Hiroyuki Imaizumi

Development of 135 Mbit/s HDTV codec

Abstract The source bit-rate of HDTV is extremely high compared with that of conventional standard TV, and a bit-rate reduction will become an important matter in the digital transmission of HDTV signals using a communication satellite or the Broadband-ISDN. The authors are developing an HDTV codec based on DCT plus motion-compensated prediction at a bit-rate of 135 Mbit/s and an original sampling frequency of the studio standard. This paper outlines the technical description of this HDTV prototype codec presently being built.

Integrated Digital Rights Management for Mobile IPTV Using Broadcasting and Communications

This paper presents a digital rights management (DRM) scheme for mobile broadcasting that integrates management via broadcasting and communications. The scheme provides access control and rights protection for subscription Mobile IPTV (Internet Protocol TV), enabling transmission of contract information to control broadcasting reception via both broadcasting wave and communications. It has transmission functions that reduce the amount of contract information that has to be transmitted through broadcasting as well as a function for transmitting contract information via communications. A PC simulation indicates that the DRM scheme is effective in terms of the transmission rate required to send contract information via broadcasting wave. We also demonstrated the feasibility of the DRM scheme by using a prototype system implemented on an SIM card. The DRM scheme enables advanced mobile receiver functions such as pay-per-view with an interactivity channel using communications and a subscription TV such as pay-per-month on mobile receivers without an interactivity channel by transmitting contract information via broadcasting wave.

Advanced Conditional Access System for Digital Broadcasting Receivers Using Metadata

This paper presents an advanced conditional access system (CAS) for digital broadcasting receivers using program-related information called metadata. Digital broadcasting receivers using metadata (DBRM) provide services enhanced by using metadata and content stored in receivers, but it is so easy to edit stored content by using metadata that broadcasters require a content usage control mechanism for DBRM. The advanced CAS provides a secure environment for content and metadata in digital broadcasting receivers by preventing tampering and ensuring that only metadata certified by the broadcaster can be used. To evaluate the advanced CAS, we also developed a smart card and a prototype receiver on a PC. We have demonstrated in an implementation experiment that the advanced CAS can be implemented securely and utilized in broadcasting services using DBRM.

A Conditional Access System for mobile broadcasting systems

This paper presents an advanced CAS which provides access control and rights protection for mobile TV content. This advanced CAS can reduce the amount of contract information transmitted through broadcasting. We also demonstrated the feasibility of the proposed CAS by using a prototype system implemented on a SIM card.

Network Broadcasting System Using Viewer Information

With the rapid spread of broadband internet networks, broadcasting services on television using IP networks will soon become a reality. The broadcasting services on television using IP networks will be available, providing variable services in response to individual demands using personal data. We carried out a questionnaire survey, and compiled technological requirements for implementing such services. One of the requirements is that the viewers personal data should be kept secure, and another is that viewers should be able to set their own disclosure rules. We created an experimental broadcasting system that satisfies these requirements and evaluated the transaction speed of the system.

An HDTV Coding Scheme using Adaptive-Dimension DCT

Coding Schemes using motion compensation and DCT are generally used for digital transmission systems of HDTV signals. In these schemes, a picture quality degradation known as mosquito-noise is sometimes a serious problem. This kind of degradation is a vital issue for HDTV which is characterized by high picture quality. In this paper, a new coding scheme named adaptive-dimension DCT is proposed; its effectiveness is explained from both theoretical and experimental viewpoints. This scheme is quite easy to implement, and suitable for HDTV coding systems that require high-speed signal processing.

A digital video scrambling system with variable concealed levels incorporating viewing licenses

In mobile TV with subscription broadcasting systems using wireless communications, streaming-based content services and download-based content services which play back stored content on receivers are being considered. These download-based content services require a function for playing back content in deteriorated video to encourage non-subscribers to purchase content, in addition to a function that allows only subscribers to view content. Therefore, content providers require a digital video scrambling method with variable concealed levels to control the video quality of stored content. We propose a digital video scrambling system with variable concealed levels incorporating viewing licenses. The system can handle H.264/AVC coding content, and the processing load for controlling the concealed level of video is low. We also verify by evaluating video quality and implementation that the proposed system is feasible for actual service.

