Why UDP is preferred for Live Streaming

Undoubtedly for live video sharing, UDP (User Data Protocol) is always recommended over TCP (Transport Control Protocol) due to some of the obvious reasons which are listed as below:

1. UDP offers reduced latency over the TCP reliability

2. In case of time sensitive applications, UDP is faster protocol as it doesn’t wait for acknowledgement from the client side and retransmission of lost packet.

3. Little pre-fetching can be achieved in live streaming and more the buffering, the greater is media play-out delay.

It is not the case that we don’t use TCP for streaming. We do use, but TCP is always preferred for VOD (Video On-Demand) due to below mentioned reasons.

Why we opt TCP for Video-On-demand?

1. Adapt the best picture quality by transmitting every frame.

2. Quite easy to monitor the bandwidth between the source and receiver

3. TCP streams can do encryption to prevent theft of videos due to guaranteed receipt of segments in correct order.

4. Due to self clocking mechanism, TCP is better for variable bandwidths that occur on the Internet.

5. TCP provides error recovery by retransmission of missing data.

Understanding UDP and TCP for live streaming:

Let’s try to understand in this way. Say, we are streaming a cricket match. While streaming the content, packets are lost due to some reason. Suppose for a minute the player did not receive the packet. Now in case of TCP, the video streaming will pause till it receives the packet. On top of it, client has to send the right acknowledgment for each segment received. Once the packets are found, TCP will send all the packets and continue sending the live stream once acknowledged. Firstly, pending packets are of no use and secondly it took a lot of time which resulted in miss match with live cricket match streaming. For VOD, it works perfectly as transmission guarantees no loss of frame.

While in case of UDP, the client is not bothered for any acknowledgement. Hence, the transmission is fast which leads to less buffering and reduced video playout delays. UDP does not care for frame loss, what matters is the on-time delivery of the content. So, it results in the complete sync with live streaming. It is also best suited in real-time conferring like skype video calling as multi-second buffers are not of any use when trying to have a conversation.

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