Setting prefetch=0 on request.dynamic doesn't work, but prefetch=1 does?

[ScuttleSE]

I have a source that looks like this

gbsfm = request.dynamic(prefetch=1, id="gbsfm", get_request)

setting prefetch to 1 makes the source work, but not the way I want. when starting LS it makes two requests to get_request, for the current song, and next song. At the end of current song, next song is played and one new request is done.

I want the initial request to only ask get_request once

I thought that was what the prefetch=0 would do, but it seems to just... disable the entire source

[toots]

Hi,

This is the default, yes. If you need more involved implementations, you can define your own. Each request dynamic source has a add method that you can use to push a new request whenever you see fit. You can also see the whole queue with queue and set the queue at once with set_queue.

This way, you can create a source, add an initial track and queue the next track when it gets near the end. Something like this:

s = request.dynamic(prefetch=0, ...)

if not s.add(some_initial_request) then
  log("Error while queueing initial request!")
end

def on_end(_, _) =
  new_request = ...
  if not s.add(new_request) then
    log("Error while queueing next request!")
  end
end

s = source.on_end(s, on_end)

Be aware, though, that doing things like that can be tricky, in particular if it takes too long to prepare the next track or if your source is behind a switch/fallback and may not get played for a while etc.

The general philosophy of our implementation designs is to choose a default implementation that is simple and fits most people's need but leave it open to implement advanced uses like this.. 🙂

[toots]

What's the code at /home/liquidsoap/config/extras/api-fetch.liq, line 41?

[rrolla]

@toots here is part of api-fetch.liq

38        if request.resolve(r) then
39            r
40        else
41            null()
42       end

[toots]

you need to handle the case where your API does not return a request:

def add() =
  r = dynamic_request()
  if null.defined(r) then
    music.add(null.get(r))
  else
    false
  end
end

if not add() then
  log("Error while queueing initial request!")
end

def on_end(_, _) =
  if not add() then
    log("Error while queueing next request!")
  end
end

[rrolla]

thanks will try

[rrolla]

Yes, this works after renaming your function add to something else, huge thanks @toots

[ScuttleSE]

Here's the beginning of my LS-file

set("harbor.bind_addr","0.0.0.0")
set("server.telnet.bind_addr", "0.0.0.0")
set("server.telnet",true)
set("log.file",false)
set("log.stdout",true)
set("log.level",3)

def get_request() =
  result = process.read.lines("python3 /home/liq/getsong.py")
  log("next song: #{result}")
  request.create(list.hd(default="", result))
end

def auth_gbsfm(params)
  user = params.user
  password = params.password
  ret = process.read.lines("python3 /home/liq/streampw.py #{password}")
  ret = list.hd(default="",ret)
  if ret == "true" then
    true
  else
    false
  end
end

#Live source

live = input.harbor("gbsfm_live",port=8889,auth=auth_gbsfm)

#Website playlist source
#gbsfm = request.dynamic(prefetch=1, id="gbsfm", get_request)

gbsfm = request.dynamic(prefetch=0,  id="gbsfm", get_request)

if not gbsfm.add(get_request()) then
  log("Error while queueing initial request!")
end

def on_end(_, _) =
  new_request = get_request()
  if not gbsfm.add(new_request) then
    log("Error while queueing next request!")
  end
end

gbsfm = source.on_end(on_end, gbsfm)

#Fallback
beees = single("/home/liq/bees.mp3")

#Make sure mono files are being played
gbsfm = audio_to_stereo(gbsfm)

#Put them all together
gbsfm = fallback(track_sensitive=false, [live, gbsfm, beees])

Running it gives me an error on the on_end part

At ices.liq, line 47, char 22-28:
Error 5: this value has type
  (_, _) -> _ (inferred at ices.liq, line 40 char 0 - line 45 char 3)
but it should be a subtype of
  source(_)

[toots]

on_end and s arguments need to be swapped, I updated my script examples above.

[rrolla]

I got a different error: #2113 (reply in thread) click on the link and reload page it will open discussion