Major events are often live-streamed over congested networks that cause quality issues, especially when a media company doesn’t have dedicated links. This is why many media operators deploy equipment in IP environments that secure and separate channels to avoid a customer or service interfering with another customer service.
Ways to improve the quality of a media broadcast during major events
So, how does a media company handle the challenges of broadcasting media during large events with thousands of watchers?
The 1+1 protection
One way to address the problem in IP environments (both managed and unmanaged), is by setting up 1+1 protection with two separate paths preferably from two different providers to ensure redundancy. This means that if a link faces issues and packets are dropped, the same packets can be sent through the other link and maintain high quality. By using hitless 1+1 protection, such as the SMPTE 2022-7 standard, at the receiving side, seamless protection and enhanced quality are achieved. While this approach solves the problem, setting up dual links can add to the cost significantly.
ARQ – Automatic Repeat Request
Another way to tackle quality issues is through ARQ, i.e. fast packet retransmission techniques for UDP media streams. The two most common protocols used are SRT and the RIST standard. They are developed for improving quality over the public internet, but can also be used to handle packet loss over congested managed networks. Productions can suffer 10-20% or sometimes even higher packet loss and still get high-quality streams.
What are UDP streams?
UDP (User Datagram Protocol) is a TCP/IP protocol widely used for streaming audio and video, VoIP (Voice over IP), and video conferencing. UDP is a so-called unreliable protocol ─ a protocol that does not check for errors during the transmission ─ as such, some jokingly refer to UDP as the “Unreliable Datagram Protocol”. But the lack of error checking functionality is not necessarily a demerit. UDP is suitable for purposes where error-checking and correction are either not necessary or are performed in the application itself. Due to its statelessness, it’s ideal for transmitting data to large numbers of viewers.
So what are UDP streams, and why should you care? Well, due to its lack of retransmission delays, it’s perfect for time-sensitive applications where dropped packets are preferred over waiting for delayed packets to retransmission, which may not always be an option in a real-time stream.
A final point that media companies need to consider is time synchronization. Media traffic is sensitive to both jitter and phase alignment, which makes pacing and frame alignment often necessary. However, this means the source and destination nodes should use the same clock, and in IP environments, transferring time can be challenging. Therefore, it is important to ensure clocks are configured correctly on both sides to avoid frame misalignment and overall poor quality.