1. Introduction
As the service of ultra-definition video contents becomes more common in broadcasting, digital cinema, and home theater, many researchers have studied deep into high efficiency video coding (HEVC) and highly improved video codecs for effectively compressing and transmitting ultra-definition video contents. With HEVC, the scalable video coding (SVC) facilitates to partially decode from one sequence of compressed video to a combination of resolution, quality, and frame rate that are optimized on platform and transmission bandwidth of user device. With the marvelous progress of video codec technologies, the disputes of copyright and ownership for preventing illegal copying and distribution and pirate edition have been issued steadily as problems on commonplace video compression. To solve disputes of copyright and ownership, many nations have legislated the standardized agreement of creative commons license (CCL) that authorizes the copyright management since 2002. However, this agreement does not protect the copyright infringement all the way in cases of illegal copying and distribution of black works or partial edition. Moreover, the wide use of online storage services, torrent programs, or cloud systems makes it very difficult to guarantee ownership rights or prevent illegal copying and distribution.
Many researchers [
1,
2,
3,
4,
5,
6,
7,
8,
9,
10,
11,
12,
13,
14] have worked on video copyright and ownership protection based on watermarking for decades. However, most of them do not meet all the requirements of data capacity, reliability, and video quality. Early stage works [
1,
2,
3,
4,
5,
6] focused on the compressed DCT domain of MPEG-2/-4, H.264 codec or the uncompressed DWT domain, considering the robustness in the face of geometric and temporal attacks. Hartung et al. [
1] presented an additive spread-spectrum watermarking technique for MPEG-2 compressed video stream that embeds the watermark in the entropy coded DCT coefficients. Swanson et al. presented an object-based transparent watermarking technique [
2] and also a temporal wavelet transform-based multi-resolution watermarking technique [
3]. Serdean et al. [
4] presented DWT-based high capacity video watermarking invariant to geometrical attacks that uses a spatial domain reference watermark. Wang et al. [
5] presented a set of robust MPEG-2 video watermarking focused on geometric processing such as cropping, removal of any rows, downscaling, frame dropping, and bit-rate reduction. Zhang et al. [
6] embedded the modified 2D 8-bit watermark pattern in the compressed domain to accommodate the computational constraints of H.264/AVC.
Recent stage works [
7,
8,
9,
10,
11,
12,
13,
14] have considered different codecs and the robustness to combination of commonly used attacks with the development of codecs. Asikuzzaman et al. [
7] embedded the watermark into one level of the dual-tree complex wavelet transform (DT DWT) of the chrominance channel and extracted the watermark depending on the resolution of the downscaled version of the watermarked frame and the information of that frame without using the key. Fallahpour et al. [
8] generated the watermark signals by the macroblock’s and frame’s indices and embedded them into the nonzero quantized DCT values of blocks, mostly the last nonzero values, enabling detection of spatial, temporal, and spatiotemporal tampering. Stutz et al. [
9] presented a non-blind watermarking for H.264/CAVLC structure-preserving substitution with high capacity without changing the length of video stream. Khalilian et al. [
10] embedded the watermark in the LL sub-band of DWT coefficients that offers the most robust PCA-based decoding. Boho et al. [
11] presented an encryption-watermarking technique for H.264/AVC and HEVC by examining the practical trade-offs between the security of encryption, the robustness of watermarking, and the possibility of transcoding. Wang et al. [
12] presented a real-time video watermarking that has the transparency and robustness to resist geometric distortions such as scaling, cropping, changing aspect ratio, frame dropping, and swapping.
