音频信号在拼接、重压缩、变速变调、伪装高质量音频等篡改操作中, 经常伴随着重采样的操作. 因此, 检测重采样是音频取证的重要方面. 提出采用二阶差分的方法来检测重采样音频, 从理论上证明了重采样的音频信号经过二阶差分处理后, 频谱上会呈现出明显的离散尖峰, 该方法也适用于常见的非线性插值情况. 运用该特点设计了重采样的自动检测方案, 研究了离散尖峰与音频时长、音频内容、音频格式的相关性. 大量实验结果表明, 该方法能够简单、快速、有效地检测重采样音频.
Audio tampering is often accompanied with re-sampling especially in audio plicing, re-compression, time-scale and pitch-scale modification, quality faking and other perations. Therefore, re-sampling detection is an important means in audio forensics. his paper proposes a new method to detect audio re-sampling. It is theoretically shown hat, if an original audio signal is re-sampled, significant peaks can be found in second-order erivative of the spectrum, and the peak position is related to re-sampling factor. This ethod is applicable to common nonlinear interpolation. Detection performance influenced by audio duration or content or format is discussed. Finally, an automatic detection scheme is described, and experimental results show that the algorithm can be used to detect resampled audio effectively.
[1] Maher R C. Audio forensic examination: authenticity, enhancement, and interpretation [J]. IEEE Signal Processing Magazine, 2009, 26(2): 84-94.
[2] Fridrich J. Security of fragile authentication watermarks with localization [C]// Proc SPIE, Security and Watermarking of Multimedia Contents. 2002: 691-700.
[3] Wong P W. A public key watermark for image verification and authentication [C]// IEEE International Conference on Image Processing. 1998: 455-459.
[4] Farid H. Image forgery detection [J]. IEEE Signal Processing Magazine, 2009, 26(2):16-26.
[5] Popescu A C, Farid H. Exposing digital forgeries by detecting traces of re-sampling [J]. IEEE Transactions on Signal Processing, 2005, 53(2): 758-767.
[6] 姚秋明, 柴佩琪, 宣国荣, 等. 基于期望最大化算法的音频取证中的篡改检测[J]. 计算机应用, 2006, 26(11): 2598-2601.
[7] 丁琦, 平西建. 基于子带平滑度的音频篡改检测[J]. 应用科学学报, 2010, 28(2): 142-146.
[8] Gallagher A C. Detection of linear and cubic interpolation in JPEG compressed images [C]// The 2nd Canadian Conference on Computer and Robot Vision. 2005: 65-72.
[9] Mahdian B, Saic S. Blind authentication using periodic properties of interpolation [J]. IEEE Transactions on Information Forensics and Security, 2008, 3(3): 529-538.
[10] WeiWM,Wang S Z, Zhang X P, et al. Estimation of image rotation angle using interpolationrelated spectral signatures with application to blind detection of image forgery [J]. IEEE Transactions on Information Forensics and Security, 2010, 5(3): 507-517.
[11] 宋枫溪, 高林. 文本分类器性能评估指标[J]. 计算机工程, 2004, 30(13): 107-109.
