diff --git a/nod/src/disc/fst.rs b/nod/src/disc/fst.rs
index 243dc50..b08e69d 100644
--- a/nod/src/disc/fst.rs
+++ b/nod/src/disc/fst.rs
@@ -61,7 +61,7 @@ impl Node {
     /// For directories, this is the parent node index in the FST.
     #[inline]
     pub fn offset(&self, is_wii: bool) -> u64 {
-        if is_wii && self.kind == 0 {
+        if is_wii && self.is_file() {
             self.offset.get() as u64 * 4
         } else {
             self.offset.get() as u64
@@ -108,7 +108,7 @@ impl<'a> Fst<'a> {
 
     /// Get the name of a node.
     #[allow(clippy::missing_inline_in_public_items)]
-    pub fn get_name(&self, node: &Node) -> Result<Cow<str>, String> {
+    pub fn get_name(&self, node: &Node) -> Result<Cow<'a, str>, String> {
         let name_buf = self.string_table.get(node.name_offset() as usize..).ok_or_else(|| {
             format!(
                 "FST: name offset {} out of bounds (string table size: {})",
@@ -128,7 +128,7 @@ impl<'a> Fst<'a> {
 
     /// Finds a particular file or directory by path.
     #[allow(clippy::missing_inline_in_public_items)]
-    pub fn find(&self, path: &str) -> Option<(usize, &Node)> {
+    pub fn find(&self, path: &str) -> Option<(usize, &'a Node)> {
         let mut split = path.trim_matches('/').split('/');
         let mut current = split.next()?;
         let mut idx = 1;
diff --git a/nod/src/disc/gcn.rs b/nod/src/disc/gcn.rs
index 0a495f7..a52b7b7 100644
--- a/nod/src/disc/gcn.rs
+++ b/nod/src/disc/gcn.rs
@@ -11,6 +11,7 @@ use super::{
     PartitionMeta, BI2_SIZE, BOOT_SIZE, SECTOR_SIZE,
 };
 use crate::{
+    disc::streams::OwnedFileStream,
     io::block::{Block, BlockIO},
     util::read::{read_box, read_box_slice, read_vec},
     Result, ResultContext,
@@ -132,6 +133,16 @@ impl PartitionBase for PartitionGC {
         }
         FileStream::new(self, node.offset(false), node.length())
     }
+
+    fn into_open_file(self: Box<Self>, node: &Node) -> io::Result<OwnedFileStream> {
+        if !node.is_file() {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Node is not a file".to_string(),
+            ));
+        }
+        OwnedFileStream::new(self, node.offset(false), node.length())
+    }
 }
 
 pub(crate) fn read_part_meta(
diff --git a/nod/src/disc/mod.rs b/nod/src/disc/mod.rs
index b800cea..10064c4 100644
--- a/nod/src/disc/mod.rs
+++ b/nod/src/disc/mod.rs
@@ -23,7 +23,7 @@ pub(crate) mod streams;
 pub(crate) mod wii;
 
 pub use fst::{Fst, Node, NodeKind};
-pub use streams::FileStream;
+pub use streams::{FileStream, OwnedFileStream, WindowedStream};
 pub use wii::{SignedHeader, Ticket, TicketLimit, TmdHeader};
 
 /// Size in bytes of a disc sector.
@@ -308,6 +308,35 @@ pub trait PartitionBase: DynClone + BufRead + Seek + Send + Sync {
     /// }
     /// ```
     fn open_file(&mut self, node: &Node) -> io::Result<FileStream>;
+
+    /// Consumes the partition instance and returns a windowed stream.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::io::Read;
+    ///
+    /// use nod::{Disc, PartitionKind, OwnedFileStream};
+    ///
+    /// fn main() -> nod::Result<()> {
+    ///     let disc = Disc::new("path/to/file.iso")?;
+    ///     let mut partition = disc.open_partition_kind(PartitionKind::Data)?;
+    ///     let meta = partition.meta()?;
+    ///     let fst = meta.fst()?;
+    ///     if let Some((_, node)) = fst.find("/disc.tgc") {
+    ///         let file: OwnedFileStream = partition
+    ///             .clone() // Clone the Box<dyn PartitionBase>
+    ///             .into_open_file(node) // Get an OwnedFileStream
+    ///             .expect("Failed to open file stream");
+    ///         // Open the inner disc image using the owned stream
+    ///         let inner_disc = Disc::new_stream(Box::new(file))
+    ///             .expect("Failed to open inner disc");
+    ///         // ...
+    ///     }
+    ///     Ok(())
+    /// }
+    /// ```
+    fn into_open_file(self: Box<Self>, node: &Node) -> io::Result<OwnedFileStream>;
 }
 
 dyn_clone::clone_trait_object!(PartitionBase);
diff --git a/nod/src/disc/streams.rs b/nod/src/disc/streams.rs
index 0af2461..cbee2fb 100644
--- a/nod/src/disc/streams.rs
+++ b/nod/src/disc/streams.rs
@@ -7,30 +7,39 @@ use std::{
 
 use super::PartitionBase;
 
