playlist consumes files at maximum rate

[vitoyucepi]

Describe the bug
playlist will consume files at maximum speed when sending to output.icecast if liquidsoap sends input.http to output.icecast at the same time.

To Reproduce

music = playlist("/tmp/test/music")

output.icecast(
  %mp3,
  music,
  host = "icecast",
  mount = "/a",
  fallible = true,
)

input_stream = input.http("http://icecast:8000/a")

output.icecast(
  %mp3,
  input_stream,
  host = "icecast",
  mount = "/b",
  fallible = true,
)

Expected behavior
playlist should consume files at a normal rate.

Version details

• OS: Debian in docker container
• Version: 2.2.4

Install method
savonet/liquidsoap:v2.2.4

Common issues
#3626
#3627
#3727 (reply in thread)

[toots]

Thank you for this report, will have a looks shortly.

[toots]

Wow that's an interesting bug!

I believe that this is behaving as intended. Let me explain:

• Icecast does not control the data flow, it simply relays the data at the rate it is given. The source client library is responsible for rate-control.
• When receiving an icecast stream, most likely than not, the stream will thus be sent rate-controled directly from the source-client.
• Liquidsoap has a notion of self-sync operator, which means that a given operator already has a built-in rate control. This is the case for input.http when connecting to an icecast server for the reason cited above.

However, with the given script, this means that the whole liquidsoap script then becomes rate-controlled by the rate at which input.http receives data.. which is the rate it is sent to by the first output.icecast.. which now isn't controlled at all by the machine's CPU like it is by default.

In other word, by sending and receiving to and from the same icecast server, the script rate-control is effectively disabled!

The solution is pretty simple, however: pass self_sync=false to input.http to prevent it from taking control of the data rate..

[vitoyucepi]

Hey @tdardly,
Take a look at the answer.
Basically, you should change your script like this.

-input_stream = clock(input.http("http://icecast:8000/a"))
+input_stream = input.http("http://icecast:8000/a", self_sync=false)

@toots,
In the original discussion at #3727 (reply in thread), I found that assigning a new clock to input.http also solves the problem.