The main problems of using video in meeting rooms and their solution

Last time we talked in detail about various video conferencing equipment for meeting rooms.

In this article we want to tell about the most frequent problems that arise when equipping and using meeting rooms. Very often they are the cause of low productivity negotiations.

So let's look at them in more detail:
')

1. Acoustic problems - all problems associated with the quality of the capture and playback of sound.
2. Lighting problems - lighting problems, such as interior decoration, the use of low-quality video cameras.
3. Communication problems - the lack of prioritization of video traffic on the network equipment, the connection of the VKS terminal through WiFi / 4G, the load from network users.

Consider these problems and their solutions in more detail.

Acoustic problems

The solution to the difficulties with the perception of the voice of the interlocutors is the primary task in designing the meeting room for video conferencing. The consequence of these problems may be the poor hearing of remote participants and the illegibility of their speech. People have to repeatedly ask each other and ask them to repeat what they have said. This leads to discomfort of communication, unproductive negotiations and rapid fatigue of participants.

The most common problems with sound:

1. The echo effect is a situation when a participant in a conference, along with a speech from remote opponents, hears his speech. The echo effect arises from the fact that the speech of the participants, reproduced in the loudspeakers of the remote side, returns through their microphone. To compensate for echo, there are software and hardware solutions called echo cancellers. Echo cancellation is the process of recognizing an originally transmitted signal that repeats with some delay in the transmitted or received signal. Once a repeating signal is recognized, it is removed by subtracting it from the transmitted or received signal.
   
   Most video client software clients (Skype, Trukonf, etc.) have either a built-in software echo canceller or automatic microphone sensitivity correction in their settings to compensate for self-excitation.
   
   
   
   Software echo cancellation does not always solve the tasks, so there is a need to use more efficient hardware echo cancellers due to the presence of specialized DSP processors for processing audio signals in them.
   
   For small meeting rooms, for example, a great solution is a professional echo canceller Phoenix Audio MT107 . For large meeting rooms, when you need to mix multiple audio sources (from two to four), the Phoenix Audio Octopus is ideal, which, among other things, has an integrated audio amplifier for the speaker system.
   
   The general scheme of operation and connection of the echo canceller using the example of Phoenix Audio MT107 is shown in the following figure:
   
   
   
2. Noises In our case, these are extraneous sounds that are not related to the speakers' speech: man-made noises (air conditioners, equipment fans), paper rustling, chairs moving back, coughing, etc.
   
   Conference microphones are focused on the human voice, that is, on the capture of sound waves in a certain frequency range. The sudden noise is knocked out of the frequency response of human speech, and the noise reduction system tries to cut it out of the general audio stream.
   The solutions described above: MT107 and Octopus , in addition to echo cancellation, are effective noise reduction systems.
   
   
3. Feedback acoustic communication. If the speakers in the conference room are located above the microphones or are directed towards them, then when you turn on several microphones, there is a high probability that the sound will be heard because the microphones will amplify the sound coming from the speakers and self-excitement.
   
   To combat this local phenomenon, acoustic feedback suppressors are used.
   
   The principle of their operation is as follows: the feedback suppressor determines at what level of frequencies the pickups start to appear and as soon as these frequencies “creep” abruptly upwards, it cuts them out.
   
   The general scheme of operation and connection of the acoustic feedback suppressor is shown in the figure below using the example of DBX AFS2 :
   
   
   
4. Weak hearing. It consists of two factors: the use of insufficiently sensitive microphones and insufficient power sound systems.
   
   Consider the first option on a specific example. A video conferencing terminal (Polycom, Cisco, etc.) with a standard microphone is installed in the meeting room. Suppose that its sensitivity is not enough to cover all the people in the room, and the hardware terminal does not support connecting more than one standard microphone.
   The solution to the problem can be connecting to the VKS terminal of third-party microphones via the mini-jack connector 3.5 mm, which is in each terminal of even the youngest models.
   
   This may be a wired or wireless congress system. The congress system is especially relevant when there are more than 10 participants in a room.
   
   
   
   Instead of a congress system, you can connect a system of desktop or ceiling microphones to the VC terminal using an audio mixer.
   
   From the desktop microphones, raven are suitable for solving this problem, and they are connected to the hardware terminals through a mixer and an echo / noise suppressor [Octopus].
   
   An excellent working option for ceiling microphones is the Biamp Devio CR-1C , which consists of a high-sensitivity ceiling microphone and a central unit.
   
   Low-power room sounding systems give poor audibility to remote participants. For example, when using built-in TV speakers in a large room. In our experience, the built-in television speakers should be used in rooms of no more than 20-25 square meters.
   
   In larger rooms, the sound from the television speakers is dissipated as people sit away from the TV. In this case, we recommend using:
   Ceiling or wall speakers with audio amplifier.
   
   Built-in speakerphones speakers.
   
   In both cases, the sound source is closer to the people and, therefore, the interlocutors hear better.
   
   
5. Adverse acoustic conditions due to the presence in the room of a large number of sound-reflecting surfaces, for example, glass walls, tables and other interior elements.
   
   In this case, for the best sound capture, we recommend using congress systems , since They are equipped with microphones with a focused diagram. Due to the narrow directivity, the microphone picks up only the voice of the speaker, and all other sounds that go beyond the limits of the radiation pattern are cut off.
   