-/// A file read stream for a [`PartitionBase`].
-pub struct FileStream<'a> {
-    base: &'a mut dyn PartitionBase,
+/// A file read stream borrowing a [`PartitionBase`].
+pub type FileStream<'a> = WindowedStream<&'a mut dyn PartitionBase>;
+
+/// A file read stream owning a [`PartitionBase`].
+pub type OwnedFileStream = WindowedStream<Box<dyn PartitionBase>>;
+
+/// A read stream with a fixed window.
+#[derive(Clone)]
+pub struct WindowedStream<T>
+where T: BufRead + Seek
+{
+    base: T,
     pos: u64,
     begin: u64,
     end: u64,
 }
 
-impl FileStream<'_> {
-    /// Creates a new file stream with offset and size.
+impl<T> WindowedStream<T>
+where T: BufRead + Seek
+{
+    /// Creates a new windowed stream with offset and size.
     ///
     /// Seeks underlying stream immediately.
     #[inline]
-    pub(crate) fn new(
-        base: &mut dyn PartitionBase,
-        offset: u64,
-        size: u64,
-    ) -> io::Result<FileStream> {
+    pub fn new(mut base: T, offset: u64, size: u64) -> io::Result<Self> {
         base.seek(SeekFrom::Start(offset))?;
-        Ok(FileStream { base, pos: offset, begin: offset, end: offset + size })
+        Ok(Self { base, pos: offset, begin: offset, end: offset + size })
     }
 }
 
-impl<'a> Read for FileStream<'a> {
+impl<T> Read for WindowedStream<T>
+where T: BufRead + Seek
+{
     #[inline]
     fn read(&mut self, out: &mut [u8]) -> io::Result<usize> {
         let buf = self.fill_buf()?;
@@ -41,7 +50,9 @@ impl<'a> Read for FileStream<'a> {
     }
 }
 
-impl<'a> BufRead for FileStream<'a> {
+impl<T> BufRead for WindowedStream<T>
+where T: BufRead + Seek
+{
     #[inline]
     fn fill_buf(&mut self) -> io::Result<&[u8]> {
         let limit = self.end.saturating_sub(self.pos);
@@ -60,7 +71,9 @@ impl<'a> BufRead for FileStream<'a> {
     }
 }
 
-impl<'a> Seek for FileStream<'a> {
+impl<T> Seek for WindowedStream<T>
+where T: BufRead + Seek
+{
     #[inline]
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
         let mut pos = match pos {
diff --git a/nod/src/disc/wii.rs b/nod/src/disc/wii.rs
index 87b1794..586fd4e 100644
--- a/nod/src/disc/wii.rs
+++ b/nod/src/disc/wii.rs
@@ -14,6 +14,7 @@ use super::{
 };
 use crate::{
     array_ref,
+    disc::streams::OwnedFileStream,
     io::{
         aes_decrypt,
         block::{Block, BlockIO, PartitionInfo},
@@ -497,4 +498,14 @@ impl PartitionBase for PartitionWii {
         }
         FileStream::new(self, node.offset(true), node.length())
     }
+
+    fn into_open_file(self: Box<Self>, node: &Node) -> io::Result<OwnedFileStream> {
+        if !node.is_file() {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Node is not a file".to_string(),
+            ));
+        }
+        OwnedFileStream::new(self, node.offset(true), node.length())
+    }
 }
diff --git a/nod/src/io/block.rs b/nod/src/io/block.rs
index 98bdbba..794f353 100644
--- a/nod/src/io/block.rs
+++ b/nod/src/io/block.rs
@@ -1,4 +1,9 @@
-use std::{cmp::min, fs, fs::File, io, path::Path};
+use std::{
+    cmp::min,
+    fs, io,
+    io::{Read, Seek},
+    path::Path,
+};
 
 use dyn_clone::DynClone;
 use zerocopy::transmute_ref;
@@ -10,11 +15,18 @@ use crate::{
         wii::{WiiPartitionHeader, HASHES_SIZE, SECTOR_DATA_SIZE},
         SECTOR_SIZE,
     },
-    io::{aes_decrypt, aes_encrypt, KeyBytes, MagicBytes},
+    io::{aes_decrypt, aes_encrypt, split::SplitFileReader, KeyBytes, MagicBytes},
     util::{lfg::LaggedFibonacci, read::read_from},
     DiscHeader, DiscMeta, Error, PartitionHeader, PartitionKind, Result, ResultContext,
 };
 
