TASK 4 ship step 3: encoder + RTMP push — FFmpeg subprocess with probed H.264 picker, BGRA stdin feed, stderr health parsing, graceful stop — 122 tests passing, 0 warnings

Services/Encoder/FfmpegEncoderProcess.cs

@@ -0,0 +1,38 @@
+using System.Diagnostics;
+using System.IO;
+
+namespace ytLive.Services.Encoder;
+
+/// <summary>
+/// The real <see cref="IEncoderProcess"/>: a <see cref="Process"/> with all three
+/// std streams redirected. Constructed by <see cref="FfmpegEncoder"/> for both the
+/// encoder subprocess and the <c>-encoders</c> probe.
+/// </summary>
+public sealed class FfmpegEncoderProcess : IEncoderProcess
+{
+    private readonly Process _process;
+
+    public FfmpegEncoderProcess() => _process = new Process { EnableRaisingEvents = true };
+
+    public void Start(ProcessStartInfo startInfo)
+    {
+        _process.StartInfo = startInfo;
+        _process.Start();
+    }
+
+    public Stream StandardInput => _process.StandardInput.BaseStream;
+    public TextReader StandardOutput => _process.StandardOutput;
+    public TextReader StandardError => _process.StandardError;
+
+    public bool HasExited => _process.HasExited;
+    public int ExitCode => _process.ExitCode;
+    public void Kill()
+    {
+        if (!_process.HasExited) _process.Kill();
+    }
+
+    public Task WaitForExitAsync(CancellationToken cancellationToken = default)
+        => _process.WaitForExitAsync(cancellationToken);
+
+    public void Dispose() => _process.Dispose();
+}