Update libwebp to 0.6.1

* lossless performance and compression improvements + a new 'cruncher' mode (-m 6 -q 100)
* ARM performance improvements with clang (15-20% w/ndk r15c)
* webp-js: emscripten/webassembly based javascript decoder
* miscellaneous bug & build fixes

1 files changed, 530 insertions, 0 deletions

diff --git a/thirdparty/libwebp/src/webp/mux.h b/thirdparty/libwebp/src/webp/mux.h
new file mode 100644
index 0000000000..28bb4a41c9
--- /dev/null
+++ b/thirdparty/libwebp/src/webp/mux.h
@@ -0,0 +1,530 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//  RIFF container manipulation and encoding for WebP images.
+//
+// Authors: Urvang (urvang@google.com)
+//          Vikas (vikasa@google.com)
+
+#ifndef WEBP_WEBP_MUX_H_
+#define WEBP_WEBP_MUX_H_
+
+#include "./mux_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define WEBP_MUX_ABI_VERSION 0x0108        // MAJOR(8b) + MINOR(8b)
+
+//------------------------------------------------------------------------------
+// Mux API
+//
+// This API allows manipulation of WebP container images containing features
+// like color profile, metadata, animation.
+//
+// Code Example#1: Create a WebPMux object with image data, color profile and
+// XMP metadata.
+/*
+  int copy_data = 0;
+  WebPMux* mux = WebPMuxNew();
+  // ... (Prepare image data).
+  WebPMuxSetImage(mux, &image, copy_data);
+  // ... (Prepare ICCP color profile data).
+  WebPMuxSetChunk(mux, "ICCP", &icc_profile, copy_data);
+  // ... (Prepare XMP metadata).
+  WebPMuxSetChunk(mux, "XMP ", &xmp, copy_data);
+  // Get data from mux in WebP RIFF format.
+  WebPMuxAssemble(mux, &output_data);
+  WebPMuxDelete(mux);
+  // ... (Consume output_data; e.g. write output_data.bytes to file).
+  WebPDataClear(&output_data);
+*/
+
+// Code Example#2: Get image and color profile data from a WebP file.
+/*
+  int copy_data = 0;
+  // ... (Read data from file).
+  WebPMux* mux = WebPMuxCreate(&data, copy_data);
+  WebPMuxGetFrame(mux, 1, &image);
+  // ... (Consume image; e.g. call WebPDecode() to decode the data).
+  WebPMuxGetChunk(mux, "ICCP", &icc_profile);
+  // ... (Consume icc_data).
+  WebPMuxDelete(mux);
+  free(data);
+*/
+
+// Note: forward declaring enumerations is not allowed in (strict) C and C++,
+// the types are left here for reference.
+// typedef enum WebPMuxError WebPMuxError;
+// typedef enum WebPChunkId WebPChunkId;
+typedef struct WebPMux WebPMux;   // main opaque object.
+typedef struct WebPMuxFrameInfo WebPMuxFrameInfo;
+typedef struct WebPMuxAnimParams WebPMuxAnimParams;
+typedef struct WebPAnimEncoderOptions WebPAnimEncoderOptions;
+
+// Error codes
+typedef enum WebPMuxError {
+  WEBP_MUX_OK                 =  1,
+  WEBP_MUX_NOT_FOUND          =  0,
+  WEBP_MUX_INVALID_ARGUMENT   = -1,
+  WEBP_MUX_BAD_DATA           = -2,
+  WEBP_MUX_MEMORY_ERROR       = -3,
+  WEBP_MUX_NOT_ENOUGH_DATA    = -4
+} WebPMuxError;
+
+// IDs for different types of chunks.
+typedef enum WebPChunkId {
+  WEBP_CHUNK_VP8X,        // VP8X
+  WEBP_CHUNK_ICCP,        // ICCP
+  WEBP_CHUNK_ANIM,        // ANIM
+  WEBP_CHUNK_ANMF,        // ANMF
+  WEBP_CHUNK_DEPRECATED,  // (deprecated from FRGM)
+  WEBP_CHUNK_ALPHA,       // ALPH
+  WEBP_CHUNK_IMAGE,       // VP8/VP8L
+  WEBP_CHUNK_EXIF,        // EXIF
+  WEBP_CHUNK_XMP,         // XMP
+  WEBP_CHUNK_UNKNOWN,     // Other chunks.
