Merge pull request lavalink-devs#485 from TopiSenpai/dev

new filters from lavadsp

IMPLEMENTATION.md

@@ -192,11 +192,13 @@ Note that filters may take a moment to apply.
         "frequency": 2.0, // 0 < x ≤ 14
         "depth": 0.5      // 0 < x ≤ 1
     },
+
     // Rotates the sound around the stereo channels/user headphones aka Audio Panning. It can produce an effect similar to: https://youtu.be/QB9EB8mTKcc (without the reverb)
     "rotation": {
         "rotationHz": 0 // The frequency of the audio rotating around the listener in Hz. 0.2 is similar to the example video above.
     },
-    //Distortion effect. It can generate some pretty unique audio effects.
+
+    // Distortion effect. It can generate some pretty unique audio effects.
     "distortion": {
         "sinOffset": 0,
         "sinScale": 1,
@@ -207,9 +209,21 @@ Note that filters may take a moment to apply.
         "offset": 0,
         "scale": 1
     } 
+
+    // Mixes both channels (left and right), with a configurable factor on how much each channel affects the other.
+    // With the defaults, both channels are kept independent from each other.
+    // Setting all factors to 0.5 means both channels get the same audio.
+    "channelMix": {
+        "leftToLeft": 1.0,
+        "leftToRight": 0.0,
+        "rightToLeft": 0.0,
+        "rightToRight": 1.0,
     }
 
-
+    // Higher frequencies get suppressed, while lower frequencies pass through this filter, thus the name low pass.
+    "lowPass": {
+        "smoothing": 20.0
+    }
 }
 ```
 

LavalinkServer/src/main/java/lavalink/server/player/filters/FilterChain.kt

@@ -23,6 +23,8 @@ class FilterChain : PcmFilterFactory {
     private val vibrato: VibratoConfig? = null
     private val distortion: DistortionConfig? = null
     private val rotation: RotationConfig? = null
+    private val channelMix: ChannelMixConfig? = null
+    private val lowPass: LowPassConfig? = null
 
     private fun buildList() = listOfNotNull(
             volume?.let { VolumeConfig(it) },
@@ -32,7 +34,9 @@ class FilterChain : PcmFilterFactory {
             tremolo,
             vibrato,
             distortion,
-            rotation
+            rotation,
+            channelMix,
+            lowPass
     )
 
     val isEnabled get() = buildList().any { it.isEnabled }

LavalinkServer/src/main/java/lavalink/server/player/filters/filterConfigs.kt

@@ -1,10 +1,12 @@
 package lavalink.server.player.filters
 
+import com.github.natanbc.lavadsp.channelmix.ChannelMixPcmAudioFilter
 import com.github.natanbc.lavadsp.karaoke.KaraokePcmAudioFilter
 import com.github.natanbc.lavadsp.timescale.TimescalePcmAudioFilter
 import com.github.natanbc.lavadsp.tremolo.TremoloPcmAudioFilter
 import com.github.natanbc.lavadsp.vibrato.VibratoPcmAudioFilter
 import com.github.natanbc.lavadsp.distortion.DistortionPcmAudioFilter
+import com.github.natanbc.lavadsp.lowpass.LowPassPcmAudioFilter
 import com.github.natanbc.lavadsp.rotation.RotationPcmAudioFilter
 import com.github.natanbc.lavadsp.volume.VolumePcmAudioFilter
 import com.sedmelluq.discord.lavaplayer.filter.AudioFilter
@@ -136,6 +138,35 @@ class RotationConfig(
     override val isEnabled: Boolean get() = rotationHz != 0.0
 }
 
+class ChannelMixConfig(
+        private val leftToLeft: Float = 1f,
+        private val leftToRight: Float = 0f,
+        private val rightToLeft: Float = 0f,
+        private val rightToRight: Float = 1f
+
+) : FilterConfig() {
+    override fun build(format: AudioDataFormat, output: FloatPcmAudioFilter): FloatPcmAudioFilter {
+        return ChannelMixPcmAudioFilter(output)
+                .setLeftToLeft(leftToLeft)
+                .setLeftToRight(leftToRight)
+                .setRightToLeft(rightToLeft)
+                .setRightToRight(rightToRight)
+    }
+
+    override val isEnabled: Boolean get() = leftToLeft != 1f || leftToRight != 0f || rightToLeft != 0f || rightToRight != 1f
+}
+
+class LowPassConfig(
+    private val smoothing: Float = 20.0f
+) : FilterConfig() {
+    override fun build(format: AudioDataFormat, output: FloatPcmAudioFilter): FloatPcmAudioFilter {
+        return LowPassPcmAudioFilter(output, format.sampleRate)
+            .setSmoothing(smoothing)
+    }
+
+    override val isEnabled: Boolean get() = smoothing != 20.0f
+}
+
 abstract class FilterConfig {
     abstract fun build(format: AudioDataFormat, output: FloatPcmAudioFilter): FloatPcmAudioFilter
     abstract val isEnabled: Boolean