Fixes race conditions in multi channel signal

When the output count changes, we build new signals instead of tempering with the previous ones. Once those new signals are built, we can adjust the buffers in the audio thread without having to worry about them getting changed.

Author: azeno

VL.Audio.UI/deployment/VL.Audio.UI.nuspec

@@ -2,7 +2,7 @@
 <package xmlns="http://schemas.microsoft.com/packaging/2011/10/nuspec.xsd">
   <metadata>
     <id>VL.Audio.UI</id>
-    <version>1.9.10</version>
+    <version>1.9.11</version>
     <title>VL.Audio.UI</title>
     <authors>vvvv</authors>
     <owners>vvvv</owners>
@@ -11,7 +11,7 @@
     <description>Extension pack for VL.Audio that brings in UI's for driver configuration and more</description>
     <tags>VL</tags>
     <dependencies>
-	  <dependency id="VL.Audio" version="1.9.10" />
+	  <dependency id="VL.Audio" version="1.9.11" />
 	  <dependency id="VL.ImGui.Skia" version="2024.6.7" />
     </dependencies>
     <license type="expression">LGPL-3.0-only</license>

VL.Audio/VL.Audio.vl

@@ -2,7 +2,7 @@
 <package xmlns="http://schemas.microsoft.com/packaging/2011/10/nuspec.xsd">
   <metadata>
     <id>VL.Audio</id>
-    <version>1.9.10</version>
+    <version>1.9.11</version>
     <title>VL.Audio</title>
     <authors>NAudio, vvvv</authors>
     <owners>vvvv</owners>

VL.Audio/deployment/VL.Audio.nuspec

@@ -1,6 +1,7 @@
 #region usings
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Runtime.InteropServices;
 
@@ -23,6 +24,8 @@ public void SetBuffer(float[] buffer)
         }
 
         float[] FBuffer;
+
+        internal float[] Buffer => FBuffer;
 
         protected override void FillBuffer(float[] buffer, int offset, int count)
         {
@@ -45,55 +48,62 @@ public override void Dispose()
     /// </summary>
     public class MultiChannelSignal : AudioSignal
     {
-        protected int FOutputCount;
+        private ImmutableArray<SingleSignal> FOutputs = ImmutableArray<SingleSignal>.Empty;
+
         public MultiChannelSignal()
         {
-            Outputs = new List<AudioSignal>();
             SetOutputCount(2);
         }
 
         public void SetOutputCount(int newCount)
         {
-            //recreate output signals?
-            if(FOutputCount != newCount)
+            if (newCount != FOutputs.Length)
             {
-                FOutputCount = newCount;
-                
-                Outputs.ResizeAndDispose(newCount, () => new SingleSignal(Read));
+                foreach (var s in FOutputs)
+                    s.Dispose();
 
-                FReadBuffers = new float[FOutputCount][];
-            }
-            
-            //make sure new buffers get assigned by the manage buffers method
-            if(FOutputCount > 0)
-            {
-                FReadBuffers = new float[FOutputCount][];
+                var outputs = ImmutableArray.CreateBuilder<SingleSignal>(newCount);
+                for (int i = 0; i < newCount; i++)
+                    outputs.Add(new SingleSignal(Read));
+                FOutputs = outputs.MoveToImmutable();
+                FNeedsRead = true;
             }
         }
-        
-        public List<AudioSignal> Outputs
-        {
-            get;
-            protected set;
-        }
-        
+
+        public IReadOnlyList<AudioSignal> Outputs => FOutputs;
+        public int OutputCount => FOutputs.Length;
+
         protected float[][] FReadBuffers;
         protected void ManageBuffers(int count)
         {
-            if(FReadBuffers[0] is null || FReadBuffers[0].Length < count)
+            var outputs = FOutputs;
+            if (!BuffersAreLargeEnough(outputs, count))
             {
-                FReadBuffers = new float[FOutputCount][];
-                for (int i = 0; i < FOutputCount; i++)
+                FReadBuffers = new float[outputs.Length][];
+                for (int i = 0; i < FReadBuffers.Length; i++)
                 {
                     FReadBuffers[i] = GC.AllocateArray<float>(count, pinned: true);
-                    (Outputs[i] as SingleSignal).SetBuffer(FReadBuffers[i]);
+                    outputs[i].SetBuffer(FReadBuffers[i]);
                 }
             }
+
+            static bool BuffersAreLargeEnough(ImmutableArray<SingleSignal> outputs, int count)
+            {
+                foreach (var o in outputs)
+                    if (!BufferIsLargeEnough(o.Buffer, count))
+                        return false;
+                return true;
+            }
+
+            static bool BufferIsLargeEnough(float[] buffer, int count)
+            {
+                return buffer != null && buffer.Length >= count;
+            }
         }
 