+  WEBP_CHUNK_NIL
+} WebPChunkId;
+
+//------------------------------------------------------------------------------
+
+// Returns the version number of the mux library, packed in hexadecimal using
+// 8bits for each of major/minor/revision. E.g: v2.5.7 is 0x020507.
+WEBP_EXTERN int WebPGetMuxVersion(void);
+
+//------------------------------------------------------------------------------
+// Life of a Mux object
+
+// Internal, version-checked, entry point
+WEBP_EXTERN WebPMux* WebPNewInternal(int);
+
+// Creates an empty mux object.
+// Returns:
+//   A pointer to the newly created empty mux object.
+//   Or NULL in case of memory error.
+static WEBP_INLINE WebPMux* WebPMuxNew(void) {
+  return WebPNewInternal(WEBP_MUX_ABI_VERSION);
+}
+
+// Deletes the mux object.
+// Parameters:
+//   mux - (in/out) object to be deleted
+WEBP_EXTERN void WebPMuxDelete(WebPMux* mux);
+
+//------------------------------------------------------------------------------
+// Mux creation.
+
+// Internal, version-checked, entry point
+WEBP_EXTERN WebPMux* WebPMuxCreateInternal(const WebPData*, int, int);
+
+// Creates a mux object from raw data given in WebP RIFF format.
+// Parameters:
+//   bitstream - (in) the bitstream data in WebP RIFF format
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   A pointer to the mux object created from given data - on success.
+//   NULL - In case of invalid data or memory error.
+static WEBP_INLINE WebPMux* WebPMuxCreate(const WebPData* bitstream,
+                                          int copy_data) {
+  return WebPMuxCreateInternal(bitstream, copy_data, WEBP_MUX_ABI_VERSION);
+}
+
+//------------------------------------------------------------------------------
+// Non-image chunks.
+
+// Note: Only non-image related chunks should be managed through chunk APIs.
+// (Image related chunks are: "ANMF", "VP8 ", "VP8L" and "ALPH").
+// To add, get and delete images, use WebPMuxSetImage(), WebPMuxPushFrame(),
+// WebPMuxGetFrame() and WebPMuxDeleteFrame().
+
+// Adds a chunk with id 'fourcc' and data 'chunk_data' in the mux object.
+// Any existing chunk(s) with the same id will be removed.
+// Parameters:
+//   mux - (in/out) object to which the chunk is to be added
+//   fourcc - (in) a character array containing the fourcc of the given chunk;
+//                 e.g., "ICCP", "XMP ", "EXIF" etc.
+//   chunk_data - (in) the chunk data to be added
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, fourcc or chunk_data is NULL
+//                               or if fourcc corresponds to an image chunk.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxSetChunk(
+    WebPMux* mux, const char fourcc[4], const WebPData* chunk_data,
+    int copy_data);
+
+// Gets a reference to the data of the chunk with id 'fourcc' in the mux object.
+// The caller should NOT free the returned data.
+// Parameters:
+//   mux - (in) object from which the chunk data is to be fetched
+//   fourcc - (in) a character array containing the fourcc of the chunk;
+//                 e.g., "ICCP", "XMP ", "EXIF" etc.
+//   chunk_data - (out) returned chunk data
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, fourcc or chunk_data is NULL
+//                               or if fourcc corresponds to an image chunk.
+//   WEBP_MUX_NOT_FOUND - If mux does not contain a chunk with the given id.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxGetChunk(
+    const WebPMux* mux, const char fourcc[4], WebPData* chunk_data);
+
+// Deletes the chunk with the given 'fourcc' from the mux object.
+// Parameters:
+//   mux - (in/out) object from which the chunk is to be deleted
+//   fourcc - (in) a character array containing the fourcc of the chunk;
+//                 e.g., "ICCP", "XMP ", "EXIF" etc.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or fourcc is NULL
+//                               or if fourcc corresponds to an image chunk.
+//   WEBP_MUX_NOT_FOUND - If mux does not contain a chunk with the given fourcc.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxDeleteChunk(
+    WebPMux* mux, const char fourcc[4]);
+
+//------------------------------------------------------------------------------
+// Images.
+
+// Encapsulates data about a single frame.
+struct WebPMuxFrameInfo {
+  WebPData    bitstream;  // image data: can be a raw VP8/VP8L bitstream
+                          // or a single-image WebP file.
+  int         x_offset;   // x-offset of the frame.
+  int         y_offset;   // y-offset of the frame.
+  int         duration;   // duration of the frame (in milliseconds).
