From: eden li <eden.li@...>
Date: 2007-05-08T16:28:37+09:00
Subject: Re: ulaw audio over network

It looks like this is a pure #sleep issue and has nothing to do with
sending data over a socket.  If you setup a simple loop and average
the time sleep actually sleeps, you get the following:

want = 0.008, actual (averaged over 1000 attempts) =
0.00800016689300537
want = 0.01, actual (averaged over 1000 attempts) = 0.0122149839401245
want = 0.012, want (averaged over 1000 attempts) = 0.0120026016235352

Not exactly sure what's so special about 10ms...

Here's what I ran to produce the output above:

def try(n)
  dt, dc = [0, 0]
  1_000.times do
    t = Time.now.to_f
    sleep n
    dt += Time.now.to_f - t
    dc += 1
  end
  dt / dc
end

[0.008, 0.01, 0.012].each do |n|
  puts "want = #{n}, actual (averaged over 1000 attempts) = #{try(n)}"
end

On May 8, 4:42 am, Earle Clubb <ecl...@valcom.com> wrote:
> Does anyone know of a good way to stream ulaw audio (read from a file)
> over a UDP socket?  I have something (mostly) working, but I can't seem
> to get the packet timing right.  If I use a 10ms sleep, the packets end
> up being ~12ms apart.  However, if I use a lower value (say 8ms), the
> packets are 8ms apart.  The code I'm using is included below.  Has
> anyone done this or something similar?
>
> Thanks,
> Earle
>
> Code:
> require 'socket'
>
> @audio_socket = UDPSocket.open
> @audio_socket.connect("239.1.1.3", 4098)
>
> def send_audio(filename)
>   data = ""
>
>   File.open(filename) do |file|
>     while file.read(80, data)
>       @audio_socket.send(data, 0)
>       sleep 0.01
>     end
>   end
> end
>
> send_audio(ARGV[0])
>
> --
> Posted viahttp://www.ruby-forum.com/.