diff --git a/src/config.rs b/src/config.rs
index 36dc7d1..15ceafe 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -17,6 +17,7 @@ pub struct Streams {
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Stream {
    pub engine: Engine,
+   pub format: Option<String>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -67,6 +68,7 @@ fn build_config_std() -> Config {
    return Config {
       streams: Streams{
          input: Stream {
+            format: None,
             engine: Engine{
                name: String::from("gui"),
                kafka: None,
@@ -75,6 +77,7 @@ fn build_config_std() -> Config {
             },
          },
          output: Stream {
+            format: None,
             engine: Engine{
                name: String::from("stdout"),
                kafka: None,
diff --git a/src/gui.rs b/src/gui.rs
index 2dc88f0..9887bcb 100644
--- a/src/gui.rs
+++ b/src/gui.rs
@@ -5,13 +5,13 @@ use iced::event;
 use iced::subscription;
 use iced::{Alignment, Element, Application, Settings, Subscription, Theme, Command};
 
-use crate::engine::OutputEngine;
+use crate::stream::OutputStream;
 
-pub fn main(outputEngine: Box<dyn OutputEngine>) -> iced::Result {
+pub fn main(outputStream: Box<dyn OutputStream>) -> iced::Result {
    let def: iced::Settings<()> = Settings::default();
    let settings = Settings{
       flags: Flags {
-         outputEngine: outputEngine,
+         outputStream: outputStream,
       },
       antialiasing: def.antialiasing,
       default_font: def.default_font,
@@ -33,7 +33,7 @@ struct Main {
 }
 
 struct Flags {
-   outputEngine: Box<dyn OutputEngine>,
+   outputStream: Box<dyn OutputStream>,
 }
 
 struct Inputs {
@@ -153,7 +153,7 @@ impl Application for Main {
                      _ => String::from(""),
                   };
                   if s.len() > 0 {
-                     self.flags.outputEngine.put(s.chars().collect());
+                     self.flags.outputStream.put(s.chars().collect());
                   }
                },
                _ => {},
diff --git a/src/main.rs b/src/main.rs
index 875105a..5eba371 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,21 +1,21 @@
 mod config;
-mod engine;
+mod stream;
 mod gui;
 
 fn main() {
    let cfg = config::build_config().unwrap();
    if cfg.streams.input.engine.name == "gui" {
-      let output_engine = engine::build_output_engine(&cfg.streams.output.engine);
-      gui::main(output_engine).unwrap();
+      let output_stream = stream::build_output_stream(&cfg.streams.output);
+      gui::main(output_stream).unwrap();
    } else {
       main_cli(cfg);
    }
 }
 
 fn main_cli(cfg: config::Config) {
-   let mut input_engine = engine::build_input_engine(&cfg.streams.input.engine);
-   let mut output_engine = engine::build_output_engine(&cfg.streams.output.engine);
+   let mut input_stream = stream::build_input_stream(&cfg.streams.input);
+   let mut output_stream = stream::build_output_stream(&cfg.streams.output);
    loop {
-      output_engine.put(input_engine.get());
+      output_stream.put(input_stream.get());
    }
 }
diff --git a/src/engine.rs b/src/stream.rs
similarity index 60%
rename from src/engine.rs
rename to src/stream.rs
index b750c43..9b49584 100644
--- a/src/engine.rs
+++ b/src/stream.rs
@@ -1,38 +1,38 @@
-use crate::config::Engine;
+use crate::config::Stream;
 
 use hidapi::HidApi;
 use rusb::UsbContext;
 use gilrs::{Gilrs, Button, Event};
 
-pub trait InputEngine {
+pub trait InputStream {
    fn get(&mut self) -> Vec<char>;
 }
 