+
+  WebPChunkId id;         // frame type: should be one of WEBP_CHUNK_ANMF
+                          // or WEBP_CHUNK_IMAGE
+  WebPMuxAnimDispose dispose_method;  // Disposal method for the frame.
+  WebPMuxAnimBlend   blend_method;    // Blend operation for the frame.
+  uint32_t    pad[1];     // padding for later use
+};
+
+// Sets the (non-animated) image in the mux object.
+// Note: Any existing images (including frames) will be removed.
+// Parameters:
+//   mux - (in/out) object in which the image is to be set
+//   bitstream - (in) can be a raw VP8/VP8L bitstream or a single-image
+//               WebP file (non-animated)
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL or bitstream is NULL.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxSetImage(
+    WebPMux* mux, const WebPData* bitstream, int copy_data);
+
+// Adds a frame at the end of the mux object.
+// Notes: (1) frame.id should be WEBP_CHUNK_ANMF
+//        (2) For setting a non-animated image, use WebPMuxSetImage() instead.
+//        (3) Type of frame being pushed must be same as the frames in mux.
+//        (4) As WebP only supports even offsets, any odd offset will be snapped
+//            to an even location using: offset &= ~1
+// Parameters:
+//   mux - (in/out) object to which the frame is to be added
+//   frame - (in) frame data.
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or frame is NULL
+//                               or if content of 'frame' is invalid.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxPushFrame(
+    WebPMux* mux, const WebPMuxFrameInfo* frame, int copy_data);
+
+// Gets the nth frame from the mux object.
+// The content of 'frame->bitstream' is allocated using malloc(), and NOT
+// owned by the 'mux' object. It MUST be deallocated by the caller by calling
+// WebPDataClear().
+// nth=0 has a special meaning - last position.
+// Parameters:
+//   mux - (in) object from which the info is to be fetched
+//   nth - (in) index of the frame in the mux object
+//   frame - (out) data of the returned frame
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or frame is NULL.
+//   WEBP_MUX_NOT_FOUND - if there are less than nth frames in the mux object.
+//   WEBP_MUX_BAD_DATA - if nth frame chunk in mux is invalid.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxGetFrame(
+    const WebPMux* mux, uint32_t nth, WebPMuxFrameInfo* frame);
+
+// Deletes a frame from the mux object.
+// nth=0 has a special meaning - last position.
+// Parameters:
+//   mux - (in/out) object from which a frame is to be deleted
+//   nth - (in) The position from which the frame is to be deleted
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL.
+//   WEBP_MUX_NOT_FOUND - If there are less than nth frames in the mux object
+//                        before deletion.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxDeleteFrame(WebPMux* mux, uint32_t nth);
+
+//------------------------------------------------------------------------------
+// Animation.
+
+// Animation parameters.
+struct WebPMuxAnimParams {
+  uint32_t bgcolor;  // Background color of the canvas stored (in MSB order) as:
+                     // Bits 00 to 07: Alpha.
+                     // Bits 08 to 15: Red.
+                     // Bits 16 to 23: Green.
+                     // Bits 24 to 31: Blue.
+  int loop_count;    // Number of times to repeat the animation [0 = infinite].
+};
+
+// Sets the animation parameters in the mux object. Any existing ANIM chunks
+// will be removed.
+// Parameters:
+//   mux - (in/out) object in which ANIM chunk is to be set/added
+//   params - (in) animation parameters.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or params is NULL.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxSetAnimationParams(
+    WebPMux* mux, const WebPMuxAnimParams* params);
+
+// Gets the animation parameters from the mux object.
+// Parameters:
+//   mux - (in) object from which the animation parameters to be fetched
+//   params - (out) animation parameters extracted from the ANIM chunk
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or params is NULL.
+//   WEBP_MUX_NOT_FOUND - if ANIM chunk is not present in mux object.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxGetAnimationParams(
+    const WebPMux* mux, WebPMuxAnimParams* params);
+
+//------------------------------------------------------------------------------
+// Misc Utilities.
+
+// Sets the canvas size for the mux object. The width and height can be
+// specified explicitly or left as zero (0, 0).
+// * When width and height are specified explicitly, then this frame bound is
+//   enforced during subsequent calls to WebPMuxAssemble() and an error is
+//   reported if any animated frame does not completely fit within the canvas.
+// * When unspecified (0, 0), the constructed canvas will get the frame bounds
+//   from the bounding-box over all frames after calling WebPMuxAssemble().
