Video conference room: the experience of creating

Training class, aka video conference room.
The class was created from scratch, both from the point of view of construction (there were bare walls) and from the point of view of the experience of implementing and using video conferencing (Skype and others like it). In 2007-2008.

What I wanted to get

• Training audience with about 30 computers.
• Room for video conferencing.

It was originally planned that foreign teachers will give lectures to our students, various seminars will be held.
Based on this, the requirements for equipment, its configuration and location were formulated:

• The audience is strongly elongated in length (12 meters), therefore the information should be displayed on several screens.
• During the conference you need to be able to transfer the image from the computer.
• Ability to shoot and speaker and participants in the classroom.
• The ability to use modern codecs for video transmission, for a greater degree of compression and a lower bit rate (at that time we had a narrow Internet access channel - 2 Mbps for the whole university)

Describe in detail the process of selecting hardware, there is no sense in software - google, forums, vendor sites, documentation for different hardware.
The main thing is that we quickly decided that we would use a ready-made hardware solution, and not software on a regular computer. Further it will be clear what advantages we have gained from this. As a guideline, when choosing equipment, foreign universities acted, in which such classes already existed and with which we planned to hold regular videoconferences, lectures, seminars.

Result

It's not interesting to write about the network and class: ordinary PCs, Ethernet 100 Mbit; and equipment for videoconferencing consider in detail.
The basis was chosen Polycom VSX 7000e version of the VSX 7800e Presenter. Briefly what he can (first of all what interested us):

• Supports multiple standards: SIP, H.323, H.239, H.264
• Connect up to 2 controlled cameras
• D-sub input for capturing video from computer
• Image output to 2 monitors (D-sub and S-video)
• Transfer video up to 704x576
• Data transfer (computer image) up to 1024x768
• Simultaneous participation of up to 4 parties (multipoint video conferencing)

This kit includes: Polycom VSX 7000e server, PowerCam controlled camera, desktop microphone, remote control.


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About the camera I want to say a few words separately: autofocus, can rotate (± 100 °), bend (± 25 °) and has 10x optical zoom. Together with the ability to preserve the position of the camera, this allows very quickly (pressing 1 button on the remote control, camera rotation speed of 300 degrees / sec) to transfer the review to the desired part of the audience. There is a more advanced version of this camera: it has a built-in microphone and can track the speaker on its own.
Additionally, two plasma panels, a second PowerCam controlled camera, a projector, a radio microphone, 2 video splitters (d-sub), 2-port KVM, sound amplifier and speakers mounted in a suspended ceiling, a 19 "wall-mounted 9U cabinet, UPS were purchased.

All the equipment was installed in the closet, and the closet itself was “hidden” under the teacher’s desk and locked with a key. UPS rack-mount 1500VA, it is powered by everything in the closet and the projector.



Later a second radio microphone (buttonhole) and a mixer / preamp were added.
Only a computer and a KVM switch are available to the teacher.



Connection diagram in the figure below.



The whole thing works in 2 modes:

• Ordinary computer class:
  KVM switches to the mode when from the computer video and audio signals go (through a divider) to the monitor of the teacher and the projector.
• Video conferencing:
  Video from the computer goes to the server, through the divider, and the output of the D-sub server to the teacher’s monitor and projector via the KVM switch.

How is the videoconference and how to manage it

Prior to the conference, the basic parameters can be configured via the on-screen menu, using the included remote control (the receiver for the remote is located not only in the server case - which is in the cabinet, under the table; but also in the cameras), or via a web interface from any computer .



In general, the remote is a very necessary thing, all control during a video conference goes through it:

• Make and answer a call
• Control your cameras and, if the remote side permits, control the remote cameras (camera selection, pan, tilt, zoom - PTZ)
• Sound control (microphone on / off, volume, ...)

Prior to the conference, with the help of a remote control, the main points are set where the cameras will look (the camera position and focal length are set). During the conference, by pressing one button on the remote, we switch between modes (like selecting a channel on a TV). It is very convenient to move between pre-selected zones in the audience: for example, from a speaker to a person asking a question from the hall or from one speaker to another.
Examples of transitions from general plans to large, and between different points with large plans.



View of the camera from the side. Initially, the camera moves from one extreme point to another with the remote control: the speed is low, you can accurately aim; in the second half of the clip - transitions between pre-defined positions.



A video from a remote participant is displayed on the screen from the projector (or the screen is divided into several parts, according to the number of participants), and a local video is displayed on the plasma screens (they are connected in parallel). If the conference is multipoint (that is, more than 2 participants), you can turn on the mode when the video of the participant who is “speaking loudly” will automatically open on the whole screen.

