add pipe example

examples/pipe_ffmpeg.rs

@@ -0,0 +1,95 @@
+use std::{
+    io::{prelude::*, Read},
+    process::{Command, Stdio},
+    thread::sleep,
+    time::Duration,
+};
+
+fn main() {
+    let mut enc_proc = match Command::new("ffplay")
+        .args(["-v", "error", "-hide_banner", "-nostats", "-i", "pipe:0"])
+        .stdin(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+    {
+        Err(e) => panic!("couldn't spawn ffplay: {}", e),
+        Ok(proc) => proc,
+    };
+
+    let mut buffer: [u8; 65424] = [0; 65424];
+
+    let mut dec_proc = match Command::new("ffmpeg")
+        .args([
+            "-f",
+            "lavfi",
+            "-i",
+            "testsrc=duration=6:size=1280x720:rate=25",
+            "-f",
+            "lavfi",
+            "-i",
+            "anoisesrc=d=6:c=pink:r=48000:a=0.5",
+            "-pix_fmt",
+            "yuv420p",
+            "-c:v",
+            "mpeg2video",
+            "-g",
+            "1",
+            "-b:v",
+            "50000k",
+            "-minrate",
+            "50000k",
+            "-maxrate",
+            "50000k",
+            "-bufsize",
+            "25000k",
+            "-c:a",
+            "s302m",
+            "-strict",
+            "-2",
+            "-ar",
+            "48000",
+            "-ac",
+            "2",
+            "-f",
+            "mpegts",
+            "-",
+        ])
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+    {
+        Err(e) => panic!("couldn't spawn ffmpeg: {}", e),
+        Ok(proc) => proc,
+    };
+
+    let mut enc_writer = enc_proc.stdin.as_ref().unwrap();
+    let dec_reader = dec_proc.stdout.as_mut().unwrap();
+
+    loop {
+        let bytes_len = match dec_reader.read(&mut buffer[..]) {
+            Ok(length) => length,
+            Err(e) => panic!("Reading error from decoder: {:?}", e)
+        };
+
+        match enc_writer.write(&buffer[..bytes_len]) {
+            Ok(_) => (),
+            Err(e) => panic!("Err: {:?}", e),
+        };
+
+        if bytes_len == 0 {
+            break;
+        }
+    }
+
+    match dec_proc.wait() {
+        Ok(_) => println!("decoding done..."),
+        Err(e) => panic!("Enc error: {:?}", e),
+    }
+
+    sleep(Duration::from_secs(1));
+
+    match enc_proc.kill() {
+        Ok(_) => println!("Playout done..."),
+        Err(e) => panic!("Enc error: {:?}", e),
+    }
+}