Broadcasting, Archiving, and Reuse of Videoconferences Through Streaming

By combining video streaming and videoconferencing, it becomes possible for any number of people to view a videoconference — either live or recorded for on-demand access at a later time. A streamed videoconference can be viewed on desktop PCs using standard streaming media players, such as Real, Windows Media or QuickTime.

Streaming can dramatically increase the utility of a videoconference. For example:

• The audience you wish to include in a meeting, conference, or class may be so large that it's not feasible to include them all in an interactive multipoint videoconference, but it is necessary to have a number of the key individuals participate in videoconference.
• You may wish to save the proceedings of a meeting.
• You may wish to make the content of a videoconference-based class available on-demand for student review.
• In fact, there may be times when you simply want to record and stream an event, lecture or meeting — you don't need to videoconference — but you do have a videoconferencing appliance in the room and wouldn't it be nice if you could employ that equipment for video streaming!

A streaming participant cannot interact in a live videoconference. Streaming is a one-way delivery of media. Various methods can be employed to provide a streaming participant the means to indirectly participate, including e-mail and chat rooms.

There are four methods to stream a videoconference:

1. All-in-one box solutions. These devices act as an H.323 device and a streaming server. In operation, the H.323 face of the device is brought into a point-to-point or multipoint videoconference. The device removes the H.26x/G.7xx video and audio from the H.323 envelope and repackages the H.26x/G.7xx into the envelope of a streaming format such as QuickTime, Real or Windows Media. The streaming face of the device then sends the content via unicast or multicast to any user with the proper popular streaming player installed on their computer. Some devices can also record and store, providing on-demand access to the content. Examples include:

   STARBACK [7] TorrentCE

   This is the easiest option for the end-user, since all they have to do is to dial into the H.323 streaming server and "invite" them to join their conference. This "special guest" will then automatically take up the recording and the streaming at predefined addresses and locations.

   First Virtual [8] Conference Server with Streaming Support

   VCON [1] VCB 1000

   These solutions can archive or record a videoconference with administrative assistance. This means that the end users should inform the administrator that they need these services, so that they are activated for the particular session.

   Virtual Rooms Videoconferencing Service (VRVS [9])

   This is not really a product but rather a worldwide service and is mentioned in the Popular Collaborative Technologies section of this cookbook. Its techniques are based on the same principles as the Starbak Torrent device, however the implementation is open and free.

2. Combination videoconferencing terminal and streaming encoder. In this approach, two standard devices — a videoconferencing terminal and a live streaming encoder are interconnected such that the analog A/V output of the videoconferencing terminal is fed directly to the input of a live streaming encoder. The encoder can be of the standard Real, Windows Media or QuickTime variety, or can be of a specialty type such as high-bandwidth MPEG-1 or MPEG-2. Unicast or multicast network transmission can be employed. The stream is viewed using a standard streaming player appropriate to the encoding choice. Content can be recorded and stored on the streaming server for on-demand access. You can find more details on how to build a streaming encoder from scratch in the following section titled "A simple streaming encoder".
3. Videoconferencing terminals with built-in H.26x multicast streaming capability. Some high-end videoconferencing terminals, such as the Polycom FX and the Tandberg 880, have the ability to multicast stream a videoconference that the unit is participating in. VCON products as well offer a multicast conference mode, where the communication itself is conducted through multicast channels, which can be viewed by many more remote participants, if the moderator allows it. The Quicktime Media Player is the most suited for multicast viewing as it has better default support to connect to multicast sessions. RealNetworks player might need to be tweaked slightly to get it to work with multicast sessions, although it sometimes works just fine.
4. Application service providers (ASP). Many videoconference bridging service providers provide a streaming option. The technology that a particular ASP employs will be either of the solutions #1 (all-in-one box) or #2 (combination terminal and encoder) described above. ASP solutions are not included in the following Comparison Guide because the service characteristics will depend on the technology employed. Investigate which technology an individual ASP utilizes and evaluate according to the Comparison Guide.

There are some pros and cons with these methods:

