PSVT Packet switched video telephony

Packet-Switched Video Telephony (PSVT) is a communication technology that enables real-time video conversations over packet-switched networks. In PSVT, video data is divided into small packets and transmitted over a network, such as the Internet, using the Internet Protocol (IP). These packets are then reassembled at the receiving end to reconstruct the video stream, allowing users to communicate visually in real-time.

PSVT is designed to provide a high-quality video calling experience by utilizing the existing infrastructure of packet-switched networks. It takes advantage of the robustness and efficiency of IP networks, which are widely deployed and offer reliable and scalable connectivity.

Here's how PSVT works:

1. Video Encoding: The video source, such as a camera, captures the visual information and converts it into a digital format. The video data is then compressed using video codecs like H.264, VP8, or VP9. Compression reduces the size of the video data, making it easier to transmit over the network.
2. Packetization: The compressed video data is divided into small packets. Each packet contains a portion of the video stream along with some header information, which includes details like source and destination IP addresses, sequence number, timestamp, and payload type. These headers help in routing and reassembling the packets correctly at the receiving end.
3. Network Transmission: The video packets are transmitted over the packet-switched network. They are routed through various network devices, such as routers and switches, based on the destination IP address. The packets may take different paths through the network, depending on the network conditions and the routing protocols being used.
4. Network Congestion and QoS: Packet-switched networks are shared resources, and congestion can occur when there is high network traffic. To ensure a smooth video calling experience, Quality of Service (QoS) mechanisms can be employed. QoS prioritizes video packets over other types of traffic to minimize latency, jitter, and packet loss. This prioritization helps maintain the quality and real-time nature of the video stream.
5. Packet Reception and Reassembly: At the receiving end, the video packets are collected. They may arrive out of order or with some packets missing due to the nature of packet-switched networks. The receiver uses the sequence numbers and timestamps in the packet headers to reorder the packets and compensate for any lost packets. Once the packets are reassembled in the correct order, the video data is passed to the decoder.
6. Video Decoding: The compressed video data is then decoded using the same codec that was used for encoding. The decoder decompresses the video packets, reconstructing the original video frames.
7. Display: The decoded video frames are displayed on the recipient's device, such as a computer screen, smartphone, or video conferencing system. The recipient can see the real-time video stream from the sender and engage in a visual conversation.
8. Bidirectional Communication: PSVT supports bidirectional communication, allowing both participants in a video call to send and receive video packets simultaneously. This enables a natural and interactive conversation between the participants, just like a face-to-face interaction.

Overall, PSVT leverages the packet-switched network infrastructure and video compression techniques to provide real-time video telephony. It offers a flexible and cost-effective solution for video communication, enabling individuals and businesses to connect and collaborate remotely, irrespective of geographical distances.