-pub fn build_input_engine(cfg: &Engine) -> Box<dyn InputEngine> {
-   match cfg.name.as_str() {
+pub fn build_input_stream(cfg: &Stream) -> Box<dyn InputStream> {
+   match cfg.engine.name.as_str() {
       "stdin" => {
-         return Box::new(InputEngineStdin{});
+         return Box::new(InputStreamStdin{});
       },
       "kafka" => {
-         return Box::new(build_input_engine_kafka(&cfg).unwrap());
+         return Box::new(build_input_stream_kafka(&cfg).unwrap());
       },
-      "udp" => return Box::new(build_input_engine_udp(&cfg).unwrap()),
-      "device" => return Box::new(build_input_engine_device(&cfg).unwrap()),
+      "udp" => return Box::new(build_input_stream_udp(&cfg).unwrap()),
+      "device" => return Box::new(build_input_stream_device(&cfg).unwrap()),
       _ => {},
    };
    assert!(false);
-   Box::new(InputEngineStdin{})
+   Box::new(InputStreamStdin{})
 }
 
-pub struct InputEngineDevice {
+pub struct InputStreamDevice {
 }
 
-pub fn build_input_engine_device(cfg: &Engine) -> Result<InputEngineDevice, String> {
-   return build_input_engine_device_gilrs(cfg)
+pub fn build_input_stream_device(cfg: &Stream) -> Result<InputStreamDevice, String> {
+   return build_input_stream_device_gilrs(cfg)
 }
 
-pub fn build_input_engine_device_gilrs(cfg: &Engine) -> Result<InputEngineDevice, String> {
-   let _device_cfg = cfg.device.as_ref().unwrap();
+pub fn build_input_stream_device_gilrs(cfg: &Stream) -> Result<InputStreamDevice, String> {
+   let _device_cfg = cfg.engine.device.as_ref().unwrap();
 
    let mut gilrs = Gilrs::new().unwrap();
 
@@ -65,8 +65,8 @@ pub fn build_input_engine_device_gilrs(cfg: &Engine) -> Result<InputEngineDevice
    return Err("do what".to_string());
 }
 
-pub fn build_input_engine_device_hidapi(cfg: &Engine) -> Result<InputEngineDevice, String> {
-   let _device_cfg = cfg.device.as_ref().unwrap();
+pub fn build_input_stream_device_hidapi(cfg: &Stream) -> Result<InputStreamDevice, String> {
+   let _device_cfg = cfg.engine.device.as_ref().unwrap();
 
    match HidApi::new() {
       Ok(api) => {
@@ -81,8 +81,8 @@ pub fn build_input_engine_device_hidapi(cfg: &Engine) -> Result<InputEngineDevic
    return Err("do what".to_string());
 }
 
-pub fn build_input_engine_device_rusb(cfg: &Engine) -> Result<InputEngineDevice, String> {
-   let _device_cfg = cfg.device.as_ref().unwrap();
+pub fn build_input_stream_device_rusb(cfg: &Stream) -> Result<InputStreamDevice, String> {
+   let _device_cfg = cfg.engine.device.as_ref().unwrap();
 
    assert!(rusb::has_capability());
 
@@ -100,26 +100,26 @@ pub fn build_input_engine_device_rusb(cfg: &Engine) -> Result<InputEngineDevice,
    return Err("do what".to_string());
 }
 
-impl InputEngine for InputEngineDevice {
+impl InputStream for InputStreamDevice {
    fn get(&mut self) -> Vec<char> {
       Err("end".to_string()).unwrap()
    }
 }
 
-pub struct InputEngineUDP {
+pub struct InputStreamUDP {
    last_socket: Option<std::net::UdpSocket>,
    port: i32,
 }
 
-pub fn build_input_engine_udp(cfg: &Engine) -> Result<InputEngineUDP, String> {
-   let udp_cfg = cfg.udp.as_ref().unwrap();
-   return Ok(InputEngineUDP{
+pub fn build_input_stream_udp(cfg: &Stream) -> Result<InputStreamUDP, String> {
+   let udp_cfg = cfg.engine.udp.as_ref().unwrap();
+   return Ok(InputStreamUDP{
       last_socket: None,
       port: udp_cfg.port,
    });
 }
 
