DiscreteCosineTransform.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#ifndef META_OCEAN_MATH_DISCRETE_COSINE_TRANSFORM_H
#define META_OCEAN_MATH_DISCRETE_COSINE_TRANSFORM_H
 
#include "ocean/math/Math.h"
 
namespace Ocean
{
 
/**
 * This class implements discrete cosine transform functions.
 * @ingroup math
 */
class OCEAN_MATH_EXPORT DiscreteCosineTransform
{
    public:
 
        /**
         * Applies a 2D discrete cosine transform for a given 2D data block.
         * The resulting coefficients are stored in an row aligned order.<br>
         * @param data Data block for that the transform is applied
         * @param xElements Number of horizontal data elements, with range [1, infinity)
         * @param yElements Number of vertical data elements, with range [1, infinity)
         * @param coefficients Resulting number of coefficients, an array with xElements * yElements values must be provided
         */
        static inline void transform2(const Scalar* data, const unsigned int xElements, const unsigned int yElements, Scalar* coefficients);
 
        /**
         * Applies a 2D discrete cosine transform for a given 2D data block that might be larger than the actual DCT data block.
         * The resulting coefficients are stored in an row aligned order.<br>
         * @param data Data block for that the transform is applied (pointer to the first element)
         * @param xElements Number of horizontal data elements, with range [1, infinity)
         * @param yElements Number of vertical data elements, with range [1, infinity)
         * @param stride Width of the entire data information including the xElements, with range [xElements, infinity)
         * @param coefficients Resulting number of coefficients, an array with xElements * yElements values must be provided
         */
        static void transform2(const Scalar* data, const unsigned int xElements, const unsigned int yElements, const unsigned int stride, Scalar* coefficients);
 
        /**
         * Applies a inverse 2D discrete cosine transform for a given set of DCT coefficients.
         * @param coefficients DCT coefficients from that the data information will be recovered
         * @param xElements Number of horizontal data elements, with range [1, infinity)
         * @param yElements Number of vertical data elements, with range [1, infinity)
         * @param data Resulting data block, an array with xElements * yElements values must be provided
         */
        static inline void iTransform2(const Scalar* coefficients, const unsigned int xElements, const unsigned int yElements, Scalar* data);
 
        /**
         * Applies a inverse 2D discrete cosine transform for a given set of DCT coefficients.
         * @param coefficients DCT coefficients from that the data information will be recovered
         * @param xElements Number of horizontal data elements, with range [1, infinity)
         * @param yElements Number of vertical data elements, with range [1, infinity)
         * @param stride Width of the data information including the xElements, with range [xElements, infinity)
         * @param data Resulting data block, a data block that might be larger than the actual number of DCT coefficients as an explicit stride parameter can be defined
         */
        static void iTransform2(const Scalar* coefficients, const unsigned int xElements, const unsigned int yElements, const unsigned int stride, Scalar* data);
};
 
inline void DiscreteCosineTransform::transform2(const Scalar* data, const unsigned int xElements, const unsigned int yElements, Scalar* coefficients)
{
    transform2(data, xElements, yElements, xElements, coefficients);
}
 
inline void DiscreteCosineTransform::iTransform2(const Scalar* coefficients, const unsigned int xElements, const unsigned int yElements, Scalar* data)
{
    iTransform2(coefficients, xElements, yElements, xElements, data);
}
 
}
 
#endif // META_OCEAN_MATH_DISCRETE_COSINE_TRANSFORM_H