+/// Required trait bounds for reading disc images.
+pub trait DiscStream: Read + Seek + DynClone + Send + Sync {}
+
+impl<T> DiscStream for T where T: Read + Seek + DynClone + Send + Sync + ?Sized {}
+
+dyn_clone::clone_trait_object!(DiscStream);
+
 /// Block I/O trait for reading disc images.
 pub trait BlockIO: DynClone + Send + Sync {
     /// Reads a block from the disc image.
@@ -78,7 +90,27 @@ pub trait BlockIO: DynClone + Send + Sync {
 
 dyn_clone::clone_trait_object!(BlockIO);
 
-/// Creates a new [`BlockIO`] instance.
+/// Creates a new [`BlockIO`] instance from a stream.
+pub fn new(mut stream: Box<dyn DiscStream>) -> Result<Box<dyn BlockIO>> {
+    let magic: MagicBytes = read_from(stream.as_mut()).context("Reading magic bytes")?;
+    stream.seek(io::SeekFrom::Start(0)).context("Seeking to start")?;
+    let io: Box<dyn BlockIO> = match magic {
+        crate::io::ciso::CISO_MAGIC => crate::io::ciso::DiscIOCISO::new(stream)?,
+        #[cfg(feature = "compress-zlib")]
+        crate::io::gcz::GCZ_MAGIC => crate::io::gcz::DiscIOGCZ::new(stream)?,
+        crate::io::nfs::NFS_MAGIC => todo!(),
+        crate::io::wbfs::WBFS_MAGIC => crate::io::wbfs::DiscIOWBFS::new(stream)?,
+        crate::io::wia::WIA_MAGIC | crate::io::wia::RVZ_MAGIC => {
+            crate::io::wia::DiscIOWIA::new(stream)?
+        }
+        crate::io::tgc::TGC_MAGIC => crate::io::tgc::DiscIOTGC::new(stream)?,
+        _ => crate::io::iso::DiscIOISO::new(stream)?,
+    };
+    check_block_size(io.as_ref())?;
+    Ok(io)
+}
+
+/// Creates a new [`BlockIO`] instance from a filesystem path.
 pub fn open(filename: &Path) -> Result<Box<dyn BlockIO>> {
     let path_result = fs::canonicalize(filename);
     if let Err(err) = path_result {
@@ -92,16 +124,16 @@ pub fn open(filename: &Path) -> Result<Box<dyn BlockIO>> {
     if !meta.unwrap().is_file() {
         return Err(Error::DiscFormat(format!("Input is not a file: {}", filename.display())));
     }
-    let magic: MagicBytes = {
-        let mut file =
-            File::open(path).with_context(|| format!("Opening file {}", filename.display()))?;
-        read_from(&mut file)
-            .with_context(|| format!("Reading magic bytes from {}", filename.display()))?
-    };
+    let mut stream = Box::new(SplitFileReader::new(filename)?);
+    let magic: MagicBytes = read_from(stream.as_mut())
+        .with_context(|| format!("Reading magic bytes from {}", filename.display()))?;
+    stream
+        .seek(io::SeekFrom::Start(0))
+        .with_context(|| format!("Seeking to start of {}", filename.display()))?;
     let io: Box<dyn BlockIO> = match magic {
-        crate::io::ciso::CISO_MAGIC => crate::io::ciso::DiscIOCISO::new(path)?,
+        crate::io::ciso::CISO_MAGIC => crate::io::ciso::DiscIOCISO::new(stream)?,
         #[cfg(feature = "compress-zlib")]
-        crate::io::gcz::GCZ_MAGIC => crate::io::gcz::DiscIOGCZ::new(path)?,
+        crate::io::gcz::GCZ_MAGIC => crate::io::gcz::DiscIOGCZ::new(stream)?,
         crate::io::nfs::NFS_MAGIC => match path.parent() {
             Some(parent) if parent.is_dir() => {
                 crate::io::nfs::DiscIONFS::new(path.parent().unwrap())?
@@ -110,13 +142,18 @@ pub fn open(filename: &Path) -> Result<Box<dyn BlockIO>> {
                 return Err(Error::DiscFormat("Failed to locate NFS parent directory".to_string()));
             }
         },
-        crate::io::wbfs::WBFS_MAGIC => crate::io::wbfs::DiscIOWBFS::new(path)?,
+        crate::io::wbfs::WBFS_MAGIC => crate::io::wbfs::DiscIOWBFS::new(stream)?,
         crate::io::wia::WIA_MAGIC | crate::io::wia::RVZ_MAGIC => {
-            crate::io::wia::DiscIOWIA::new(path)?
+            crate::io::wia::DiscIOWIA::new(stream)?
         }
-        crate::io::tgc::TGC_MAGIC => crate::io::tgc::DiscIOTGC::new(path)?,
-        _ => crate::io::iso::DiscIOISO::new(path)?,
+        crate::io::tgc::TGC_MAGIC => crate::io::tgc::DiscIOTGC::new(stream)?,
+        _ => crate::io::iso::DiscIOISO::new(stream)?,
     };
+    check_block_size(io.as_ref())?;
+    Ok(io)
+}
+
+fn check_block_size(io: &dyn BlockIO) -> Result<()> {
     if io.block_size_internal() < SECTOR_SIZE as u32
         && SECTOR_SIZE as u32 % io.block_size_internal() != 0
     {
@@ -133,7 +170,7 @@ pub fn open(filename: &Path) -> Result<Box<dyn BlockIO>> {
             SECTOR_SIZE
         )));
     }
-    Ok(io)
+    Ok(())
 }
 
