gramps
93719a286d
Step-down used a flat 3 Mbps (4 for vertical) as its floor — a number that had nothing to do with the tier being streamed. With CBR holding the target, that floor is a real picture-quality floor, so it has to follow YouTube's published H.264 table (support.google.com/youtube/answer/2853702): 6 at 1080p60, 5 at 1080p30, 3 at 720p. Models/RateLadder is that table as pure policy. Vertical is not a separate row: 1080x1920 and 1920x1080 are the same pixel count, so the frame rate alone picks the band. StepDownPolicy takes the floor as an optional constructor argument and refuses one above the starting rate, so an unusual start cannot begin under its own floor. Omitted, the historical 3/4 floor still applies, which keeps the existing policy tests meaningful and lets a caller opt in. One consequence worth knowing: the three-step budget can stop above the floor (12 → 9.6 → 7.7 → 6.2 from a 20% loss), so the floor is a limit, not a target. 669 pass, 0 warnings.
106 lines
4.2 KiB
C#
106 lines
4.2 KiB
C#
using System;
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using System.Windows;
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using ytLive.Helpers;
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using ytLive.Models;
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using ytLive.Services;
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using ytLive.Services.Encoder;
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namespace ytLive.ViewModels;
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/// <summary>
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/// TASK 33, slice 3: the session's step-down watch — policy feed, one encoder relaunch, one toast.
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///
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/// <para>Kept in its own file because it is the only place that both reads the pump's stats and acts on
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/// the session; the pure decision lives in <see cref="StepDownPolicy"/>, the sentence in
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/// <see cref="StepDownPlanner"/>.</para>
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/// </summary>
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public partial class MainViewModel
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{
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private StepDownPlanner? _stepDownPlanner;
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private (int Width, int Height, int Fps, double BitrateMbps)? _encoderTierOverride;
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private bool _stepDownBusy;
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/// <summary>Starts the watch for this broadcast. Called once per session, before the pump starts.</summary>
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private void StartStepDownWatch()
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{
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var quality = OutputProfile.Resolve(SelectedQuality, QualityOptions, HasProOutput);
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_encoderTierOverride = null;
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_stepDownPlanner = new StepDownPlanner(
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new StepDownPolicy(quality.Width, quality.Height, quality.Fps, quality.Bitrate,
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floorBitrateMbps: RateLadder.For(quality).Minimum),
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_sessionStartedAtUtc ?? DateTime.UtcNow);
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_framePump.StatsReported += OnPumpStatsReported;
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}
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/// <summary>Ends the watch. Called from StopStream on every path, so a stale planner can never
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/// carry a spent budget into the next broadcast.</summary>
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private void StopStepDownWatch()
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{
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_framePump.StatsReported -= OnPumpStatsReported;
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_stepDownPlanner = null;
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_encoderTierOverride = null;
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_stepDownBusy = false;
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_screenCaptureManager.ShedLoad(false); // never carry a shed cadence into the next show
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}
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/// <summary>Runs on the PUMP thread, so it must never block: the restart it may trigger stops the
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/// very loop that raised this event. Decide here (pure and fast), act on the dispatcher.</summary>
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private void OnPumpStatsReported(object? sender, FramePumpStats stats)
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{
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if (_stepDownPlanner is not { } planner) return;
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var decision = planner.Observe(stats, DateTime.UtcNow);
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if (!decision.Acted) return;
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var dispatcher = Application.Current?.Dispatcher;
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if (dispatcher == null) return;
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_ = dispatcher.InvokeAsync(() => ApplyStepDownAsync(decision));
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}
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private async void ApplyStepDownAsync(StepDownDecision decision)
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{
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var planner = _stepDownPlanner;
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if (planner == null || _stepDownBusy) return;
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_stepDownBusy = true;
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var landed = planner.Current;
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try
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{
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if (decision.Action == StepAction.ShedCaptureCadence)
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{
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_screenCaptureManager.ShedLoad(true);
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AppLog.Write($"Capture load shed: {decision.Why}");
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return;
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}
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_encoderTierOverride = landed;
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AppLog.Write($"Quality step-down: {decision.Why}");
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await _framePump.ChangeEncoderAsync(
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_audioMixer.StopLive,
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() => _audioMixer.StartLive(InstanceProfile.AudioPipeName(EncoderOptions.DefaultAudioPipeName)));
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// Show what is actually going out. The dropdown keeps the creator's choice — the policy
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// does not get to rewrite their intent, only the encoder's output.
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CurrentHealth.FPS = landed.Fps;
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CurrentHealth.CurrentBitrate = landed.BitrateMbps;
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ResolutionBadgeText = $"{landed.Width}×{landed.Height} @ {landed.Fps} fps · lowered";
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OnPropertyChanged(nameof(CurrentHealth));
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OnPropertyChanged(nameof(ResolutionBadgeText));
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var copy = StepDownPlanner.Describe(decision, landed);
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if (copy.Length > 0)
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_notifications.Info("Quality lowered", copy);
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AppLog.Write($"Quality step-down complete: {StepDownPlanner.ReportLine(DateTime.Now, decision)}");
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}
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catch (Exception ex)
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{
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AppLog.Write($"Quality step-down failed: {ex.Message}", AppLogMessageType.Error, AppLogErrorClass.Class2);
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}
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finally
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{
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_stepDownBusy = false;
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}
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}
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}
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