TASK 21 slice 2a: native-FPS probe seam (ffprobe parse + derive sibling)

- FfmpegFrameRateParser (pure): prefers avg_frame_rate= then r_frame_rate=, rational N/N/M, unknown/0 -> null. - IFrameRateProbe + FfmpegFrameRateProbe: derives sibling ffprobe.exe from the located ffmpeg dir, reuses the IDecodeProcess seam for the ffprobe subprocess text; null if ffprobe absent. - FfmpegLocator now also extracts ffprobe.exe (ProbeFileName) from the pinned archive, conditional so old caches without it degrade to no pacing. - Tests: 6 pure parser units + 1 probe integration via fake locator/process; FfmpegLocatorTests still green. 15/15, 0 warnings. Pacing (probe->delay) is slice 2b. Derivative reference: standard ffprobe avg_frame_rate probing used across OBS/media tooling.
2026-08-31 19:45:48 -07:00
parent 071ec8be0c
commit 8fa78423e6
7 changed files with 267 additions and 4 deletions
@@ -0,0 +1,116 @@
+using System.Diagnostics;
+using System.IO;
+using Xunit;
+using ytLive.Services;
+using ytLive.Services.Encoder;
+
+namespace ytLive.Tests;
+
+/// <summary>
+/// TASK 21 (slice 2): the ffprobe frame-rate parser is pure (synthetic text, no
+/// probe); the one integration test drives the real <see cref="FfmpegFrameRateProbe"/>
+/// against a fake locator + fake probe subprocess end to end.
+/// </summary>
+public class FfmpegFrameRateParserTests
+{
+    // ─── Pure parser (unit) ───
+
+    [Fact]
+    public void Parse_AvgFrameRate_Rational()
+    {
+        var out0 = "codec_name=h264\navg_frame_rate=30/1\nr_frame_rate=30/1\n";
+        Assert.Equal(30.0, FfmpegFrameRateParser.ParseFrameRate(out0));
+    }
+
+    [Fact]
+    public void Parse_AvgFrameRate_29_97()
+    {
+        var out0 = "avg_frame_rate=30000/1001\nr_frame_rate=30/1\n";
+        Assert.Equal(30000.0 / 1001.0, FfmpegFrameRateParser.ParseFrameRate(out0)!.Value, 3);
+    }
+
+    [Fact]
+    public void Parse_PrefersAvgOverRFrame()
+    {
+        var out0 = "avg_frame_rate=25/1\nr_frame_rate=30000/1001\n";
+        Assert.Equal(25.0, FfmpegFrameRateParser.ParseFrameRate(out0));
+    }
+
+    [Fact]
+    public void Parse_FallsBackToRFrame_WhenAvgUnknown()
+    {
+        var out0 = "avg_frame_rate=0/0\nr_frame_rate=50/1\n";
+        Assert.Equal(50.0, FfmpegFrameRateParser.ParseFrameRate(out0));
+    }
+
+    [Fact]
+    public void Parse_IntegerValue_HasUnitDenominator()
+    {
+        var out0 = "avg_frame_rate=60\n";
+        Assert.Equal(60.0, FfmpegFrameRateParser.ParseFrameRate(out0));
+    }
+
+    [Theory]
+    [InlineData("avg_frame_rate=0/0\nr_frame_rate=0/0\n")]
+    [InlineData("")]
+    [InlineData("codec_name=h264\n")]
+    public void Parse_Unknown_ReturnsNull(string output)
+    {
+        Assert.Null(FfmpegFrameRateParser.ParseFrameRate(output));
+    }
+
+    // ─── The one integration test: probe against fake locator + fake subprocess ───
+
+    [Fact]
+    public async Task Probe_ReturnsParsedFps_FromFakeSubprocess()
+    {
+        var toolsDir = CreateTempDir();
+        try
+        {
+            // ffprobe.exe must exist next to the located ffmpeg for the sibling
+            // derivation to return a usable path.
+            var probeExe = Path.Combine(toolsDir, "ffprobe.exe");
+            File.WriteAllText(probeExe, "ffprobe");
+
+            var fakeOutput = "codec_name=h264\navg_frame_rate=24000/1001\nr_frame_rate=24000/1001\n";
+            var probe = new FfmpegFrameRateProbe(
+                new FakeLocator(toolsDir),
+                () => new FakeProbeProcess(System.Text.Encoding.UTF8.GetBytes(fakeOutput)));
+
+            var fps = await probe.ProbeAsync(@"C:\videos\clip.mp4");
+            Assert.Equal(24000.0 / 1001.0, fps!.Value, 3);
+        }
+        finally
+        {
+            Directory.Delete(toolsDir, recursive: true);
+        }
+    }
+
+    private static string CreateTempDir()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "ytllive-tests-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        return dir;
+    }
+
+    private sealed class FakeLocator : IFfmpegLocator
+    {
+        private readonly string _dir;
+        public FakeLocator(string dir) => _dir = dir;
+        public Task<string> LocateAsync(CancellationToken ct = default)
+            => Task.FromResult(Path.Combine(_dir, "ffmpeg.exe"));
+    }
+
+    private sealed class FakeProbeProcess : IDecodeProcess
+    {
+        private readonly MemoryStream _stream;
+        public FakeProbeProcess(byte[] bytes) => _stream = new MemoryStream(bytes);
+        public void Start(ProcessStartInfo startInfo) { }
+        public Stream StandardOutput => _stream;
+        public bool HasExited => _stream.Position >= _stream.Length;
+        public int ExitCode => 0;
+        public void Kill() { }
+        public Task WaitForExitAsync(CancellationToken ct = default) => Task.CompletedTask;
+        public void Dispose() => _stream.Dispose();
+    }
+}