 /// Wii partition information.
diff --git a/nod/src/io/ciso.rs b/nod/src/io/ciso.rs
index 3df10af..3f61465 100644
--- a/nod/src/io/ciso.rs
+++ b/nod/src/io/ciso.rs
@@ -2,7 +2,6 @@ use std::{
     io,
     io::{Read, Seek, SeekFrom},
     mem::size_of,
-    path::Path,
 };
 
 use zerocopy::{little_endian::*, AsBytes, FromBytes, FromZeroes};
@@ -10,9 +9,8 @@ use zerocopy::{little_endian::*, AsBytes, FromBytes, FromZeroes};
 use crate::{
     disc::SECTOR_SIZE,
     io::{
-        block::{Block, BlockIO, PartitionInfo},
+        block::{Block, BlockIO, DiscStream, PartitionInfo},
         nkit::NKitHeader,
-        split::SplitFileReader,
         Format, MagicBytes,
     },
     static_assert,
@@ -36,18 +34,16 @@ static_assert!(size_of::<CISOHeader>() == SECTOR_SIZE);
 
 #[derive(Clone)]
 pub struct DiscIOCISO {
-    inner: SplitFileReader,
+    inner: Box<dyn DiscStream>,
     header: CISOHeader,
     block_map: [u16; CISO_MAP_SIZE],
     nkit_header: Option<NKitHeader>,
 }
 
 impl DiscIOCISO {
-    pub fn new(filename: &Path) -> Result<Box<Self>> {
-        let mut inner = SplitFileReader::new(filename)?;
-
+    pub fn new(mut inner: Box<dyn DiscStream>) -> Result<Box<Self>> {
         // Read header
-        let header: CISOHeader = read_from(&mut inner).context("Reading CISO header")?;
+        let header: CISOHeader = read_from(inner.as_mut()).context("Reading CISO header")?;
         if header.magic != CISO_MAGIC {
             return Err(Error::DiscFormat("Invalid CISO magic".to_string()));
         }
@@ -64,18 +60,18 @@ impl DiscIOCISO {
             }
         }
         let file_size = SECTOR_SIZE as u64 + block as u64 * header.block_size.get() as u64;
-        if file_size > inner.len() {
+        let len = inner.seek(SeekFrom::End(0)).context("Determining stream length")?;
+        if file_size > len {
             return Err(Error::DiscFormat(format!(
                 "CISO file size mismatch: expected at least {} bytes, got {}",
-                file_size,
-                inner.len()
+                file_size, len
             )));
         }
 
         // Read NKit header if present (after CISO data)
-        let nkit_header = if inner.len() > file_size + 4 {
+        let nkit_header = if len > file_size + 4 {
             inner.seek(SeekFrom::Start(file_size)).context("Seeking to NKit header")?;
-            NKitHeader::try_read_from(&mut inner, header.block_size.get(), true)
+            NKitHeader::try_read_from(inner.as_mut(), header.block_size.get(), true)
         } else {
             None
         };
diff --git a/nod/src/io/gcz.rs b/nod/src/io/gcz.rs
index adf42ee..5230d0d 100644
--- a/nod/src/io/gcz.rs
+++ b/nod/src/io/gcz.rs
@@ -2,7 +2,6 @@ use std::{
     io,
     io::{Read, Seek, SeekFrom},
     mem::size_of,
-    path::Path,
 };
 
 use adler::adler32_slice;
@@ -12,8 +11,7 @@ use zstd::zstd_safe::WriteBuf;
 
 use crate::{
     io::{
-        block::{Block, BlockIO},
-        split::SplitFileReader,
+        block::{Block, BlockIO, DiscStream},
         MagicBytes,
     },
     static_assert,
@@ -38,7 +36,7 @@ struct GCZHeader {
 static_assert!(size_of::<GCZHeader>() == 32);
 
 pub struct DiscIOGCZ {
-    inner: SplitFileReader,
+    inner: Box<dyn DiscStream>,
     header: GCZHeader,
     block_map: Box<[U64]>,
     block_hashes: Box<[U32]>,
@@ -60,21 +58,19 @@ impl Clone for DiscIOGCZ {
 }
 
 impl DiscIOGCZ {
-    pub fn new(filename: &Path) -> Result<Box<Self>> {
-        let mut inner = SplitFileReader::new(filename)?;
-
+    pub fn new(mut inner: Box<dyn DiscStream>) -> Result<Box<Self>> {
         // Read header
-        let header: GCZHeader = read_from(&mut inner).context("Reading GCZ header")?;
+        let header: GCZHeader = read_from(inner.as_mut()).context("Reading GCZ header")?;
         if header.magic != GCZ_MAGIC {
             return Err(Error::DiscFormat("Invalid GCZ magic".to_string()));
         }
 
