How to use bpm sound processing function?

[rrolla]

Hello, i read api reference http://savonet.sourceforge.net/doc-svn/reference.html#bpm

bpm(?id:string,?every:float,((float)->unit),
 source(audio='#a,video='#b,midi='#c))->
source(audio='#a,video='#b,midi='#c)

but cannot understand how to use it.

my goal is to log currentBpm in liquidsoap log.

here my script fragment

def show_bpm(currentBpm) =
  log(currentBpm)
end

# Music
songs = playlist("~/radio/music.m3u")

security = single("say:Hello, this is G-radio \
                     We are currently having some \
                     technical difficulties but we'll \
                     be back soon so stay tuned!")

s = fallback(track_sensitive = false, [songs, security])

s = bpm(every=1., show_bpm , s)

s = smart_crossfade(s)
s = amplify(1.,override="replay_gain", s)

error message, line 40 is where bpm function starts

At line 40, char 24:
  this value has type
    (string,...)->_ (inferred at line 17 char 1 - line 19 char 3)
  but it should be a subtype of
    (float,...)->_

Thanks

[toots]

Hi @djbeater !

The typing system is getting in you way.. :-)

The BPM is a floating number, something like 2.3, etc. liquidsoap is being specific about the type of data it passes around and the log function only takes string values, something like: "2.3" etc.

You can convert float into strings in at least two ways:

• Call string_of
• Use the #{...} interpolation syntax.

Here's a solution with the first one:

def show_bpm(currentBpm) =
  log(string_of(currentBpm))
end