From: Mathieu Bouchard <matju@...>
Date: 2001-03-13T17:04:25+09:00
Subject: [ruby-talk:12560] Re: audio recording from soundcard

On Tue, 13 Mar 2001, Sm�rk wrote:
> hi,
> is it possible to record audio from a sound card with ruby?



Hi, I have not tried that yet, but I just wrote this code to play a
440 Hz tone to a sound card. Requires Linux, though. 



module LinuxSound
	PCM_WRITE_BITS     = 0xc0045005
	PCM_WRITE_CHANNELS = 0xc0045006
	PCM_WRITE_RATE     = 0xc0045002
end

class IO; def ioctl_int_ptr(arg1,arg2)
	tmp = arg2 * 2**32
	foo = [2*tmp.id + 16].pack("l").unpack("P4")[0]
	# if it crashes, just insert foo.reverse! here.
        tmp_ptr = (foo[0]+0x100*foo[1])+0x10000*(foo[2]+0x100*foo[3])
	ioctl(arg1,tmp_ptr+4)
end end

sound = File.open("/dev/dsp","w")
sound.ioctl_int_ptr(LinuxSound::PCM_WRITE_BITS,8)
sound.ioctl_int_ptr(LinuxSound::PCM_WRITE_CHANNELS,1)
sound.ioctl_int_ptr(LinuxSound::PCM_WRITE_RATE,44100)

wavelength = 100

sample = ""
wavelength.times {|x|
	y = Math.sin(x*2*Math::PI/wavelength)
	sample << (128+127*y).to_i.chr
}

sample *= 16

while true
	sound.write sample
end



matju