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

2026-08-12 20:32:24 -07:00
parent e494dce311
commit ba427e85e1
13 changed files with 891 additions and 62 deletions
@@ -0,0 +1,46 @@
+namespace ytLive.Services.Encoder;
+
+/// <summary>
+/// Builds the FFmpeg command line for a live RTMP push (TASK 4 ship step 3):
+/// raw BGRA frames via stdin (paced <c>-re</c>), silent placeholder audio via lavfi
+/// <c>anullsrc</c> (the WASAPI step replaces this input), H.264 + AAC encoding, FLV
+/// muxing to the ingestion URL. Pure — the encoder just starts
+/// <c>ffmpeg.exe [Build(...)]</c>.
+/// </summary>
+public static class FfmpegArgs
+{
+    public static IReadOnlyList<string> Build(EncoderOptions options, string videoEncoder)
+    {
+        var gop = options.GopSize;
+        return
+        [
+            "-hide_banner",
+            "-loglevel", "info",
+            "-stats",
+            "-stats_period", "0.5",
+            "-re",
+            "-f", "rawvideo",
+            "-pix_fmt", "bgra",
+            "-video_size", $"{options.Width}x{options.Height}",
+            "-framerate", options.Fps.ToString(),
+            "-i", "pipe:0",
+            "-f", "lavfi",
+            "-i", $"anullsrc=channel_layout=stereo:sample_rate={options.AudioSampleRate}",
+            "-c:v", videoEncoder,
+            "-b:v", $"{options.BitrateKbps}k",
+            "-maxrate", $"{options.BitrateKbps}k",
+            "-bufsize", $"{options.BitrateKbps * 2}k",
+            "-g", gop.ToString(),
+            "-keyint_min", gop.ToString(),
+            "-sc_threshold", "0",
+            "-bf", "0",
+            "-pix_fmt", "yuv420p",
+            "-c:a", "aac",
+            "-b:a", "128k",
+            "-ar", options.AudioSampleRate.ToString(),
+            "-ac", options.AudioChannels.ToString(),
+            "-f", "flv",
+            options.RtmpUrl,
+        ];
+    }
+}