+// Parameters:
+//   mux - (in) object to which the canvas size is to be set
+//   width - (in) canvas width
+//   height - (in) canvas height
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL; or
+//                               width or height are invalid or out of bounds
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxSetCanvasSize(WebPMux* mux,
+                                              int width, int height);
+
+// Gets the canvas size from the mux object.
+// Note: This method assumes that the VP8X chunk, if present, is up-to-date.
+// That is, the mux object hasn't been modified since the last call to
+// WebPMuxAssemble() or WebPMuxCreate().
+// Parameters:
+//   mux - (in) object from which the canvas size is to be fetched
+//   width - (out) canvas width
+//   height - (out) canvas height
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, width or height is NULL.
+//   WEBP_MUX_BAD_DATA - if VP8X/VP8/VP8L chunk or canvas size is invalid.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxGetCanvasSize(const WebPMux* mux,
+                                              int* width, int* height);
+
+// Gets the feature flags from the mux object.
+// Note: This method assumes that the VP8X chunk, if present, is up-to-date.
+// That is, the mux object hasn't been modified since the last call to
+// WebPMuxAssemble() or WebPMuxCreate().
+// Parameters:
+//   mux - (in) object from which the features are to be fetched
+//   flags - (out) the flags specifying which features are present in the
+//           mux object. This will be an OR of various flag values.
+//           Enum 'WebPFeatureFlags' can be used to test individual flag values.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or flags is NULL.
+//   WEBP_MUX_BAD_DATA - if VP8X/VP8/VP8L chunk or canvas size is invalid.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxGetFeatures(const WebPMux* mux,
+                                            uint32_t* flags);
+
+// Gets number of chunks with the given 'id' in the mux object.
+// Parameters:
+//   mux - (in) object from which the info is to be fetched
+//   id - (in) chunk id specifying the type of chunk
+//   num_elements - (out) number of chunks with the given chunk id
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, or num_elements is NULL.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxNumChunks(const WebPMux* mux,
+                                          WebPChunkId id, int* num_elements);
+
+// Assembles all chunks in WebP RIFF format and returns in 'assembled_data'.
+// This function also validates the mux object.
+// Note: The content of 'assembled_data' will be ignored and overwritten.
+// Also, the content of 'assembled_data' is allocated using malloc(), and NOT
+// owned by the 'mux' object. It MUST be deallocated by the caller by calling
+// WebPDataClear(). It's always safe to call WebPDataClear() upon return,
+// even in case of error.
+// Parameters:
+//   mux - (in/out) object whose chunks are to be assembled
+//   assembled_data - (out) assembled WebP data
+// Returns:
+//   WEBP_MUX_BAD_DATA - if mux object is invalid.
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or assembled_data is NULL.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN WebPMuxError WebPMuxAssemble(WebPMux* mux,
+                                         WebPData* assembled_data);
+
+//------------------------------------------------------------------------------
+// WebPAnimEncoder API
+//
+// This API allows encoding (possibly) animated WebP images.
+//
+// Code Example:
+/*
+  WebPAnimEncoderOptions enc_options;
+  WebPAnimEncoderOptionsInit(&enc_options);
+  // Tune 'enc_options' as needed.
+  WebPAnimEncoder* enc = WebPAnimEncoderNew(width, height, &enc_options);
+  while(<there are more frames>) {
+    WebPConfig config;
+    WebPConfigInit(&config);
+    // Tune 'config' as needed.
+    WebPAnimEncoderAdd(enc, frame, timestamp_ms, &config);
+  }
+  WebPAnimEncoderAdd(enc, NULL, timestamp_ms, NULL);
+  WebPAnimEncoderAssemble(enc, webp_data);
+  WebPAnimEncoderDelete(enc);
+  // Write the 'webp_data' to a file, or re-mux it further.
+*/
+
+typedef struct WebPAnimEncoder WebPAnimEncoder;  // Main opaque object.
+
+// Forward declarations. Defined in encode.h.
+struct WebPPicture;
+struct WebPConfig;
+
+// Global options.
+struct WebPAnimEncoderOptions {
+  WebPMuxAnimParams anim_params;  // Animation parameters.
+  int minimize_size;    // If true, minimize the output size (slow). Implicitly
+                        // disables key-frame insertion.
+  int kmin;
+  int kmax;             // Minimum and maximum distance between consecutive key
+                        // frames in the output. The library may insert some key
+                        // frames as needed to satisfy this criteria.
+                        // Note that these conditions should hold: kmax > kmin
+                        // and kmin >= kmax / 2 + 1. Also, if kmax <= 0, then
+                        // key-frame insertion is disabled; and if kmax == 1,
+                        // then all frames will be key-frames (kmin value does
+                        // not matter for these special cases).
