Danny Hong

XFlavor: bridging bits and objects in media representation

Flavor is a formal language developed for describing compressed bitstream syntax, especially the bitstreams representing multimedia objects. A translator is also available for translating a Flavor description into C++ or Java code. The code includes bitstream parsing and generating operations that can readily be used by software developers with essentially zero additional programming. After briefly describing the latest version of Flavor, we propose an extension - XFlavor - that provides XML features by transforming the traditional bitstream representation of multimedia data into a corresponding XML representation.

H.264 hierarchical P coding in the context of ultra-low delay, low complexity applications

Despite the attention that hierarchical B picture coding has received, little attention has been given to a related technique called hierarchical P picture coding. P picture only coding without reverse prediction is necessary in constrained bit rate applications that require ultra-low delay and/or low complexity, such as videoconferencing. Such systems, however, have been using the traditional IPPP picture coding structure almost exclusively. In this paper, we investigate the use of hierarchical P coding vs. traditional IPPP coding and demonstrate that it has significant advantages which have not yet been well documented or understood. From a pure coding efficiency point of view, we show that for encoders configured to use ultra-low delay and low complexity coding tools, hierarchical P coding achieves an average advantage of 7.86% BD-rate and 0.34 dB BD-SNR.

Flavor: a formal language for audio-visual object representation

We present Flavor, a formal language for audio-visual object representation, that has been developed to describe any coded multimedia data in formats such as GIF, JPEG and MPEG. The language comes with a translator for generating C++/Java code from the Flavor description, and the generated code can include bitstream reading, writing and tracing methods. Since Version 5.0, the translator has been enhanced to also support XML. With the enhanced translator, the generated C++/Java code can include a method for producing XML documents that correspond to the bitstreams described by Flavor. The description can also be used to generate a corresponding XML schema. Additionally, a software tool for converting XML representation of multimedia data back into bitstream form is provided.

Arithmetic coding with adaptive context-tree weighting for the H.264 video coders

We propose applying an adaptive context-tree weighting (CTW) method in the H.264 video coders. We first investigate two different ways to incorporating the CTW method into an H.264 coder and compare the coding effectiveness of using the method with that of using the context models specified in the H.264 standard. We then describe a novel approach for automatically adapting the CTW method based on the syntactic element to be coded and the encoding parameters. We show that our CTW-based arithmetic coding method yields similar or better compression results compared with the context-based adaptive arithmetic coding method used in H.264, without having to specify so many context models.

MPEG-4 systems

We briefly describe the process for creating an MP4 file and introduce the software tools used for the creation. Then, we describe the architecture of an MP4 player - Flavor Player - that implements the MPEG-4 Systems specification. The Flavor Player implements 2-D composition and depth ordering of objects, object animation, user interaction, MPEG-J, IPMP framework, and MP4 file support. Additionally, we describe a simplified version of the Flavor Player - Mild Flavor - that only implements the Object Descriptor Profile. Unlike the Flavor Player, Mild Flavor is also used to create and edit MP4 files in addition to playback.

Memory-Efficient Semi-Quasi Renormalization for Arithmetic Coding

We propose a highly efficient, look-up table-based, renormalization method that can be used by any binary arithmetic encoder with the follow-on procedure. It replaces the time-consuming branching operations in the renormalization process with table look-ups and some simple bit-wise operations. We show that our new renormalization method outperforms the currently used ones with much less memory requirement than the previously known, table-based quasi-coder

XFlavor: providing XML features in media representation

We present XFlavor, a framework for providing XML representation of multimedia data. XFlavor can be used to convert multimedia data back and forth between binary and XML representations. Compared to bitstreams, XML documents are easier to access and manipulate, and consequently, the development of multimedia processing software is greatly facilitated, as one generic XML parser can be used to read and write different types of data in XML form.

A real-time mobile video newsgathering and broadcast system using a wireless LAN

We introduce a video newsgathering system called mobile broadcast video. The system is designed to use a wireless LAN and low earth orbit satellite technology for increased mobility and wide area coverage. It offers broadcast-quality video by using the MPEG-2 standard for audio/video compression and multiplexing. Our prototype uses off-the-shelf hardware components with all system software developed in-house. We present our implementation, focusing particularly on real-time live video acquisition and fast delivery of the high-rate compressed data over a wireless LAN. We also introduce an effective MPEG-2 transport stream level error concealment scheme that increases subjective played-back audiovisual quality in the case of packet losses. Through experimental results, we demonstrate that an economical, high-quality, real-time solution for mobile video newsgathering and broadcasting is realizable using even wireless 802.11b LANs.

Memory-efficient semi-quasi-arithmetic coding

A highly efficient, lookup table-based, renormalization method is proposed, which can be used by any binary arithmetic coder with the follow-on procedure. It replaces the time-consuming branching operations in the renormalization process with table lookups and some simple bit-wise operations. We show that the proposed method is much faster than the one used by the M coder in the CABAC entropy coding scheme of the H.264 video coding standard. Our method requires much less memory than the previously known, table-based quasi-coder.