2. Introduction

The UCL Mbone tools, namely RAT and VIC (as adopted and developed by UCL) have been deployed in a number of conferencing environments, most notably AccessGrid and VRVS. Since UCL has had minimal resources to maintain these tools over the last few years, their development has diverged and fragmented. We plan to change that under the SUMOVER project. 

The goal of the workshop was to bring together the key people in the projects that are using the tools and work on a plan for their future support and development.  

The three day meeting was made available for remote participation using a ‘PIG’ installation of AG2.4 connected to the Manchester ‘Shakespeare’ Venue. Additionally a Jabber room was used for discussion and questions between the participants, and to assist in debugging of the session. 

All presentations and the agenda are available online on the project website:

http://www.cs.ucl.ac.uk/research/sumover/

3. Agenda

Monday 28th November

12:30 Buffet lunch

13:30 Welcome and Sumover Project outline, Piers O'Hanlon (UCL)

14:30 Presentations:

    *  Scaling Multimedia Conferencing, Colin Perkins (University Of Glasgow)

    *  AGSC, Mike Daw (University of Manchester)

16:00 Coffee

16:15 Presentations:

    * VRVS/EVO, Phillipe Galvez (Caltech/Cern)

    * VRVS/EVO video/audio tools, Pavel Farkas (Caltech/University of Brno)

    * AG, Tom Uram (Argonne National Labs, USA) [presentation over AG]

18:10 day end 

Tuesday 29th November

09:30 Presentations:

    * Activities in the IETF, Colin Perkins (University Of Glasgow)

    * VRVS video/audio (continued)

    * Conferencing and WebC@ast @ DESY, Reinhard Eisberg (DESY)

11:00 Coffee

12:30 Lunch

13:30 Software management systems, Socrates Varakliotis (UCL)

    * Source code Management

    * Bug/feature tracking

14:30 Tools architecture, status and new features, Piers O'Hanlon (UCL)

    * Common Library

    * ANU use of UCL Common library, Rhys Hawkins (ANU) [presented by Piers O'Hanlon]

    * RAT

16:00 Coffee

16:15 Presentation:

    * An intro to the inSORS Grid, Terry Burke (inSORS) [presentation over AG/inSORS]

17:00 Tools architecture, status and new features (continued), Piers O'Hanlon (UCL):

    * VIC

18:00 Day End

20:00 Workshop Dinner 

Wednesday 30th November

09:30 Security, platforms, documentation, hardware, Piers O'Hanlon (UCL)

    * Collaboration initiatives

    * Formation of Evaluation Steering Group

11:00 Coffee

11:15 Open Discussion on future

13:00-13:55 Lunch

14:00 Workshop end

4. Meeting report

The meeting began with an introduction by UCL on the SUMOVER project, which was followed by a number of talks from the attendees. Then a series of presentations were given by UCL, which were followed by relevant discussions.

1. Monday 28th November

The day began with a general welcome followed by an introduction to the SUMOVER project from O’Hanlon, and Kirstein.  

The first presentation was from Colin Perkins on his work on “Scaling multimedia conferencing ”. The presentations raised issues on congestion control of real-time media streams, which UCL said they planned to investigate as regards use of DCCP, as opposed to the application level approach taken by Glasgow. Glasgow is currently pursuing an application level TFRC/RTP implementation which uses currently fixed packets sizes. Perkins has code that can support DV and HDTV drivers for video capture, though HD hardware is highly specialised and expensive. There was general agreement that it would be very helpful to the community to investigate systems to support the operation of ACE systems in areas where multicast connectivity is not good enough or not possible. 

Mike Daw presented on “AGSC activities related to the Mbone tools”. It was mentioned that there are currently 70 UK AG nodes. There were some discussions around compatibility of AG2 with a new version of inSORS, especially with regards to its new H.264 video support. UCL mentioned that NCHC have done a VIC port of H.264 which they plan to integrate into the UCL source tree. Concerns were raised by Perkins as to that fact that H.264 is encumbered by various patents, though as yet no application using the ffmpeg codec library H.264 has been sued. 

Phillipe Galvez presented on VRVS and its new incarnation, known as EVO. It was mentioned that VRVS runs of portions of the Global Ring Network for Advanced Application Development (GLORIAD) -www.gloriad.org. Perkins voiced disapproval of the use of RTCP by VRVS for signalling and control – since it is not designed for such use, and it is an unreliable communication channel. Perkins mentioned there is a new attribute planned for the Session Description Protocol which will allow for the labelling of media sources e.g. main camera, overhead camera etc. The availability of the VRVS source code to UCL was brought up; Galvez answered that it is closed source as Caltech impose some restrictions on them, plus they may be considering commercialisation. UCL mentioned that open source would be useful and is not necessarily incompatible with commercialisation – all tools are under a BSD style licence which imposes minimal restrictions, which are easily met. When questioned about platform availability, Galvez responded that the current deployment is: 80% Windows, 10% Mac and Linux. Galvez mentioned that VRVS employs a non-standard tunnelling technique, so that all media traffic is transported over a single port. 