         protected void Read(int offset, int count)
         {
-            if(FNeedsRead && FOutputCount > 0)
+            if (FNeedsRead && FOutputs.Length > 0)
             {
                 ManageBuffers(count);
                 FillBuffers(FReadBuffers, offset, count);
@@ -122,36 +132,6 @@ public override void Dispose()
             base.Dispose();
         }
     }
-    
-    public static class ListExtra
-    {
-        public static void ResizeAndDispose<T>(this List<T> list, int newSize, Func<T> create)
-        {
-            int count = list.Count;
-            if(newSize < count)
-            {
-                var itemCount = count - newSize;
-                var toRemove = list.GetRange(newSize, itemCount);
-                toRemove.Reverse();
-                foreach(var item in toRemove)
-                {
-                    list.Remove(item);
-                    var disposable = item as IDisposable;
-                    if(item != null)
-                        disposable.Dispose();
-                }
-            }
-            else if(newSize > count)
-            {
-                var itemCount = newSize - count;
-                
-                for(int i=0; i < itemCount; i++)
-                {
-                    list.Add(create());
-                }
-            }
-        }
-    }
 }
 
 

VL.Audio/src/Core/MultiChannelSignal.cs

@@ -25,11 +25,7 @@ public AudioSignalToAudioStream()
 
         public IReadOnlyList<AudioSignal> Update(IReadOnlyList<AudioSignal> input, string metadata, out AudioStream audioStream)
         {
-            if (input.Count != FOutputCount)
-            {
-                SetOutputCount(input.Count);
-                FNeedsRead = true;
-            }
+            SetOutputCount(input.Count);
 
             Input = input;
             _metadata = metadata;

VL.Audio/src/Nodes/AudioSignalToAudioStream.cs

@@ -42,7 +42,7 @@ protected override void FillBuffers(float[][] buffers, int offset, int sampleCou
             }
             else
             {
-                if (audioFrame.ChannelCount != FOutputCount)
+                if (audioFrame.ChannelCount != OutputCount)
                 {
                     SetOutputCount(audioFrame.ChannelCount);
                     ManageBuffers(sampleCount);

VL.Audio/src/Nodes/AudioSourceToAudioSignal.cs

@@ -2,7 +2,7 @@
   "profiles": {
     "VL.Audio": {
       "commandName": "Executable",
-      "executablePath": "C:\\Program Files\\vvvv\\vvvv_gamma_5.3-0192-g8dd4ea9c96\\vvvv.exe",
+      "executablePath": "C:\\Program Files\\vvvv\\vvvv_gamma_7.0-0305-g98ea128603-win-x64\\vvvv.exe",
       "commandLineArgs": "--package-repositories $(ParentDirectoryOfThisRepo) --editable-packages VL.Audio"
     }
   }