         // Read block map and hashes
         let block_count = header.block_count.get();
-        let block_map =
-            read_box_slice(&mut inner, block_count as usize).context("Reading GCZ block map")?;
-        let block_hashes =
-            read_box_slice(&mut inner, block_count as usize).context("Reading GCZ block hashes")?;
+        let block_map = read_box_slice(inner.as_mut(), block_count as usize)
+            .context("Reading GCZ block map")?;
+        let block_hashes = read_box_slice(inner.as_mut(), block_count as usize)
+            .context("Reading GCZ block hashes")?;
 
         // header + block_count * (u64 + u32)
         let data_offset = size_of::<GCZHeader>() as u64 + block_count as u64 * 12;
diff --git a/nod/src/io/iso.rs b/nod/src/io/iso.rs
index 167a816..484b85b 100644
--- a/nod/src/io/iso.rs
+++ b/nod/src/io/iso.rs
@@ -1,28 +1,28 @@
 use std::{
     io,
     io::{Read, Seek, SeekFrom},
-    path::Path,
 };
 
 use crate::{
     disc::SECTOR_SIZE,
     io::{
-        block::{Block, BlockIO, PartitionInfo},
-        split::SplitFileReader,
+        block::{Block, BlockIO, DiscStream, PartitionInfo},
         Format,
     },
-    DiscMeta, Result,
+    DiscMeta, Result, ResultContext,
 };
 
 #[derive(Clone)]
 pub struct DiscIOISO {
-    inner: SplitFileReader,
+    inner: Box<dyn DiscStream>,
+    stream_len: u64,
 }
 
 impl DiscIOISO {
-    pub fn new(filename: &Path) -> Result<Box<Self>> {
-        let inner = SplitFileReader::new(filename)?;
-        Ok(Box::new(Self { inner }))
+    pub fn new(mut inner: Box<dyn DiscStream>) -> Result<Box<Self>> {
+        let stream_len = inner.seek(SeekFrom::End(0)).context("Determining stream length")?;
+        inner.seek(SeekFrom::Start(0)).context("Seeking to start")?;
+        Ok(Box::new(Self { inner, stream_len }))
     }
 }
 
@@ -34,16 +34,15 @@ impl BlockIO for DiscIOISO {
         _partition: Option<&PartitionInfo>,
     ) -> io::Result<Block> {
         let offset = block as u64 * SECTOR_SIZE as u64;
-        let total_size = self.inner.len();
-        if offset >= total_size {
+        if offset >= self.stream_len {
             // End of file
             return Ok(Block::Zero);
         }
 
         self.inner.seek(SeekFrom::Start(offset))?;
-        if offset + SECTOR_SIZE as u64 > total_size {
+        if offset + SECTOR_SIZE as u64 > self.stream_len {
             // If the last block is not a full sector, fill the rest with zeroes
-            let read = (total_size - offset) as usize;
+            let read = (self.stream_len - offset) as usize;
             self.inner.read_exact(&mut out[..read])?;
             out[read..].fill(0);
         } else {
@@ -58,7 +57,7 @@ impl BlockIO for DiscIOISO {
         DiscMeta {
             format: Format::Iso,
             lossless: true,
-            disc_size: Some(self.inner.len()),
+            disc_size: Some(self.stream_len),
             ..Default::default()
         }
     }
diff --git a/nod/src/io/tgc.rs b/nod/src/io/tgc.rs
index 685b5f8..310fd52 100644
--- a/nod/src/io/tgc.rs
+++ b/nod/src/io/tgc.rs
@@ -2,7 +2,6 @@ use std::{
     io,
     io::{Read, Seek, SeekFrom},
     mem::size_of,
-    path::Path,
 };
 
 use zerocopy::{big_endian::U32, AsBytes, FromBytes, FromZeroes};
@@ -10,8 +9,7 @@ use zerocopy::{big_endian::U32, AsBytes, FromBytes, FromZeroes};
 use crate::{
     disc::SECTOR_SIZE,
     io::{
-        block::{Block, BlockIO, PartitionInfo},
-        split::SplitFileReader,
+        block::{Block, BlockIO, DiscStream, PartitionInfo},
         Format, MagicBytes,
     },
     util::read::{read_box_slice, read_from},
@@ -56,17 +54,19 @@ struct TGCHeader {
 
