Efficient detection of a spatial spread-spectrum watermark in MPEG video streams

Watermarking is a technique for embedding imperceptible labels in audio/visual content. Important parameters for any watermarking scheme are imperceptibility, robustness, security, payload, error rates and complexity. In the past few years enormous progress has been made with respect to most of these parameters, except maybe for the latter one. We address this topic of complexity by presenting an efficient method for detecting a spatial video watermark directly in an MPEG video stream. The naive approach would be to do a full MPEG decoding and then apply spatial watermark detection. However, such a full decoding approach would imply large memory and processing resources. We show that, at the cost of a slight decrease of performance, large reductions in complexity are possible. More in particular we show how high speed MPEG parsing, high speed inverse DCT processing and motion compensation can be avoided. On a more abstract level, this paper would like to encourage others to give more prominence to embedding and detection complexity as an important parameter in the design of watermarking schemes.