gramps
8fa78423e6
- 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.
68 lines
2.6 KiB
C#
68 lines
2.6 KiB
C#
using System.Diagnostics;
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using System.IO;
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using ytLive.Services.Encoder;
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namespace ytLive.Services;
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/// <summary>
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/// TASK 21 (slice 2): resolves the native frame rate of a media file so the
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/// decoder can pace frames to real time. Seam so <see cref="MediaVideoSource"/>
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/// never touches ffprobe directly and tests can fake the whole probe.
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/// </summary>
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public interface IFrameRateProbe
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{
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/// <summary>Native video FPS for <paramref name="path"/>, or null when unknown
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/// (no video stream, ffprobe unavailable, unparsable).</summary>
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Task<double?> ProbeAsync(string path, CancellationToken cancellationToken = default);
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}
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/// <summary>
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/// Default probe: locates ffmpeg (via <see cref="IFfmpegLocator"/>), derives the
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/// sibling <c>ffprobe.exe</c> from its directory, and asks ffprobe for the
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/// <c>avg_frame_rate</c>/<c>r_frame_rate</c>. Reuses the binary-stdout
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/// <see cref="IDecodeProcess"/> seam for the subprocess (ffprobe text is read from
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/// the same raw stdout). Returns null (no pacing) if ffprobe is unavailable.
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/// </summary>
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public sealed class FfmpegFrameRateProbe : IFrameRateProbe
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{
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private readonly IFfmpegLocator _locator;
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private readonly Func<IDecodeProcess> _probeProcessFactory;
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public FfmpegFrameRateProbe(IFfmpegLocator locator, Func<IDecodeProcess> probeProcessFactory)
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{
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_locator = locator;
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_probeProcessFactory = probeProcessFactory;
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}
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public async Task<double?> ProbeAsync(string path, CancellationToken cancellationToken = default)
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{
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if (string.IsNullOrWhiteSpace(path)) return null;
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var ffmpegPath = await _locator.LocateAsync(cancellationToken).ConfigureAwait(false);
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var ffprobePath = Path.Combine(Path.GetDirectoryName(ffmpegPath) ?? string.Empty, "ffprobe.exe");
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if (!File.Exists(ffprobePath)) return null;
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var startInfo = new ProcessStartInfo
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{
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FileName = ffprobePath,
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Arguments =
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$"-v error -select_streams v:0 " +
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$"-show_entries stream=avg_frame_rate,r_frame_rate " +
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$"-of default=noprint_wrappers=1 \"{path}\"",
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UseShellExecute = false,
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RedirectStandardOutput = true,
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RedirectStandardError = true,
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CreateNoWindow = true,
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};
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using var process = _probeProcessFactory();
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process.Start(startInfo);
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string output;
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using (var reader = new StreamReader(process.StandardOutput))
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output = reader.ReadToEnd();
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await process.WaitForExitAsync(cancellationToken).ConfigureAwait(false);
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return FfmpegFrameRateParser.ParseFrameRate(output);
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}
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}
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