There was interest expressed in the use and deployment of peer-to-peer communication systems such as Aspen from Berkeley (Andrew Swan), and Orta which is being developed in Glasgow. Galvez also mentioned that EVO plans to deploy a P2P system, known as Panda(network)/Koala(end system); again, however, the source is not available, though APIs may be made available. It is planned to deploy the Panda system on their existing 83 ‘reflector’ nodes. The EVO system supports monitoring using Monalisa: http://monalisa.cacr.caltech.edu/monalisa.htm 

Pavel Farkas presented on the new VRVS/EVO video/audio tools. It was noted that a new java based audio client for EVO is in development, which will supersede RAT. VRVS says it maybe possible to feed changes (MBUS removal, multi-threaded operation etc) to RAT back to UCL. Discussion arose on the idiosyncratic codec implementations in H.323 conferencing units – VRVS have spent some time debugging the H.261 codec, from their OpenMASH-based version of VIC, to work with commercial implementations. The issue of H.323 inter-working was discussed; Roger Bolam mentioned that UKERNA would probably be supporting H.323 systems for a number of years to come, however inter-working was not seen as a major part of the media tools work, until a reliable H.323-AG gateway was in place. UKERNA also expressed interest in SIP interoperation, though this is another signalling protocol which requires gatewaying. It was mentioned that certain codecs stalled momentarily when they received out-of-order packets – this was observed to be due to the fact that smaller packets were re-ordered (arrived earlier) on certain networks where VRVS is used. Thus VRVS have re-engineered VIC to send equally sized packets. Additionally Perkins mentioned that on certain link types back-to-back packets had been known to get re-ordered.  

RAT stability was mentioned – Perkins and VRVS agreed that the MBUS was the source of some stability issues – especially reliable MBUS messaging. Issues of buffering were also raised – RAT’s play-out buffer can get oversized (resulting in choppy audio) if silence suppression is not enabled. Other problems were seen as a result of RAT’s multi-process based operation – e.g. when the GUI process dies it can [confusingly] leave the media-engine running. Also interface selection problems were highlighted – particularly on machines with multiple interfaces. It was also mentioned that error messages should contain more useful information, and possibly automated bug feedback. UCL resolved to investigate these issues. VRVS are interested in MacOSX RAT fixes and an Apple native GUI (Carbon) to RAT. 

Tom Uram presented via AccessGrid on the recently released AccessGrid 2.4 toolkit and media tools. The issue of firewall control was raised and Tom replied that AG2.4 can automatically configure the WinXP (SP2) firewall. AG2.4 cannot currently configure Linux’s iptables firewall.

2. Tuesday 29^th November

Colin Perkins (IETF AVT & MMUSIC working group chair) presented on Activities in the IETF. It was mentioned that SDPv2 work has stopped, though there is ongoing effort to revise the original SDP spec. The work on Internet Media Guides (IMG) for describing collections of multimedia sessions may, in principle, be useful in the ACE environments however they would clearly need to be integrated into the current systems. Useful codecs covered in IETF include iLBC and AMR. iLBC might be preferred to Speex as it less likely to be patent encumbered. There was also strong encouragement to consider using NAT traversal options available today or currently under standardisation, such as STUN, TURN and ICE, however it was understood that such traversal would not be implemented by the tools themselves. 

Reinhard Eisberg presented on “Conferencing and WebC@ast at DESY”.  UCL asked about their DirectX filter-graph based mixer - it is currently only an internal project. 

A presentation was given by Piers O'Hanlon on attaining a common code base and licensing issues. O’Hanlon raised the question of whether the current licensing model (currently BSD style) for the tools was appropriate – it was generally agreed that it was. Questions were put to the VRVS team as to source availability but their basic position was that it was unfortunately not going to be made available. This means that whilst inter-working testing can be performed, limited effort can be allocated to fixing any problems that arise as without source code these are not easily resolvable. Any such issues will be communicated to VRVS and dealt with in through discussion. 

Socrates Varakliotis presented UCL’s work on Software management systems. It was mentioned that both AG and VRVS use CVS internally, however Subversion is becoming a popular alternative that aims to improve stability and manageability. Conversion tools exist for converting existing CVS repositories to Subversion. Bug and feature tracking systems have also been reviewed and presented by UCL. There was general agreement that an interactive source management solution would be useful in terms of taking the tools forward. 

