diff --git a/src/main.rs b/src/main.rs
index 4ca8922..64fd307 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -8,7 +8,8 @@ use std::error::Error;
 use std::fs::File;
 use std::io::Write;
 use clap::{App, Arg, SubCommand};
-use reskit::soundtrack::dmf::DmfModule;
+use reskit::soundtrack::engines::echo::EchoFormat;
+use reskit::soundtrack::formats::dmf::DmfModule;
 use reskit::utility;
 use reskit::tileset;
 
diff --git a/src/reskit/soundtrack/engines/echo.rs b/src/reskit/soundtrack/engines/echo.rs
new file mode 100644
index 0000000..e2a0d91
--- /dev/null
+++ b/src/reskit/soundtrack/engines/echo.rs
@@ -0,0 +1,7 @@
+use std::{collections::HashMap, error::Error};
+
+pub trait EchoFormat {
+
+    fn get_eefs( &self ) -> Result<HashMap<String, Vec<u8>>, Box<dyn Error>>;
+
+}
\ No newline at end of file
diff --git a/src/reskit/soundtrack/engines/mod.rs b/src/reskit/soundtrack/engines/mod.rs
new file mode 100644
index 0000000..8417595
--- /dev/null
+++ b/src/reskit/soundtrack/engines/mod.rs
@@ -0,0 +1 @@
+pub mod echo;
\ No newline at end of file
diff --git a/src/reskit/soundtrack/dmf.rs b/src/reskit/soundtrack/formats/dmf.rs
similarity index 98%
rename from src/reskit/soundtrack/dmf.rs
rename to src/reskit/soundtrack/formats/dmf.rs
index 0cc8c04..2b3424e 100644
--- a/src/reskit/soundtrack/dmf.rs
+++ b/src/reskit/soundtrack/formats/dmf.rs
@@ -1,8 +1,6 @@
 use std::{error::Error, fs::File, io::Read, convert::TryInto, collections::HashMap, cmp::{min, max}};
 use flate2::read::ZlibDecoder;
-use crate::reskit::{utility::{get_string, get_u8, skip, get_u32, get_i8, get_i32, get_u16, get_i16, Ring}, soundtrack::types::{SampleRate, SampleFormat, PsgEnvelope}};
-
-use super::types::{Sample, Note, PsgSettings};
+use crate::reskit::{utility::{get_string, get_u8, skip, get_u32, get_i8, get_i32, get_u16, get_i16, Ring}, soundtrack::{types::{SampleRate, SampleFormat, PsgEnvelope, Note, Sample, PsgSettings}, engines::echo::EchoFormat}};
 
 const DMF_MAGIC_NUMBER: &'static str = ".DelekDefleMask.";
 const DMF_SUPPORTED_VERSION: u8 = 0x18;
@@ -596,7 +594,11 @@ impl DmfModule {
          )
     }
 
-    pub fn get_eefs( &self ) -> Result<HashMap<String, Vec<u8>>, Box<dyn Error>> {
+}
+
+impl EchoFormat for DmfModule {
+
+    fn get_eefs( &self ) -> Result<HashMap<String, Vec<u8>>, Box<dyn Error>> {
         let mut eefs: HashMap<String, Vec<u8>> = HashMap::new();
 
         for instrument in &self.instruments {
@@ -725,11 +727,6 @@ impl DmfModule {
         Ok( eefs )
     }
 
-    pub fn get_esf( &self ) -> Result<Vec<u8>, Box<dyn Error>> {
-        // TODO !!
-        todo!()
-    }
-
 }
 
 fn get_eef_volume( dmf_volume: u8 ) -> Result<u8, Box<dyn Error>> {
diff --git a/src/reskit/soundtrack/formats/mod.rs b/src/reskit/soundtrack/formats/mod.rs
new file mode 100644
index 0000000..16a4aad
--- /dev/null
+++ b/src/reskit/soundtrack/formats/mod.rs
@@ -0,0 +1 @@
+pub mod dmf;
\ No newline at end of file
diff --git a/src/reskit/soundtrack/mod.rs b/src/reskit/soundtrack/mod.rs
index 3b4ac3e..4ed58f9 100644
--- a/src/reskit/soundtrack/mod.rs
+++ b/src/reskit/soundtrack/mod.rs
@@ -1,2 +1,3 @@
-pub mod dmf;
+pub mod formats;
+pub mod engines;
 pub mod types;
\ No newline at end of file