However, most of existing techniques have difficulty in practical commercialization because of some considerable defects. The watermark embedded in a video raw data prior to compression may be lost during quantization. Furthermore, it is very difficult for the watermark to keep the robustness to geometric processing such as rotation, translation, and cropping of any frame. Watermarking techniques in the compression domain have been worked out by controlling some compression parameters to minimize the loss of watermark in the process of quantization or video editing. However, the watermark may be lost in the re-compression of decoded video data or the trans-coding by different codecs. Thus, watermarking techniques considering a specific codec have not coped with a variety of video codes [
13,
14] as well as standard video codecs. Furthermore, they have not coped with a multi-view video coding (MVC), which creates a variety of output streams of a single source, and a hierarchical compression, such as scalable video coding (SVC). Therefore, an effective and reliable integrated copyright protection system for video content technologies that develop and grow exponentially is needed. Besides, Niu et al. [
15] presented a reversible watermarking scheme for H.264/AVC using histogram shifting of motion vector, and Xu [
16] presented an efficient commutative encryption and watermarking scheme for HEVC standard, unlike H.264/AVC. Ma et al. [
17] presented a video watermarking on H.264 compressed domain using the syntactic elements of the compressed bit stream, but Marren et al. [
18] designed a scalable architecture for uncompressed-domain of watermarked videos using fast encoders, which re-uses the coding information from a single, previously-encoded, unwatermarked video. Abdi et al. [
19] presented a real-time watermarking scheme for H.264/AVC video stream by modifying the number of nonzero-quantized AC (alternating current) coefficients in a 4 × 4 block of I frame.
Like living things, video codec has evolved continuously according to the IT/ICT ecosystem. Existing video watermarking systems cannot keep up with the evolution of video codecs. To solve this problem, we consider the watermarking system and video codecs as a biological environment such as a virus. We have designed a scenario of infectious watermarking that models the relationship between video content and video codecs to biological viruses and hosts [
20]. The feature of this scenario is that the watermark is continuously infected through the transcoding process of video contents through a repetitive re-embedding process on the codec. In this scenario, we introduced codec and content based watermarking techniques. The first codec-based watermarking scheme hides DCT coefficients in 4 × 4 block units of codec repeatedly to adapt to various codecs. The second content-based watermarking embeds the robust watermark in the ROI (Region of Interest)-based DCT coefficients of the original video data. In this scenario, however, codec-based watermarking can accumulate image degradation due to persistent and repetitive watermark re-embedding and has a limited re-embedding process on various codecs. Therefore, it is necessary to modify the scenario with a viral reversible/irreversible watermarking method for watermark authentication that is effective in the iterative detection/mutation/re-embedding process.
In this paper, we propose a scenario to integrate infectious watermark authentication, infectious watermark generation and management, content-based watermark embedding, and codec-based watermark embedding technique for continuous watermark infection through continuous transcoding detection/mutation/re-embedding. We also propose a codec-based infectious watermarking technology incorporating irreversible and reversible watermarking techniques. In this paper, we call this scenario a viral infectious watermarking (VIW) model that uses the biological virus theory for an integrated copyright protection system that copes with various video codecs such as H.264/AVC or HEVC.
In our VIW model, we assume two things. The codecs are regarded as the host with infective agent since the infected video by the first watermark, called pathogen, passes over any codecs through a number of routes. The infected video is, secondly, infected by two kinds of watermark—mutant and contagion—whenever it passes over processes of playing, streaming, editing, or transcoding. Following these assumptions, we define our VIW model by four steps: Viral infectious watermark generation and management, kernel-based VIW, content-based VIW, and VIW verification. Then, we presented total irreversible and reversible kernel-based VIW methods and content-based VIW method in our model. The existing kernel-based watermarking method [
20] embeds irreversible watermark bits in high frequency coefficients in DCT 4 × 4 block units. The proposed kernel-based method embeds the reversible watermark in units of MB blocks according to the strength, adaptive to the inter/intra frame, and embeds the irreversible watermark in the existing high frequency coefficients in units of 4 × 4 blocks. Therefore, unlike the conventional method [
20], the proposed method simultaneously detects both reversible and irreversible watermarks, thereby detecting the watermark adaptively in the detection/mutation/re-embedding process. From experimental results, we verified that our VIW model based on biological virus theory is effective in integrated or multiple video codecs.
This paper is organized as follows.
Section 2 introduces the scenario of VIW model and related video watermarking.
Section 3 describes the techniques for our VIW model.
Section 4 analyzes the experimental results of our watermarking, and
Section 5 then presents our conclusions of this paper.