feat(editor/checks): check for delayed hitsounds

I really just borrowed the implementation from MapsetVerifier

osu.Game.Tests/Editing/Checks/CheckDelayedHitsoundsTest.cs

@@ -0,0 +1,97 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.IO;
+using System.Linq;
+using ManagedBass;
+using Moq;
+using NUnit.Framework;
+using osu.Game.Beatmaps;
+using osu.Game.Models;
+using osu.Game.Rulesets.Edit;
+using osu.Game.Rulesets.Edit.Checks;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Tests.Beatmaps;
+using osu.Game.Tests.Resources;
+using osuTK.Audio;
+
+namespace osu.Game.Tests.Editing.Checks
+{
+    [TestFixture]
+    public class CheckDelayedHitsoundsTest
+    {
+        private CheckDelayedHitsounds check = null!;
+        private IBeatmap beatmap = null!;
+
+        [SetUp]
+        public void SetUp()
+        {
+            check = new CheckDelayedHitsounds();
+            beatmap = new Beatmap<HitObject>
+            {
+                BeatmapInfo = new BeatmapInfo
+                {
+                    BeatmapSet = new BeatmapSetInfo
+                    {
+                        Files =
+                        {
+                            new RealmNamedFileUsage(new RealmFile { Hash = "abcdef" }, "normal-hitnormal.wav"),
+                        }
+                    }
+                }
+            };
+
+            if (!Bass.Init(0) && Bass.LastError != Errors.Already)
+                throw new AudioException("Could not initialize Bass.");
+        }
+
+        [Test]
+        public void TestNoDelayedHitsounds()
+        {
+            using var resourceStream = TestResources.OpenResource("Samples/hitsound-no-delay.wav");
+            Assert.IsEmpty(check.Run(getContext(resourceStream)));
+        }
+
+        [Test]
+        public void TestMinorDelayedHitsounds()
+        {
+            using (var resourceStream = TestResources.OpenResource("Samples/hitsound-minor-delay.wav"))
+            {
+                var issues = check.Run(getContext(resourceStream)).ToList();
+
+                Assert.That(issues, Has.Count.EqualTo(1));
+                Assert.That(issues.Single().Template is CheckDelayedHitsounds.IssuTemplateMinorDelay);
+            }
+        }
+
+        [Test]
+        public void TestDelayedHitsounds()
+        {
+            using var resourceStream = TestResources.OpenResource("Samples/hitsound-delay.wav");
+
+            var issues = check.Run(getContext(resourceStream)).ToList();
+
+            Assert.That(issues, Has.Count.EqualTo(1));
+            Assert.That(issues.Single().Template is CheckDelayedHitsounds.IssueTemplateDelay);
+        }
+
+        [Test]
+        public void TestConsequentlyDelayedHitsounds()
+        {
+            using var resourceStream = TestResources.OpenResource("Samples/hitsound-consequent-delay.wav");
+
+            var issues = check.Run(getContext(resourceStream)).ToList();
+
+            Assert.That(issues, Has.Count.EqualTo(1));
+            Assert.That(issues.Single().Template is CheckDelayedHitsounds.IssueTemplateConsequentDelay);
+        }
+
+        private BeatmapVerifierContext getContext(Stream? resourceStream)
+        {
+            var mockWorkingBeatmap = new Mock<TestWorkingBeatmap>(beatmap, null, null);
+            mockWorkingBeatmap.Setup(w => w.GetStream(It.IsAny<string>())).Returns(resourceStream);
+
+            return new BeatmapVerifierContext(beatmap, mockWorkingBeatmap.Object);
+        }
+    }
+}

osu.Game/Rulesets/Edit/BeatmapVerifier.cs

@@ -26,6 +26,7 @@ namespace osu.Game.Rulesets.Edit
             new CheckFewHitsounds(),
             new CheckTooShortAudioFiles(),
             new CheckAudioInVideo(),
+            new CheckDelayedHitsounds(),
 
