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#ifndef WEBP_WEBP_DECODE_H_
15#define WEBP_WEBP_DECODE_H_
16
17#include "./types.h"
18
19#ifdef __cplusplus
20extern "C" {
21#endif
22
23#define WEBP_DECODER_ABI_VERSION 0x0208 // MAJOR(8b) + MINOR(8b)
24
25// Note: forward declaring enumerations is not allowed in (strict) C and C++,
26// the types are left here for reference.
27// typedef enum VP8StatusCode VP8StatusCode;
28// typedef enum WEBP_CSP_MODE WEBP_CSP_MODE;
29typedef struct WebPRGBABuffer WebPRGBABuffer;
30typedef struct WebPYUVABuffer WebPYUVABuffer;
31typedef struct WebPDecBuffer WebPDecBuffer;
32typedef struct WebPIDecoder WebPIDecoder;
33typedef struct WebPBitstreamFeatures WebPBitstreamFeatures;
34typedef struct WebPDecoderOptions WebPDecoderOptions;
35typedef struct WebPDecoderConfig WebPDecoderConfig;
36
37// Return the decoder's version number, packed in hexadecimal using 8bits for
38// each of major/minor/revision. E.g: v2.5.7 is 0x020507.
39WEBP_EXTERN(int) WebPGetDecoderVersion(void);
40
41// Retrieve basic header information: width, height.
42// This function will also validate the header, returning true on success,
43// false otherwise. '*width' and '*height' are only valid on successful return.
44// Pointers 'width' and 'height' can be passed NULL if deemed irrelevant.
45WEBP_EXTERN(int) WebPGetInfo(const uint8_t* data, size_t data_size,
46 int* width, int* height);
47
48// Decodes WebP images pointed to by 'data' and returns RGBA samples, along
49// with the dimensions in *width and *height. The ordering of samples in
50// memory is R, G, B, A, R, G, B, A... in scan order (endian-independent).
51// The returned pointer should be deleted calling WebPFree().
52// Returns NULL in case of error.
53WEBP_EXTERN(uint8_t*) WebPDecodeRGBA(const uint8_t* data, size_t data_size,
54 int* width, int* height);
55
56// Same as WebPDecodeRGBA, but returning A, R, G, B, A, R, G, B... ordered data.
57WEBP_EXTERN(uint8_t*) WebPDecodeARGB(const uint8_t* data, size_t data_size,
58 int* width, int* height);
59
60// Same as WebPDecodeRGBA, but returning B, G, R, A, B, G, R, A... ordered data.
61WEBP_EXTERN(uint8_t*) WebPDecodeBGRA(const uint8_t* data, size_t data_size,
62 int* width, int* height);
63
64// Same as WebPDecodeRGBA, but returning R, G, B, R, G, B... ordered data.
65// If the bitstream contains transparency, it is ignored.
66WEBP_EXTERN(uint8_t*) WebPDecodeRGB(const uint8_t* data, size_t data_size,
67 int* width, int* height);
68
69// Same as WebPDecodeRGB, but returning B, G, R, B, G, R... ordered data.
70WEBP_EXTERN(uint8_t*) WebPDecodeBGR(const uint8_t* data, size_t data_size,
71 int* width, int* height);
72
73
74// Decode WebP images pointed to by 'data' to Y'UV format(*). The pointer
75// returned is the Y samples buffer. Upon return, *u and *v will point to
76// the U and V chroma data. These U and V buffers need NOT be passed to
77// WebPFree(), unlike the returned Y luma one. The dimension of the U and V
78// planes are both (*width + 1) / 2 and (*height + 1)/ 2.
79// Upon return, the Y buffer has a stride returned as '*stride', while U and V
80// have a common stride returned as '*uv_stride'.
81// Return NULL in case of error.
82// (*) Also named Y'CbCr. See: http://en.wikipedia.org/wiki/YCbCr
83WEBP_EXTERN(uint8_t*) WebPDecodeYUV(const uint8_t* data, size_t data_size,
84 int* width, int* height,
85 uint8_t** u, uint8_t** v,
86 int* stride, int* uv_stride);
87
88// Releases memory returned by the WebPDecode*() functions above.
