From a09397dbd6ca1e9bffe27d29fd2ad707c1d9506f Mon Sep 17 00:00:00 2001
From: minjaesong <alswo9628@gmail.com>
Date: Fri, 17 Nov 2023 20:52:25 +0900
Subject: [PATCH] audioengine: filter stack processing

---
 src/net/torvald/terrarum/audio/AudioMixer.kt  |  1 +
 .../terrarum/audio/MixerTrackProcessor.kt     | 38 +++++++++----------
 .../terrarum/audio/TerrarumAudioMixerTrack.kt |  2 +-
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/src/net/torvald/terrarum/audio/AudioMixer.kt b/src/net/torvald/terrarum/audio/AudioMixer.kt
index 1c28050a6..5ed1e04bc 100644
--- a/src/net/torvald/terrarum/audio/AudioMixer.kt
+++ b/src/net/torvald/terrarum/audio/AudioMixer.kt
@@ -32,6 +32,7 @@ object AudioMixer: Disposable {
 
     private val masterTrack = TerrarumAudioMixerTrack("Master", true).also { master ->
         tracks.forEach { master.addSidechainInput(it, 1.0) }
+//        master.filters[0] = Lowpass(240, TerrarumAudioMixerTrack.SAMPLING_RATE)
     }
 
     private val musicTrack: TerrarumAudioMixerTrack
diff --git a/src/net/torvald/terrarum/audio/MixerTrackProcessor.kt b/src/net/torvald/terrarum/audio/MixerTrackProcessor.kt
index c1490ee6f..97acb5510 100644
--- a/src/net/torvald/terrarum/audio/MixerTrackProcessor.kt
+++ b/src/net/torvald/terrarum/audio/MixerTrackProcessor.kt
@@ -19,13 +19,6 @@ class MixerTrackProcessor(val bufferSize: Int, val track: TerrarumAudioMixerTrac
 
     internal val streamBuf = AudioProcessBuf(bufferSize)
     internal val sideChainBufs = Array(track.sidechainInputs.size) { AudioProcessBuf(bufferSize) }
-//    internal val outBufL0 = FloatArray(bufferSize / 4)
-//    internal val outBufR0 = FloatArray(bufferSize / 4)
-//    internal val outBufL1 = FloatArray(bufferSize / 4)
-//    internal val outBufR1 = FloatArray(bufferSize / 4)
-
-
-    private val testFilter = Lowpass(240, SAMPLING_RATE)
 
     private var fout0 = listOf(FloatArray(bufferSize / 4), FloatArray(bufferSize / 4))
     private var fout1 = listOf(FloatArray(bufferSize / 4), FloatArray(bufferSize / 4))
@@ -97,21 +90,28 @@ class MixerTrackProcessor(val bufferSize: Int, val track: TerrarumAudioMixerTrac
 
 
             // run the input through the stack of filters
-            val filterStack = track.filters.filter { !it.bypass }
+            val filterStack = track.filters.filter { !it.bypass && it !is NullFilter }
 
-            val fin0 = listOf(samplesL0, samplesR0)
-            val fin1 = listOf(samplesL1, samplesR1)
-            fout0 = fout1
-            fout1 = listOf(FloatArray(bufferSize / 4), FloatArray(bufferSize / 4))
-            val filter = if (track.isMaster) testFilter else NullFilter
-            filter(fin0, fin1, fout0, fout1)
+            if (filterStack.isEmpty()) {
+                fout1 = listOf(samplesL1, samplesR1)
+            }
+            else {
+                var fin0 = listOf(samplesL0, samplesR0)
+                var fin1 = listOf(samplesL1, samplesR1)
+                fout0 = fout1
+                fout1 = listOf(FloatArray(bufferSize / 4), FloatArray(bufferSize / 4))
 
+                filterStack.forEachIndexed { index, it ->
+                    it(fin0, fin1, fout0, fout1)
+                    fin0 = fout0
+                    fin1 = fout1
+                    if (index < filterStack.lastIndex) {
+                        fout0 = listOf(FloatArray(bufferSize / 4), FloatArray(bufferSize / 4))
+                        fout1 = listOf(FloatArray(bufferSize / 4), FloatArray(bufferSize / 4))
+                    }
+                }
+            }
 
-            // final writeout
-//            System.arraycopy(samplesL0, 0, outBufL0, 0, outBufL0.size)
-//            System.arraycopy(samplesR0, 0, outBufR0, 0, outBufR0.size)
-//            System.arraycopy(samplesL1, 0, outBufL1, 0, outBufL1.size)
-//            System.arraycopy(samplesR1, 0, outBufR1, 0, outBufR1.size)
 
             // by this time, the output buffer is filled with processed results, pause the execution
             if (!track.isMaster) {
diff --git a/src/net/torvald/terrarum/audio/TerrarumAudioMixerTrack.kt b/src/net/torvald/terrarum/audio/TerrarumAudioMixerTrack.kt
index 6e701bbdb..8eeb89f0b 100644
--- a/src/net/torvald/terrarum/audio/TerrarumAudioMixerTrack.kt
+++ b/src/net/torvald/terrarum/audio/TerrarumAudioMixerTrack.kt
@@ -35,7 +35,7 @@ class TerrarumAudioMixerTrack(val name: String, val isMaster: Boolean = false):
         get() = fullscaleToDecibels(volume)
         set(value) { volume = decibelsToFullscale(value) }
 
-    val filters = Array(4) { NullFilter }
+    val filters: Array<TerrarumAudioFilter> = Array(4) { NullFilter }
 
     internal val sidechainInputs = Array<Pair<TerrarumAudioMixerTrack, TrackVolume>?>(16)  { null }
     internal fun getSidechains(): List<TerrarumAudioMixerTrack?> = sidechainInputs.map { it?.first }