-impl InputEngine for InputEngineUDP {
+impl InputStream for InputStreamUDP {
    fn get(&mut self) -> Vec<char> {
       let addr = "0.0.0.0:".to_string() + &self.port.to_string();
       println!("$ echo -n 'hello world' | nc -4u -w0 localhost {}", &self.port.to_string());
@@ -130,7 +130,7 @@ impl InputEngine for InputEngineUDP {
       let mut buf = [0; 128];
       let result = self.last_socket.as_ref().unwrap().recv_from(&mut buf);
       if result.is_err() {
-         println!("InputEngineUDP: failed to recv: {:?}", result.err());
+         println!("InputStreamUDP: failed to recv: {:?}", result.err());
          self.last_socket = None;
          return Vec::<char>::new();
       }
@@ -140,23 +140,23 @@ impl InputEngine for InputEngineUDP {
    }
 }
 
-pub struct InputEngineKafka {
+pub struct InputStreamKafka {
 }
 
-pub fn build_input_engine_kafka(cfg: &Engine) -> Result<InputEngineKafka, String> {
-   let _kafka_cfg = cfg.kafka.as_ref().unwrap();
+pub fn build_input_stream_kafka(cfg: &Stream) -> Result<InputStreamKafka, String> {
+   let _kafka_cfg = cfg.engine.kafka.as_ref().unwrap();
    return Err("do what".to_string());
 }
 
-impl InputEngine for InputEngineKafka {
+impl InputStream for InputStreamKafka {
    fn get(&mut self) -> Vec<char> {
       Err("end".to_string()).unwrap()
    }
 }
 
-pub struct InputEngineStdin {}
+pub struct InputStreamStdin {}
 
-impl InputEngine for InputEngineStdin {
+impl InputStream for InputStreamStdin {
    fn get(&mut self) -> Vec<char> {
       let stdin = std::io::stdin();
       let mut result = String::new();
@@ -169,45 +169,45 @@ impl InputEngine for InputEngineStdin {
 mod test_input {
    use super::*;
 
-   struct InputEngineTest {}
-   impl InputEngine for InputEngineTest {
+   struct InputStreamTest {}
+   impl InputStream for InputStreamTest {
       fn get(&mut self) -> Vec<char> {
          return "hello world".chars().collect();
       }
    }
 
    #[test]
-   fn test_input_engine_impl() {
-      let mut input_engine_test = InputEngineTest{};
-      _test_input_engine_impl(&mut input_engine_test);
+   fn test_input_stream_impl() {
+      let mut input_stream_test = InputStreamTest{};
+      _test_input_stream_impl(&mut input_stream_test);
    }
 
-   fn _test_input_engine_impl(engine: &mut dyn InputEngine) {
+   fn _test_input_stream_impl(engine: &mut dyn InputStream) {
       assert_eq!("hello world".to_string(), engine.get().iter().cloned().collect::<String>());
    }
 }
 
-pub trait OutputEngine {
+pub trait OutputStream {
    fn put(&mut self, v: Vec<char>);
 }
 
-pub fn build_output_engine(cfg: &Engine) -> Box<dyn OutputEngine> {
-   return _build_output_engine(cfg)
+pub fn build_output_stream(cfg: &Stream) -> Box<dyn OutputStream> {
+   return _build_output_stream(cfg)
 }
 
-pub fn _build_output_engine(cfg: &Engine) -> Box<dyn OutputEngine> {
-   if cfg.name.as_str() == "stdout" {
-      return Box::new(OutputEngineStdout{});
-   } else if cfg.name.as_str() == "udp" {
-      return Box::new(build_output_engine_udp(&cfg).unwrap());
+pub fn _build_output_stream(cfg: &Stream) -> Box<dyn OutputStream> {
+   if cfg.engine.name.as_str() == "stdout" {
+      return Box::new(OutputStreamStdout{});
+   } else if cfg.engine.name.as_str() == "udp" {
+      return Box::new(build_output_stream_udp(&cfg).unwrap());
    }
    assert!(false);
-   Box::new(OutputEngineStdout{})
+   Box::new(OutputStreamStdout{})
 }
 