A presentation was given, over AccessGrid, by Terry Burke, on their inSORS platform. It was mentioned that they are working on native version of inSORS for Linux (Red Hat Enterprise 3) and Mac. Questions were raised on the nature of their ‘improved encryption’ – Burke said that it has not been finalised. UCL asked whether inSORS use any tunnelling for media traffic – Burke said no tunnelling was used and the streams are sent on multiple ports, usually over unicast. UCL also asked whether the newly integrated inSORS H.264 codec would interoperate with other implementations, such as the one from NCHC, which has been integrated into VIC. Burke said that currently inSORS supports three H.264 profiles (small/medium/large) and any interoperability tests would depend on whether these profiles are supported by the NCHC VIC. inSORS support to the AG version of VIC to maintain compatibility may have licensing implications. 

Piers O'Hanlon presented slides on behalf of Rhys Hawkins on use of the UCL common library. There was some discussion on the benefits of using the common library; Perkins noted they had used it in multi-threaded systems without trouble, though he is interested in integration of the multi-threaded patches mentioned in Hawkins’ talk. 

Piers O'Hanlon presented slides on “Tools architecture, status and new features”. Discussion was had over the potential modifications and new features that could be added to the tools, and the importance (to different parties) of each one. UCL mentioned that manpower is limited on the SUMOVER project so only a limited number of new developments can be undertaken by the SUMOVER project, though UCL would welcome external work on any proposed features. UCL brought up the possibility of software echo cancellation; however it was seen as relatively low priority since cheaper echo cancellation devices are appearing. VRVS have been successfully using USB based audio devices – a USB audio device (combined microphone and speaker) with built-in echo cancellation from Phoenix was passed around meeting participants (www.phnxaudio.com). 

3. Wednesday  30^th November

Piers O'Hanlon presented slides on Security, platforms, documentation, and hardware. Discussion was had regarding UCL’s mention of Secure Real-Time Protocol (SRTP) – it was agreed that whilst it would be nice to have, it was not high on the list of features required by the community. The discussion on supported platforms concluded that whilst Mac support would be useful it will not be considered as important as WinXP and Linux support. It was concluded that the SUMOVER project could not realistically provide general ‘supported hardware’ recommendations, though they can list successfully tested hardware, and allow for users to document their own experiences. 

UCL raised the topic of the SUMOVER Evaluation and Steering Advice Group (ESAG), which is planned as a lightweight forum for group members to provide input and evaluation advice to the project. A number of attendees were interested in participation: Colin, Mike, Philipe, Louis, Andy. A number of names of people of not present were collected and these people will be contacted: Tom, Barz, Deb, Rhys, Steve-Smith.

5. Action points

A first pass at an ordered list of new features/modifications was discussed in the workshop, which was based on an initial email from Mike Daw. A cleaned-up version is reproduced here (from the presentation on the website). This list will be placed on the project website, in due course in such a way that items may be ranked by online-users; 

• Set up decent CMS (e.g. Trac) - feature requests/voting,
• Bug tracking & dev visible/contributable by others – designation of representative at sites.
• Visibility: AGportal, AG-TECH, Freshmeat, srcforge
• Put up this list – Working items
• Wiki style hardware support listing
• Clear labelling of unstable features – not to be compiled into distributed versions
• GUI simplification
• Clean compilation
• RAT
• Multithreaded mode
• Mbus stability – fix reliable mode
• MBUS without multicast – using some form of inter-process communication
• Padlock icon to indicate security mode
• Better error reporting – automatic bug reporting
• Push-to-talk
• VIC
• List receivers in main window
• Padlock security icon
• Integration of new codecs: H.264 (from NCHC)
• Add a start-up GUI to RAT/VIC where user can supply address, keys, codec
• VIC
• Full screen video/arbitrary video resizing (external contribution)
• Smart tiling – work from NCHC - All video in one
• Who's speaking functionality (external contribution)
• Thumbnail sorting
• Desktop sharing (compatible with inSORS?)
• inSORS: H.264 “Data mode?”
• VRVS: H.263 baseline
• Video subtitling/watermarking (like the news!) 
• Firewall/NAT traversal (UMTP?)
• Port number in use
• P2P (e.g. Orta, Aspen) support – source specific behaviours (external contribution)
• SRTP support
• Signalling issues, rekeying
• H.263 improved (UKERNA) – dependent upon GW initiative
• Low bandwidth support (i.e. don't receive video if don't want)

6. Conclusions

The workshop was considered very useful by the attendees and the SUMOVER project members. The project would like to keep the momentum and maintain interaction between the workshop attendees. The workshop is one of the first main stages of the SUMOVER project, which plans to take forward the work done. This will initially involve creating a suitably interactive and inclusive web presence conducive to collaboration and code sharing. Subsequently code management systems will be made available and access granted to selected external contributors. The ESAG will be set up and members informed, though the level of input expected is up to the individuals involved. 
 

7. Attendees list

8. Glossary