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/*
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE 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.
*/
#ifndef MODULES_AUDIO_PROCESSING_TRANSIENT_WPD_TREE_H_
#define MODULES_AUDIO_PROCESSING_TRANSIENT_WPD_TREE_H_
#include <stddef.h>
#include <memory>
#include "modules/audio_processing/transient/wpd_node.h"
namespace webrtc {
// Tree of a Wavelet Packet Decomposition (WPD).
//
// The root node contains all the data provided; for each node in the tree, the
// left child contains the approximation coefficients extracted from the node,
// and the right child contains the detail coefficients.
// It preserves its state, so it can be multiple-called.
//
// The number of nodes in the tree will be 2 ^ levels - 1.
//
// Implementation details: Since the tree always will be a complete binary tree,
// it is implemented using a single linear array instead of managing the
// relationships in each node. For convience is better to use a array that
// starts in 1 (instead of 0). Taking that into account, the following formulas
// apply:
// Root node index: 1.
// Node(Level, Index in that level): 2 ^ Level + (Index in that level).
// Left Child: Current node index * 2.
// Right Child: Current node index * 2 + 1.
// Parent: Current Node Index / 2 (Integer division).
class WPDTree {
public:
// Creates a WPD tree using the data length and coefficients provided.
WPDTree(size_t data_length,
const float* high_pass_coefficients,
const float* low_pass_coefficients,
size_t coefficients_length,
int levels);
~WPDTree();
// Returns the number of nodes at any given level.
static int NumberOfNodesAtLevel(int level) { return 1 << level; }
// Returns a pointer to the node at the given level and index(of that level).
// Level goes from 0 to levels().
// Index goes from 0 to the number of NumberOfNodesAtLevel(level) - 1.
//
// You can use the following formulas to get any node within the tree:
// Notation: (Level, Index of node in that level).
// Root node: (0/0).
// Left Child: (Current node level + 1, Current node index * 2).
// Right Child: (Current node level + 1, Current node index * 2 + 1).
// Parent: (Current node level - 1, Current node index / 2) (Integer division)
//
// If level or index are out of bounds the function will return NULL.
WPDNode* NodeAt(int level, int index);
// Updates all the nodes of the tree with the new data. `data_length` must be
// teh same that was used for the creation of the tree.
// Returns 0 if correct, and -1 otherwise.
int Update(const float* data, size_t data_length);
// Returns the total number of levels below the root. Root is cosidered level
// 0.
int levels() const { return levels_; }
// Returns the total number of nodes.
int num_nodes() const { return num_nodes_; }
// Returns the total number of leaves.
int num_leaves() const { return 1 << levels_; }
private:
size_t data_length_;
int levels_;
int num_nodes_;
std::unique_ptr<std::unique_ptr<WPDNode>[]> nodes_;
};
} // namespace webrtc
#endif // MODULES_AUDIO_PROCESSING_TRANSIENT_WPD_TREE_H_
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