diff --git a/src/fmt.rs b/src/fmt.rs
index c789c1a..aec3bab 100644
--- a/src/fmt.rs
+++ b/src/fmt.rs
@@ -1,5 +1,9 @@
 use uuid::Uuid;
 use super::common_format::{CommonFormat, UUID_PCM,UUID_BFORMAT_PCM};
+use std::io::Cursor;
+
+use byteorder::LittleEndian;
+use byteorder::WriteBytesExt;
 
 #[allow(dead_code)]
 
@@ -181,7 +185,7 @@ pub struct WaveFmt {
 
 
 impl WaveFmt {
-    
+
     pub fn valid_bits_per_sample(&self) -> u16 {
         if let Some(ext) = self.extended_format {
             ext.valid_bits_per_sample
@@ -274,6 +278,46 @@ impl WaveFmt {
         vec![0i32; self.channel_count as usize]
     }
 
+    /// Calculate the size of a byte buffer needed to hold audio data of this 
+    /// format for a given number of frames
+    pub fn buffer_length(&self, frame_count: u64) -> usize {
+        (self.block_alignment as u64 * frame_count) as usize
+    }
+
+    // Write frames into a byte vector
+    pub fn pack_frames(&self, from_frames: &[i32], into_bytes: &mut Vec<u8>) -> () {
+        let mut write_cursor = Cursor::new(into_bytes);
+
+        assert!(from_frames.len() % self.channel_count as usize == 0, 
+            "frames buffer does not contain a number of samples % channel_count == 0");
+
+            for n in 0..from_frames.len() {
+                match (self.valid_bits_per_sample(), self.bits_per_sample) {
+                    (0..=8,8) => write_cursor.write_u8((from_frames[n] + 0x80) as u8 ).unwrap(), // EBU 3285 §A2.2
+                    (9..=16,16) => write_cursor.write_i16::<LittleEndian>(from_frames[n] as i16).unwrap(),
+                    (10..=24,24) => write_cursor.write_i24::<LittleEndian>(from_frames[n]).unwrap(),
+                    (25..=32,32) => write_cursor.write_i32::<LittleEndian>(from_frames[n]).unwrap(),
+                    (b,_)=> panic!("Unrecognized integer format, bits per sample {}, channels {}, block_alignment {}", 
+                        b, self.channel_count, self.block_alignment)
+                }
+            }
+        ()
+    }
+
+    /// Read bytes into frames
+    // pub fn unpack_frames(&self, from_bytes: &[u8], into_frames: &mut Vec<i32>) -> () {
+    //     for n in 0..(from_bytes.len()) {
+    //         buffer[n] = match (self.format.bits_per_sample, framed_bits_per_sample) {
+    //             (0..=8,8) => self.inner.read_u8()? as i32 - 0x80_i32, // EBU 3285 §A2.2
+    //             (9..=16,16) => self.inner.read_i16::<LittleEndian>()? as i32,
+    //             (10..=24,24) => self.inner.read_i24::<LittleEndian>()?,
+    //             (25..=32,32) => self.inner.read_i32::<LittleEndian>()?,
+    //             (b,_)=> panic!("Unrecognized integer format, bits per sample {}, channels {}, block_alignment {}", 
+    //                 b, self.format.channel_count, self.format.block_alignment)
+    //         }
+    //     }
+    // }
+
 
     /// Channel descriptors for each channel.
     pub fn channels(&self) -> Vec<ChannelDescriptor> {
diff --git a/src/wavewriter.rs b/src/wavewriter.rs
index cdec19a..151f9c9 100644
--- a/src/wavewriter.rs
+++ b/src/wavewriter.rs
@@ -16,48 +16,23 @@ use byteorder::WriteBytesExt;
 /// 
 /// 
 pub struct AudioFrameWriter<W> where W: Write + Seek {
-    inner : WaveChunkWriter<W>,
-    framed_bits_per_sample : u16,
-    bits_per_sample: u16,
-    channel_count: u16,
-    block_alignment: u16,
+    inner : WaveChunkWriter<W>
 }
 
 impl<W> AudioFrameWriter<W> where W: Write + Seek {
 
     fn new(inner: WaveChunkWriter<W>) -> Self {
-        let fbps = inner.inner.format.bits_per_sample;
-        let ba = inner.inner.format.block_alignment;
-        let cc = inner.inner.format.channel_count;
-        let bps = inner.inner.format.valid_bits_per_sample();
-        AudioFrameWriter {
-            inner, 
-            framed_bits_per_sample: fbps,
-            bits_per_sample: bps,
-            channel_count: cc,
-            block_alignment: ba,
-        }
+        AudioFrameWriter { inner }
     }
 
     fn write_integer_frames_to_buffer(&self, from_frames :&[i32], to_buffer : &mut Vec<u8>) -> () {
-        let mut write_cursor = Cursor::new(to_buffer);
-
-        assert!(from_frames.len() % self.channel_count as usize == 0, 
+        assert!(from_frames.len() % self.inner.inner.format.channel_count as usize == 0, 
             "frames buffer does not contain a number of samples % channel_count == 0");
-
-            for n in 0..from_frames.len() {
-                match (self.bits_per_sample, self.framed_bits_per_sample) {
-                    (0..=8,8) => write_cursor.write_u8((from_frames[n] + 0x80) as u8 ).unwrap(), // EBU 3285 §A2.2
-                    (9..=16,16) => write_cursor.write_i16::<LittleEndian>(from_frames[n] as i16).unwrap(),
-                    (10..=24,24) => write_cursor.write_i24::<LittleEndian>(from_frames[n]).unwrap(),
-                    (25..=32,32) => write_cursor.write_i32::<LittleEndian>(from_frames[n]).unwrap(),
-                    (b,_)=> panic!("Unrecognized integer format, bits per sample {}, channels {}, block_alignment {}", 
-                        b, self.channel_count, self.block_alignment)
-                }
-            }
+        self.inner.inner.format.pack_frames(&from_frames, to_buffer);
         ()
     }
 
+    /// Write interleaved samples in `buffer`
     pub fn write_integer_frames(&mut self, buffer: &[i32]) -> Result<u64,Error> {
         let mut write_buffer = vec![0u8; 0];
 
@@ -65,11 +40,9 @@ impl<W> AudioFrameWriter<W> where W: Write + Seek {
 
         self.inner.write(&write_buffer)?;
         self.inner.flush()?;
-        Ok(write_buffer.len() as u64 / self.channel_count as u64)
+        Ok(write_buffer.len() as u64 / self.inner.inner.format.channel_count as u64)
     }
 
-
-
     /// Finish writing audio frames and unwrap the inner `WaveWriter`.
     /// 
     /// This method must be called when the client has finished writing audio
@@ -421,7 +394,7 @@ fn test_write_bext() {
 // NOTE! This test of RF64 writing passes on my machine but because it takes 
 // nearly 5 mins to run I have omitted it from the source for now...
 
-#[test]
+//#[test]
 fn test_create_rf64() {
     use std::io::Cursor;
     use super::fourcc::ReadFourCC;