When a remote speaker includes data transfer (video from a computer), it is output to the projector, and the image of the remote speaker is moved to the plasma. Those. we also see the "presentation" from the computer and the speaker himself, and this not badly reinforces the "presence effect".

The microphone in the kit is omnidirectional, but the audience is very elongated, which is why the radio microphone is also used in addition. In general, according to the instructions, omnidirectional microphones can be cascaded, but we did not need this. In the case of a conference, when a translator participates on our side, omnidirectional microphones are not needed at all - only a translator uses a microphone.

To connect a computer (it is not necessary to use a teacher’s computer, sometimes you need to connect a speaker’s laptop), this box is used:



Perfect interface: there is only one button on it. Press it and the picture from the computer connected to it starts to be transmitted to the remote side; press again - the transfer stops.

Video and audio quality

As it was said at the very beginning, at the time of creation, we had a 2-Mbps Internet channel. During business hours, the channel was almost always 100% full. Therefore, initially during conferences, calls at a speed of 256 or 384 kbps were used. Packet losses (not only losses are meant as loss of packets, but also significant delays, that is, when the data is no longer relevant) periodically there were more than 10%.
At the same time, we received excellent sound (there was no noticeable loss of sound), and not a bad picture (7-10 frames / s). With such a bitrate, there was a noticeable pause of 1-2 seconds when the first frame appeared from the computer. Initially, the frame appeared with very strong compression artifacts, and within 1-2 seconds it became completely clear. These figures are approximate, by eye, moreover, it strongly depends on the chosen priorities: where the bit rate will be spent more - on the speaker’s video or on computer data.
It is clear that when a packet disappears, the picture freezes, but in fact it surprised the attitude of this profession to people who are in different professions. IT specialists "painfully" reacted to fading, attitude to these fading as in the joke "not neatly, doctor." At the same time, ordinary users, even at 256 kbit / s, with packet losses, periodic sinking of the picture, were delighted with video conferencing. Apparently the whole thing is in perception: an IT person first of all sees equipment, equipment, technologies, protocols; and a simple user - participates in a video conference and he does not care how it is done. Although it may be the case that IT people are more difficult to surprise.

Experience and conclusions

Someone would say: put the software “XXX” or “YYY” and get the same, but for less money (or for free). I disagree with that. Usually such people offer solutions like Skype, SIP clients, but they forget about a few very important things:

• Cost of equipment with comparable characteristics. Is it not necessary to buy cameras for software implementation? Need to. But for some reason people forget that camera-driven (PTZ) cameras cost money and are not small. A monitor, projector, acoustics?
• The complexity of software maintenance: you need to adjust, somehow cross with an additionally purchased hardware.
• The complexity of using the software: during the presentation, we manage one remote control. And what about software? Take out the keyboard and mouse? Connect the console (another piece of hardware that you need to connect, configure and cross with the existing software)

During the study of this subject area was not (maybe bad looking) not a single complete system based on software for a regular PC.
In our case, we got a ready-made, complete system that needed to be set up to a minimum, and using this system is no more difficult than a TV or DVD player, i.e it can be used by any person who knows how to handle the remote control.

The experience of operating this class once again proved that we did the right thing when we decided to use a ready-made hardware solution. As a rule, problems on the “other side” arose in the case of using different software, rather than hardware solutions.
In my opinion, the main difference between hardware and software solutions is their great forethought and completeness. Those. either we buy a ready-made solution and apply it from ourselves, or we buy a bunch of cubes, and as in the children's designer we are trying to assemble something. It is logical that for talking 1 on 1, sitting in front of a computer and a simple webcam with skype'om, for larger projects, this is not enough.

If we draw an analogy with servers, then the hardware solution is like a branded HP or IBM server in comparison with a self-assembled server. Both solutions have the right to exist, both will work, but they are distinguished by reliability, reasonableness of use cases, ease of operation. And after all, it is from pleasant trifles or vice versa inconveniences that the overall impression of the product is formed.

What now?

If we were collecting this class this year, you would most likely choose Polycom with its HDX series (this is a continuation of the VSX series, but with the ability to transfer video in HD quality), but not because of what you want and need HD quality, but due to the fact that previous models are discontinued.
Even after a few years, there is no need to change our VSX 7000e system to something from the HDX series, there are two reasons:

1. We need a much wider Internet channel, to a large extent this is a purely Russian problem, and foreigners have fewer problems with it.
2. And with whom to communicate in HD quality? This is not only our problem, it is a worldwide problem, the era of HD video conferencing has not yet come, it is only approaching.

About participants

The project was implemented by two programmers: Alexander Novikov (the author of the article) and Alexander Gubaev (editing the article), under the leadership of Eldar Alikramovich Kurbanov.