Digital imagery is important in many applications today, and the security of digital imagery is important today and is likely to gain in importance in the near future. The emerging international standard ISO/IEC JPEG-2000 Security (JPSEC) is designed to provide security for digital imagery, and in particular digital imagery coded with the JPEG-2000 image coding standard. One of the primary goals of a standard is to ensure interoperability between creators and consumers produced by different manufacturers. The JPSEC standard, similar to the popular JPEG and MPEG family of standards, specifies only the bitstream syntax and the receiver's processing, and not how the bitstream is created or the details of how it is consumed. This paper examines the interoperability for the JPSEC standard, and presents an example JPSEC consumption process which can provide insights in the design of JPSEC consumers. Initial interoperability tests between different groups with independently created implementations of JPSEC creators and consumers have been successful in providing the JPSEC security services of confidentiality (via encryption) and authentication (via message authentication codes, or MACs). Further interoperability work is on-going.
The capture, processing, delivery, and display or printing of digital images is important today and will become even more important in the future. Important additional future challenges include the remote browsing of images, image adaptation to support diverse clients, and providing security services such as confidentiality and authentication. In this context, an important functionality is secure transcoding: providing end-to-end security between the content creator and the content consumer, while enabling a potentially untrusted mid-network node or proxy to adapt the content to be best matched for delivery to the consumer - where the adaptation is performed without requiring the node or proxy to unprotect (i.e., decrypt) the content. In prior work, secure transcoding was shown to be possible through a framework referred to as Secure Scalable Streaming, which was originally designed for video streaming applications. Secure transcoding was identified as being possible within the ISO/IEC JPEG-2000 Security (JPSEC) standardization effort, and this paper describes how the JPSEC standard was designed to support rate-distortion (R-D) optimized secure transcoding.
Multimedia communication and streaming media services will become mainstream network infrastructure applications in the coming decade. However, there are many challenges that must be overcome. These challenges include the Internet’s limited ability to handle real-time, low-latency media streams, the need for media security, and an uncertainty of the killer app. The nature of these challenges lends itself to enabling technology innovations in the media delivery and media processing space. Specifically, we envision an overlay infrastructure that supports networked media services that couple media delivery with in-network media processing. The media overlay should be programmable to allow rapid deployment of new applications and services and manageable so as to support the evolving requirements of the resulting usage models. Furthermore, the media overlay should allow for the delivery of protected media content for applications that have security requirements. A properly architected infrastructure can enable real-time multimedia communication and streaming media services in light of the inherent challenges.
In this paper, we first review the on-going JPSEC standardization activity. Its goal is to extend the baseline JPEG 2000 specification to provide a standardized framework for secure imaging, in order to support tools needed to secure digital images, such as content protection, data integrity check, authentication, and conditional access control. We then present two examples of JPSEC tools. The first one is a technique for secure scalable streaming and secure transcoding. It allows the protected JPSEC codestream to be transcoded while preserving the protection, i.e. without requiring unprotecting (e.g. decrypting) the codestream. The second one is a technique for conditional access control. It can be used for access control by resolution or quality, but also by regions of interest.
In general, existing segment-based caching strategies target one of the following two performance objectives: (1) reducing client startup delay by giving a high priority to cache the beginning segments of media objects, or (2) reducing server traffic by caching popular segments of media objects. Our previous study has shown that the approach targeting the second objective has several advantages over the first one. However, we have also observed that the effort of improving server traffic reduction can increase client startup delay, which may potentially offset the overall performance gain. Little work so far has considered these two objectives in concert. In this paper, we first build an analytical model for these two types of typical segment-based caching approaches. The analysis on the model reveals the nature of the trade-off between two performance objectives and the bounds of each are given under certain circumstances. To provide a feasible way to evaluate different strategies, we propose a new comprehensive performance metric based on the analysis. To understand this performance trade-off, we restructure the adaptive-lazy segmentation strategy with a heuristic replacement policy to improve overall performance. The evaluation results confirm our analysis and show the effectiveness of our proposed new performance metric.
KEYWORDS: Video, Detection and tracking algorithms, Computer programming, Motion estimation, Video compression, Standards development, Spatial resolution, Video processing, Digital video discs, Televisions
We present an MPEG-2 to H.263 transcoder that accepts an interlaced MPEG-2 bitstream as the input and produces a lower-bitrate progressive H.263 bitstream as the output. As both DVD and digital television may use MPEG-2 interlaced sequences, a potential application of such a transcoder is the transmission of a digital television signal over a wireless medium. Another application is transcoding interlaced DVD content for use on lower-resolution thin clients with progressive displays. The proposed algorithm exploits the properties of the MPEG-2 and H.263 compression standards to perform interlaced to progressive (field to frame) conversion with spatial downsampling and frame-rate reduction in a CPU and memory efficient manner, while additionally minimizing picture quality degradation as measured by PSNR. This is the first algorithm to our knowledge that effectively uses both spatial and temporal downsampling in an MPEG-2 to H.263 field to frame transcoder in order to achieve substantial bitrate reduction. This paper discusses recoding experiments used to determine appropriate source and target coding parameters for the transcoder, provides a detailed description of the transcoding algorithm, and describes the performance of a software implementation of the transcoder.
We present several compressed-domain methods for reverse- play transcoding of MPEG video streams. A reverse-play transcoder takes any original MPEG IPB bitstream as input and creates an output MPEG IPB bitstream which, when decoded by a generic MPEG decoder, displays the original video games in reverse order. A baseline spatial-domain method requires decoding the MPEG bitstream, storing and reordering the decoded video frames, and re-encoding the reordered video. The proposed compressed-domain transcoding methods achieve an order of magnitude reduction in computational complexity over the baseline spatial-domain approach. Much of the savings are achieved by using the forward motion vector fields available in the forward-play MPEG bitstream to efficiently generate the reverse motion vector fields used in the reverse-play MPEG bitstream. Furthermore, the storage requirements of the compressed-domain methods are reduced and the resulting image quality is within 0.6 dB of the baseline spatial-domain approach for a difficult highly detailed computer-generated video sequence. For more typical video sequences, the resulting image quality is even closer to the baseline spatial-domain approach.
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