89WEBP_EXTERN(void) WebPFree(void* ptr);
90
91// These five functions are variants of the above ones, that decode the image
92// directly into a pre-allocated buffer 'output_buffer'. The maximum storage
93// available in this buffer is indicated by 'output_buffer_size'. If this
94// storage is not sufficient (or an error occurred), NULL is returned.
95// Otherwise, output_buffer is returned, for convenience.
96// The parameter 'output_stride' specifies the distance (in bytes)
97// between scanlines. Hence, output_buffer_size is expected to be at least
98// output_stride x picture-height.
99WEBP_EXTERN(uint8_t*) WebPDecodeRGBAInto(
100 const uint8_t* data, size_t data_size,
101 uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
102WEBP_EXTERN(uint8_t*) WebPDecodeARGBInto(
103 const uint8_t* data, size_t data_size,
104 uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
105WEBP_EXTERN(uint8_t*) WebPDecodeBGRAInto(
106 const uint8_t* data, size_t data_size,
107 uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
108
109// RGB and BGR variants. Here too the transparency information, if present,
110// will be dropped and ignored.
111WEBP_EXTERN(uint8_t*) WebPDecodeRGBInto(
112 const uint8_t* data, size_t data_size,
113 uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
114WEBP_EXTERN(uint8_t*) WebPDecodeBGRInto(
115 const uint8_t* data, size_t data_size,
116 uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
117
118// WebPDecodeYUVInto() is a variant of WebPDecodeYUV() that operates directly
119// into pre-allocated luma/chroma plane buffers. This function requires the
120// strides to be passed: one for the luma plane and one for each of the
121// chroma ones. The size of each plane buffer is passed as 'luma_size',
122// 'u_size' and 'v_size' respectively.
123// Pointer to the luma plane ('*luma') is returned or NULL if an error occurred
124// during decoding (or because some buffers were found to be too small).
125WEBP_EXTERN(uint8_t*) WebPDecodeYUVInto(
126 const uint8_t* data, size_t data_size,
127 uint8_t* luma, size_t luma_size, int luma_stride,
128 uint8_t* u, size_t u_size, int u_stride,
129 uint8_t* v, size_t v_size, int v_stride);
130
131//------------------------------------------------------------------------------
132// Output colorspaces and buffer
133
134// Colorspaces
135// Note: the naming describes the byte-ordering of packed samples in memory.
136// For instance, MODE_BGRA relates to samples ordered as B,G,R,A,B,G,R,A,...
137// Non-capital names (e.g.:MODE_Argb) relates to pre-multiplied RGB channels.
138// RGBA-4444 and RGB-565 colorspaces are represented by following byte-order:
139// RGBA-4444: [r3 r2 r1 r0 g3 g2 g1 g0], [b3 b2 b1 b0 a3 a2 a1 a0], ...
140// RGB-565: [r4 r3 r2 r1 r0 g5 g4 g3], [g2 g1 g0 b4 b3 b2 b1 b0], ...
141// In the case WEBP_SWAP_16BITS_CSP is defined, the bytes are swapped for
142// these two modes:
143// RGBA-4444: [b3 b2 b1 b0 a3 a2 a1 a0], [r3 r2 r1 r0 g3 g2 g1 g0], ...
144// RGB-565: [g2 g1 g0 b4 b3 b2 b1 b0], [r4 r3 r2 r1 r0 g5 g4 g3], ...
145
146typedef enum WEBP_CSP_MODE {
147 MODE_RGB = 0, MODE_RGBA = 1,
148 MODE_BGR = 2, MODE_BGRA = 3,
149 MODE_ARGB = 4, MODE_RGBA_4444 = 5,
150 MODE_RGB_565 = 6,
151 // RGB-premultiplied transparent modes (alpha value is preserved)
152 MODE_rgbA = 7,
153 MODE_bgrA = 8,
154 MODE_Argb = 9,
155 MODE_rgbA_4444 = 10,
156 // YUV modes must come after RGB ones.
