Asp Forum - Re: process .wav file?

mike re-v

11/8/2003 3:19:00 AM

Sorry I should have specified linux platform
I've looked at the RAA several keywd searches
like 1.) sound i/o
2)i/o sound linux
3).wav
I don't see anything relative.
I'm probably not using RAA correctly
please advise
thanks
re-v
--- Bill Kelly <billk@cts.com> wrote:
> Hi,
>
> From: "mike re-v" <mrmrmr50@yahoo.com>
> >
> > I would like to play a very short sound effect(
> .wav
> > file )
> > repeatedly.
> > ############################################
> > aFile = File.new("foo.wav", "r")
> > # ... process the file
> >
> > aFile.close
> > ###########################################
> > the above code is found in pickaxe pg 108
> > I can r/w regex loop, count words, or characters
> in a
> > txt file. Where would you suggest I look to play
> the
> > .wav (process) the file using Ruby?
>
> Have a look at: http://www.ruby-talk...
>
>
> Hope this helps,
>
> Bill
>
>
>
>

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2 Answers

Zachary P. Landau

11/8/2003 5:53:00 AM

> Sorry I should have specified linux platform
> I've looked at the RAA several keywd searches
> like 1.) sound i/o
> 2)i/o sound linux
> 3).wav
> I don't see anything relative.
> I'm probably not using RAA correctly
> please advise
> thanks
> re-v

It won't be very cross-platform, but since it is a wav, you can just
open /dev/dsp and write directly to that. Wav files are basically
just audio dumps, so that usually works.

--
Zachary P. Landau <kapheine@hypa.net>
GPG: gpg --recv-key 0x24E5AD99 | http://kapheine.hypa.net/ka...

Bill Kelly

11/8/2003 4:07:00 PM

Hi,

From: "mike re-v" <mrmrmr50@yahoo.com>
>
> Sorry I should have specified linux platform
> I've looked at the RAA several keywd searches
> like 1.) sound i/o
> 2)i/o sound linux
> 3).wav
> I don't see anything relative.

Not sure if this will be of any help, but I wrote some
code awhile back to parse WAV files and read/write the
format chunk (sample rate, etc.) and extract the audio
samples from the WAV... (Doesn't play the sound, tho!)

For what it's worth I'll attach the code below...

Regards,

Bill

~~ wavtweak.rb ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#
# WAV format info at: http://www.borg.com/~jglatt/tec...
#

class NotRIFFFormat < StandardError; end
class NotWAVEFormat < StandardError; end

def read_chunk_header(file)
hdr = file.read(8)
chunkName, chunkLen = hdr.unpack("A4V")
end

def parse_wav(file)
riff, riffLen = read_chunk_header(file)
raise NotRIFFFormat unless riff == 'RIFF'
riffEnd = file.tell + riffLen
wave = file.read(4)
raise NotWAVEFormat unless wave == 'WAVE'
while file.tell < riffEnd
chunkName, chunkLen = read_chunk_header(file)
fpos = file.tell
yield file, chunkName, chunkLen if block_given?
file.seek(fpos + chunkLen)
end
end

class WaveFmtChunk

# short AudioFormat; PCM = 1 (i.e. Linear quantization)
# Values other than 1 indicate some
# form of compression.
# unsigned short NumChannels; Mono = 1, Stereo = 2, etc.
# unsigned long SampleRate; 8000, 44100, etc.
# unsigned long ByteRate; == SampleRate * NumChannels * BitsPerSample/8
# unsigned short BlockAlign; == NumChannels * BitsPerSample/8
# The number of bytes for one sample including
# all channels.
# unsigned short BitsPerSample; 8 bits = 8, 16 bits = 16, etc.

attr_reader :audioFormat, :numChannels,
:sampleRate, :byteRate,
:blockAlign, :bitsPerSample

PACK_FMT = "vvVVvv"

def initialize(binRepr)
@audioFormat, @numChannels,
@sampleRate, @byteRate,
@blockAlign, @bitsPerSample = binRepr.unpack(PACK_FMT)
end

def to_s
[ @audioFormat, @numChannels,
@sampleRate, @byteRate,
@blockAlign, @bitsPerSample ].pack(PACK_FMT)
end

def set_sample_rate(rate)
@byteRate = calc_byte_rate(rate)
@sampleRate = rate
end

def calc_byte_rate(srate, numch = @numChannels, bitss = @bitsPerSample)
srate * numch * (bitss / 8)
end
end

def handle_fmt_chunk(file, chunkLen)
fmtDatPos = file.tell
fmt = WaveFmtChunk.new(file.read(chunkLen))
print "srate is #{fmt.sampleRate} brate is #{fmt.byteRate}\n"

# Tweak the sample rate (without resampling the data)
#
# fmt.set_sample_rate(45750) # (52245)
# print "srate now #{fmt.sampleRate} brate now #{fmt.byteRate}\n"
# fs = fmt.to_s
# print "writing new fmt data, len #{fs.length} bytes "
# fs.each_byte {|c| printf("%02x", c) }
# print "\n"
# file.seek(fmtDatPos)
# print "cur file ofst #{file.tell}\n"
# file.write(fmt)
# print "post write file ofst #{file.tell}\n"
end

def handle_data_chunk(file, chunkLen)
data = file.read(chunkLen)
end

ARGV.each do |fname|
puts "#{fname}"
File.open(fname, File::RDWR) do |f|
f.binmode
f.seek(0)
parse_wav(f) do |file, chunkName, chunkLen|
puts "'#{chunkName}' size #{chunkLen}"
case chunkName
when 'fmt' then handle_fmt_chunk(file, chunkLen)
when 'data' then handle_data_chunk(file, chunkLen)
end
end
end
end
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

comp.lang.ruby

Re: process .wav file?

mike re-v

Zachary P. Landau

Bill Kelly

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