diff --git a/Cargo.lock b/Cargo.lock
index fc18a40..8a65575 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -15,6 +15,7 @@ dependencies = [
  "anyhow",
  "crossbeam",
  "ncdufmt",
+ "serde_json",
  "tar",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 027cda7..48b6047 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,4 +15,5 @@ members = [
 anyhow = "1.0.75"
 crossbeam = { version = "0.8.2", features = ["crossbeam-channel"] }
 ncdufmt = {path="./ncdufmt/"}
+serde_json = "1.0.108"
 tar = "0.4.40"
diff --git a/ncdufmt/src/lib.rs b/ncdufmt/src/lib.rs
index 45ee6e9..7e16431 100644
--- a/ncdufmt/src/lib.rs
+++ b/ncdufmt/src/lib.rs
@@ -19,7 +19,7 @@ use serde::{Deserialize, Serialize};
 // This is based on https://dev.yorhel.nl/ncdu/jsonfmt
 
 #[derive(Debug, PartialEq, Clone)]
-struct NcduFile {
+pub struct NcduFile {
     pub major_version: MajorVersion,
     pub minor_version: MinorVersion,
     pub header_metadata: HeaderMetadata,
@@ -125,10 +125,10 @@ pub struct HeaderMetadata {
 
 impl HeaderMetadata {
     /// Construct a HeaderMetadata with the current time
-    pub fn new(progname: String, progver: String) -> Self {
+    pub fn new(progname: impl AsRef<str>, progver: impl AsRef<str>) -> Self {
         Self {
-            progname,
-            progver,
+            progname: progname.as_ref().to_string(),
+            progver: progver.as_ref().to_string(),
             timestamp: SystemTime::now()
                 .duration_since(SystemTime::UNIX_EPOCH)
                 .as_ref()
@@ -140,8 +140,8 @@ impl HeaderMetadata {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Directory {
-    info: InfoBlock,
-    contents: Vec<FileOrDirectory>,
+    pub info: InfoBlock,
+    pub contents: Vec<FileOrDirectory>,
 }
 
 impl Serialize for Directory {
@@ -295,6 +295,24 @@ pub struct InfoBlock {
     pub extended_info_block: Option<ExtendedInfoBlock>,
 }
 
+impl InfoBlock {
+    pub fn new(name: impl AsRef<str>) -> Self {
+        Self {
+            name: name.as_ref().to_string(),
+            dev: Default::default(),
+            asize: Default::default(),
+            dsize: Default::default(),
+            hlnkc: Default::default(),
+            ino: Default::default(),
+            nlink: Default::default(),
+            read_error: Default::default(),
+            excluded: Default::default(),
+            notreg: Default::default(),
+            extended_info_block: Default::default(),
+        }
+    }
+}
+
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
 pub struct ExtendedInfoBlock {
     /// Number, user ID who owns the file. Accepted values are in the range 0 <= uid < 2^31.
diff --git a/src/collector.rs b/src/collector.rs
new file mode 100644
index 0000000..9cef6ba
--- /dev/null
+++ b/src/collector.rs
@@ -0,0 +1,51 @@
+use std::io::Write;
+
+use crate::types;
+use anyhow::Result;
+use ncdufmt::{MajorVersion, MinorVersion, HeaderMetadata, InfoBlock, NcduFile, Directory, FileOrDirectory};
+
+/// Builds an ncdu file from a stream
+pub fn build_ncdu_file(rx: crossbeam::channel::Receiver<types::Entry>/*, _writer: impl Write*/) -> Result<NcduFile> {
+    let mut ret = NcduFile {
+        major_version: MajorVersion::default(),
+        minor_version: MinorVersion::default(),
+        header_metadata: HeaderMetadata::new("test-program", "0.1.1"),
+        contents: Directory {
+            info: InfoBlock::new("test-filename.tar".to_string()),
+            contents: Vec::default(),
+        }
+    };
+    
+    while let Ok(entry) = rx.recv() {
+        let mut e = InfoBlock::new(entry.path.to_string_lossy());
+        e.asize = entry.size;
+        ret.contents.contents.push(FileOrDirectory::File(e)  );
+    }
+
+    Ok(ret)
+}
+
+
+
+#[cfg(test)]
+mod tests {
+    use std::fs::File;
+
+    use super::*;
+
+    #[test]
+    fn simple_tree() {
+        // Check that this tar file of mine has a Cargo.lock and 10 entries
+        let reader = File::open("./test-tar.tar").unwrap();
+        let (tx, rx) = crossbeam::channel::bounded(100);
+
+        crate::tar::get_entries(tx, reader).unwrap();
+
+        let ret = build_ncdu_file(rx).unwrap();
+
+        eprintln!("{ret:#?}");
+        eprintln!("{}", serde_json::to_string(&ret).unwrap());
+
+        panic!();
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 6f6bb31..26427d0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,7 @@
 mod tar;
 mod types;
+mod collector;
+
 fn main() {
     println!("Hello, world!");
 }
diff --git a/src/tar.rs b/src/tar.rs
index f31cf1f..0dc2d36 100644
--- a/src/tar.rs
+++ b/src/tar.rs
@@ -9,8 +9,8 @@ use tar::Archive;
 ///
 /// The tar file must be in a decompressed state
 pub fn get_entries(
-    reader: impl Read,
     tx: crossbeam::channel::Sender<types::Entry>,
+    reader: impl Read,
 ) -> Result<()> {
     let mut archive = Archive::new(reader);
 
@@ -38,7 +38,7 @@ mod tests {
         let reader = File::open("./test-tar.tar").unwrap();
         let (tx, rx) = crossbeam::channel::bounded(100);
 
-        get_entries(reader, tx).unwrap();
+        get_entries(tx, reader).unwrap();
 
         let mut results = vec![];
         while let Ok(entry) = rx.recv() {