basic abstracted input demuxing

src/demux/input.rs

@@ -0,0 +1,21 @@
+use std::error::Error;
+use std::io;
+use std::io::Read;
+
+use crate::util;
+use crate::demux::flv;
+
+pub trait FileReader {
+    fn init(&mut self) -> Result<util::Metadata, Box<dyn Error>>;
+    fn read_nalu(&mut self) -> Result<util::NALUPacket, Box<dyn Error>>;
+}
+
+pub fn new_reader() -> Result<impl FileReader, Box<dyn Error>> {
+    let mut stdin_hndl = io::stdin();
+    let mut byte1 = [0u8; 1];
+    stdin_hndl.read_exact(&mut byte1)?;
+    match &byte1[0] {
+        0x46 => flv::new_reader(stdin_hndl),
+        _ => Err(Box::new(util::GenericError::UnknownSyncByte))
+    }
+}