Dynamic sources

Liquidsoap supports dynamic creation and destruction of sources during the execution of a script. The following gives an example of this.

First some outlines:

• This example is meant to create a new source and outputs. It is not easy currently to change a source being streamed
• The idea is to create a new output using a telnet/server command.
• In order for a Liquidsoap script to run without an active source at startup, it is necessary to include settings.init.force_start := true at the start of the script.

In this example, we will register a command that dynamically create a new output based on an encoded stream and output it to an arbitrary url, as supported by the ffmpeg copy encoder. This script can be used to create a dynamic restreaming platform.

Here's the code:

settings.init.force_start := true
settings.server.telnet := true

# Replace the path here with a path to some video files:
s = playlist("/path/to/files")

streams = ref([])
count = ref(0)

enc = %ffmpeg(
 format="flv",
 %audio.copy,
 %video.copy
)

def create_stream(url) =
 if list.assoc.mem(url, !streams) then
 "Stream for url #{url} already exists!"
 else
 out = output.url(id="restream-#{!count}", fallible=true, url=url, enc, s)
 count := !count + 1
 streams := [...!streams, (url, out.shutdown)]
 "OK!"
 end
end

def delete_stream(url) =
 if not list.assoc.mem(url, !streams) then
 "Stream for url #{url} does not exists!"
 else
 shutdown = list.assoc(url, !streams)
 shutdown()
 streams := list.filter((fun (el) -> fst(el) != url), !streams)
 "OK!"
 end
end

server.register(namespace="restream",
 description="Redirect a stream.",
 usage="start <url>",
 "start",
 create_stream)
server.register(namespace="restream",
 description="Stop a dynamic playlist.",
 usage="stop <url>",
 "stop",
 delete_stream)

After executing this script, you should see two telnet commands:

• restream.start <uri>
• restream.stop <uri>

which you can use to create/destroy dynamically your sources.