def encode_io(io, options = '')
      ret_io, writer = IO.pipe
      command = "#{ffmpeg_command} -loglevel 0 -i - #{options} -f s16le -ar 48000 -ac 2 #{filter_volume_argument} pipe:1"
      spawn(command, in: io, out: writer)
      ret_io
    end
def encode_io(io, options = '')
      ret_io, writer = IO.pipe
      command = "#{ffmpeg_command} -loglevel 0 -i - #{options} -f s16le -ar 48000 -ac 2 #{filter_volume_argument} pipe:1"
      spawn(command, in: io, out: writer)
      ret_io
    end
Encodes an arbitrary IO audio stream using ffmpeg. Accepts pretty much any media format, even videos with audio
 tracks. For a list of supported audio formats, see https://ffmpeg.org/general.html#Audio-Codecs.
 @param io [IO] The stream to encode.
 @param options [String] ffmpeg options to pass after the -i flag
 @return [IO] the audio, encoded as s16le PCM