Melih Pazarci

A MPEG2-transparent scrambling technique

The paper proposes a video scrambling technique that allows an unauthorized user to have an arbitrarily degraded view of a program, yet it is totally transparent to MPEG-2 encoding. Video components are block-coded using a mix of linear transformations of pixel values. The parameter data is embedded in the scrambled video. The proposed technique is applicable to any digital broadcast scheme that is based on MPEG-2 compression, including DVB-S/C/T and ATSC.

A Compatible High-Definition Television System (SLSC) with Chrominance and Aspect Ratio Improvements

Analyse detaillee de ce systeme entierement compatible avec les normes NTSC. Amelioration des performances. Circuits codeurs et decodeurs

Data embedding in scrambled digital video

A technique for embedding data in scrambled MPEG video is described. The embedding technique is applied to the video sequence jointly with the video scrambling algorithm. The scrambling operation together with the data embedding process are performed prior to MPEG encoding, and the scrambled and data-embedded video is MPEG-2 encoded with a minimal increase in the MPEG bitrate. The applied technique uses premanipulation of the block scrambling parameters to generate interblock differentials to embed the data bits. Embedded data has sufficient robustness to resist the MPEG encoding attack. The data channel capability of the system arises due to the scrambling process and is not available when the video is not scrambled. The data embedding scrambler precedes input of any MPEG-2 compliant encoder. The technique is totally independent of the MPEG level, profile and parameters, and is applicable to all MPEG-2 based broadcast schemes including ATSC and DVB-S/C/T.

Compatible High Definition Television Broadcast Systems

This paper describes NTSC compatible HIDTV systems with incremental improvement potential. The systems are capable of increased horizontal and vertical resolution, reduced crosstalk between the components, and a wide aspect ratio. Experimental results on a split-luminance system show that 600 lines of horizontal resolution are achieved after the luminance signal band has been divided at the encoder and recombined at the decoder. Spatial splitting of the picture is employed to increase the aspect ratio. A low cost HDTV system is also presented that uses a modulated-signal combination. With this system, considerable simplification is possible with a slight reduction in resolution. All proposed systems are fully NTSC compatible and utilize two standard 6 MHz channels for transmission. The improvements can be realized incrementally because of their downward compatibility at the receiver.

An adaptive ghost processor for broadcast television

An adaptive recursive ghost processor subsystem, a smart system that minimizes TV ghosts and transmission distortions without producing new picture artifacts, is described. The ghost canceller structure and the processing algorithm are very efficient in the number of taps, performance, and convergence speed. The subsystem requires a training signal in the vertical interval and performs the ghost reduction in the baseband. A complex IIR (infinite impulse response) configuration with a nonlinear adaptation algorithm is used. The processor is usable in digital NTSC (National Television System Committee) and EDTV/HDTV (extended-definition/high-definition TV) receivers, and is intended for the reception of vestigial-sideband-format VHF/UHF cable and broadcast video distribution. >

Additive vs. image dependent DWT-DCT based watermarking

We compare our earlier additive and image dependent watermarking schemes for digital images and videos. Both schemes employ DWT followed by DCT. Pseudo-random watermark values are added to mid-frequency DWT-DCT coefficients in the additive scheme. In the image dependent scheme, the watermarking coefficients are modulated with original mid-frequency DWT-DCT coefficients to increase the efficiency of the watermark embedding. Schemes are compared to each other and comparison results including Stirmark 3.1 benchmark tests are presented.

Image Reconstruction in a Wide Aspect Ratio HDTV System

One of the important characteristics of a high-definition television (HDTV) image is a wide aspect ratio. In some HDTV systems the image is segmented and different formats are used to transmit portions of the image. We address the problem of image reconstruction at the receiver and present an analysis of a wide aspect ratio HDTV system. Several image reconstruction techniques are described, including a channel-dependent design, and their effectiveness discussed. We also present a channel-independent system for image reconstruction that utilizes a vertical interval test line. Performance has been evaluated, via computer simulation, using still images. The results indicate an imperceptible amount of artifacts at the edge-center joints with an overlap as small as one picture element for the channel-independent reconstruction technique.

A matched-resolution wide aspect-ratio HDTV system

A fully NTSC-compatible two-channel wide-aspect-ratio high-definition television (HDTV) system with equal vertical and horizontal resolutions is described. The wideband Y, I, Q components are spectrally split into low-frequency and high-frequency bands. However, only the low-frequency components are spatially split into center and edge segments. The low-frequency edge signals are NTSC encoded and decoded using the existing hardware for the compatible center signals. The proposed system produces minimal crossluminance and crosschrominance, and provides equal edge and center resolutions. >

Forensic audio authentication analysis technique of first or higher generation copies of analog magnetic audio tapes

In forensic audio examination, standard listening and visual sound spectrogram analysis methods often lead to incorrect conclusions due to the losses in data when the tape is copied. Furthermore, conducting the standard examinations on audio files which are digitally edited and re-recorded on the tapes, leaving very little trace behind, also result in incorrect decisions made by forensic experts. In this study, a novel and a very simple technique was developed, where the electronic edit traces on an electronically edited tape become easily detectable on copy generation tapes. Thus, regardless of the duplication speed, copied tapes can be analyzed for their originality and integrity with this technique and digital changes on them can be determined. The technique is based on increasing the tape playback speed by modifying the playback system of a player device. This essentially alters the time base of the signal and expands the low frequency scale of the recording in the frequency domain, and makes manipulation marks easily observable. It can be applied to most analog magnetic tape recorder devices. Edit marks can be precisely detected with minimal loss of time by using specially modified nonstandard devices rather than available conventional standard devices.

A DWT-DCT based digital watermarking technique

Many watermark algorithms exist for the the frequency domain using the DCT or the DWT. In this paper, we propose a new watermark algorithm using the DWT for harmony with the human visual system, and the DCT for robustness against signal processing attacks.