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/FfmpegProgressParser.cs

@@ -0,0 +1,47 @@
+using System.Text.RegularExpressions;
+
+namespace ytLive.Services.Encoder;
+
+/// <summary>A decoded ffmpeg <c>-stats</c> progress line (pure data).</summary>
+public readonly record struct FfmpegProgress(
+    long Frame,
+    double Fps,
+    double BitrateKbps,
+    TimeSpan Duration,
+    long SizeBytes);
+
+/// <summary>
+/// Pure parser for ffmpeg's periodic <c>frame= fps= size= time= bitrate=</c> stderr
+/// lines (the <c>-stats</c>/<c>-stats_period</c> output). Unit-tested in isolation
+/// so the encoder loop stays a thin wire.
+/// </summary>
+public static class FfmpegProgressParser
+{
+    // frame=  123 fps= 59.9 q=28.0 size=   1024KiB time=00:00:02.04 bitrate= 4000.1kbits/s speed=1.00x
+    private static readonly Regex Line = new(
+        @"frame=\s*(?<frame>\d+)\s+fps=\s*(?<fps>[\d.]+).*?"
+        + @"size=\s*(?<size>\d+)KiB.*?"
+        + @"time=(?<time>\d{2}):(?<min>\d{2}):(?<sec>[\d.]+).*?"
+        + @"bitrate=\s*(?<bitrate>[\d.]+)kbits/s",
+        RegexOptions.Compiled | RegexOptions.CultureInvariant);
+
+    /// <summary>Returns null for non-progress lines (errors, warnings, banner).</summary>
+    public static FfmpegProgress? TryParse(string line)
+    {
+        if (string.IsNullOrWhiteSpace(line)) return null;
+        var m = Line.Match(line);
+        if (!m.Success) return null;
+
+        var frame = long.Parse(m.Groups["frame"].Value);
+        var fps = double.Parse(m.Groups["fps"].Value, System.Globalization.CultureInfo.InvariantCulture);
+        var size = long.Parse(m.Groups["size"].Value);
+        var bitrate = double.Parse(m.Groups["bitrate"].Value, System.Globalization.CultureInfo.InvariantCulture);
+
+        var hours = int.Parse(m.Groups["time"].Value);
+        var minutes = int.Parse(m.Groups["min"].Value);
+        var seconds = double.Parse(m.Groups["sec"].Value, System.Globalization.CultureInfo.InvariantCulture);
+        var duration = TimeSpan.FromSeconds(hours * 3600 + minutes * 60 + seconds);
+
+        return new FfmpegProgress(frame, fps, bitrate, duration, size * 1024);
+    }
+}