emulator: radio
type: utility
core_classification: pure_libretro
source: "https://git.libretro.com/libretro/libretro-radio"
upstream: "https://github.com/fpscan/libretro-radio"
author: "fpscan, gadsby"
profiled_date: "2026-09-17"
source_commit: "5d7d786ad1d8703a52184ff2ee39712c46ed67c9"
upstream_commit: "5d7d786ad1d8703a52184ff2ee39712c46ed67c9"
core_version: "1.1"
display_name: "Internet Radio (Radio)"
cores:
  - radio
systems: []

notes: |
  Streams internet radio and plays local MP3 and WAV files behind a tuner
  display with five visualisers. The station list is built once in
  retro_load_game, in this order: the content when it is given, then
  radio_stations.m3u in the system directory, then the same name in the save
  directory, then in the working directory, then the 100 most clicked
  stations of the radio-browser.info API over plain HTTP, and last eight
  SomaFM streams compiled into the core. Each step runs only while the list
  is still empty, so the first source that yields a station wins.
  ref: libretro-radio.c:2409-2488

  Content is an .m3u or .txt playlist, or a single .mp3 or .wav file. A
  playlist is read line by line: an EXTINF line names the next entry, any
  other line that is not a comment is a stream URL or a local file path,
  and a bare host gets http:// prepended. Up to 256 entries are kept and
  each is given a fake FM frequency for the tuner. A playlist that parses to
  zero entries counts as no content and the chain above continues, which is
  what the zero-byte empty.m3u in the repository is for. Local audio is
  opened from the path the playlist or the frontend gives; a WAV must be
  PCM or float with a fmt and a data chunk.
  ref: libretro-radio.c:1965-1971, libretro-radio.c:37,
       libretro-radio.c:2221-2291, libretro-radio.c:2419-2435,
       libretro-radio.c:746-797, libretro-radio.c:800-871

  Streaming is a hand-written HTTP/1.0 client over an AF_INET socket: the
  URL scheme is stripped, an https:// entry is joined in clear on the port
  it names or 80, ICY status lines are accepted and up to five redirects
  are followed. No TLS library, certificate store or font file is read; the
  8x8 glyphs are a table in the binary. MP3 decoding is libmad, compiled in
  from the libretro-deps submodule.
  ref: libretro-radio.c:517-548, libretro-radio.c:564-743,
       libretro-radio.c:81, Makefile:30-45, .gitlab-ci.yml:13-17

  The presets are the loaded list seen through the Active Preset core
  option, which selects entries 1 to 100 by index; a list longer than that
  is still walked with up and down on the pad. retro_load_game accepts a
  null game, but retro_set_environment only sets the pixel format and the
  variables and never announces SET_SUPPORT_NO_GAME, so the frontend still
  demands a content path and the .info supports_no_game only shows the
  Start Core entry.
  ref: libretro-radio.c:977-991, libretro-radio.c:1984-1999,
       libretro-radio.c:2068-2073

  The GitLab project is the copy the buildbot builds through its own CI,
  from the same tree as the author's GitHub repository, and the Makefile
  names the binary radio_libretro.
  ref: .gitlab-ci.yml:10, Makefile:17

files:
  - name: radio_stations.m3u
    path: "radio_stations.m3u"
    required: false
    category: game_data
    validation: [existence]
    unsourceable: "station list the user writes, one stream URL or local audio path per line, with no name or entry the code expects"
    description: "default station list, read when the content yields no station"
    note: >-
      Opened from the system directory, then from the save directory, then
      from the working directory, each only while no station has been
      loaded yet. Parsed like a content playlist and accepted once one entry
      comes out of it; a missing or empty file hands over to the
      radio-browser.info API and then to the eight built-in SomaFM streams.
      A file put here replaces those two fallbacks for every start without
      content.
    source_ref: "libretro-radio.c:2437-2461, libretro-radio.c:2278-2291, libretro-radio.c:2464-2481"