Basics of Video Conference

PeopleLink Corporate Solutions Pvt Ltd

PeopleLink Corporate Solutions Pvt Ltd

Basics of Video Conference

Conferencing Types

Web Conferencing - Web Conferencing is where a presenter can deliver a presentation over the web to a group of geographically dispersed participants. Web Conferencing is an online tool that makes it possible to share data as well as audio as part of a meeting. That data may be in the form of some sort of video, sharing documents, spreadsheets, presentations and even desktops. Unlike video conferencing, there is usually not the need for special equipment; a web conference can be attended using just about any computer with an Internet connection and a sufficient amount of resources to support the data transfer. In this NO Live Video is transmitted or Very Low quality Video is transmitted but participants can hear what the presenter is saying.

Webcasting /Streaming – is a One way broadcast, in which a live or pre-recorded program is sent from a central location out to viewers – I.e streamed over the Internet. To make the video TV quality, it requires powerful servers, and lots of Internet bandwidth, which is why the base cost of a Webcast can be very high. Streaming media is a technology developed to compress and transfer video and/or audio data through the Internet in such a way that the file can start to play while it is downloading. The content can either be “live" or “archived”. The distribution is fine for large events in which there can’t be much interaction between the audience and the presenter anyway. 

Web casting is used for 1 way viewing while Web Conferencing is 2 way Interactive.

Unified Communications: Unified communications (UC) is the integration of real-time communication services such as instant messaging (chat), telephony (including IP telephony), video chatting, data sharing (including web connected electronic whiteboards -IWB's or Interactive White Boards), call control and speech recognition with non-real-time communication services such as unified messaging (integrated voice mail, e-mail, SMS and fax).

Codec

CODEC - A codec is a hardware device or computer program capable of encoding and/or decoding a digital data signal. A codec is a program (an implementation) which can read or write digital files. A codec encodes a data stream or signal for transmission, storage or encryption, or decodes it for playback or editing. Codec’s are used in videoconferencing, streaming media and video editing applications. In Video Conferencing (Two types of Codec’s are used , one for Audio and one for Video). Any Video Conferencing Product whose Audio Codec and Video Codec’s are highly Bandwidth efficient, then they are considered to be the Best

STANDARDS of Video Codec

H.264/ MPEG4 SVC (Scalable Video Coding) / H.264 VBR/CBR /H.264 Std are compression standard that enables video conferencing systems to achieve highly error resilient high definition IP video transmission over the public Internet without compromising on quality of service . These standards have enabled wide scale deployment of high definition desktop video conferencing with reduced latency between transmitting source and receiver, resulting in fluid communication without pauses. Out of these Technologies H.264VBR/CBR is the best compression and achieves best Video quality at lowest bandwidth.

H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T) that defines the protocols to provide audio-video communication sessions on ANY packet network. It address multimedia communications over ISDN, the PSTN or SS7, and 3G mobile networks.

Audio Codec’s used in Video Conferencing: G.723, G.729, CELP, GIPS etc

Video Conferencing & Types

Video Conferencing

Video Conferencing typically uses video cameras or webcams to make a person in a remote location appear to be in the same room for a live face to face discussion. According to ITU, Video Conference is broadly Categorized into three segments

1.Standard Definition Video Conference : Any codec ( software/hardware) which has the capability to Send and receive Video of 352x288 Pixels @ 30 frames per second or above ie 640X 480 pixels@ 30frames per second to give a Live Audio Video quality is defined as Standard definition video conference. 2.High Definition Video Conference : Any codec ( software/hardware) which has the capability to Send and receive Video of 1280x 720 Pixels @ 30 frames per second to give a Live Audio Video quality is defined as High definition video conference.

3. Full High Definition Video Conference device : Any codec ( software/hardware) which has the capability to Send and receive Video of 1920x 1080 Pixels @ 30 frames per second to give a Live Audio Video quality is defined as Full High definition video conference. It is also called TelePresence System when used with state-of-the art room designs, video cameras, High End displays, High end sound-systems and processors using high capacity bandwidth transmissions.