-pub struct OutputEngineStdout {}
+pub struct OutputStreamStdout {}
 
-impl OutputEngine for OutputEngineStdout {
+impl OutputStream for OutputStreamStdout {
    fn put(&mut self, v: Vec<char>) {
       println!("{}", v.iter().cloned().collect::<String>());
    }
@@ -217,50 +217,50 @@ impl OutputEngine for OutputEngineStdout {
 mod test_output {
    use super::*;
 
-   struct OutputEngineTest {}
-   impl OutputEngine for OutputEngineTest {
+   struct OutputStreamTest {}
+   impl OutputStream for OutputStreamTest {
       fn put(&mut self, _v: Vec<char>) {
       }
    }
 
    #[test]
-   fn test_output_engine_impl() {
-      let mut output_engine_test = OutputEngineTest{};
-      _test_output_engine_impl(&mut output_engine_test);
+   fn test_output_stream_impl() {
+      let mut output_stream_test = OutputStreamTest{};
+      _test_output_stream_impl(&mut output_stream_test);
    }
 
-   fn _test_output_engine_impl(engine: &mut dyn OutputEngine) {
+   fn _test_output_stream_impl(engine: &mut dyn OutputStream) {
       engine.put("teehee".to_string().chars().collect());
    }
 }
 
-pub struct OutputEngineUDP {
+pub struct OutputStreamUDP {
    last_socket: Option<std::net::UdpSocket>,
    host: String,
    port: i32,
 }
 
-pub fn build_output_engine_udp(cfg: &Engine) -> Result<OutputEngineUDP, String> {
-   let udp_cfg = cfg.udp.as_ref().unwrap();
-   return Ok(OutputEngineUDP{
+pub fn build_output_stream_udp(cfg: &Stream) -> Result<OutputStreamUDP, String> {
+   let udp_cfg = cfg.engine.udp.as_ref().unwrap();
+   return Ok(OutputStreamUDP{
       last_socket: None,
       host: udp_cfg.host.clone().unwrap(),
       port: udp_cfg.port,
    });
 }
 
-impl OutputEngine for OutputEngineUDP {
+impl OutputStream for OutputStreamUDP {
    fn put(&mut self, v: Vec<char>) {
       if self.last_socket.is_none() {
          let result = std::net::UdpSocket::bind("127.0.0.1:".to_string() + &(self.port+10).to_string());
          if result.is_err() {
-            println!("OutputEngineUDP: failed to bind to 127.0.0.1:{}: {:?}", &(self.port+10).to_string(), result.err());
+            println!("OutputStreamUDP: failed to bind to 127.0.0.1:{}: {:?}", &(self.port+10).to_string(), result.err());
             return;
          }
          self.last_socket = Some(result.unwrap());
          let result = self.last_socket.as_ref().unwrap().connect(self.host.to_string() + ":" + &self.port.to_string());
          if result.is_err() {
-            println!("OutputEngineUDP: failed to connect to {}:{}: {:?}", self.host.to_string(), self.port.to_string(), result.err());
+            println!("OutputStreamUDP: failed to connect to {}:{}: {:?}", self.host.to_string(), self.port.to_string(), result.err());
             self.last_socket = None;
             return;
          }
@@ -268,7 +268,7 @@ impl OutputEngine for OutputEngineUDP {
 
       let result = self.last_socket.as_ref().unwrap().send(&v.iter().cloned().collect::<String>().as_bytes());
       if result.is_err() {
-         println!("OutputEngineUDP: failed to send: {:?}", result.err());
+         println!("OutputStreamUDP: failed to send: {:?}", result.err());
          self.last_socket = None;
       }
    }