Identified-Service Support System and Its Application to Network Broadcasting Services

Individualization of network services will be a key factor attracting users because customer satisfaction with identified services such as location-specific and time-specific news could increased by collecting and analyzing user information. Balancing the trade-off between privacy and individualization, however, will require the use of technical mechanisms we call identified-service support systems (ISSS). Here we describe the basic concept of an ISSS and describe its technical requirements. We propose an ISSS architecture combining user-information analysis for individualization, access control for privacy protection, shuffling data management for preventing the leakage of personal information, and digital signatures for authenticating the integrity of partially disclosed documents. We also describe the protocols, GUIs, and data management implementations of a prototype ISSS developed for personalized broadcasting services. An ISSS could protect user privacy against inside attacks as well as third-party attacks and could support various kinds of identified services.

An experiment of 3D model estimation for generation of a VRML animation from multi-view HDTV images

1.はじめに 任意の視点からの映像生成の目的で複数のハイビジョ ンカメラを被写体の周囲に配置して撮影した多視点画像を 用いて、被写体の3次元形状を推定し、3次元形状モデル を VRML で記述して表示する実験を行っている[1]。本稿 では、3次元形状モデル生成においてブロックマッチング 法と視体積交差法を併用することで3次元形状の推定結果 が向上し、生成したアニメーションの画質が改善されること を報告する。 2. 3次元形状モデル生成手順 3次元形状モデルの生成を以下の三つの手順により行 う。 2.1 被写体の全周映像撮影 図1に示すように9台のハイビジョンカメラを被写体を取 り囲むように配置する。円周の半径は 2.5m、カメラ間隔は ほぼ等間隔とする。被写体領域をクロマキー処理により簡 単に取得するため、背景にブルーバックを用いている。ク ロマキー処理により被写体領域を各カメラについて求め る。 2.2 3次元モデルの生成 カメラから被写体までの距離推定手法として視体積交差 法とブロックマッチング法を併用する。視体積交差法では、 被写体の概形を低い計算コストで求めることができるが、 曲面形状の中でも特に凹面となる形状は正しく推定するこ とができない。一方、ブロックマッチング法では、凹面を含 めた曲面についても距離推定が可能であるが、計算コスト が大きい。 そこで、被写体領域から視体積交差法により求めた被写 体の概形を探索範囲としてブロックマッチング法を適用す ることにより、高速で精度の高い距離推定を実現している。 各カメラ位置で画素ごとに推定した被写体までの距離値 から離散的マーチングキューブ法により被写体の表面形状 を表す三角パッチを得る。三角パッチの各頂点には、画像 の中で対応する画素の色情報を与える。 2.3 VRML ブラウザによるアニメーション表示 表面形状を表す三角パッチモデルは1フレームごとに VRML の IndexedFaceSet 形状ノードにより記述する。表 示する VRML データを JavaScript により切り替えてアニ メーション表示をする。動画表示を行いながらマウス操作 などによりスムーズに視点位置を移動して表示することが 可能である。 3. 3次元形状推定実験結果の比較 図2は推定した3次元形状に基づき、視点位置を移動し て生成される画像を1フレーム分表示したものである。3次 元形状の推定精度を比較するため、実カメラを配置してい ない被写体の真上に視点位置を設定した。被写体の腕か ら胸の部分は撮影用のカメラからは凹面形状となるため、 (a)の視体積交差法のみの3次元形状モデルでは形状が 正しく推定できず画質が劣化しているが、ブロックマッチン グ法を併用することで(b)のように形状が正しく推定され画 質も向上する。アニメーション表示をすると(a)では推定誤 差がフレーム毎に変化するため画像劣化が顕著となる。 4.むすび 視体積交差法とブロックマッチング法を併用して3次元形 状を推定することで、VRML アニメーションの画質が向上 することを示した。今後は生成するアニメーションの画質向 上の観点から3次元形状推定の精度や処理速度を改善す る手法の検討を進めていく。 参考文献 [1]片山他,“多視点ハイビジョンカメラによる任意視点映像生成シス テムの試作”,信学総大D-11-160, Mar. 2002. 〒157-8510 東京都世田谷区砧 1-10-11 TEL:03-5494-3193

A system for generating arbitrary viewpoint images from HDTV multi-camera images

In this paper, we propose a system for generating arbitrary viewpoint images. The system is based on image measurement and consists of three steps: HDTV image recording, modeling from images and displaying arbitrary viewpoint images. The model data is converted to VRML models. In order to estimate 3D shapes, we developed a new modeling algorithm using the block matching method as well as the volume intersection method. The proposed algorithm achieves fast and precise modeling. It is confirmed that the derived human model with motion can be smoothly played in a VRML browser on a PC, and the viewing position of the observer can be changed by mouse control.