157 MODE_YUV = 11, MODE_YUVA = 12, // yuv 4:2:0
158 MODE_LAST = 13
159} WEBP_CSP_MODE;
160
161// Some useful macros:
162static WEBP_INLINE int WebPIsPremultipliedMode(WEBP_CSP_MODE mode) {
163 return (mode == MODE_rgbA || mode == MODE_bgrA || mode == MODE_Argb ||
164 mode == MODE_rgbA_4444);
165}
166
167static WEBP_INLINE int WebPIsAlphaMode(WEBP_CSP_MODE mode) {
168 return (mode == MODE_RGBA || mode == MODE_BGRA || mode == MODE_ARGB ||
169 mode == MODE_RGBA_4444 || mode == MODE_YUVA ||
170 WebPIsPremultipliedMode(mode));
171}
172
173static WEBP_INLINE int WebPIsRGBMode(WEBP_CSP_MODE mode) {
174 return (mode < MODE_YUV);
175}
176
177//------------------------------------------------------------------------------
178// WebPDecBuffer: Generic structure for describing the output sample buffer.
179
180struct WebPRGBABuffer { // view as RGBA
181 uint8_t* rgba; // pointer to RGBA samples
182 int stride; // stride in bytes from one scanline to the next.
183 size_t size; // total size of the *rgba buffer.
184};
185
186struct WebPYUVABuffer { // view as YUVA
187 uint8_t* y, *u, *v, *a; // pointer to luma, chroma U/V, alpha samples
188 int y_stride; // luma stride
189 int u_stride, v_stride; // chroma strides
190 int a_stride; // alpha stride
191 size_t y_size; // luma plane size
192 size_t u_size, v_size; // chroma planes size
193 size_t a_size; // alpha-plane size
194};
195
196// Output buffer
197struct WebPDecBuffer {
198 WEBP_CSP_MODE colorspace; // Colorspace.
199 int width, height; // Dimensions.
200 int is_external_memory; // If non-zero, 'internal_memory' pointer is not
201 // used. If value is '2' or more, the external
202 // memory is considered 'slow' and multiple
203 // read/write will be avoided.
204 union {
205 WebPRGBABuffer RGBA;
206 WebPYUVABuffer YUVA;
207 } u; // Nameless union of buffer parameters.
208 uint32_t pad[4]; // padding for later use
209
210 uint8_t* private_memory; // Internally allocated memory (only when
211 // is_external_memory is 0). Should not be used
212 // externally, but accessed via the buffer union.
213};
214
215// Internal, version-checked, entry point
216WEBP_EXTERN(int) WebPInitDecBufferInternal(WebPDecBuffer*, int);
217
218// Initialize the structure as empty. Must be called before any other use.
219// Returns false in case of version mismatch
220static WEBP_INLINE int WebPInitDecBuffer(WebPDecBuffer* buffer) {
221 return WebPInitDecBufferInternal(buffer, WEBP_DECODER_ABI_VERSION);
222}
223
224// Free any memory associated with the buffer. Must always be called last.
225// Note: doesn't free the 'buffer' structure itself.
226WEBP_EXTERN(void) WebPFreeDecBuffer(WebPDecBuffer* buffer);
227
228//------------------------------------------------------------------------------
229// Enumeration of the status codes
230
231typedef enum VP8StatusCode {
232 VP8_STATUS_OK = 0,
233 VP8_STATUS_OUT_OF_MEMORY,
234 VP8_STATUS_INVALID_PARAM,
235 VP8_STATUS_BITSTREAM_ERROR,
236 VP8_STATUS_UNSUPPORTED_FEATURE,
237 VP8_STATUS_SUSPENDED,
238 VP8_STATUS_USER_ABORT,
239 VP8_STATUS_NOT_ENOUGH_DATA
240} VP8StatusCode;
241
242//------------------------------------------------------------------------------
243// Incremental decoding
244//
245// This API allows streamlined decoding of partial data.
246// Picture can be incrementally decoded as data become available thanks to the
247// WebPIDecoder object. This object can be left in a SUSPENDED state if the
248// picture is only partially decoded, pending additional input.
249// Code example:
250//
251// WebPInitDecBuffer(&output_buffer);
252// output_buffer.colorspace = mode;
253// ...