VL.Audio/src/Properties/launchSettings.json

@@ -15,7 +15,7 @@ public int OutputChannelCount
         {
             get
             {
-                return this.FOutputCount;
+                return this.OutputCount;
             }
             set
             {
@@ -31,12 +31,12 @@ protected override void FillBuffers(float[][] buffer, int offset, int count)
             if (FInput != null && FInput.Count != 0) 
             {
                 FTempBuffer = BufferHelpers.Ensure(FTempBuffer, count);
-                for (int outSlice = 0; outSlice < FOutputCount; outSlice++)
+                for (int outSlice = 0; outSlice < buffer.Length; outSlice++)
                 {
                     var outbuf = buffer[outSlice];
                     for (int inSlice = 0; inSlice < FInput.Count; inSlice++)
                     {
-                        var gain = GainMatrix[outSlice + inSlice * FOutputCount];
+                        var gain = GainMatrix[outSlice + inSlice * buffer.Length];
                         var inSig = FInput[inSlice];
                         if (inSig != null)
                         {

VL.Audio/src/Signals/Routing/MatrixMixerSignal.cs

@@ -11,6 +11,11 @@ namespace VL.Audio
 {
     public class FileStreamSignal : MultiChannelSignal
     {
+        private readonly BlockingCollection<AudioFileReaderVVVV> FFileQueue = new(boundedCapacity: 1);
+        private readonly BlockingCollection<float> FSeekQueue = new(boundedCapacity: 1);
+        private readonly ManualResetEvent FInTheWorks = new ManualResetEvent(true);
+        private AudioFileReaderVVVV FAudioFile;
+
         public bool FLoop;
 
         public bool FPlay = false;
@@ -21,19 +26,31 @@ public class FileStreamSignal : MultiChannelSignal
 
         public TimeSpan FSeekTime;
 
-        public AudioFileReaderVVVV FAudioFile;
+        public double Speed { get; set; }
+
+        public float Volume { get; set; } = 1f;
+
+        public float Position => FAudioFile != null ? (float)FAudioFile.CurrentTime.TotalSeconds : 0f;
+
+        public float Duration { get; private set; }
+
+        public bool CanSeek { get; private set; }
+
+        public int Channels { get; private set; }
+
+        public int OriginalSampleRate { get; private set; }
 
-        private BlockingCollection<AudioFileReaderVVVV> FFileQueue = new(boundedCapacity: 1);
-        private ManualResetEvent FInTheWorks = new ManualResetEvent(true);
+        public string OriginalFormat { get; private set; }
 
-        public double Speed 
+        public void Seek(float seekTime)
         {
-            get;
-            set;
+            if (!FSeekQueue.TryAddSafe(seekTime))
+            {
+                FSeekQueue.TryTake(out _);
+                FSeekQueue.TryAddSafe(seekTime);
+            }
         }
 
-        public float Volume { get; set; } = 1f;
-
         public void OpenFile(string filename)
         {
             if (FFileQueue.TryTake(out var oldfile))
@@ -45,11 +62,23 @@ public void OpenFile(string filename)
                 //NOTE: switching between files of different output count may cause troubles here:
                 SetOutputCount(audiofile.WaveFormat.Channels);
                 FFileQueue.TryAddSafe(audiofile);
+
+                Duration = (float)audiofile.TotalTime.TotalSeconds;
+                CanSeek = audiofile.CanSeek;
+                Channels = audiofile.WaveFormat.Channels;
+                OriginalSampleRate = audiofile.WaveFormat.SampleRate;
+                OriginalFormat = audiofile.OriginalFileFormat.ToString();
             }
             else 
             {
                 SetOutputCount(0);
                 FFileQueue.TryAddSafe(null);
+
+                Duration = default;
+                CanSeek = default;
+                Channels = default;
+                OriginalSampleRate = default;
+                OriginalFormat = string.Empty;
             }
         }
 
@@ -74,6 +103,9 @@ protected override void FillBuffers(float[][] buffer, int offset, int sampleCoun
             FInTheWorks.Reset();
             try
             {
+                if (FSeekQueue.TryTake(out var seekTime))
+                    FAudioFile.CurrentTime = TimeSpan.FromSeconds(seekTime);
+
                 FAudioFile.Volume = Volume;
 
                 var channels = FAudioFile.WaveFormat.Channels;