gistfile1.rb

require 'stringio'
require 'base64'

def read_varint(io)
  value = index = 0
  begin
    byte = io.readchar
    value |= (byte & 0x7f) << (7 * index)
    index += 1
  end while (byte & 0x80).nonzero?
  value
end

def decode_base64_protobuf(string)
  values = []
  io = StringIO.new(Base64.decode64(string))  
  until io.eof?
    bits = read_varint(io)
    values[(bits >> 3) - 1] = 
      case bits & 0x07
      when 0; read_varint(io)
      when 2; io.read(read_varint(io))
      end
  end
  values
end

if __FILE__ == $0
  STDIN.each do |line|
    puts decode_base64_protobuf(line.split[-1]).join("\t")
  end
end

Avi offered as input the string "CKeTAxCmmfRHGK6trLv1prbkEiCglsTnBDgBMAA="

For context: this is a minimal decoder for a tiny (but useful) subset of Google's Protocol Buffers format