 #[derive(Clone)]
 pub struct DiscIOTGC {
-    inner: SplitFileReader,
+    inner: Box<dyn DiscStream>,
+    stream_len: u64,
     header: TGCHeader,
     fst: Box<[u8]>,
 }
 
 impl DiscIOTGC {
-    pub fn new(filename: &Path) -> Result<Box<Self>> {
-        let mut inner = SplitFileReader::new(filename)?;
+    pub fn new(mut inner: Box<dyn DiscStream>) -> Result<Box<Self>> {
+        let stream_len = inner.seek(SeekFrom::End(0)).context("Determining stream length")?;
+        inner.seek(SeekFrom::Start(0)).context("Seeking to start")?;
 
         // Read header
-        let header: TGCHeader = read_from(&mut inner).context("Reading TGC header")?;
+        let header: TGCHeader = read_from(inner.as_mut()).context("Reading TGC header")?;
         if header.magic != TGC_MAGIC {
             return Err(Error::DiscFormat("Invalid TGC magic".to_string()));
         }
@@ -75,7 +75,7 @@ impl DiscIOTGC {
         inner
             .seek(SeekFrom::Start(header.fst_offset.get() as u64))
             .context("Seeking to TGC FST")?;
-        let mut fst = read_box_slice(&mut inner, header.fst_size.get() as usize)
+        let mut fst = read_box_slice(inner.as_mut(), header.fst_size.get() as usize)
             .context("Reading TGC FST")?;
         let root_node = Node::ref_from_prefix(&fst)
             .ok_or_else(|| Error::DiscFormat("Invalid TGC FST".to_string()))?;
@@ -89,7 +89,7 @@ impl DiscIOTGC {
             }
         }
 
-        Ok(Box::new(Self { inner, header, fst }))
+        Ok(Box::new(Self { inner, stream_len, header, fst }))
     }
 }
 
@@ -101,16 +101,15 @@ impl BlockIO for DiscIOTGC {
         _partition: Option<&PartitionInfo>,
     ) -> io::Result<Block> {
         let offset = self.header.header_offset.get() as u64 + block as u64 * SECTOR_SIZE as u64;
-        let total_size = self.inner.len();
-        if offset >= total_size {
+        if offset >= self.stream_len {
             // End of file
             return Ok(Block::Zero);
         }
 
         self.inner.seek(SeekFrom::Start(offset))?;
-        if offset + SECTOR_SIZE as u64 > total_size {
+        if offset + SECTOR_SIZE as u64 > self.stream_len {
             // If the last block is not a full sector, fill the rest with zeroes
-            let read = (total_size - offset) as usize;
+            let read = (self.stream_len - offset) as usize;
             self.inner.read_exact(&mut out[..read])?;
             out[read..].fill(0);
         } else {
@@ -149,7 +148,7 @@ impl BlockIO for DiscIOTGC {
         DiscMeta {
             format: Format::Tgc,
             lossless: true,
-            disc_size: Some(self.inner.len() - self.header.header_offset.get() as u64),
+            disc_size: Some(self.stream_len - self.header.header_offset.get() as u64),
             ..Default::default()
         }
     }
diff --git a/nod/src/io/wbfs.rs b/nod/src/io/wbfs.rs
index 11f584f..8749225 100644
--- a/nod/src/io/wbfs.rs
+++ b/nod/src/io/wbfs.rs
@@ -2,16 +2,14 @@ use std::{
     io,
     io::{Read, Seek, SeekFrom},
     mem::size_of,
-    path::Path,
 };
 
 use zerocopy::{big_endian::*, AsBytes, FromBytes, FromZeroes};
 
 use crate::{
     io::{
-        block::{Block, BlockIO, PartitionInfo},
+        block::{Block, BlockIO, DiscStream, PartitionInfo},
         nkit::NKitHeader,
-        split::SplitFileReader,
         DiscMeta, Format, MagicBytes,
     },
     util::read::{read_box_slice, read_from},
@@ -35,18 +33,6 @@ impl WBFSHeader {
 
     fn block_size(&self) -> u32 { 1 << self.block_size_shift }
 
-    // fn align_lba(&self, x: u32) -> u32 { (x + self.sector_size() - 1) & !(self.sector_size() - 1) }
-    //
-    // fn num_wii_sectors(&self) -> u32 {
-    //     (self.num_sectors.get() / SECTOR_SIZE as u32) * self.sector_size()
-    // }
-    //
-    // fn max_wii_sectors(&self) -> u32 { NUM_WII_SECTORS }
-    //
-    // fn num_wbfs_sectors(&self) -> u32 {
-    //     self.num_wii_sectors() >> (self.wbfs_sector_size_shift - 15)
-    // }
-
     fn max_blocks(&self) -> u32 { NUM_WII_SECTORS >> (self.block_size_shift - 15) }
 }
 
