
466 if (status == VP8_STATUS_OK) { // Decode
467 if (!VP8LDecodeImage(dec)) {
468 status = dec->status_;
475 if (status != VP8_STATUS_OK) {
476 WebPFreeDecBuffer(params->output);
482 static uint8_t* DecodeIntoRGBABuffer(WEBP_CSP_MODE colorspace,
483 const uint8_t* const data,
486 int stride, size_t size) {
487 WebPDecParams params;
492 WebPInitDecBuffer(&buf);
493 WebPResetDecParams(¶ms);
494 params.output = &buf;
495 buf.colorspace = colorspace;
496 buf.u.RGBA.rgba = rgba;
497 buf.u.RGBA.stride = stride;
498 buf.u.RGBA.size = size;
499 buf.is_external_memory = 1;
500 if (DecodeInto(data, data_size, ¶ms) != VP8_STATUS_OK) {
506 uint8_t* WebPDecodeRGBInto(const uint8_t* data, size_t data_size,
507 uint8_t* output, size_t size, int stride) {
508 return DecodeIntoRGBABuffer(MODE_RGB, data, data_size, output, stride, size);
511 uint8_t* WebPDecodeRGBAInto(const uint8_t* data, size_t data_size,
512 uint8_t* output, size_t size, int stride) {
513 return DecodeIntoRGBABuffer(MODE_RGBA, data, data_size, output, stride, size);
516 uint8_t* WebPDecodeARGBInto(const uint8_t* data, size_t data_size,
517 uint8_t* output, size_t size, int stride) {
518 return DecodeIntoRGBABuffer(MODE_ARGB, data, data_size, output, stride, size);
521 uint8_t* WebPDecodeBGRInto(const uint8_t* data, size_t data_size,
522 uint8_t* output, size_t size, int stride) {
523 return DecodeIntoRGBABuffer(MODE_BGR, data, data_size, output, stride, size);
526 uint8_t* WebPDecodeBGRAInto(const uint8_t* data, size_t data_size,
527 uint8_t* output, size_t size, int stride) {
528 return DecodeIntoRGBABuffer(MODE_BGRA, data, data_size, output, stride, size);
531 uint8_t* WebPDecodeYUVInto(const uint8_t* data, size_t data_size,
532 uint8_t* luma, size_t luma_size, int luma_stride,
533 uint8_t* u, size_t u_size, int u_stride,
534 uint8_t* v, size_t v_size, int v_stride) {
535 WebPDecParams params;
536 WebPDecBuffer output;
537 if (luma == NULL) return NULL;
538 WebPInitDecBuffer(&output);
539 WebPResetDecParams(¶ms);
540 params.output = &output;
541 output.colorspace = MODE_YUV;
542 output.u.YUVA.y = luma;
543 output.u.YUVA.y_stride = luma_stride;
544 output.u.YUVA.y_size = luma_size;
546 output.u.YUVA.u_stride = u_stride;
547 output.u.YUVA.u_size = u_size;
549 output.u.YUVA.v_stride = v_stride;
550 output.u.YUVA.v_size = v_size;
551 output.is_external_memory = 1;
552 if (DecodeInto(data, data_size, ¶ms) != VP8_STATUS_OK) {
558 //------------------------------------------------------------------------------
560 static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* const data,
561 size_t data_size, int* const width, int* const height,
562 WebPDecBuffer* const keep_info) {
563 WebPDecParams params;
564 WebPDecBuffer output;
566 WebPInitDecBuffer(&output);
567 WebPResetDecParams(¶ms);
568 params.output = &output;
569 output.colorspace = mode;
571 // Retrieve (and report back) the required dimensions from bitstream.
572 if (!WebPGetInfo(data, data_size, &output.width, &output.height)) {
575 if (width != NULL) *width = output.width;
576 if (height != NULL) *height = output.height;
579 if (DecodeInto(data, data_size, ¶ms) != VP8_STATUS_OK) {
582 if (keep_info != NULL) { // keep track of the side-info
583 WebPCopyDecBuffer(&output, keep_info);
585 // return decoded samples (don't clear 'output'!)
