diff --git a/src/demux/nalu.rs b/src/demux/nalu.rs
deleted file mode 100644
index 5a0c143..0000000
--- a/src/demux/nalu.rs
+++ /dev/null
@@ -1,50 +0,0 @@
-use crate::util;
-
-pub fn prepend_v_flv(data: Vec<u8>, metadata: &util::Metadata) -> Vec<u8> {
-    match metadata.video.codec {
-        Some(util::VideoCodec::H264) => preprocess_h264(data),
-        None => panic!("not possible for codec to be None by this point")
-    }
-}
-
-pub fn prepend_a_flv(data: Vec<u8>, metadata: &util::Metadata) -> Vec<u8> {
-    return data;
-}
-
-fn parse_avcc(mut data: Vec<u8>) -> (Vec<u8>, Vec<u8>) {
-    data.drain(..6);
-    let mut buff = [0u8; 2];
-    buff.copy_from_slice(data.drain(..2).as_slice());
-    let sps_len = u16::from_be_bytes(buff) as usize;
-    let sps = data.drain(..sps_len).collect::<Vec<u8>>();
-    data.drain(..1);
-    let mut buff = [0u8; 2];
-    buff.copy_from_slice(data.drain(..2).as_slice());
-    let pps_len = u16::from_be_bytes(buff) as usize;
-    let pps = data.drain(..pps_len).collect::<Vec<u8>>();
-    return (sps, pps);
-}
-
-fn preprocess_h264(mut data: Vec<u8>) -> Vec<u8> {
-    let mut nalu = vec![0u8, 0u8, 0u8, 1u8];
-    if data[1] == 0 {
-        data.drain(..5);
-        let (mut sps, mut pps) = parse_avcc(data);
-        nalu.append(&mut sps);
-        nalu.append(&mut vec![0u8, 0u8, 0u8, 1u8]);
-        nalu.append(&mut pps);
-        return nalu;
-    } else if data[1] == 2 {
-        return vec![0u8; 0];
-    } else {
-        data.drain(..5);
-        loop {
-            let mut buff = [0u8; 4];
-            buff.copy_from_slice(data.drain(..4).as_slice());
-            let nalu_len = u32::from_be_bytes(buff) as usize;
-            nalu.extend_from_slice(data.drain(..nalu_len).as_slice());
-            if data.len() <= 4 {return nalu}
-            nalu.append(&mut vec![0u8, 0u8, 0u8, 1u8]);
-        }
-    }
-}
diff --git a/src/demux/nalu_flv.rs b/src/demux/nalu_flv.rs
new file mode 100644
index 0000000..883bcf1
--- /dev/null
+++ b/src/demux/nalu_flv.rs
@@ -0,0 +1,99 @@
+use crate::util;
+
+pub fn prepend_v(data: Vec<u8>, metadata: &util::Metadata) -> Vec<u8> {
+    match metadata.video.codec {
+        Some(util::VideoCodec::H264) => preprocess_h264(data),
+        None => panic!("not possible for codec to be None by this point")
+    }
+}
+
+pub fn prepend_a(data: Vec<u8>, metadata: &util::Metadata) -> Vec<u8> {
+    match metadata.audio.codec {
+        Some(util::AudioCodec::AAC) => preprocess_aac(data, metadata),
+        None => panic!("not possible for codec to be None by this point")
+    }
+}
+
+fn parse_avcc(mut data: Vec<u8>) -> (Vec<u8>, Vec<u8>) {
+    data.drain(..6);
+    let mut buff = [0u8; 2];
+    buff.copy_from_slice(data.drain(..2).as_slice());
+    let sps_len = u16::from_be_bytes(buff) as usize;
+    let sps = data.drain(..sps_len).collect::<Vec<u8>>();
+    data.drain(..1);
+    let mut buff = [0u8; 2];
+    buff.copy_from_slice(data.drain(..2).as_slice());
+    let pps_len = u16::from_be_bytes(buff) as usize;
+    let pps = data.drain(..pps_len).collect::<Vec<u8>>();
+    return (sps, pps);
+}
+
+fn preprocess_h264(mut data: Vec<u8>) -> Vec<u8> {
+    let mut nalu = vec![0u8, 0u8, 0u8, 1u8];
+    match data[1] {
+        0 => {
+            data.drain(..5);
+            let (mut sps, mut pps) = parse_avcc(data);
+            nalu.append(&mut sps);
+            nalu.append(&mut vec![0u8, 0u8, 0u8, 1u8]);
+            nalu.append(&mut pps);
+            return nalu;
+        },
+        2 => {return vec![0u8; 0];},
+        1 => {
+            data.drain(..5);
+            loop {
+                let mut buff = [0u8; 4];
+                buff.copy_from_slice(data.drain(..4).as_slice());
+                let nalu_len = u32::from_be_bytes(buff) as usize;
+                nalu.extend_from_slice(data.drain(..nalu_len).as_slice());
+                if data.len() <= 4 {return nalu}
+                nalu.append(&mut vec![0u8, 0u8, 0u8, 1u8]);
+            }
+        },
+        _ => {panic!("cannot be any other value")}
+    }
+}
+
+fn make_adts_head(metadata: &util::Metadata, data_len: usize) -> Vec<u8> {
+    let aot_idx = 1u8;
+    let frame_len = (data_len + 7) as u16;
+    let samplerate_idx: u8 = match metadata.audio.samplerate {
+        96000 => 0,
+        88200 => 1,
+        64000 => 2,
+        48000 => 3,
+        44100 => 4,
+        32000 => 5,
+        24000 => 6,
+        22050 => 7,
+        16000 => 8,
+        12000 => 9,
+        11025 => 10,
+        8000 => 11,
+        7350 => 12,
+        _ => {panic!("invalid samplerate")}
+    };
+    let chan_conf_idx = metadata.audio.channels;
+    let mut head = vec![0xffu8, 0xf1u8, 0u8, 0u8, 0u8, 0u8, 0xfcu8];
+    head[2] = (aot_idx << 6) | (samplerate_idx << 2) | (chan_conf_idx >> 2);
+    head[3] = ((chan_conf_idx & 0x3) << 6) | ((frame_len >> 11) as u8);
+    head[4] = ((frame_len >> 3) & 0xff) as u8;
+    head[5] = (((frame_len << 5) & 0xff) as u8) | 0x1f;
+    return head
+}
+
+fn preprocess_aac(mut data: Vec<u8>, metadata: &util::Metadata) -> Vec<u8> {
+    match data[1] {
+        0 => {
+            return vec![0u8; 0];
+        },
+        1 => {
+            data.drain(..2);
+            let mut nalu = make_adts_head(metadata, data.len());
+            nalu.append(&mut data);
+            return nalu;
+        },
+        _ => {panic!("cannot be any other value")}
+    }
+}