@@ -55,7 +41,7 @@ const NUM_WII_SECTORS: u32 = 143432 * 2; // Double layer discs
 
 #[derive(Clone)]
 pub struct DiscIOWBFS {
-    inner: SplitFileReader,
+    inner: Box<dyn DiscStream>,
     /// WBFS header
     header: WBFSHeader,
     /// Map of Wii LBAs to WBFS LBAs
@@ -65,14 +51,12 @@ pub struct DiscIOWBFS {
 }
 
 impl DiscIOWBFS {
-    pub fn new(filename: &Path) -> Result<Box<Self>> {
-        let mut inner = SplitFileReader::new(filename)?;
-
-        let header: WBFSHeader = read_from(&mut inner).context("Reading WBFS header")?;
+    pub fn new(mut inner: Box<dyn DiscStream>) -> Result<Box<Self>> {
+        let header: WBFSHeader = read_from(inner.as_mut()).context("Reading WBFS header")?;
         if header.magic != WBFS_MAGIC {
             return Err(Error::DiscFormat("Invalid WBFS magic".to_string()));
         }
-        let file_len = inner.len();
+        let file_len = inner.seek(SeekFrom::End(0)).context("Determining stream length")?;
         let expected_file_len = header.num_sectors.get() as u64 * header.sector_size() as u64;
         if file_len != expected_file_len {
             return Err(Error::DiscFormat(format!(
@@ -81,8 +65,11 @@ impl DiscIOWBFS {
             )));
         }
 
+        inner
+            .seek(SeekFrom::Start(size_of::<WBFSHeader>() as u64))
+            .context("Seeking to WBFS disc table")?;
         let disc_table: Box<[u8]> =
-            read_box_slice(&mut inner, header.sector_size() as usize - size_of::<WBFSHeader>())
+            read_box_slice(inner.as_mut(), header.sector_size() as usize - size_of::<WBFSHeader>())
                 .context("Reading WBFS disc table")?;
         if disc_table[0] != 1 {
             return Err(Error::DiscFormat("WBFS doesn't contain a disc".to_string()));
@@ -95,12 +82,12 @@ impl DiscIOWBFS {
         inner
             .seek(SeekFrom::Start(header.sector_size() as u64 + DISC_HEADER_SIZE as u64))
             .context("Seeking to WBFS LBA table")?; // Skip header
-        let block_map: Box<[U16]> = read_box_slice(&mut inner, header.max_blocks() as usize)
+        let block_map: Box<[U16]> = read_box_slice(inner.as_mut(), header.max_blocks() as usize)
             .context("Reading WBFS LBA table")?;
 
         // Read NKit header if present (always at 0x10000)
         inner.seek(SeekFrom::Start(0x10000)).context("Seeking to NKit header")?;
-        let nkit_header = NKitHeader::try_read_from(&mut inner, header.block_size(), true);
+        let nkit_header = NKitHeader::try_read_from(inner.as_mut(), header.block_size(), true);
 
         Ok(Box::new(Self { inner, header, block_map, nkit_header }))
     }
diff --git a/nod/src/io/wia.rs b/nod/src/io/wia.rs
index 99fd144..1bfa8e0 100644
--- a/nod/src/io/wia.rs
+++ b/nod/src/io/wia.rs
@@ -2,7 +2,6 @@ use std::{
     io,
     io::{Read, Seek, SeekFrom},
     mem::size_of,
-    path::Path,
 };
 
 use zerocopy::{big_endian::*, AsBytes, FromBytes, FromZeroes};
@@ -14,9 +13,8 @@ use crate::{
         SECTOR_SIZE,
     },
     io::{
-        block::{Block, BlockIO, PartitionInfo},
+        block::{Block, BlockIO, DiscStream, PartitionInfo},
         nkit::NKitHeader,
-        split::SplitFileReader,
         Compression, Format, HashBytes, KeyBytes, MagicBytes,
     },
     static_assert,
@@ -502,7 +500,7 @@ impl Decompressor {
 }
 
 pub struct DiscIOWIA {
-    inner: SplitFileReader,
+    inner: Box<dyn DiscStream>,
     header: WIAFileHeader,
     disc: WIADisc,
     partitions: Box<[WIAPartition]>,
@@ -549,17 +547,16 @@ fn verify_hash(buf: &[u8], expected: &HashBytes) -> Result<()> {
 }
 
 impl DiscIOWIA {
-    pub fn new(filename: &Path) -> Result<Box<Self>> {
-        let mut inner = SplitFileReader::new(filename)?;
-
+    pub fn new(mut inner: Box<dyn DiscStream>) -> Result<Box<Self>> {
         // Load & verify file header
-        let header: WIAFileHeader = read_from(&mut inner).context("Reading WIA/RVZ file header")?;
+        let header: WIAFileHeader =
+            read_from(inner.as_mut()).context("Reading WIA/RVZ file header")?;
         header.validate()?;
         let is_rvz = header.is_rvz();
         // log::debug!("Header: {:?}", header);
 
