Daniel Barlow

#!/usr/bin/ruby

# ruby FFI gem rocks!  http://rdoc.info/projects/ffi/ffi

# Please note this is experimental code and has awful APIs.
# Learn from it (if you can find anything to learn), but please do not use
# it as-is

require 'rubygems'
require 'ffi'

module PortAudio
  extend FFI::Library
  ffi_lib 'portaudio'

  module Format
    Int16=0x8
  end
  attach_function :Pa_Initialize, [], :int # typedef int PaError
  attach_function :Pa_GetVersion, [], :int
  attach_function :Pa_GetErrorText, [:int], :string
  attach_function :Pa_OpenDefaultStream, [:pointer,:int,:int,:ulong,:double,:ulong,:pointer,:pointer], :int
  attach_function :Pa_StartStream, [:pointer], :int
  attach_function :Pa_IsStreamActive, [:pointer], :int
  attach_function :Pa_WriteStream, [:pointer,:pointer,:ulong], :int
  attach_function :Pa_GetStreamWriteAvailable, [:pointer], :long
  def self.or_raise
    ret=yield
    if(ret<0) then
      text=Pa_GetErrorText(ret)
      raise "PortAudio error #{ret}, #{text}"
    end
    ret
  end
  def self.initialize
    init=self.Pa_Initialize
    if init!=0 then
      # how do we test this path?
      text=Pa_GetErrorText(init)
      raise "Pa_Initialize returned #{init}, #{text}"
    end
    v=PortAudio.Pa_GetVersion
    if v<1899 then
      raise "PortAudio version #{v} is too old: need 1899 or newer"
    end
  end
  def self.open_default_stream(n_input_channels,n_output_channels,
                               format,rate,frames_per_buffer)
    @out=FFI::MemoryPointer.new :pointer
    puts    @out.inspect
    Pa_OpenDefaultStream(@out,n_input_channels,n_output_channels,
                         format,rate,frames_per_buffer,nil,nil)
    return @out.get_pointer(0)
  end
  def self.start_stream(stream)
    self.or_raise {
      PortAudio.Pa_StartStream(stream)
    }
  end
  def self.stream_write_available(stream)
    self.or_raise {
      self.Pa_GetStreamWriteAvailable(stream)
    }
  end
end


buf=nil
file='/big/media/Music/from_usb_stick/Hot Chip/The Warning/Over and Over.mp3'
open("|/usr/local/bin/mplayer -quiet -really-quiet -vc null -vo null -ao pcm:nowaveheader:file=/dev/stdout:fast '#{file}'") { |f|
  buf=f.read
}
#buf=buf.slice(0,16000)
puts buf.length

PortAudio.initialize
stream=PortAudio.open_default_stream(0,2,PortAudio::Format::Int16,44100,256);
puts "stream is #{stream}"
puts PortAudio.Pa_IsStreamActive(stream)
PortAudio.start_stream(stream)
puts PortAudio.Pa_IsStreamActive(stream)
off=0
while off<buf.length do
  frames=PortAudio.stream_write_available(stream)
  puts "off #{off} frames #{frames}"
  PortAudio.Pa_WriteStream(stream,buf.slice(off,frames*4),frames)
  off+=frames*4
end