Class: Typingpool::Filer::Audio

Inherits:
Typingpool::Filer show all
Defined in:
lib/typingpool/filer/audio.rb

Overview

Convenience wrapper for audio files.You can convert to mp3s, split into multiple files, and dynamically read the bitrate.

Instance Attribute Summary

Attributes inherited from Typingpool::Filer

#path

Instance Method Summary collapse

Methods inherited from Typingpool::Filer

#<=>, #as, #dir, #initialize, #mv!, #read, #to_s, #to_stream, #write

Methods included from Utility::Castable

#as, included

Constructor Details

This class inherits a constructor from Typingpool::Filer

Instance Method Details

#bitrate ⇒ Object

Reads the bitrate of the audio file via ffmpeg. Returns an integer corresponding to kb/s, or nil if the bitrate could not be determined.



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# File 'lib/typingpool/filer/audio.rb', line 36

def bitrate
  out, err, status = Open3.capture3('ffmpeg', '-i', @path)
  bitrate = err.match(/(\d+) kb\/s/)
  return bitrate ? bitrate[1].to_i : nil
end

#mp3? ⇒ Boolean

Does the file have a ‘.mp3’ extension?

Returns:

  • (Boolean) 


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# File 'lib/typingpool/filer/audio.rb', line 10

def mp3?
  File.extname(@path).downcase.eql?('.mp3')
end

#offset ⇒ Object

Extracts from the filename the offset time of the chunk relative to the original from which it was split. Format is minute.seconds. Suitable for use on files created by ‘split’ method.



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# File 'lib/typingpool/filer/audio.rb', line 78

def offset
  match = File.basename(@path).match(/\d+\.\d\d\b/)
  return match[0] if match
end

#split(interval_in_min_dot_seconds, basename = File.basename(path, '.*'), dest = dir) ⇒ Object

Splits an mp3 into smaller files.

Params

interval_in_min_dot_seconds

Split the file into chunks this

large. The interval should be of the format
minute.seconds, for example 2 minutes 15 seconds
would be written as "2.15". For further details on
interval format, consult the documentation for
mp3split, a command-line unix utility.
basename

Name the new chunks using this base. Default is the basename of the original file.

dest

Destination directory for the new chunks as a Filer::Dir. Default is the same directory as the original file.

Returns

Filer::Files containing the new files.



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# File 'lib/typingpool/filer/audio.rb', line 57

def split(interval_in_min_dot_seconds, basename=File.basename(path, '.*'), dest=dir)
  #We have to cd into the wrapfile directory and do everything
  #there because old/packaged versions of mp3splt were
  #retarded at handling absolute directory paths
  ::Dir.chdir(dir.path) do
    Utility.system_quietly('mp3splt', '-t', interval_in_min_dot_seconds, '-o', "#{basename}.@m.@s", File.basename(path)) 
  end
  files = Filer::Files::Audio.new(dir.select{|file| File.basename(file.path).match(/^#{Regexp.escape(basename) }\.\d+\.\d+\.mp3$/) })
  if files.to_a.empty?
    raise Error::Shell, "Could not find output from `mp3splt` on #{path}"
  end
  if dest.path != dir.path
    files.mv!(dest)
  end
  files.sort
end

#to_mp3(dest = self.dir.file("#{File.basename(@path, '.*') }.mp3"), bitrate = nil) ⇒ Object

Convert to mp3 via ffmpeg.

Params

dest

Filer object corresponding to the path the mp3 version should end up at.

bitrate

If passed, bitrate should be an integer corresponding to kb/s. If not, we use the bitrate from the current file or, if that can’t be read, default to 192kbps. Does not check if the file is already an mp3. Returns a new Filer::Audio representing the new mp3 file.

Returns

Filer::Audio containing the new mp3.



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# File 'lib/typingpool/filer/audio.rb', line 26

def to_mp3(dest=self.dir.file("#{File.basename(@path, '.*') }.mp3"), bitrate=nil)
  bitrate ||= self.bitrate || 192
  Utility.system_quietly('ffmpeg', '-i', @path, '-acodec', 'libmp3lame', '-ab', "#{bitrate}k", '-ac', '2', dest)
  File.exists?(dest) or raise Error::Shell, "Could not found output from `ffmpeg` on #{path}"
  self.class.new(dest.path)
end