254// WebPIDecoder* idec = WebPINewDecoder(&output_buffer);
255// while (additional_data_is_available) {
256// // ... (get additional data in some new_data[] buffer)
257// status = WebPIAppend(idec, new_data, new_data_size);
258// if (status != VP8_STATUS_OK && status != VP8_STATUS_SUSPENDED) {
259// break; // an error occurred.
260// }
261//
262// // The above call decodes the current available buffer.
263// // Part of the image can now be refreshed by calling
264// // WebPIDecGetRGB()/WebPIDecGetYUVA() etc.
265// }
266// WebPIDelete(idec);
267
268// Creates a new incremental decoder with the supplied buffer parameter.
269// This output_buffer can be passed NULL, in which case a default output buffer
270// is used (with MODE_RGB). Otherwise, an internal reference to 'output_buffer'
271// is kept, which means that the lifespan of 'output_buffer' must be larger than
272// that of the returned WebPIDecoder object.
273// The supplied 'output_buffer' content MUST NOT be changed between calls to
274// WebPIAppend() or WebPIUpdate() unless 'output_buffer.is_external_memory' is
275// not set to 0. In such a case, it is allowed to modify the pointers, size and
276// stride of output_buffer.u.RGBA or output_buffer.u.YUVA, provided they remain
277// within valid bounds.
278// All other fields of WebPDecBuffer MUST remain constant between calls.
279// Returns NULL if the allocation failed.
280WEBP_EXTERN(WebPIDecoder*) WebPINewDecoder(WebPDecBuffer* output_buffer);
281
282// This function allocates and initializes an incremental-decoder object, which
283// will output the RGB/A samples specified by 'csp' into a preallocated
284// buffer 'output_buffer'. The size of this buffer is at least
285// 'output_buffer_size' and the stride (distance in bytes between two scanlines)
286// is specified by 'output_stride'.
287// Additionally, output_buffer can be passed NULL in which case the output
288// buffer will be allocated automatically when the decoding starts. The
289// colorspace 'csp' is taken into account for allocating this buffer. All other
290// parameters are ignored.
291// Returns NULL if the allocation failed, or if some parameters are invalid.
292WEBP_EXTERN(WebPIDecoder*) WebPINewRGB(
293 WEBP_CSP_MODE csp,
294 uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
295
296// This function allocates and initializes an incremental-decoder object, which
297// will output the raw luma/chroma samples into a preallocated planes if
298// supplied. The luma plane is specified by its pointer 'luma', its size
299// 'luma_size' and its stride 'luma_stride'. Similarly, the chroma-u plane
300// is specified by the 'u', 'u_size' and 'u_stride' parameters, and the chroma-v
301// plane by 'v' and 'v_size'. And same for the alpha-plane. The 'a' pointer
302// can be pass NULL in case one is not interested in the transparency plane.
303// Conversely, 'luma' can be passed NULL if no preallocated planes are supplied.
304// In this case, the output buffer will be automatically allocated (using
305// MODE_YUVA) when decoding starts. All parameters are then ignored.
306// Returns NULL if the allocation failed or if a parameter is invalid.
307WEBP_EXTERN(WebPIDecoder*) WebPINewYUVA(
308 uint8_t* luma, size_t luma_size, int luma_stride,
309 uint8_t* u, size_t u_size, int u_stride,
310 uint8_t* v, size_t v_size, int v_stride,
311 uint8_t* a, size_t a_size, int a_stride);
312
313// Deprecated version of the above, without the alpha plane.
314// Kept for backward compatibility.
315WEBP_EXTERN(WebPIDecoder*) WebPINewYUV(
316 uint8_t* luma, size_t luma_size, int luma_stride,
317 uint8_t* u, size_t u_size, int u_stride,
318 uint8_t* v, size_t v_size, int v_stride);
319
320// Deletes the WebPIDecoder object and associated memory. Must always be called
321// if WebPINewDecoder, WebPINewRGB or WebPINewYUV succeeded.
322WEBP_EXTERN(void) WebPIDelete(WebPIDecoder* idec);
323
324// Copies and decodes the next available data. Returns VP8_STATUS_OK when
325// the image is successfully decoded. Returns VP8_STATUS_SUSPENDED when more
326// data is expected. Returns error in other cases.