586 return WebPIsRGBMode(mode) ? output.u.RGBA.rgba : output.u.YUVA.y;
589 uint8_t* WebPDecodeRGB(const uint8_t* data, size_t data_size,
590 int* width, int* height) {
591 return Decode(MODE_RGB, data, data_size, width, height, NULL);
594 uint8_t* WebPDecodeRGBA(const uint8_t* data, size_t data_size,
595 int* width, int* height) {
596 return Decode(MODE_RGBA, data, data_size, width, height, NULL);
599 uint8_t* WebPDecodeARGB(const uint8_t* data, size_t data_size,
600 int* width, int* height) {
601 return Decode(MODE_ARGB, data, data_size, width, height, NULL);
604 uint8_t* WebPDecodeBGR(const uint8_t* data, size_t data_size,
605 int* width, int* height) {
606 return Decode(MODE_BGR, data, data_size, width, height, NULL);
609 uint8_t* WebPDecodeBGRA(const uint8_t* data, size_t data_size,
610 int* width, int* height) {
611 return Decode(MODE_BGRA, data, data_size, width, height, NULL);
614 uint8_t* WebPDecodeYUV(const uint8_t* data, size_t data_size,
615 int* width, int* height, uint8_t** u, uint8_t** v,
616 int* stride, int* uv_stride) {
617 WebPDecBuffer output; // only to preserve the side-infos
618 uint8_t* const out = Decode(MODE_YUV, data, data_size,
619 width, height, &output);
622 const WebPYUVABuffer* const buf = &output.u.YUVA;
625 *stride = buf->y_stride;
626 *uv_stride = buf->u_stride;
627 assert(buf->u_stride == buf->v_stride);
632 static void DefaultFeatures(WebPBitstreamFeatures* const features) {
633 assert(features != NULL);
634 memset(features, 0, sizeof(*features));
635 features->bitstream_version = 0;
638 static VP8StatusCode GetFeatures(const uint8_t* const data, size_t data_size,
639 WebPBitstreamFeatures* const features) {
640 if (features == NULL || data == NULL) {
641 return VP8_STATUS_INVALID_PARAM;
643 DefaultFeatures(features);
645 // Only parse enough of the data to retrieve the features.
646 return ParseHeadersInternal(data, data_size,
647 &features->width, &features->height,
648 &features->has_alpha, &features->has_animation,
652 //------------------------------------------------------------------------------
655 int WebPGetInfo(const uint8_t* data, size_t data_size,
656 int* width, int* height) {
657 WebPBitstreamFeatures features;
659 if (GetFeatures(data, data_size, &features) != VP8_STATUS_OK) {
664 *width = features.width;
666 if (height != NULL) {
667 *height = features.height;
673 //------------------------------------------------------------------------------
674 // Advance decoding API
676 int WebPInitDecoderConfigInternal(WebPDecoderConfig* config,
678 if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
679 return 0; // version mismatch
681 if (config == NULL) {
684 memset(config, 0, sizeof(*config));
685 DefaultFeatures(&config->input);
686 WebPInitDecBuffer(&config->output);
690 VP8StatusCode WebPGetFeaturesInternal(const uint8_t* data, size_t data_size,
691 WebPBitstreamFeatures* features,
693 if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
694 return VP8_STATUS_INVALID_PARAM; // version mismatch
696 if (features == NULL) {
697 return VP8_STATUS_INVALID_PARAM;
699 return GetFeatures(data, data_size, features);
702 VP8StatusCode WebPDecode(const uint8_t* data, size_t data_size,
703 WebPDecoderConfig* config) {
704 WebPDecParams params;
705 VP8StatusCode status;
707 if (config == NULL) {
708 return VP8_STATUS_INVALID_PARAM;
711 status = GetFeatures(data, data_size, &config->input);
712 if (status != VP8_STATUS_OK) {
713 if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
714 return VP8_STATUS_BITSTREAM_ERROR; // Not-enough-data treated as error.
719 WebPResetDecParams(¶ms);
720 params.output = &config->output;
721 params.options = &config->options;
722 status = DecodeInto(data, data_size, ¶ms);
727 //------------------------------------------------------------------------------
728 // Cropping and rescaling.
730 int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
731 VP8Io* const io, WEBP_CSP_MODE src_colorspace) {
732 const int W = io->width;
733 const int H = io->height;
734 int x = 0, y = 0, w = W, h = H;
737 io->use_cropping = (options != NULL) && (options->use_cropping > 0);
738 if (io->use_cropping) {
739 w = options->crop_width;
740 h = options->crop_height;
741 x = options->crop_left;
742 y = options->crop_top;
743 if (!WebPIsRGBMode(src_colorspace)) { // only snap for YUV420 or YUV422
745 y &= ~1; // TODO(later): only for YUV420, not YUV422.
747 if (x < 0 || y < 0 || w <= 0 || h <= 0 || x + w > W || y + h > H) {
748 return 0; // out of frame boundary error
753 io->crop_right = x + w;
754 io->crop_bottom = y + h;
759 io->use_scaling = (options != NULL) && (options->use_scaling > 0);
760 if (io->use_scaling) {
761 if (options->scaled_width <= 0 || options->scaled_height <= 0) {
764 io->scaled_width = options->scaled_width;
765 io->scaled_height = options->scaled_height;
769 io->bypass_filtering = options && options->bypass_filtering;
772 #ifdef FANCY_UPSAMPLING
773 io->fancy_upsampling = (options == NULL) || (!options->no_fancy_upsampling);
776 if (io->use_scaling) {
777 // disable filter (only for large downscaling ratio).
778 io->bypass_filtering = (io->scaled_width < W * 3 / 4) &&
779 (io->scaled_height < H * 3 / 4);
780 io->fancy_upsampling = 0;
785 //------------------------------------------------------------------------------
787 #if defined(__cplusplus) || defined(c_plusplus)