attempt at opus nalu reading

src/encode/codecs/audio.rs

@@ -2,6 +2,8 @@ use std::error::Error;
 use std::process::{Child, Command, Stdio, ChildStdin};
 use std::sync::Arc;
 use std::fs::File;
+use std::io::Read;
+use std::io;
 
 use crate::util;
 use crate::encode::codecs::Encoder;
@@ -20,7 +22,19 @@ impl Encoder for OpusEncoder {
     }
 
     fn read_nalu(&mut self) -> Result<util::NALUPacket, Box<dyn Error + Send + Sync>> {
-        todo!();
+        let mut stdout = self.cmd.stdout.as_mut().unwrap();
+        let mut buff = [0u8; 27];
+        match stdout.read_exact(&mut buff) {
+            Ok(_) => (),
+            Err(err) if err.kind() == io::ErrorKind::UnexpectedEof => return Err(Box::new(util::EncoderError::EOF)),
+            Err(err) => return Err(Box::new(err))
+        };
+        let num_segments = buff[buff.len() - 1] as usize;
+        let mut segment_table_buff = vec![0u8; num_segments];
+        stdout.read_exact(&mut segment_table_buff)?;
+        let mut data = vec![0u8; segment_table_buff.iter().sum::<u8>() as usize];
+        stdout.read_exact(&mut data)?;
+        return Ok(util::NALUPacket {packet_type: util::NALUPacketType::Audio(util::AudioCodec::OPUS), packet_data: data});
     }
 }