basic flv packet reading

src/demux/flv.rs

@@ -5,10 +5,43 @@ use std::io::Read;
 use crate::util;
 use crate::demux::input;
 
+enum FLVTagType {
+    Metadata,
+    Audio,
+    Video,
+}
+
+impl TryFrom<u8> for FLVTagType {
+    type Error = util::GenericError;
+    fn try_from(type_byte: u8) -> Result<Self, Self::Error> {
+        match type_byte {
+            8 => Ok(FLVTagType::Audio),
+            9 => Ok(FLVTagType::Video),
+            18 => Ok(FLVTagType::Metadata),
+            _ => Err(Self::Error::FLVUnknownTagType)
+        }
+    }
+}
+
 pub struct FLVReader {
     stdin: io::Stdin
 }
 
+impl FLVReader {
+    fn read_packet(&mut self) -> Result<(FLVTagType, Vec<u8>), Box<dyn Error>> {
+        let mut tag_head = [0u8; 11];
+        self.stdin.read_exact(&mut tag_head)?;
+        let tag_type = FLVTagType::try_from(tag_head[0])?;
+        let tag_data_len = (u32::from_be_bytes(tag_head[..4].try_into()?) & 0xffffff) as usize;
+        let mut packet_data = vec![0u8; tag_data_len];
+        self.stdin.read_exact(packet_data.as_mut_slice())?;
+        let mut packet_foot = [0u8; 4];
+        self.stdin.read_exact(&mut packet_foot)?;
+
+        return Ok((tag_type, packet_data));
+    }
+}
+
 impl input::FileReader for FLVReader {
     fn init(&mut self) -> Result<util::Metadata, Box<dyn Error>> {
         todo!();