Radio stations are increasingly broadcasting programmes over the internet instead of or as well as via conventional means (analogue or digital transmissions). However, anyone listening to a programme by different methods will soon realise that the internet broadcast is delayed when compared to the standard radio version, often by a considerable number of seconds, and the reason for this may not be obvious.
Analogue and digital radio signals will suffer some delay due to the time taken for a signal to travel from the source (possibly an outside broadcast) to your radio via the broadcast station and any latency caused by the broadcaster’s equipment. However, the signals travel at the speed of light so any delays are generally negligible.
Causes of Internet Radio Delays
Internet broadcasts are prone to much greater delays and these can be imposed by the broadcaster. Sometimes these are for commercial reasons, with the advertisements on the radio output being replaced by other content for the smaller internet audience. Live broadcasts may also be delayed so the content can be censored in order to remove unsuitable content (which can also apply to traditional broadcasting).
The more common reason for delay is simply due to the nature of internet broadcasting. Whilst analogue radio signals are encoded to AM or FM, transmitted, then decoded when received, involving a very slight delay at each end, internet broadcasting has much more scope for delay. Rather than being transmitted directly from the station to a radio, internet signals go through a series of nodes and be decoded and encoded at each one.
The internet is simply, as indicated by its name, a series of interconnected networks of computers, hubs, routers and other devices. The broadcast radio signal is sent to the IP address of your computer but goes via your Internet Service Provider (ISP) where the server decodes the message and determines the best route to get it to you.
The route can involve several intervening links and each will impose a small delay as it decodes, encodes and retransmits. The speed of each transmission will depend on whether this is wireless, by wire or over optic fibre. The time for each process will be small, generally fractions of seconds, but overall may add up due to the number of processes involved.
Radio signals, like all internet data, are transmitted as a series of packets and these may be delayed if a link is busy. Additionally, packets may fail to be delivered and need to be retransmitted. To overcome these problems, data is received into a buffer on your computer and the transmission is only played when the data is completely received.
This buffering ensures the stream is continuous but can cause delays in addition to others resulting from internet use. Although these delays can be appreciable at times, you’ll only be aware of them if listening to time-significant events and they’re unlikely to spoil your enjoyment.