Class: Radio::Signal::ALSA

Inherits:
Object
  • Object
show all
Defined in:
lib/radio/signals/alsa.rb

Constant Summary collapse

CP_REGEX = 
/:\s*(capture|playback)\s*(\d+)\s*$/
CD_REGEX = 
/^(\d+)-(\d+):\s*/

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ ALSA

Returns a new instance of ALSA.



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# File 'lib/radio/signals/alsa.rb', line 74

def initialize options
  @stream = ::ALSA::PCM::Capture.new
  @stream.open options[:id]
  if input = options[:input]
    @channel_i = input[0]
    @channel_q = input[1]
  end
end

Class Method Details

.devices ⇒ Object 



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# File 'lib/radio/signals/alsa.rb', line 45

def self.devices
  return {} unless defined? ::ALSA::PCM
  # Funky read to get around old Linux bug
  # http://kerneltrap.org/mailarchive/git-commits-head/2009/4/17/5510664
  pcm = ::File.open('/proc/asound/pcm') do |io|
    io.read_nonblock 32768
  end
  result = {}
  pcm.each_line do |line|
    capture = 0
    2.times do
      line.gsub! CP_REGEX, ''
      capture = $2.to_i if $1 == 'capture'
    end
    line.gsub! CD_REGEX, ''
    device = "hw:#{$1.to_i},#{$2.to_i}"
    ::ALSA::PCM::Capture.open(device) do |stream|
      params = stream.hardware_parameters
      result[device] = {
        name: line,
        rates: [params.sample_rate],
        input: params.channels,
        output: 0
      }
    end rescue nil
  end
  result
end

.status ⇒ Object 



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# File 'lib/radio/signals/alsa.rb', line 27

def self.status
  if defined? ::ALSA::PCM
    return "Loaded: %d devices" % devices.count
  end
  unless defined? @is_linux
    @is_linux = (`uname`.strip == 'Linux') rescue false
  end
  return "Unsupported: requires Linux" unless @is_linux
  if defined? ::ALSA
    'Unavailable: install ALSA to your OS'
  else
    'Unavailable: gem install ruby-alsa'
  end
end

Instance Method Details

#in(samples) ⇒ Object 



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# File 'lib/radio/signals/alsa.rb', line 96

def in samples
  out=nil
  buf_size = @stream.hw_params.buffer_size_for(samples)
  FFI::MemoryPointer.new(:char, buf_size) do |buffer|
    @stream.read_buffer buffer, samples
    out = buffer.read_string(buf_size)
    NArray.to_na(out, NArray::SINT).to_f.div! 32767
  end
  stream_channels = @stream.hardware_parameters.channels
  sample_size = buf_size / samples / stream_channels
  out = case sample_size
  when 1 then NArray.to_na(out,NArray::BYTE).to_f.collect!{|v|(v-128)/127}
  when 2 then NArray.to_na(out,NArray::SINT).to_f.div! 32767
  # when 3 then NArray.to_na(d,NArray::???).to_f.collect!{|v|(v-8388608)/8388607}
  else
    raise "Unsupported sample size: #{@sample_size}" 
  end
  return out if channels == 1 and stream_channels == 1
  out.reshape! stream_channels, out.size/stream_channels
  if channels == 1
    out[@channel_i,true]
  else
    c_out = NArray.scomplex out[0,true].size
    c_out[0..-1] = out[@channel_i,true]
    c_out.imag = out[@channel_q,true]
    c_out
  end
end

#input_channels ⇒ Object 



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# File 'lib/radio/signals/alsa.rb', line 87

def input_channels
  return 2 if @channel_q and @stream.hardware_parameters.channels > 1
  1
end

#output_channels ⇒ Object 



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# File 'lib/radio/signals/alsa.rb', line 92

def output_channels
  0
end

#rate ⇒ Object 



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# File 'lib/radio/signals/alsa.rb', line 83

def rate
  @stream.hardware_parameters.sample_rate
end

#stop ⇒ Object 



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# File 'lib/radio/signals/alsa.rb', line 125

def stop
  @stream.close
end