Listening to web radio and audio streams with a media player

How a radio station broadcasts on the Internet

A web radio works on a simple principle: the sound from the transmitter is continuously encoded by software, sent to a broadcast server, then redistributed to each listener who connects. Unlike a file you download, the stream has no beginning or end: the player receives the data as it flows, keeps a few seconds in a buffer and plays it.

Two main technical families coexist:

• the continuous HTTP stream, inherited from Icecast and Shoutcast servers: a single connection stays open and the sound arrives without interruption. It is the most widespread method for radio;
• the segmented HLS stream: the sound is cut into small files of a few seconds, listed in a .m3u8 manifest that the player rereads regularly. This method, identical to that of video, makes large-scale delivery easier and lets quality adapt to the available speed.

For the listener, the difference is mostly practical: a continuous stream starts almost instantly, while an HLS stream is often ten to thirty seconds behind live, but copes better with network changes, for example when switching from Wi-Fi to 4G.

Audio formats: MP3, AAC and the others

Sound is compressed by a codec, which determines the quality obtained for a given bitrate. Bitrate is expressed in kilobits per second (kb/s).

Which bitrate to choose?

Many stations offer several streams for the same station. In practice:

• on a smart speaker or a phone, 128 kb/s in MP3 or 96 kb/s in AAC give a result hard to tell from a higher bitrate for speech and most music;
• on a hi-fi system or good headphones, aim for 192 kb/s or more, or a high-quality AAC stream;
• on mobile data, an HE-AAC stream at 48 or 64 kb/s spares your plan.

To estimate consumption, divide the bitrate by eight to get kilobytes per second: a 128 kb/s stream uses about 16 kB/s, or nearly 58 MB per hour. One hour at 64 kb/s is about 29 MB, one hour at 320 kb/s about 144 MB.

Finding a station's official address

The only safe source for a stream address is the station itself. An official address is stable and good quality, and you listen to the station under the conditions it intended, with any advertising that funds it.

Where to look on the station's website

1. Look for a page titled "Listen with your player", "Stream links", "Listen elsewhere" or "Our audio streams", often placed in the help, the FAQ or the footer.
2. Some stations offer a download button for a small .m3u or .pls file: this file simply contains the stream address.
3. Failing that, the help page for smart speakers or tabletop Internet radios often lists the direct addresses.
4. If nothing is published, contact the station through its form: many stations are happy to share their links with listeners.

Major public and private groups, like community stations, generally publish several addresses per station, per format and per bitrate. Collaborative web radio directories can help you spot a station, but their links are not always up to date nor always from the station: check that an address really points to a server of the station or of its broadcast provider.

What is allowed and what is not

Listening for free to the stream that a station itself makes available to the public is perfectly legal. On the other hand, rebroadcasting that stream (on your own site, in a public place, in a shop) requires permissions and rights, notably from music rights management societies. A personal playlist for your own listening poses no difficulty; publishing it so that others can benefit goes beyond that framework.

PLS files, M3U files and direct links

Radio addresses come in three forms:

• a direct link to the stream, for example https://flux.radio.example/station-128.mp3;
• a .pls file, a simple list format inherited from Shoutcast, containing one or more addresses;
• an .m3u or .m3u8 file, which can be either a simple list of addresses or an HLS manifest.

A PLS file looks like this:

[playlist]
NumberOfEntries=1
File1=https://flux.radio.example/station-128.mp3
Title1=Example Radio
Length1=-1
Version=2

Open it with a text editor: the File1= line contains the real address, which you can copy into your own playlist. Be wary of unencrypted http:// addresses: they often work, but some recent systems block them by default in apps; prefer the https:// variant when the station offers it.

Adding stations to an M3U playlist

A personal M3U playlist lets you gather your stations in a single list, sorted by genre, with their logo. The syntax is identical to that of a video playlist:

#EXTM3U
#EXTINF:-1 tvg-logo="https://www.radio.example/logo.png" group-title="News",Example Radio News
https://flux.radio.example/info-aac-96.aac
#EXTINF:-1 tvg-logo="https://www.radio.example/logo-jazz.png" group-title="Music",Example Radio Jazz
https://flux.radio.example/jazz-192.mp3
#EXTINF:-1 group-title="Music",Example Radio Classical (HLS)
https://flux.radio.example/classique/master.m3u8

A few rules to follow:

• the first line is always #EXTM3U;
• each station takes two lines: the #EXTINF line with the name after the comma, then the stream address;
• the duration -1 indicates an endless stream;
• group-title creates the sections shown by the player;
• save the file in UTF-8 so that accented characters display correctly.

Each attribute is explained in detail in our article on the M3U format. A libmpv-based player like AICKO IPTV plays these audio streams exactly like video streams, with no special setting: MP3, AAC or HLS. The player's features are presented on the video and audio player page.

Metadata: current track and show name

Icecast-type servers can send ICY metadata in the middle of the stream: the title and artist of the current track, or the name of the show. Not all players display it, and not all stations send it. HLS streams use other mechanisms, less often used by players.

Solving common problems

Also remember that Internet radio is not the only digital option: DAB+, digital terrestrial radio, offers good quality without using data, on a compatible set.

Summary

• A web radio is broadcast as a continuous stream (Icecast, Shoutcast) or as segmented HLS.
• 128 kb/s in MP3 or 96 kb/s in AAC are enough for everyday listening; 128 kb/s uses about 58 MB per hour.
• Always take the stream address from the station's official website.
• .pls and .m3u files are just containers of addresses, easy to read in a text editor.
• A personal M3U playlist gathers your stations by genre, for your private listening.

Frequently asked questions

Why is Internet radio behind FM?

The sound has to be encoded, carried, then buffered by the player. With an HLS stream, the cutting into segments adds several more seconds. A delay of ten to thirty seconds is common.

What is the difference between a .pls file and an .m3u file?

They are two formats for lists of addresses. PLS comes from Shoutcast and numbers each entry; M3U is more universal and accepts attributes such as the logo or the group. In both cases, the real stream address can be read in a text editor.

Can I share my radio playlist?

You can tell a friend or relative where to find the official links. However, rebroadcasting streams or publishing a list for a wide audience goes beyond private listening and falls under broadcast rights.

How much data does an hour of radio use?

About 29 MB at 64 kb/s, 58 MB at 128 kb/s and 144 MB at 320 kb/s. Divide the bitrate in kb/s by eight to get consumption in kilobytes per second.