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// 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.
// -----------------------------------------------------------------------------
// Internal header for mux library.
// Author: Urvang (
#ifndef WEBP_MUX_MUXI_H_
#define WEBP_MUX_MUXI_H_
#include <stdlib.h>
#include "../dec/vp8i.h"
#include "../dec/vp8li.h"
#include "../webp/mux.h"
#ifdef __cplusplus
extern "C" {
// Defines and constants.
// Chunk object.
typedef struct WebPChunk WebPChunk;
struct WebPChunk {
uint32_t tag_;
int owner_; // True if *data_ memory is owned internally.
// VP8X, ANIM, and other internally created chunks
// like ANMF are always owned.
WebPData data_;
WebPChunk* next_;
// MuxImage object. Store a full WebP image (including ANMF chunk, ALPH
// chunk and VP8/VP8L chunk),
typedef struct WebPMuxImage WebPMuxImage;
struct WebPMuxImage {
WebPChunk* header_; // Corresponds to WEBP_CHUNK_ANMF.
WebPChunk* alpha_; // Corresponds to WEBP_CHUNK_ALPHA.
WebPChunk* img_; // Corresponds to WEBP_CHUNK_IMAGE.
WebPChunk* unknown_; // Corresponds to WEBP_CHUNK_UNKNOWN.
int width_;
int height_;
int has_alpha_; // Through ALPH chunk or as part of VP8L.
int is_partial_; // True if only some of the chunks are filled.
WebPMuxImage* next_;
// Main mux object. Stores data chunks.
struct WebPMux {
WebPMuxImage* images_;
WebPChunk* iccp_;
WebPChunk* exif_;
WebPChunk* xmp_;
WebPChunk* anim_;
WebPChunk* vp8x_;
WebPChunk* unknown_;
int canvas_width_;
int canvas_height_;
// CHUNK_INDEX enum: used for indexing within 'kChunks' (defined below) only.
// Note: the reason for having two enums ('WebPChunkId' and 'CHUNK_INDEX') is to
// allow two different chunks to have the same id (e.g. WebPChunkId
// 'WEBP_CHUNK_IMAGE' can correspond to CHUNK_INDEX 'IDX_VP8' or 'IDX_VP8L').
typedef enum {
IDX_VP8X = 0,
#define NIL_TAG 0x00000000u // To signal void chunk.
typedef struct {
uint32_t tag;
WebPChunkId id;
uint32_t size;
} ChunkInfo;
extern const ChunkInfo kChunks[IDX_LAST_CHUNK];
// Chunk object management.
// Initialize.
void ChunkInit(WebPChunk* const chunk);
// Get chunk index from chunk tag. Returns IDX_UNKNOWN if not found.
CHUNK_INDEX ChunkGetIndexFromTag(uint32_t tag);
// Get chunk id from chunk tag. Returns WEBP_CHUNK_UNKNOWN if not found.
WebPChunkId ChunkGetIdFromTag(uint32_t tag);
// Convert a fourcc string to a tag.
uint32_t ChunkGetTagFromFourCC(const char fourcc[4]);
// Get chunk index from fourcc. Returns IDX_UNKNOWN if given fourcc is unknown.
CHUNK_INDEX ChunkGetIndexFromFourCC(const char fourcc[4]);
// Search for nth chunk with given 'tag' in the chunk list.
// nth = 0 means "last of the list".
WebPChunk* ChunkSearchList(WebPChunk* first, uint32_t nth, uint32_t tag);
// Fill the chunk with the given data.
WebPMuxError ChunkAssignData(WebPChunk* chunk, const WebPData* const data,
int copy_data, uint32_t tag);
// Sets 'chunk' at nth position in the 'chunk_list'.
// nth = 0 has the special meaning "last of the list".
// On success ownership is transferred from 'chunk' to the 'chunk_list'.
WebPMuxError ChunkSetNth(WebPChunk* chunk, WebPChunk** chunk_list,
uint32_t nth);
// Releases chunk and returns chunk->next_.
WebPChunk* ChunkRelease(WebPChunk* const chunk);
// Deletes given chunk & returns chunk->next_.
WebPChunk* ChunkDelete(WebPChunk* const chunk);
// Deletes all chunks in the given chunk list.
void ChunkListDelete(WebPChunk** const chunk_list);
// Returns size of the chunk including chunk header and padding byte (if any).
static WEBP_INLINE size_t SizeWithPadding(size_t chunk_size) {
return CHUNK_HEADER_SIZE + ((chunk_size + 1) & ~1U);
// Size of a chunk including header and padding.
static WEBP_INLINE size_t ChunkDiskSize(const WebPChunk* chunk) {
const size_t data_size = chunk->data_.size;
assert(data_size < MAX_CHUNK_PAYLOAD);
return SizeWithPadding(data_size);
// Total size of a list of chunks.
size_t ChunkListDiskSize(const WebPChunk* chunk_list);
// Write out the given list of chunks into 'dst'.
uint8_t* ChunkListEmit(const WebPChunk* chunk_list, uint8_t* dst);
// MuxImage object management.
// Initialize.
void MuxImageInit(WebPMuxImage* const wpi);
// Releases image 'wpi' and returns wpi->next.
WebPMuxImage* MuxImageRelease(WebPMuxImage* const wpi);
// Delete image 'wpi' and return the next image in the list or NULL.
// 'wpi' can be NULL.
WebPMuxImage* MuxImageDelete(WebPMuxImage* const wpi);
// Count number of images matching the given tag id in the 'wpi_list'.
// If id == WEBP_CHUNK_NIL, all images will be matched.
int MuxImageCount(const WebPMuxImage* wpi_list, WebPChunkId id);
// Update width/height/has_alpha info from chunks within wpi.
// Also remove ALPH chunk if not needed.
int MuxImageFinalize(WebPMuxImage* const wpi);
// Check if given ID corresponds to an image related chunk.
static WEBP_INLINE int IsWPI(WebPChunkId id) {
switch (id) {
case WEBP_CHUNK_IMAGE: return 1;
default: return 0;
// Pushes 'wpi' at the end of 'wpi_list'.
WebPMuxError MuxImagePush(const WebPMuxImage* wpi, WebPMuxImage** wpi_list);
// Delete nth image in the image list.
WebPMuxError MuxImageDeleteNth(WebPMuxImage** wpi_list, uint32_t nth);
// Get nth image in the image list.
WebPMuxError MuxImageGetNth(const WebPMuxImage** wpi_list, uint32_t nth,
WebPMuxImage** wpi);
// Total size of the given image.
size_t MuxImageDiskSize(const WebPMuxImage* const wpi);
// Write out the given image into 'dst'.
uint8_t* MuxImageEmit(const WebPMuxImage* const wpi, uint8_t* dst);
// Helper methods for mux.
// Checks if the given image list contains at least one image with alpha.
int MuxHasAlpha(const WebPMuxImage* images);
// Write out RIFF header into 'data', given total data size 'size'.
uint8_t* MuxEmitRiffHeader(uint8_t* const data, size_t size);
// Returns the list where chunk with given ID is to be inserted in mux.
WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, WebPChunkId id);
// Validates the given mux object.
WebPMuxError MuxValidate(const WebPMux* const mux);
#ifdef __cplusplus
} // extern "C"
#endif /* WEBP_MUX_MUXI_H_ */