Abstract: A novel method was proposed to detect double H.264 compression with the same quantization parameter, based on the dual encoding parameter model composed of Intra Prediction MacroBlock Modes (IPMBM) and the quantized discrete cosine transform (DCT) coefficients of I frames. The method designed the classfication feature based on the property that coding parameters of single compressed videos and double compressed videos have different convergencies. Firstly, the input video was recompressed repeatedly with the same quantization parameter. Then, the IPMBMs and the quantized DCT coefficients were extracted from I frames. The numbers of altered IPMBMs and quantized DCT cofficients between adjacent recompressions were used to calculate the classification feature. Finally, the extracted feature was fed to the trained support vector machine to detect double H.264 compression. Experimental results show that the proposed method can detect double H.264 compression correctly and efficiently.

Key words: double compression, same quantization parameter, intra prediction modes, discrete cosine transform (DCT) coefficients