local function print_media(m)
  local name = m.name
  local type_, enabled, loop, output
  local inputs = {}
  local options = {}
  local instances = {}
  loop = ""
  for _,c in ipairs(m.children) do
    if c.name=="type" then
      type_ = c.value
    elseif c.name=="enabled" then
      enabled = c.value
    elseif c.name=="loop" then
      loop = c.value
    elseif c.name=="output" then
      output = c.value
    elseif c.name=="inputs" then
      insert_children(c,inputs)
    elseif c.name=="options" then
      insert_children(c,options)
    elseif c.name=="instances" then
      if c.children then
        for _, d in ipairs(c.children) do
          local instance = "<instance "
          for _,e in ipairs(d.children) do
            instance = instance .. e.name .. "=\"" .. e.value .. "\" "
          end
          instance = instance .. "/>"
          table.insert(instances,instance)
        end
      end
    end
  end
  print("<"..type_.." name=\""..name.."\" enabled=\""..enabled.."\" loop=\""..loop.."\">\n")
  print("<output>"..output.."</output>\n")
  print_table("input",inputs)
  print_table("option",options)
  print "<instances>\n"
  if #instances ~= 0 then
    print(table.concat(instances))
  end
  print "</instances>\n"
  print("</"..type_..">\n")
end