What’s Best For Streaming, HLS Or ICY?

When it comes to streaming your radio station online, you have a lot of options - which is a good thing, but it can sometimes be overwhelming as well. At the end of the day, you want your listeners to click “Listen Live” and have the stream start playing and not be interrupted with technical glitches or buffering.

So, what’s the best way to do this? When we think of streaming, usually we think about bit rates and codecs (For example 128kbps MP3 or 64kbps AAC), but did you know that there is more than just bit rates and codecs? Think of your bit rates and codecs as wires wrapped in a larger sheath. The sheath in this case is called the Streaming Protocol, and while there are quite a few different streaming protocols, we are going to look at the two most prominent in audio today.

History of ICY and HLS

ICY (Fun tidbit, ICY stands for “I Can Yell,”) has been around since 1998 and is tried and true and you can stream most codecs including MP3 and AAC codecs. HLS or HTTP Live Streaming has been around since 2009 and supports both MP3 and AAC codecs. Its main use is for video streaming, but as us audiophiles know all too well, if it works for video, we can make it work for audio. Besides this, the main differentiating feature is that ICY streams are persistent, meaning that when the stream starts, it does not stop until the listener clicks stop/pause while HLS typically sends 5 or 10 second chunks of audio at a time.

Pros and Cons of ICY and HLS

When streaming with a persistent stream (ICY), you can often encounter buffering if the available bandwidth the user has suddenly drops, which stinks, but the fact of the matter is that with available bandwidth and so much of it nowadays combined with better internet connectivity and reliability, the chances of a drop in bandwidth or having enough bandwidth is not really an issue anymore. Further, ICY streams are near universal when it comes to playing - it plays anywhere with access to the Internet—you don’t need a player and most apps support ICY streaming and decoding of an mp3 audio stream

Now with HLS, you are able to ensure quality streaming even if there is a drop in bandwidth. We see this mostly with mobile listening while on the road. As your cell signal bounces from tower to tower or if you drive through a dreaded dead zone, the transition is not always graceful. With HLS delivering chunks of audio at a time, you can literally lose your bandwidth connection for several seconds, but your stream would continue to play on (because the player downloaded several chunks of audio still available for playback locally).

Both streaming protocol pros far outweigh the cons. ICY’s limitations are with the stream itself—you can only send one stream at a time and risk buffering—while HLS limitations are with the amount of streaming and mobile app vendors that support playback.

Benefits of Adaptive Bitrate Streaming

An additional benefit is that HLS (if configured to do so) can make use of Adaptive Bit Rate (ABR); this is where you are simultaneously streaming two or more bit rates at the same time and different Kbps - for example, you can send a 48kbbs, 64kbps, and a 96kbps AAC stream and the player will decide which stream is the most optimal based on bandwidth and latency.. So you can go from a 96kbps stream and hit a drop in bandwidth for some time and the HLS will then send a lower bit rate that can still be sent with bandwidth available to it without even a hiccup in the stream. As your bandwidth increases, the bit rate will automatically increase as well.

Where is HLS Supported?

With HLS, you need a player and an app that supports HLS playback. Not all streaming providers or mobile apps support this, so when looking into HLS, make sure to ask your vendors if they support HLS, and even more specifically Adaptive Bitrate if you choose to leverage this.