+  int allow_mixed;      // If true, use mixed compression mode; may choose
+                        // either lossy and lossless for each frame.
+  int verbose;          // If true, print info and warning messages to stderr.
+
+  uint32_t padding[4];  // Padding for later use.
+};
+
+// Internal, version-checked, entry point.
+WEBP_EXTERN int WebPAnimEncoderOptionsInitInternal(
+    WebPAnimEncoderOptions*, int);
+
+// Should always be called, to initialize a fresh WebPAnimEncoderOptions
+// structure before modification. Returns false in case of version mismatch.
+// WebPAnimEncoderOptionsInit() must have succeeded before using the
+// 'enc_options' object.
+static WEBP_INLINE int WebPAnimEncoderOptionsInit(
+    WebPAnimEncoderOptions* enc_options) {
+  return WebPAnimEncoderOptionsInitInternal(enc_options, WEBP_MUX_ABI_VERSION);
+}
+
+// Internal, version-checked, entry point.
+WEBP_EXTERN WebPAnimEncoder* WebPAnimEncoderNewInternal(
+    int, int, const WebPAnimEncoderOptions*, int);
+
+// Creates and initializes a WebPAnimEncoder object.
+// Parameters:
+//   width/height - (in) canvas width and height of the animation.
+//   enc_options - (in) encoding options; can be passed NULL to pick
+//                      reasonable defaults.
+// Returns:
+//   A pointer to the newly created WebPAnimEncoder object.
+//   Or NULL in case of memory error.
+static WEBP_INLINE WebPAnimEncoder* WebPAnimEncoderNew(
+    int width, int height, const WebPAnimEncoderOptions* enc_options) {
+  return WebPAnimEncoderNewInternal(width, height, enc_options,
+                                    WEBP_MUX_ABI_VERSION);
+}
+
+// Optimize the given frame for WebP, encode it and add it to the
+// WebPAnimEncoder object.
+// The last call to 'WebPAnimEncoderAdd' should be with frame = NULL, which
+// indicates that no more frames are to be added. This call is also used to
+// determine the duration of the last frame.
+// Parameters:
+//   enc - (in/out) object to which the frame is to be added.
+//   frame - (in/out) frame data in ARGB or YUV(A) format. If it is in YUV(A)
+//           format, it will be converted to ARGB, which incurs a small loss.
+//   timestamp_ms - (in) timestamp of this frame in milliseconds.
+//                       Duration of a frame would be calculated as
+//                       "timestamp of next frame - timestamp of this frame".
+//                       Hence, timestamps should be in non-decreasing order.
+//   config - (in) encoding options; can be passed NULL to pick
+//            reasonable defaults.
+// Returns:
+//   On error, returns false and frame->error_code is set appropriately.
+//   Otherwise, returns true.
+WEBP_EXTERN int WebPAnimEncoderAdd(
+    WebPAnimEncoder* enc, struct WebPPicture* frame, int timestamp_ms,
+    const struct WebPConfig* config);
+
+// Assemble all frames added so far into a WebP bitstream.
+// This call should be preceded by  a call to 'WebPAnimEncoderAdd' with
+// frame = NULL; if not, the duration of the last frame will be internally
+// estimated.
+// Parameters:
+//   enc - (in/out) object from which the frames are to be assembled.
+//   webp_data - (out) generated WebP bitstream.
+// Returns:
+//   True on success.
+WEBP_EXTERN int WebPAnimEncoderAssemble(WebPAnimEncoder* enc,
+                                        WebPData* webp_data);
+
+// Get error string corresponding to the most recent call using 'enc'. The
+// returned string is owned by 'enc' and is valid only until the next call to
+// WebPAnimEncoderAdd() or WebPAnimEncoderAssemble() or WebPAnimEncoderDelete().
+// Parameters:
+//   enc - (in/out) object from which the error string is to be fetched.
+// Returns:
+//   NULL if 'enc' is NULL. Otherwise, returns the error string if the last call
+//   to 'enc' had an error, or an empty string if the last call was a success.
+WEBP_EXTERN const char* WebPAnimEncoderGetError(WebPAnimEncoder* enc);
+
+// Deletes the WebPAnimEncoder object.
+// Parameters:
+//   enc - (in/out) object to be deleted
+WEBP_EXTERN void WebPAnimEncoderDelete(WebPAnimEncoder* enc);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_WEBP_MUX_H_ */