327WEBP_EXTERN(VP8StatusCode) WebPIAppend(
328 WebPIDecoder* idec, const uint8_t* data, size_t data_size);
329
330// A variant of the above function to be used when data buffer contains
331// partial data from the beginning. In this case data buffer is not copied
332// to the internal memory.
333// Note that the value of the 'data' pointer can change between calls to
334// WebPIUpdate, for instance when the data buffer is resized to fit larger data.
335WEBP_EXTERN(VP8StatusCode) WebPIUpdate(
336 WebPIDecoder* idec, const uint8_t* data, size_t data_size);
337
338// Returns the RGB/A image decoded so far. Returns NULL if output params
339// are not initialized yet. The RGB/A output type corresponds to the colorspace
340// specified during call to WebPINewDecoder() or WebPINewRGB().
341// *last_y is the index of last decoded row in raster scan order. Some pointers
342// (*last_y, *width etc.) can be NULL if corresponding information is not
343// needed.
344WEBP_EXTERN(uint8_t*) WebPIDecGetRGB(
345 const WebPIDecoder* idec, int* last_y,
346 int* width, int* height, int* stride);
347
348// Same as above function to get a YUVA image. Returns pointer to the luma
349// plane or NULL in case of error. If there is no alpha information
350// the alpha pointer '*a' will be returned NULL.
351WEBP_EXTERN(uint8_t*) WebPIDecGetYUVA(
352 const WebPIDecoder* idec, int* last_y,
353 uint8_t** u, uint8_t** v, uint8_t** a,
354 int* width, int* height, int* stride, int* uv_stride, int* a_stride);
355
356// Deprecated alpha-less version of WebPIDecGetYUVA(): it will ignore the
357// alpha information (if present). Kept for backward compatibility.
358static WEBP_INLINE uint8_t* WebPIDecGetYUV(
359 const WebPIDecoder* idec, int* last_y, uint8_t** u, uint8_t** v,
360 int* width, int* height, int* stride, int* uv_stride) {
361 return WebPIDecGetYUVA(idec, last_y, u, v, NULL, width, height,
362 stride, uv_stride, NULL);
363}
364
365// Generic call to retrieve information about the displayable area.
366// If non NULL, the left/right/width/height pointers are filled with the visible
367// rectangular area so far.
368// Returns NULL in case the incremental decoder object is in an invalid state.
369// Otherwise returns the pointer to the internal representation. This structure
370// is read-only, tied to WebPIDecoder's lifespan and should not be modified.
371WEBP_EXTERN(const WebPDecBuffer*) WebPIDecodedArea(
372 const WebPIDecoder* idec, int* left, int* top, int* width, int* height);
373
374//------------------------------------------------------------------------------
375// Advanced decoding parametrization
376//
377// Code sample for using the advanced decoding API
378/*
379 // A) Init a configuration object
380 WebPDecoderConfig config;
381 CHECK(WebPInitDecoderConfig(&config));
382
383 // B) optional: retrieve the bitstream's features.
384 CHECK(WebPGetFeatures(data, data_size, &config.input) == VP8_STATUS_OK);
385
386 // C) Adjust 'config', if needed
387 config.no_fancy_upsampling = 1;
388 config.output.colorspace = MODE_BGRA;
389 // etc.
390
391 // Note that you can also make config.output point to an externally
392 // supplied memory buffer, provided it's big enough to store the decoded
393 // picture. Otherwise, config.output will just be used to allocate memory
394 // and store the decoded picture.
395
396 // D) Decode!
397 CHECK(WebPDecode(data, data_size, &config) == VP8_STATUS_OK);
398
399 // E) Decoded image is now in config.output (and config.output.u.RGBA)
400
401 // F) Reclaim memory allocated in config's object. It's safe to call
402 // this function even if the memory is external and wasn't allocated
403 // by WebPDecode().
404 WebPFreeDecBuffer(&config.output);
405*/
406
407// Features gathered from the bitstream
408struct WebPBitstreamFeatures {
409 int width; // Width in pixels, as read from the bitstream.