Difference between Software & Hardware MCU

Hardware based MCU's are generally H.323/SIP based and come generally in multiples of 12port configuration. However the same 12 Port MCU can become a 24Port if the Video End Points connecting to it are joining at standard definition resolution and the same MCU can become 8 port or less if all endpoints are Joining at 1080P resolution. MCU's ports increase or decrease based on call rate at which video conference end point joins. ( This happens because there is a set hardware in MCU which can handle processing up to a particular point , since Standard Definition requires lesser processing power so no of video end points which can be connected increase, while as to process each FULL HD 1080P video Processing power required is very high so capability of MCU to hold concurrent calls decreases.

Software based MCU: Software based MCU's are generally license dependent , no matter you connect all of them in SD or full HD. No of locations that can connect to the conference will be same. This happens because user has the flexibility to choose there own hardware server , so depending on what his need is he can go for higher end or lower end server. Upgrading more ports is also easy as it is just a License upgrade and can be done in multiples of 1. Apart from that the advantage which it brings is long life, even if the hardware server in which software MCU is hosted dies after 3-4 years. Customer can chose to shift the MCU software to another server which costs fractional in comparison to new hardware MCU. Also software brings in the Big Value of Up gradation, same software after few years can be upgraded at fraction of cost to the new technology available at that point of time..

Common terms used in Video Conferencing

Video Encoding: Video encoding in simple terms means the capability of Video Conference end point also termed as CODEC ( hardware/software) to transmit a High resolution video to other endpoint or MCU. Many Codec’s have capability to Encode from 480p to 720p and Highest at 1080P.

Video Decoding :Video encoding in simple terms means the capability of Video Conference end point also termed as CODEC ( hardware/software) to receive a High resolution video from other endpoint or MCU. Many Codec’s have capability to decode from 480p/ 720p /1080p/1440p and up to 4080p ( this is combined resolution of many HD Videos sent from MCU to end Point).

PTZ Camera : Capability of a Camera to Pan , Tilt and zoom is shortly referred as PTZ Camera. PTZ Camera's are available in the Optical Zoom range of 3X to 25X. 10x zoom is more popular as it covers most of the Conference Rooms except for few large conference rooms with seating capacity greater than 30 members. The maximum PAN (horizontal rotation) movement of a camera is 360 degree and Maximum Tilt is 180 degree ( UP/DOWN) movement.

Presets in PTZ camera : In order to avoid pressing of multiple buttons ( pan, tilt and zoom) to certain degree to achieve the best image of a participant. We can configure a preset with which we can set the best pan/tilt and zoom view of a particular participant.

Contd…

VAS (Voice Activated Switching) Technology - If there are four people in a conference, the site which is talking will be automatically seen in the bigger screen. This technology has failed as even there is a slight noise created at a location, microphone is not able to understand if this is a sound or a noise and it starts sending that locations video into the Bigger screen.

This is alternatively getting replaced by double click switching “ user can bring anyone who is talking to bigger screen by simply double clicking on his Video”

Voice Activated Switching cameras: This is capability of the codec which is in turn connected to PTZ Camera and microphone to sense a signal from a particular microphone in a conference room and then automatically rotate and Zoom to the particular participant. This technology has also phased out due to Non-Intelligibility of the codec to identify between Human voice and disturbance created on Conference table by hand tapping etc.

This technology is alternatively replaced by “Push to talk “button system. The buttons are embedded inside the Conference table in between every 2-3 participants and if someone has to talk they press the button and camera rotates and zooms to the particular participant. This is widely successful

Lip Sync – Matching the movement of lips to the sound.

RESOLUTION & Frame Rate

Resolution: Image created as a result of No. Of Pixels or dots used. It is simply defined as quality of image measured in terms of pixels. For eg 2mega pixel, 5 mega pixel etc

Frame Rate : Also called fame frequency is the rate at which any imaging device produces unique consecutive images called frames. It is measured in Frames per second ( fps). Frame rate above 25Fps is defined as Live Video without any jerks.

Based on Size of frame ( horizontal and Vertical pixels available in image) and speed at which they are sent over the network “FPS “ ) . Video Conference can be broadly divided into

Standard Definition : SD : 320 x 240 @ 30fps / 352 x 288 @ 30fps (CD Quality)Optical Definition OD: 640 x 480 @ 30 fps (DVD Quality ) VGA – 800 x 600 @ 30fpsHD : 1280 x 720 p @ 30 fpsFull HD : 1920 x 1080 @ 30fps

The Maximum resolution of any standard LCD/LED/PROJECTOR ETC available is 1920Pixels horizontal and 1080Pixels Vertical. Except of High end expensive displays like VIDEO WALLS where resolution can go up to 4080p.

