Introduction to Video Conferencing

Introduction

The Internet is designed to allow communication between clients and servers. Typically, the client initiates a request, and the server responds to it. The flow is also similar for real-time applications where users communicate with each other. However, because the request of each user relays through an intermediate server, an additional lag or delay is inevitable. When it comes to video conferencing, the flow may not be optimal, especially when the server is too far away from the user, because it can add delay and lag due to the size of the data and result in glitchy playback.

We know that user-perceived latency mainly depends on the transfer time and processing time. Usually, live streams don’t require a lot of processing, and are forwarded from servers that can be miles away from users. Let’s discuss some available ways to solve this problem of extra miles.

Real-time communication

Real-time communication requires the shortest path to transmit data, which is possible through peer-to-peer communication. Still, it becomes problematic when participants are behind different Network Address Translation (NAT) Network Address Translation (NAT) is the replacement of a user's private IP with an Internet Service Provider's (ISP) public IP.areas. To overcome this problem, a signaling server is used that allows both the communicating parties to share their multimedia session descriptions that include the port, IP addresses and  other information essential for the communication. Let's see how signaling helps in sharing this multimedia session information.

Note: A multimedia session is used to identify media-related metadata essential for media transmission, processing, etc. It is also helpful for identifying and enabling device-specific features compatible with other participants.

Signaling and connecting

Signaling refers to the successful initiation of a multimedia session between participants willing to participate in the audio/video conference. However, before the communication starts, clients must exchange and agree on multimedia session information, such as communication addresses (IP and port), media descriptions (text, audio, video, etc.), and other metadata. This information is usually sent via the session description protocol (SDP).

The session description protocol (SDP) is a format for describing session information in a standardized form. It is just a description format, must be delivered using protocols like Session Initiation Protocol (SIP) or Session Announcement Protocol (SAP)The Session announcement protocol is a set of rules for sharing session information among groups of multicast groups. The users then listen to these well-known groups to receive session announcements. , which are specially designed to share session information between participants. Let's take the session initiation protocol (SIP) as an example, due to its versatility, ...