Modulated Complex Lapped Transform Research Articles

Цифровое маркирование аудиосигналов, основанное на модуляции MCLT-коэффициентов

Audio data hiding techniques have various applications such as audio watermarking and steganography. This article provides a brief description of a new method of digital audio watermarking that has been developed based on a modulated complex lapped transform (MCLT). The new audio watermarking algorithm saves the sound quality of the marked signals. The experimental results show the dependence of the sound quality of the marked audio signal on the parameters of the marking method. Moreover, the results of the experiments show the influence of various attacks on the marked audio signal. Based on conducted experiments, it is concluded that the new method of digital audio watermarking can be used to confirm the authenticity of audio files distributed through the Internet or to confirm the integrity of the transmitted audio files.

An acoustic data transmission system based on audio data hiding: method and performance evaluation

Abstract Acoustic data transmission (ADT) forms a branch of the audio data hiding techniques with its capability of communicating data in short-range aerial space between a loudspeaker and a microphone. In this paper, we propose an acoustic data transmission system extending our previous studies and give an in-depth analysis of its performance. The proposed technique utilizes the phases of modulated complex lapped transform (MCLT) coefficients of the audio signal. To achieve a good trade-off between the audio quality and the data transmission performance, the enhanced segmental SNR adjustment (SSA) algorithm is proposed. Moreover, we also propose a scheme to use multiple microphones for ADT technique. This multi-microphone ADT technique further enhances the transmission performance while ensuring compatibility with the single microphone system. From a series of experimental results, it has been found that the transmission performance improves when the length of the MCLT frame gets longer at the cost of the audio quality degradation. In addition, a good trade-off between the audio quality and data transmission performance is achieved by means of SSA algorithm. The experimental results also reveal that the proposed multi-microphone method is useful in enhancing the transmission performance.

Audio Fingerprinting Using a Robust Hash Function Based on the MCLT Peak-Pair

In this paper, we propose an audio fingerprinting using robust hash based on the MCLT (Modulated Complex Lapped Transform) peak-pair. In existing methods, the robust audio fingerprinting is not generated if various distortions occurred; time-scaling, pith-shifting and equalization. To solve this problem, we used the spectrum of the MCLT, an adaptive thresholding method for detection of prominent peaks and the novel hash function in the audio fingerprinting. Experimental results show that the proposed method is highly robust in various distorted environments and achieves better identification rates compared to other methods.

New Recursive Fast Radix-2 Algorithm for the Modulated Complex Lapped Transform

A new recursive fast radix-2 algorithm for an efficient computation of the modulated complex lapped transform (MCLT) is presented. Based on a new proposed alternative recursive sparse matrix factorization for the MDCT (modified discrete cosine transform) matrix and a relation between the MDCT and the MDST (modified discrete sine transform), firstly a new recursive fast radix-2 MDST algorithm is derived. The corresponding fast MDCT and MDST computational structures are regular and complementary to each other. Consequently, this fact enables us by their composition to construct a fast MCLT computational structure representing the fast recursive radix-2 MCLT algorithm. The fast MCLT computational structure is regular and all its stages may be realized in parallel. Combining the proposed fast radix-2 MCLT algorithm with an existing generalized fast mixed-radix MDCT algorithm defined for the composite lengths N = 2 × qm, m ≥ 2, where q is an odd positive integer, we can compute the MCLT for the composite lengths N = 2n × qm, n, m ≥ 2, thus supporting a wider range of transform sizes compared to existing fast MCLT algorithms.

Spectral Magnitude Adjustment for MCLT-Based Acoustic Data Transmission

Acoustic data transmission is a technique which embeds data in a sound wave imperceptibly and detects it at a receiver. The data are embedded in an original audio signal and transmitted through the air by playing back the data-embedded audio using a loudspeaker. At the receiver, the data are extracted from the received audio signal captured by a microphone. In our previous work, we proposed an acoustic data transmission system designed based on phase modification of the modulated complex lapped transform (MCLT) coefficients. In this paper, we propose the spectral magnitude adjustment (SMA) technique which not only enhances the quality of the data-embedded audio signal but also improves the transmission performance of the system.

On the Implementation of a Hardware Architecture for an Audio Data Hiding System

Data hiding systems have emerged as a solution against the piracy problem, particularly those based on quantization have been widely used for its simplicity and high performance. Several data hiding applications, such as broadcasting monitoring and live performance watermarking, require a real-time multi-channel behavior. While Digital Signal Processors (DSP) have been used for implementing these schemes achieving real-time performance for audio signal processing, custom hardware architectures offer the possibility of fully exploiting the inherent parallelism of this type of algorithms for more demanding applications. This paper presents an efficient hardware implementation of a Rational Dither Modulation (RDM) algorithm-based data hiding system in the Modulated Complex Lapped Transform (MCLT) domain. In general terms, the proposed hardware architecture is conformed by an MCLT processor, an Inverse MCLT processor, a Coordinate Rotation Digital Computer (CORDIC) and an RDM-QIM processor. Results of implementing the proposed hardware architecture on a Field Programmable Gate Array (FPGA) are presented and discussed.

Robust Data Hiding for MCLT Based Acoustic Data Transmission

Acoustic data transmission enables a short-range wireless communication between the loudspeaker and microphone. A transmitter embeds a data stream into a base audio signal such as music or commercial advertisement and broadcasts the data through the air by playing back the data-embedded sound using a loudspeaker. A receiver picks up the sound signal using microphone and extracts the hidden message. In our previous work, we proposed an acoustic data transmission system which takes advantage of the phase modification of the modulated complex lapped transform (MCLT) coefficients. In this letter, we propose several techniques to realize a more robust communication system in real noisy environment.

