| // Copyright 2012 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. |
| // ----------------------------------------------------------------------------- |
| // |
| // Author: Jyrki Alakuijala (jyrki@google.com) |
| // |
| // Models the histograms of literal and distance codes. |
| |
| #ifndef WEBP_ENC_HISTOGRAM_H_ |
| #define WEBP_ENC_HISTOGRAM_H_ |
| |
| #include <assert.h> |
| #include <stddef.h> |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include <string.h> |
| |
| #include "./backward_references.h" |
| #include "webp/format_constants.h" |
| #include "webp/types.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| // A simple container for histograms of data. |
| typedef struct { |
| // literal_ contains green literal, palette-code and |
| // copy-length-prefix histogram |
| uint32_t* literal_; // Pointer to the allocated buffer for literal. |
| uint32_t red_[NUM_LITERAL_CODES]; |
| uint32_t blue_[NUM_LITERAL_CODES]; |
| uint32_t alpha_[NUM_LITERAL_CODES]; |
| // Backward reference prefix-code histogram. |
| uint32_t distance_[NUM_DISTANCE_CODES]; |
| int palette_code_bits_; |
| double bit_cost_; // cached value of VP8LHistogramEstimateBits(this) |
| double literal_cost_; // Cached values of dominant entropy costs: |
| double red_cost_; // literal, red & blue. |
| double blue_cost_; |
| } VP8LHistogram; |
| |
| // Collection of histograms with fixed capacity, allocated as one |
| // big memory chunk. Can be destroyed by calling WebPSafeFree(). |
| typedef struct { |
| int size; // number of slots currently in use |
| int max_size; // maximum capacity |
| VP8LHistogram** histograms; |
| } VP8LHistogramSet; |
| |
| // Create the histogram. |
| // |
| // The input data is the PixOrCopy data, which models the literals, stop |
| // codes and backward references (both distances and lengths). Also: if |
| // palette_code_bits is >= 0, initialize the histogram with this value. |
| void VP8LHistogramCreate(VP8LHistogram* const p, |
| const VP8LBackwardRefs* const refs, |
| int palette_code_bits); |
| |
| // Return the size of the histogram for a given palette_code_bits. |
| int VP8LGetHistogramSize(int palette_code_bits); |
| |
| // Set the palette_code_bits and reset the stats. |
| void VP8LHistogramInit(VP8LHistogram* const p, int palette_code_bits); |
| |
| // Collect all the references into a histogram (without reset) |
| void VP8LHistogramStoreRefs(const VP8LBackwardRefs* const refs, |
| VP8LHistogram* const histo); |
| |
| // Free the memory allocated for the histogram. |
| void VP8LFreeHistogram(VP8LHistogram* const histo); |
| |
| // Free the memory allocated for the histogram set. |
| void VP8LFreeHistogramSet(VP8LHistogramSet* const histo); |
| |
| // Allocate an array of pointer to histograms, allocated and initialized |
| // using 'cache_bits'. Return NULL in case of memory error. |
| VP8LHistogramSet* VP8LAllocateHistogramSet(int size, int cache_bits); |
| |
| // Allocate and initialize histogram object with specified 'cache_bits'. |
| // Returns NULL in case of memory error. |
| // Special case of VP8LAllocateHistogramSet, with size equals 1. |
| VP8LHistogram* VP8LAllocateHistogram(int cache_bits); |
| |
| // Accumulate a token 'v' into a histogram. |
| void VP8LHistogramAddSinglePixOrCopy(VP8LHistogram* const histo, |
| const PixOrCopy* const v); |
| |
| // Estimate how many bits the combined entropy of literals and distance |
| // approximately maps to. |
| double VP8LHistogramEstimateBits(const VP8LHistogram* const p); |
| |
| // This function estimates the cost in bits excluding the bits needed to |
| // represent the entropy code itself. |
| double VP8LHistogramEstimateBitsBulk(const VP8LHistogram* const p); |
| |
| static WEBP_INLINE int VP8LHistogramNumCodes(int palette_code_bits) { |
| return NUM_LITERAL_CODES + NUM_LENGTH_CODES + |
| ((palette_code_bits > 0) ? (1 << palette_code_bits) : 0); |
| } |
| |
| // Builds the histogram image. |
| int VP8LGetHistoImageSymbols(int xsize, int ysize, |
| const VP8LBackwardRefs* const refs, |
| int quality, int histogram_bits, int cache_bits, |
| VP8LHistogramSet* const image_in, |
| uint16_t* const histogram_symbols); |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif // WEBP_ENC_HISTOGRAM_H_ |