The concept here to understand is if the total effective pixels that any display has is maximum 1920X1080 so even if the videos which have higher no of pixels then this will be of no use as the quality output from the display is maximum 1080p unless a High resolution Video wall is used.

Important Concept on Resolution Management done by Most of Hardware Video Conference Codecs &

MCU'S

In a hardware Codec or even in some software code’s when a Video conference is done and a particular model of codec

claims to encode 1080p and decode 1080p which means it has capability to receive maximum 1080P in total ( whether it is

one to one video conference or a 10 party Video conference the total size of all 10 videos put together is 1080p@30fps.So

the system has inherent capability to automatically reduce the resolution to lesser size if multiple videos are viewed by

Codec ( in any case the total effective resolution of all videos put together is 1080p). In Some advanced software based

systems Like PeopleLink have the capability to send 1080p videos and receive up to 4080p videos as all video streams are

individual streams and MCU doesn’t combine them to make them as one stream so in a 4 party conference if all

participants are sending 1080p video then they can receive multiple videos at resolution of 1080p. This has no relevance

since the total maximum effective pixels which a display has is 1920x1080p , This only brings advantage when a high

resolution video wall is used or else PeopleLink Tele Presence module is used which allows to connect multiple displays

and one can send each location video in a separate display in full screen.

Resolution Management

Echo & Noise Cancellation

Echo: When the Participant in a conference hears his own voice coming back from the remote location, it is termed as echo. This creates lot of disturbance in the conference.

Echo Cancellation : Echo cancellation is a technology is used to cancel the echo completely either by using a dedicated DSP ( digital signal processor) or without using a DS.Important Note: If the Echo Cancellation devise is installed at location A and not at location B, Location A will still hear his echo while as there will be no echo heard at Location B.

Ambient Noise: Ambient noise is defined as the basic level noise of a room which will be higher in case of usage of Window AC, FAN, Projector noise Etc. A good quality room has ambient Noise level of 35 to 38db. It is recommended to use Split and quiet AC;s in conference rooms. There is a BIG Impact of Ambient Noise on the quality of Audio which is sent to the far end Location as microphone is able to hear it and sends this disturbed Noise to other location.

Noise Cancellation – Noise cancellation is a Technology used to cancel the Noise ( Sound coming from Fan, Ac’s, Projectors etc) at a microphone level so that after the microphone hears by using intelligent Noise cancellation Algorithms along with Dedicated DSP based devices.

Recommendations for improving Audio Quality in a Room: Reflective Materials like Glass tables and partitions should be completely avoided. Also if there are bare cemented walls and hard surface. It can create multiple audio reflections, To Avoid that Sound absorbing material Like Carpets, Drapes, False Ceiling with high sound absorbing capability is required so Sound absorbing material like Wooden panels etc should be used in the walls. By using right sound absorbing material we can avoid multiple reflections of audio and hence high quality audio will be received at other end of the conference.

There is a tremendous impact of Lighting and Background Color on the overall Video Quality. If the room is Poorly Lit or

has more Light, in both the scenarios the Video quality will not be good. For poorly lit rooms the Video captured will be

hazy and slow , for more bright rooms the extra light will create multiple reflections from walls and hard surface which will

impact Video Quality and have patchy images.

Lighting: The Best Lighting arrangement can be ensured by ensuring that Dispersed Light falls on the Participants

instead of Direct Light. The Lux level of 550- max 600 is considered optimal. We should always use diffused lights to

get this type of effect so that the entire room is well lit without any Light Patches.

Back Ground Color: We should always use Dark Color’s and plain Colors like (Blue, Grey, Orange)are well

recommended. The dull colors like (White, cream etc).. Creates a blurry image and participants face is not well

demarcated. Stripes and designs should be prohibited as it puts lot of processing load on camera which is most of the

time in auto focusing mode.

Impact of Lighting / Background Color on Video Conference

Thanks