New Fast Algorithm for Modulated Complex Lapped Transform with Arbitrary Windowing Function

摘要: 该文提出了一种任意窗函数的复数调制重叠变换(MCLT)的快速计算方法。针对输入信号长度为2M 的MCLT，该算法将其转化为长度为2M的II型离散 Hartley 变换，然后对后者运用快速算法。与现有算法相比，该方法能够达到最少的算术运算量。 关键词: 音频处理; 重叠转换; 快速算法; 离散 Hartley 转换

Acoustic Data Transmission Based on Modulated Complex Lapped Transform

Acoustic data transmission is a technique to embed the data in a sound wave imperceptibly and to detect it at the receiver. This letter proposes a novel acoustic data transmission system designed based on the modulated complex lapped transform (MCLT). In the proposed system, data is embedded in an audio file by modifying the phases of the original MCLT coefficients. The data can be transmitted by playing the embedded audio and extracting it from the received audio. By embedding the data in the MCLT domain, the perceived quality of the resulting audio could be kept almost similar as the original audio. The system can transmit data at several hundreds of bits per second (bps), which is sufficient to deliver some useful short messages.

New Fast Algorithm for Modulated Complex Lapped Transform With Sine Windowing Function

A novel algorithm for fast computation of the modulated complex lapped transform (MCLT) with sine windowing function is presented. For the MCLT of length-2 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> input data sequence, the proposed algorithm is based on computing a length-2 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> type-II generalized discrete Hartley transform. Comparison with existing algorithms shows that the proposed method achieves the minimal number of arithmetic operations.

Fast Algorithm for Modulated Complex Lapped Transform

A new algorithm for the modulated complex lapped transform (MCLT) with a sine windowing function is presented. It is shown that by merging the windowing operation with the main computation, both the real and the imaginary parts of the MCLT with 2N inputs can be obtained from two N-point discrete cosine transforms of type II (DCTs-II) of appropriate inputs. The resulting algorithm is computationally very efficient. In general, the value of N is an even number. When N is a power of 2, the proposed algorithm uses only N log N + 2 real multiplications (including the scaling factors in the DCT computation), with none of those being outside the DCT blocks.

Data hiding in audio signal using Rational Dither Modulation

A data hiding system in audio signals based on a Rational Dither Modulation is proposed, which hides information in the Modulated Complex Lapped Transform (MCLT) domain. The proposed system is able to hide around of 689bits per second, while keeping a CD-quality audio signal. Objective and subjective evaluations show robustness to classical attacks and transparency to the Human Auditory System (HAS), respectively. Comparison results, in similar conditions, with some other algorithms reported in the literature are also provided.

A Novel DCT-Based Algorithm for Computing the Modulated Complex Lapped Transform

In this correspondence, we propose a novel discrete cosine transform (DCT)-based algorithm for the fast computation of the modulated complex lapped transform (MCLT), which we have previously proposed. The method is mainly based on two DCTs and two stages of butterfly operations. For a length-M MCLT, the proposed algorithm requires only Mlog <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> M multiplications for the sine window and Mlog <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> M+2M multiplications for any other window function. Thus, the multiplicative complexity of the proposed algorithm is superior to any other previous algorithm, without any penalty on the total number of multiplications and additions

Sparse audio representations using the MCLT

We consider sparse representations of audio based around the modulated complex lapped transform (MCLT) and a generalized iteratively reweighted least squares algorithm which can be interpreted as a variation of expectation maximization. We compare this mildly overcomplete representation to the more traditional modified discrete cosine transform (MDCT) in terms of coding cost and explore the possibility of extending it to a dual-resolution analysis using a pair of MCLT transforms, illustrating its potential application for audio modification.

New Algorithm for Modulated Complex Lapped Transform With Symmetrical Window Function

An algorithm for the fast computation of modulated complex lapped transform (MCLT) with symmetrical window function is proposed. The method is based on two discrete cosine transforms (DCTs), two stages of butterfly operations and additional multiplications. The real or imaginary part of the MCLT coefficients can be independently obtained from one of the two blocks of DCT coefficients. The proposed algorithm not only reduces the computational complexity compared with previous algorithms, but also has regular architecture which is suitable for hardware implementations.

Fast algorithm for the modulated complex lapped transform

A new algorithm for fast computation of the modulated complex lapped transform (MCLT) is presented. For a length-M MCLT, the algorithm is based on computing a length-2M fast Fourier transform plus M butterfly-like stages, without data shuffling. That reduces the number of operations and memory accesses needed to compute the MCLT when compared to previous algorithms. Compared to the original type-4 discrete-cosine-transform-based algorithm, an implementation of the new algorithm leads to 25% faster execution.

A nonuniform modulated complex lapped transform

A nonuniform modulated complex lapped transform (NMCLT) is introduced in this paper as a two-stage extension of the modulated complex lapped transform (MCLT). The NMCLT is a new nonuniform oversampled filter bank with a better combination of time- and frequency-domain localization than previous designs, Adaptive nonuniform subband decompositions can be easily generated by varying the number of coefficients brought to the second stage on a frame-by-frame basis. The NMCLT is ideally suited for processing wideband signals such as audio, with reduced time-spreading artifacts.