From 71a7840a2d2b2d117b1567ae0f71cb1a60195fb2 Mon Sep 17 00:00:00 2001
From: VoidX <voidxb@gmail.com>
Date: Sat, 4 May 2024 22:54:48 +0200
Subject: [PATCH] Correct block size handling for downmixed render targets

---
 Cavern.Format/Output/AudioWriter.cs                |  6 +++++-
 CavernSamples/CavernizeGUI/MainWindow.Exporting.cs |  4 ++--
 CavernSamples/CavernizeGUI/MainWindow.Rendering.cs | 10 ++++------
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/Cavern.Format/Output/AudioWriter.cs b/Cavern.Format/Output/AudioWriter.cs
index f46e68c0..be48375e 100644
--- a/Cavern.Format/Output/AudioWriter.cs
+++ b/Cavern.Format/Output/AudioWriter.cs
@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 
+using Cavern.Format.Common;
 using Cavern.Format.Consts;
 using Cavern.Format.Container;
 
@@ -114,7 +115,10 @@ internal static Stream Open(string path) =>
         /// <param name="channels">Channel count of the input array</param>
         /// <param name="from">Start position in the input array (inclusive)</param>
         /// <param name="to">End position in the input array (exclusive)</param>
-        /// <remarks>This function is destructive, <paramref name="samples"/> will be unusable after the operation.</remarks>
+        /// <remarks>This function is destructive, <paramref name="samples"/> will be unusable after the operation.
+        /// Also, make sure when this <see cref="AudioWriter"/> is writing into a <see cref="ContainerWriter"/>, its
+        /// <see cref="RenderTrack.timeStep"/> is set correctly - not to a multiple of <paramref name="channels"/>,
+        /// but <paramref name="channelLimit"/>.</remarks>
         public virtual void WriteChannelLimitedBlock(float[] samples, int channelLimit, int channels, long from, long to) {
             long targetSample = from;
             for (long sourceSample = from; sourceSample < to; sourceSample += channels) {
diff --git a/CavernSamples/CavernizeGUI/MainWindow.Exporting.cs b/CavernSamples/CavernizeGUI/MainWindow.Exporting.cs
index fe292d79..5c9ec1eb 100644
--- a/CavernSamples/CavernizeGUI/MainWindow.Exporting.cs
+++ b/CavernSamples/CavernizeGUI/MainWindow.Exporting.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.IO;
 using System.Numerics;
 using System.Threading;
 
@@ -122,7 +121,8 @@ RenderStats WriteRender(Track target, AudioWriter writer, RenderTarget renderTar
             int cachePosition = 0;
             float[] writeCache = null;
             bool flush = false;
-            writeCache = new float[blockSize];
+            // The size of writeCache makes sure ContainerWriters get correct sized blocks when written with WriteChannelLimitedBlock
+            writeCache = new float[blockSize / renderTarget.OutputChannels * Listener.Channels.Length];
 
             bool wasError = false;
             while (progressor.Rendered < target.Length) {
diff --git a/CavernSamples/CavernizeGUI/MainWindow.Rendering.cs b/CavernSamples/CavernizeGUI/MainWindow.Rendering.cs
index 85b19f09..ad25184f 100644
--- a/CavernSamples/CavernizeGUI/MainWindow.Rendering.cs
+++ b/CavernSamples/CavernizeGUI/MainWindow.Rendering.cs
@@ -99,7 +99,7 @@ Action Render(string path) {
             Codec codec = ((ExportFormat)audio.SelectedItem).Codec;
             BitDepth bits = codec == Codec.PCM_Float ? BitDepth.Float32 : force24Bit.IsChecked ? BitDepth.Int24 : BitDepth.Int16;
             if (!codec.IsEnvironmental()) {
-                SetBlockSize();
+                SetBlockSize(activeRenderTarget);
                 string exportFormat = path[^4..].ToLower(CultureInfo.InvariantCulture);
                 bool mkvTarget = exportFormat.Equals(".mkv");
                 string exportName = mkvTarget ? path[..^4] + waveExtension : path;
@@ -195,7 +195,7 @@ Action GetRenderTask() {
                     }
                 }
             } else {
-                SetBlockSize();
+                SetBlockSize((RenderTarget)renderTarget.SelectedItem);
                 try {
                     return () => RenderTask(target, null, false, false, null);
                 } catch (Exception e) {
@@ -209,7 +209,7 @@ Action GetRenderTask() {
         /// <summary>
         /// Setup write cache block size depending on active settings.
         /// </summary>
-        void SetBlockSize() {
+        void SetBlockSize(RenderTarget target) {
             blockSize = FiltersUsed ? roomCorrection[0].Length : defaultWriteCacheLength;
             if (blockSize < listener.UpdateRate) {
                 blockSize = listener.UpdateRate;
@@ -217,9 +217,7 @@ void SetBlockSize() {
                 // Cache handling is written to only handle when its size is divisible with the update rate - it's faster this way
                 blockSize += listener.UpdateRate - blockSize % listener.UpdateRate;
             }
-
-            bool virtualizerFilterUsed = Listener.HeadphoneVirtualizer || speakerVirtualizer.IsChecked;
-            blockSize *= virtualizerFilterUsed ? VirtualizerFilter.VirtualChannels : Listener.Channels.Length;
+            blockSize *= target.OutputChannels;
         }
 
         /// <summary>