• Video and audio quality
• Con: Solutions #1 (all-in-one box), and #3 (terminals with built-in) repackage the H.26x/G.7xx compressed video and audio. Although H.26x compressed video can be streamed, it's not optimized for streaming. The video quality of H.26x is more susceptible to degradation from network congestion and packet loss than the made-for-streaming formats such as Real and Windows Media, in case that is a problem on your network. . Also, the H.26x formats don't provide dynamic bandwidth adjusting capabilities such as Real SureStream and Windows Media Intelligent Streaming.
• Pro: Solution #2 (combination terminal and encoder) decodes the H.26x of the videoconference to baseband video and audio, and re-encodes to a made-for-streaming format. Solution #2 provides video of a more consistent quality and can take advantage of advanced streaming features such as dynamic bandwidth.
• Networking
• Con: Solution #3 (terminals with built-in) requires IP multicast network transmission. Multicast is sparsely supported in the commercial Internet. Support in university and commercial sector intranets is varied. Internet2 supports multicast. Terminals with built-in are only feasible if your audience is on multicast-enabled networks.
• Pro: Solutions #1 (all-in-one box) and #2 (combination terminal and encoder) support unicast and multicast network transports.
• Operation and Management
• Con: Solution #2 (combination terminal and encoder) can be complex to manage if your institution doesn't already support live media streaming and have people managing that infrastructure. Videoconference scheduling systems don't support viewing the pair of devices (videoconference terminal and encoder) as a single logical entity, and none of the popular scheduling systems currently control a Real, Windows or QuickTime encoder. Some scheduling system vendors are considering support for this configuration.
• Pro: Solution #3 (terminals with built-in) and Solution #1 (all-in-one box) are very easy to operate and manage.
• Features
• Con: Solution #3 (terminals with built-in) doesn't have the ability to record a videoconference.
• Pro: Solution #1 (all-in-one box) has only a very small time delay between the video conference and the streamed video, unlike all others. This makes it possible to have quasi-real-time interaction with streamed video using feedback methods such as chat.

Comparison Guide

What to have in mind

Streaming over the Internet creates an unavoidable delay in the delivery of a videoconference. This is in contrast to the near-real time delivery of streams between the participants of an H.323 conference. H.323 protocols are fine-tuned to allow the fastest possible delivery. Streaming protocols on the other hand focus on ensuring reliable delivery at the expense of speed. All nodes in a streaming process, from the source encoder to the servers or content delivery network and up to the player software in the client computer, store a few seconds of the passing stream in their memory, to recover from possible temporary data losses over the network. This process is called "buffering". It is obvious that the delay in the delivery of a stream is the combined buffering in all the transmission stages. This can easily reach 1 minute during a transmission. So it is important to have in mind that someone watching a conference through streaming will be at least a few seconds behind. This is useful to know when tuning your settings. If the viewer of a stream reports low audio quality and you fix it at the source, there will be this delay until the viewer hears the improved audio on his side. The exception to this is the all-in-one box, such as from Starbak. In that case, the time delay is very small because no decoding to analog and re-encoding back to digital is done.

Another issue, often overlooked is that videoconference sessions often are accompanied by some form of data sharing like a Power point presentation in the simplest scenario. Archiving a videoconference by itself without the presentation might leave the viewer wondering what the speakers are talking about during the session. One technique is to send the Power Point as part of the original video, so it gets streamed and recorded automatically. Another useful technique is to combine a recorded video with slides and other media via multimedia authoring tools such as SMIL (Synchronized Multimedia Integration Language), which creates combined presentations that can be played in most Media Players today. This would however require post-processing time spent to create the combined presentation. SMIL is outside the scope of this manual, so if you need further information you may find it at the relevant pages of the World Wide Web Consortium [10].

A simple streaming encoder

"Need forges the arts" as the Ancient Greeks used to say. If you need to record a videoconference with little time and resources at your hands, or just want to try out how it can be done, here is a short recipe to build your own streaming encoder, to be used in combination with a videoconference system as in method #2 above.

1. Get a computer with at least 1GHz CPU, 128MB of memory and enough hard disk to accommodate your recordings. A rule of thumb for storage space is: if you are recording at xKbps streaming bandwidth, then you need x/2 Mbytes of storage per recording hour. As an example if you are recording at 300Kbps then you would need 150 Mbytes per hour of recorded material.
2. Install a capture card that can accept audio and video signals as inputs. Some VGA cards already have this feature, although it is best to use a specialized card such as the Viewcast Osprey 210, which costs less than $200.
3. Download and install encoder software for the media format of your choice. Microsoft offers Windows Media Encoder and Real Networks offers Helix Producer for free on their Web sites.
4. Connect audio and video outputs from your videoconference system (you may find them labeled as VCR outputs) to the inputs of the card.
5. Start the videoconference and then start recording or streaming from the software package you installed. Both of the above software packages include wizards that step you through the configuration process. Helix Producer in particular offers a command line interface that can be very useful when you want to make a turnkey system. If you include the command to start encoding in the startup sequence, then you just need to press the Power On button and the computer will start streaming or recording with your predefined settings.
6. When you are finished, stop the encoder software.

The most common problem that arises when streaming or recording a session with method #2, is the mixing of the two sound signals: the local and the remote. Many videoconference systems offer a "mixing" mode that combines both signals, but its quality is below par. It is safer to use a small recording mixer with the following setup:

• Connect the microphone to one of the mixer inputs. This is usually impossible to do with the microphones that come with videoconference systems, so you will need an external one.
• Connect the audio output of the videoconference system to another mixer input.
• Feed an output of the mixer that contains only the microphone signal into the audio input of the videoconference system.
• Feed a mix of the two input signals into your encoder machine, and possibly to the speaker system of the room.