Mark Palkow

Global serverless videoconferencing over IP

In recent years the capabilities of the common Internet infrastructure have increased to an extent where data intensive communication services may mature to become popular, reliable applications. Videoconferencing over IP can be seen as such a highly prominent candidate. However, heavy infrastructure and complicated call handling hinder acceptance of standard solutions.This paper presents a more lightweight framework--both communication scheme and conferencing software--to overcome these deficiencies. A simple, ready-to-use global location scheme for conference users is proposed. First practical experiences are reported.

A FAST WAVELET-BASED VIDEO CODEC AND ITS APPLICATION IN AN IP VERSION 6-READY SERVERLESS VIDEOCONFERENCING SYSTEM

The purpose of this paper is twofold: On the one hand, we propose a fast wavelet-based video codec which is implemented into a real-time video conferencing tool. The proposed codec uses temporal frame difference coding, a computationally low-complex 5/3 tap wavelet transform, and a fast entropy coding scheme based on Golomb–Rice codes. On the other hand, we present an application of the video conferencing tool in a serverless peer-to-peer IP-based communication framework. For mobile communication we propose a simple, ready-to-use location scheme for video conference users in a global network.

Peer-to-peer videoconferencing with H.264 software codec for mobiles

A rapidly growing number of carriers offer wireless video services to their customers, taking advantage of high quality video codecs implemented in dedicated hardware of selected mobile devices. In this paper we introduce a video conferencing software, which seamlessly integrates mobile with stationary users in a provider and device independent fashion. Innovations of this work are twofold. At first we report on a mobile realization of an H.264 video codec and its performance on a standard consumer Smartphone. Operating within the tight bounds of real-time compliance on mobiles, this software is an adapted version of a highly optimized H.264 codec. This DAVC codec, which we introduce along the line, significantly out-performs compatible H.264 realizations and allows for a scalable adaptation of its frame rate. In the second part we present a barrier-resistant peer-to-peer group communication scheme, which scales well for medium-size conferences and accounts for the heterogeneous nature of mobile and stationary participants. An outlook on mobility related group communication issues and future optimizations based on structured communication layers concludes the work.

Connecting the worlds: Multipoint videoconferencing integrating H.323 and IPv4, SIP and IPv6 with autonomous sender authentication

In this paper we present a multipoint media conference software with extended network capabilities. Its core components combine an advanced, highly efficient H.264/AVC video coding system. Session signaling follows the SIP standard and simultaneously supports IPv4 and IPv6. Built upon an underlying peer-to-peer communication scheme, it further supports advanced integration with legacy MCUs and thereby enables hybrid sessions that extend into the H.323 world. We demonstrate how our software can span fully functional conferences across these worlds by deploying a passive gateway peer. Finally, we address security issues arising in distributed conferencing systems. It is shown, how the use of cryptographically generated identifiers enables the application to authenticate data on a packet level, thereby preventing abuse and impersonation of the conference overlay network.

An optimized 11.264-based video conferencing software for mobile devices

Mobile phones and related gadgets in networks are on the spot to deliver sufficient performance for rich multimedia applications and communication. In this report we introduce a video conferencing software, which seamlessly integrates mobile with stationary users into fully distributed multi-party conversations. Innovations related to this work are twofold. At first we report on a highly optimized realisation of a 11.264 codec and our implementation experiences of the video conference software on a consumer mobile. Within the tight bounds of real-time requirements on mobiles, the coding software out performs compatible 11.264 realizations. At second we present an integrated peer-to-peer group communication solution, which scales well for medium-size conferences and accounts for the heterogeneous nature of mobile and stationary participants.

Distributed SIP conference management with autonomously authenticated sources and its application to an H.264 videoconferencing software for mobiles

The design of conferencing systems for achieving efficient and flexible communication in a fully distributed, infrastructure-independent fashion is a promising direction, both in terms of research and practical development. In the particular case of video communication, the seamless adaptation to heterogeneous mobile devices poses an additional strong challenge to those seeking for interoperable and easy-to-deploy solutions. In this paper, we make several contributions towards a generic peer-to-peer (P2P) videoconferencing solution that extends into the mobile realm. We describe the essential building blocks for conference management and media distribution that are necessary for a distributed conferencing approach. Establishing a distributed SIP conference focus, participants share the conference according to their individually given capabilities and resources in terms of bandwidth and processing power rather than in a centralized and fixed way. Overall concepts and SIP-primitives for such an autonomous organization are presented. Security issues that derive from this decentralized identity management are resolved by so-called Overlay AuthoCast, a novel use of cryptographically generated identifiers. Furthermore, this work is dedicated to the development of a software-based H.264 video codec implementation and the specific aspects resulting from tuning such a highly resource-intensive software codec to the given target platform of a standard consumer smartphone.

Adaptive Temporal Scalability of H.264-Compliant Video Conferencing in Heterogeneous Mobile Environments

In this paper, we present a multipoint video conferencing system that adapts to heterogeneous members including mobiles. The system is built upon a low complexity scalable extension of our H.264 codec DAVC, and a congestion-aware dynamic adaptation layer. Our temporally scaled video codec DSVC has the same RD performance as the non-scaled version with comparable configuration. We achieve this by QP cascading, i.e., assigning gradually refining quantization parameters to the declining temporal layers. We present and analyse a mobile-compliant version of DSVC at reduced complexity that still admits comparable performance. Finally, we report on early work of dynamic layer tuning. Derived of delay variation measures, senders exploit scalable video layering to adapt the video transmission to varying network conditions. Initial results indicate that video performance remains close to optimal.

A distributed multimedia communication system and its applications to E-learning

In this paper we report on a multimedia communication system including a VCoIP (Video Conferencing over IP) software with a distributed architecture and its applications for teaching scenarios. It is a simple, ready-to-use scheme for distributed presenting, recording and streaming multimedia content. We also introduce and investigate concepts and experiments to IPv6 user and session mobility, with the special focus on real-time video group communication. Index Terms — Video and multi media conferencing, Elearning, Mobile IPv6, Multicast Mobility

Let's Meet at the Mobile - Learning Dialogs with a Video Conferencing Software for Mobile Devices

Mobile phones and related gadgets in networks are omnipresent at our students, advertising itself as the platform for mobile, pervasive learning. Currently, these devices rapidly open and enhance, being soon able to serve as a major platform for rich, open multimedia applications and communication. In this report we introduce a video conferencing software, which seamlessly integrates mobile with stationary users into fully distributed multi-party conversations. Following the paradigm of flexible, user-initiated group communication, we present an integrated solution, which scales well for medium-size conferences and accounts for the heterogeneous nature of mobile and stationary participants. This approach allows for a spontaneous, location independent establishment of video dialogs, which is of particular importance in interactive learning scenarios. The work is based on a highly optimized realization of a H.264 codec.

Video-based e-learning in groups: combining SIP and multicast in a mobile learning internet infrastructure

Rich multimedia communication in groups is the instrument of choice in various e-learning situations and is best achieved by videoconferencing, supplemented by collaborative tools. In this paper, we report on various distributed synchronous and asynchronous video-based teaching and learning scenarios using stationary and mobile technologies over IP. They are realised by a multimedia communication system including a VideoConferencing over IP (VCoIP) software with hybrid architecture derived from a SIP-initiated P2P model. The system is based on a fast, highly efficient H.264/AVC video codec implementation. We investigate new concepts for nomadic IPv6 user and session mobility, focussing on real-time group communication.