             // Files
             new CheckZeroByteFiles(),

osu.Game/Rulesets/Edit/Checks/CheckDelayedHitsounds.cs

@@ -0,0 +1,138 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using osu.Framework.Audio.Track;
+using osu.Game.Audio;
+using osu.Game.Extensions;
+using osu.Game.Rulesets.Edit.Checks.Components;
+
+namespace osu.Game.Rulesets.Edit.Checks
+{
+    public class CheckDelayedHitsounds : ICheck
+    {
+        /// <summary>
+        /// Threshold at which point the sample is considered silent.
+        /// </summary>
+        private const float silence_threshold = 0.001f;
+
+        private const float falloff_factor = 0.95f;
+        private const int delay_threshold = 5;
+        private const int delay_threshold_negligible = 1;
+
+        private readonly string[] audioExtensions = { "mp3", "ogg", "wav" };
+        private readonly string[] sampleBankPrefixes = { HitSampleInfo.BANK_NORMAL, HitSampleInfo.BANK_SOFT, HitSampleInfo.BANK_DRUM };
+
+        public CheckMetadata Metadata => new CheckMetadata(CheckCategory.Audio, "Delayed hit sounds.");
+
+        public IEnumerable<IssueTemplate> PossibleTemplates => new IssueTemplate[]
+        {
+            new IssueTemplateConsequentDelay(this),
+            new IssueTemplateDelay(this),
+            new IssuTemplateMinorDelay(this)
+        };
+
+        private float getAverageAmplitude(Waveform.Point point) => (point.AmplitudeLeft + point.AmplitudeRight) / 2;
+
+        public IEnumerable<Issue> Run(BeatmapVerifierContext context)
+        {
+            var beatmapSet = context.Beatmap.BeatmapInfo.BeatmapSet;
+
+            if (beatmapSet == null)
+                yield break;
+
+            foreach (var file in beatmapSet.Files)
+            {
+                using (Stream stream = context.WorkingBeatmap.GetStream(file.File.GetStoragePath()))
+                {
+                    if (stream == null)
+                        continue;
+
+                    if (!hasAudioExtension(file.Filename))
+                        continue;
+
+                    if (!isHitSound(file.Filename))
+                        continue;
+
+                    Waveform waveform = new Waveform(stream);
+
+                    var points = waveform.GetPoints();
+
+                    // Skip muted samples
+                    if (points.Length == 0 || points.Sum(getAverageAmplitude) <= silence_threshold)
+                        continue;
+
+                    float maxAmplitude = points.Select(getAverageAmplitude).Max();
+
+                    int consequentDelay = 0;
+                    int delay = 0;
+                    float amplitude = 0;
+
+                    while (delay + consequentDelay < points.Length)
+                    {
+                        amplitude += getAverageAmplitude(points[delay]);
+
+                        // Reached peak amplitude/transient
+                        if (amplitude >= maxAmplitude)
+                            break;
+
+                        amplitude *= falloff_factor;
+
+                        if (amplitude < silence_threshold)
+                        {
+                            amplitude = 0;
+                            consequentDelay++;
+                        }
+
+                        delay++;
+                    }
+
+                    if (consequentDelay >= delay_threshold)
+                        yield return new IssueTemplateConsequentDelay(this).Create(file.Filename, consequentDelay);
+                    else if (consequentDelay + delay >= delay_threshold)
+                        yield return new IssueTemplateDelay(this).Create(file.Filename, consequentDelay, delay);
+                    else if (consequentDelay + delay >= delay_threshold_negligible)
+                        yield return new IssuTemplateMinorDelay(this).Create(file.Filename, consequentDelay, delay);
+                }
+            }
+        }
+
+        private bool hasAudioExtension(string filename) => audioExtensions.Any(filename.ToLowerInvariant().EndsWith);
+        private bool isHitSound(string filename) => sampleBankPrefixes.Select(p => p + "-").Any(filename.ToLowerInvariant().StartsWith);
+
+        public class IssueTemplateConsequentDelay : IssueTemplate
+        {
+            public IssueTemplateConsequentDelay(ICheck check)
+                : base(check, IssueType.Error,
+                    "\"{0}\" has a {1:0.##} ms period of complete silence at the start.")
+            {
+            }
+
+            public Issue Create(string filename, int pureDelay) => new Issue(this, filename, pureDelay);
+        }
+
+        public class IssueTemplateDelay : IssueTemplate
+        {
+            public IssueTemplateDelay(ICheck check)
+                : base(check, IssueType.Warning,
+                    "\"{0}\" has a transient delay of ~{1:0.##} ms, of which {2:0.##} ms is complete silence.")
+            {
+            }
+
+            public Issue Create(string filename, int pureDelay, int delay) => new Issue(this, filename, delay, pureDelay);
+        }
+
+        public class IssuTemplateMinorDelay : IssueTemplate
+        {
+            public IssuTemplateMinorDelay(ICheck check)
+                : base(check, IssueType.Negligible,
+                    "\"{0}\"has a transient delay of ~{1:0.##} ms, of which {2:0.##} ms is complete silence.")
+            {
+            }
+
+            public Issue Create(string filename, int pureDelay, int delay) => new Issue(this, filename, delay, pureDelay);
+        }
+    }
+}