410 int height; // Height in pixels, as read from the bitstream.
411 int has_alpha; // True if the bitstream contains an alpha channel.
412 int has_animation; // True if the bitstream is an animation.
413 int format; // 0 = undefined (/mixed), 1 = lossy, 2 = lossless
414
415 uint32_t pad[5]; // padding for later use
416};
417
418// Internal, version-checked, entry point
419WEBP_EXTERN(VP8StatusCode) WebPGetFeaturesInternal(
420 const uint8_t*, size_t, WebPBitstreamFeatures*, int);
421
422// Retrieve features from the bitstream. The *features structure is filled
423// with information gathered from the bitstream.
424// Returns VP8_STATUS_OK when the features are successfully retrieved. Returns
425// VP8_STATUS_NOT_ENOUGH_DATA when more data is needed to retrieve the
426// features from headers. Returns error in other cases.
427static WEBP_INLINE VP8StatusCode WebPGetFeatures(
428 const uint8_t* data, size_t data_size,
429 WebPBitstreamFeatures* features) {
430 return WebPGetFeaturesInternal(data, data_size, features,
431 WEBP_DECODER_ABI_VERSION);
432}
433
434// Decoding options
435struct WebPDecoderOptions {
436 int bypass_filtering; // if true, skip the in-loop filtering
437 int no_fancy_upsampling; // if true, use faster pointwise upsampler
438 int use_cropping; // if true, cropping is applied _first_
439 int crop_left, crop_top; // top-left position for cropping.
440 // Will be snapped to even values.
441 int crop_width, crop_height; // dimension of the cropping area
442 int use_scaling; // if true, scaling is applied _afterward_
443 int scaled_width, scaled_height; // final resolution
444 int use_threads; // if true, use multi-threaded decoding
445 int dithering_strength; // dithering strength (0=Off, 100=full)
446 int flip; // flip output vertically
447 int alpha_dithering_strength; // alpha dithering strength in [0..100]
448
449 uint32_t pad[5]; // padding for later use
450};
451
452// Main object storing the configuration for advanced decoding.
453struct WebPDecoderConfig {
454 WebPBitstreamFeatures input; // Immutable bitstream features (optional)
455 WebPDecBuffer output; // Output buffer (can point to external mem)
456 WebPDecoderOptions options; // Decoding options
457};
458
459// Internal, version-checked, entry point
460WEBP_EXTERN(int) WebPInitDecoderConfigInternal(WebPDecoderConfig*, int);
461
462// Initialize the configuration as empty. This function must always be
463// called first, unless WebPGetFeatures() is to be called.
464// Returns false in case of mismatched version.
465static WEBP_INLINE int WebPInitDecoderConfig(WebPDecoderConfig* config) {
466 return WebPInitDecoderConfigInternal(config, WEBP_DECODER_ABI_VERSION);
467}
468
469// Instantiate a new incremental decoder object with the requested
470// configuration. The bitstream can be passed using 'data' and 'data_size'
471// parameter, in which case the features will be parsed and stored into
472// config->input. Otherwise, 'data' can be NULL and no parsing will occur.
473// Note that 'config' can be NULL too, in which case a default configuration
474// is used. If 'config' is not NULL, it must outlive the WebPIDecoder object
475// as some references to its fields will be used. No internal copy of 'config'
476// is made.
477// The return WebPIDecoder object must always be deleted calling WebPIDelete().
478// Returns NULL in case of error (and config->status will then reflect
479// the error condition, if available).
480WEBP_EXTERN(WebPIDecoder*) WebPIDecode(const uint8_t* data, size_t data_size,
481 WebPDecoderConfig* config);
482
483// Non-incremental version. This version decodes the full data at once, taking
484// 'config' into account. Returns decoding status (which should be VP8_STATUS_OK
485// if the decoding was successful). Note that 'config' cannot be NULL.
486WEBP_EXTERN(VP8StatusCode) WebPDecode(const uint8_t* data, size_t data_size,
487 WebPDecoderConfig* config);
488
489#ifdef __cplusplus
490} // extern "C"
491#endif
492
493#endif /* WEBP_WEBP_DECODE_H_ */
494