Fixed looped audio playback position calculation (#6325)

* fix: looped audio position calculation

* refactor: tiny clean up

* move comment

* fix: review changes

* remove `

* rerun tests

* Remove unecessary formatting changes

---------

Co-authored-by: PJB3005 <pieterjan.briers+git@gmail.com>

Robust.Client/Audio/AudioSystem.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Numerics;
 using JetBrains.Annotations;
-using OpenTK.Audio.OpenAL;
 using Robust.Client.GameObjects;
 using Robust.Client.Graphics;
 using Robust.Client.Player;
@@ -17,7 +16,6 @@ using Robust.Shared.Exceptions;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
-using Robust.Shared.Map.Components;
 using Robust.Shared.Physics;
 using Robust.Shared.Physics.Components;
 using Robust.Shared.Physics.Systems;
@@ -182,14 +180,16 @@ public sealed partial class AudioSystem : SharedAudioSystem
         }
 
         // If playback position changed then update it.
-        var position = (float) ((entity.Comp.PauseTime ?? Timing.CurTime) - entity.Comp.AudioStart).TotalSeconds;
+        var totalLen = GetAudioLengthImpl(entity.Comp.FileName).TotalSeconds;
+        var position = CalculateAudioPosition(entity, (float) totalLen);
+
         var currentPosition = entity.Comp.Source.PlaybackPosition;
         var diff = Math.Abs(position - currentPosition);
 
         // Don't try to set the audio too far ahead.
         if (!string.IsNullOrEmpty(entity.Comp.FileName))
         {
-            if (position > GetAudioLengthImpl(entity.Comp.FileName).TotalSeconds - _audioEndBuffer)
+            if (position > totalLen - _audioEndBuffer)
             {
                 entity.Comp.StopPlaying();
                 return;
@@ -251,7 +251,7 @@ public sealed partial class AudioSystem : SharedAudioSystem
         length ??= GetAudioLength(component.FileName);
 
         // If audio came into range then start playback at the correct position.
-        var offset = ((entity.Comp.PauseTime ?? Timing.CurTime) - component.AudioStart).TotalSeconds;
+        var offset = CalculateAudioPosition(entity, (float) length.Value.TotalSeconds);
 
         if (TryAudioLimit(component.FileName))
         {
@@ -289,7 +289,7 @@ public sealed partial class AudioSystem : SharedAudioSystem
 
         if (offset > 0)
         {
-            component.PlaybackPosition = (float) offset;
+            component.PlaybackPosition = offset;
         }
     }
 
@@ -755,10 +755,7 @@ public sealed partial class AudioSystem : SharedAudioSystem
         var comp = entity.Comp;
         var source = comp.Source;
 
-        // TODO clamp the offset inside of SetPlaybackPosition() itself.
-        var offset = audioP.PlayOffsetSeconds;
-        var maxOffset = Math.Max((float) stream.Length.TotalSeconds - 0.01f, 0f);
-        offset = Math.Clamp(offset, 0f, maxOffset);
+        var offset = CalculateAudioPosition(entity, (float)stream.Length.TotalSeconds, audioP.PlayOffsetSeconds);
         source.PlaybackPosition = offset;
 
         source.StartPlaying();

Robust.Shared/Audio/Systems/SharedAudioSystem.cs

@@ -75,6 +75,7 @@ public abstract partial class SharedAudioSystem : EntitySystem
             return;
 
         var audioLength = GetAudioLength(entity.Comp.FileName);
+        position = CalculateAudioPosition(entity!, (float)audioLength.TotalSeconds, position);
 
         if (audioLength.TotalSeconds < position)
         {
@@ -86,12 +87,6 @@ public abstract partial class SharedAudioSystem : EntitySystem
             return;
         }
 
-        if (position < 0f)
-        {
-            Log.Error($"Tried to set playback position for {ToPrettyString(entity.Owner)} / {entity.Comp.FileName} outside of bounds");
-            return;
-        }
-
         // If we're paused then the current position is <pause time - start time>, else it's <cur time - start time>
         var currentPos = (entity.Comp.PauseTime ?? Timing.CurTime) - entity.Comp.AudioStart;
         var timeOffset = TimeSpan.FromSeconds(position - currentPos.TotalSeconds);
@@ -315,6 +310,36 @@ public abstract partial class SharedAudioSystem : EntitySystem
         return GetAudioPath(resolved);
     }
 
+    /// <summary>
+    /// Calculates the current playback position of an audio entity
+    /// and clamps it to the range from 0 to (length - 0.01f).
+    /// </summary>
+    /// <param name="ent">The audio entity.</param>
+    /// <param name="length">
+    /// The total length of the audio file.
+    /// If null, the method retrieves the length using <see cref="GetAudioLength"/>.
+    /// </param>
+    /// <param name="position">
+    /// A precomputed playback position.
+    /// If provided, it will be added to the calculation.
+    /// </param>
+    /// <returns>The playback position as a float.</returns>
+    protected float CalculateAudioPosition(Entity<AudioComponent> ent, float? length = null, float? position = null)
+    {
+        position ??= (float) ((ent.Comp.PauseTime ?? Timing.CurTime) - ent.Comp.AudioStart).TotalSeconds;
+        length ??= (float) GetAudioLength(ent.Comp.FileName).TotalSeconds;
+
+        // Looped audio has no conceptual start or end.
+        if (ent.Comp.Params.Loop)
+            position %= length;
+
+        // TODO clamp the offset inside of AudioSource.SetPlaybackPosition() itself.
+        var maxOffset = Math.Max((float) length - 0.01f, 0f);
+        position = Math.Clamp(position.Value, 0f, maxOffset);
+
+        return position.Value;
+    }
+
     #region AudioParams
 
     [return: NotNullIfNotNull(nameof(specifier))]