   Also in such adverse acoustic conditions, microphone arrays have proven themselves well:
   
   
   • Audio Phoenix Condor with intellectual adaptation of the volume of the voice, depending on the removal of the speaker from the microphone array.
     
     
   • Shure Microflex Advance MXA910 with functions of automatic mixing, correction of frequency and reduction of the echo effect.
   
   Architectural solutions help to partially absorb the reflected sound - fabric blinds on the windows, sound-absorbing flooring, and sound-absorbing panels.

Light and technical problems.

These include the mistakes in the design of the meeting room, which interfere with the quality capture and display of video.

1. Wrong lighting. It is not recommended to use fluorescent lamps and spotlights in a room for video conferencing. This leads to uneven lighting and flickering of the image obtained from video cameras. The second is sometimes solved by the built-in professional flicker compensation of 50-60 Hz built-in professional video cameras . But it is almost impossible to compensate for the areas of blackout and illumination with camera functionality. As a result of improper lighting, the camera will try to work through too dark areas, or highlights, this can lead to frequent refocusing and changing the overall brightness of the picture.
   
   The solution to such problems is the use of diffused light based on LED lamps, evenly distributed over the ceiling of the meeting room in the area of ​​the conference table.
   
   You also need to avoid back or side lights, sunlight from the windows on the face and the camera lens.
   
   You can evaluate the quality of lighting by looking at the meeting room through the camera of a mobile phone in video mode - this will reveal the main problems with the flickering of light, sharp contrast and focusing.
   
   
2. Non-optimal interior colors and background. The wall opposite the camera is an important detail in the design of the meeting room. It is better to place a company logo and a clock showing local time. In the decoration of the room is better to avoid the motley colors, black and bright white, complex patterns in the interior. All this may prevent the camera from focusing and distracting participants from the speaker.
   
   
3. Non-optimal video display and capture devices. When designing display facilities, it is better to eliminate the use of projectors, since they are more suitable for presentations. In order to provide the necessary brightness and contrast, you have to mute the light in the room. While in video conferencing it is necessary to provide high quality images with good illumination of the room, which is required for high-quality video capture. Given these requirements, it is best to use LCD TVs, video walls or interactive video panels .
   
   
4. As a means of capturing video, it is recommended to use professional cameras for video conferencing. They have the necessary qualities to work in meeting rooms and conference rooms. Among these qualities are high sensitivity, tilt / rotate / zoom functionality, built-in image correction functionality, as well as the function of automatic camera pointing at participants. Web cameras should be left for personal use, and even more so you should avoid using cameras built into mobile devices or laptops in meeting rooms. The quality of the picture from such cameras will make communication uncomfortable and unpleasant for your opponents. Those who participated in a similar group conference on Skype from a laptop will understand me. It’s almost impossible to understand who is in the group now appeals to you - the picture is not clear, the voices are indistinguishable. And this is despite the fact that the image was broadcast on a 55-inch panel a meter from the table.

Communication problems

These include problems related to the video transmission channel: insufficient bandwidth, high packet delay, Wi-Fi connection, lack of traffic prioritization, etc. The more of the following recommendations your network administrator can provide, the better video quality you will receive.

1. Use a wireless connection over Wi-Fi. Terminal VKS in the meeting room must have a wired connection to the network. Although in fact, often under the table in the meeting room is not held a network cable or for it is not connected outlet.
   
   
2. Video and audio traffic is critical to the delay of data packets in the communication channel. Therefore, you need to ensure the QoS policy by placing the traffic of the VCS in a separate subnet or VLAN. You also need to set up prioritization and marking of VKS traffic so that it is transmitted first and foremost, and requests from browsers, mail clients and other traffic that is not critical for delays have lower priority. For example, configure Priority Queue for real-time RTP traffic, as well as for signaling traffic that uses specific ports: 5060 UDP in case of [SIP] or 4307 [TCP] if you use TrueConf .
   
   
3. Abandon an asymmetrical Internet connection in favor of symmetrical. An asymmetric connection, including ADSL, when the incoming speed is much higher than the outgoing speed, can cause poor communication quality for your interlocutors.
   
   
4. Provide high availability and better connection speed for a group video conferencing server or MCU. Outgoing traffic on the server during conferences significantly exceeds incoming traffic. Therefore, it makes sense to place the server in a good data center with a gigabit Internet channel, connecting it to your VPN network to ensure for all conference participants a good connection to the server. By the way, the software server VCS TrueConf for this purpose has a special version in the Amazon AWS Marketplace application store.
   
   
5. Use modern solutions for video conferencing, because they will be able to quickly adapt to changing connection conditions and will be able to break through NAT and Firewall.

findings

It is not always possible to design a meeting room “from scratch” at the stage of its construction. Often, meeting rooms are rooms adjacent to the common office space or vacant utility rooms with all their features. This article talked about how to solve the most common problems.

We would be happy if in the comments to the article you share your experience or tasks that you would like to solve, and we can advise you on how to solve them.

In addition, you can address your task directly to the author of this article, Tatyana usikova@unitsolutions.ru , usikova@unitsolutions.ru , and get not only professional advice, but also a discount on equipment using the promotion unitfix .