         // Load & verify disc header
-        let mut disc_buf: Vec<u8> = read_vec(&mut inner, header.disc_size.get() as usize)
+        let mut disc_buf: Vec<u8> = read_vec(inner.as_mut(), header.disc_size.get() as usize)
             .context("Reading WIA/RVZ disc header")?;
         verify_hash(&disc_buf, &header.disc_hash)?;
         disc_buf.resize(size_of::<WIADisc>(), 0);
@@ -576,14 +573,14 @@ impl DiscIOWIA {
         // log::debug!("Disc: {:?}", disc);
 
         // Read NKit header if present (after disc header)
-        let nkit_header = NKitHeader::try_read_from(&mut inner, disc.chunk_size.get(), false);
+        let nkit_header = NKitHeader::try_read_from(inner.as_mut(), disc.chunk_size.get(), false);
 
         // Load & verify partition headers
         inner
             .seek(SeekFrom::Start(disc.partition_offset.get()))
             .context("Seeking to WIA/RVZ partition headers")?;
         let partitions: Box<[WIAPartition]> =
-            read_box_slice(&mut inner, disc.num_partitions.get() as usize)
+            read_box_slice(inner.as_mut(), disc.num_partitions.get() as usize)
                 .context("Reading WIA/RVZ partition headers")?;
         verify_hash(partitions.as_ref().as_bytes(), &disc.partition_hash)?;
         // log::debug!("Partitions: {:?}", partitions);
@@ -597,7 +594,7 @@ impl DiscIOWIA {
                 .seek(SeekFrom::Start(disc.raw_data_offset.get()))
                 .context("Seeking to WIA/RVZ raw data headers")?;
             let mut reader = decompressor
-                .wrap((&mut inner).take(disc.raw_data_size.get() as u64))
+                .wrap(inner.as_mut().take(disc.raw_data_size.get() as u64))
                 .context("Creating WIA/RVZ decompressor")?;
             read_box_slice(&mut reader, disc.num_raw_data.get() as usize)
                 .context("Reading WIA/RVZ raw data headers")?
@@ -621,7 +618,7 @@ impl DiscIOWIA {
                 .seek(SeekFrom::Start(disc.group_offset.get()))
                 .context("Seeking to WIA/RVZ group headers")?;
             let mut reader = decompressor
-                .wrap((&mut inner).take(disc.group_size.get() as u64))
+                .wrap(inner.as_mut().take(disc.group_size.get() as u64))
                 .context("Creating WIA/RVZ decompressor")?;
             if is_rvz {
                 read_box_slice(&mut reader, disc.num_groups.get() as usize)
diff --git a/nod/src/lib.rs b/nod/src/lib.rs
index 1a85d13..0371afa 100644
--- a/nod/src/lib.rs
+++ b/nod/src/lib.rs
@@ -64,11 +64,14 @@ use std::{
 };
 
 pub use disc::{
-    ApploaderHeader, DiscHeader, DolHeader, FileStream, Fst, Node, NodeKind, PartitionBase,
-    PartitionHeader, PartitionKind, PartitionMeta, SignedHeader, Ticket, TicketLimit, TmdHeader,
-    BI2_SIZE, BOOT_SIZE, SECTOR_SIZE,
+    ApploaderHeader, DiscHeader, DolHeader, FileStream, Fst, Node, NodeKind, OwnedFileStream,
+    PartitionBase, PartitionHeader, PartitionKind, PartitionMeta, SignedHeader, Ticket,
+    TicketLimit, TmdHeader, WindowedStream, BI2_SIZE, BOOT_SIZE, SECTOR_SIZE,
+};
+pub use io::{
+    block::{DiscStream, PartitionInfo},
+    Compression, DiscMeta, Format, KeyBytes,
 };
-pub use io::{block::PartitionInfo, Compression, DiscMeta, Format, KeyBytes};
 
 mod disc;
 mod io;
@@ -170,6 +173,23 @@ impl Disc {
         Ok(Disc { reader, options: options.clone() })
     }
 
+    /// Opens a disc image from a read stream.
+    #[inline]
+    pub fn new_stream(stream: Box<dyn DiscStream>) -> Result<Disc> {
+        Disc::new_stream_with_options(stream, &OpenOptions::default())
+    }
+
+    /// Opens a disc image from a read stream with custom options.
+    #[inline]
+    pub fn new_stream_with_options(
+        stream: Box<dyn DiscStream>,
+        options: &OpenOptions,
+    ) -> Result<Disc> {
+        let io = io::block::new(stream)?;
+        let reader = disc::reader::DiscReader::new(io, options)?;
+        Ok(Disc { reader, options: options.clone() })
+    }
+
     /// The disc's primary header.
     #[inline]
     pub fn header(&self) -> &DiscHeader { self.reader.header() }