Greatly clean up audio code (YARC-Official#407)

* Replace audio isSpeedup flag with a direct speed value
Gets rid of the depenency on PlayMode in the audio code

* Clean up song preview contexts
They don't need to be interfaced, they're already designed to work with any backend lol
Also fixed a couple warnings in SongSelection

* Add SetPosition method to IStemChannel

* Rework BassMoggStem
Heavily de-duplicated code and simplified things, and created an interface for it

* Account for channels that aren't part of a mixer when setting position

* Split out .mogg-specific mixing code into its own mixer

* Move audio code to a YARG.Audio namespace

* Remove unused using directives in audio code

* Fix BASS.FX and BASS.Mix versions not being logged correctly

* Accidentally broke song previews lol

Assets/Script/Audio/AudioEnums.cs

@@ -1,4 +1,4 @@
-namespace YARG {
+namespace YARG.Audio {
 	public enum SongStem {
 		Master = -2,
 		Sfx = -1,

Assets/Script/Audio/AudioHelpers.cs

@@ -1,8 +1,7 @@
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 
-namespace YARG {
+namespace YARG.Audio {
 	public static class AudioHelpers {
 		public static readonly IList<string> SupportedStems = new[] {
 			"song",

Assets/Script/Audio/Bass/BassAudioManager.cs

@@ -5,13 +5,12 @@
 using System.Threading;
 using Cysharp.Threading.Tasks;
 using ManagedBass;
+using ManagedBass.Fx;
+using ManagedBass.Mix;
 using UnityEngine;
-using XboxSTFS;
-using YARG.Serialization;
 using YARG.Song;
-using Debug = UnityEngine.Debug;
 
-namespace YARG {
+namespace YARG.Audio.BASS {
 	public class BassAudioManager : MonoBehaviour, IAudioManager {
 		public bool UseStarpowerFx { get; set; }
 		public bool IsChipmunkSpeedup { get; set; }
@@ -31,14 +30,6 @@ public class BassAudioManager : MonoBehaviour, IAudioManager {
 		public float CurrentPositionF => (float) GetPosition();
 		public float AudioLengthF { get; private set; }
 
-		private IPreviewContext _currentPreviewContext;
-		public IPreviewContext PreviewContext {
-			get {
-				_currentPreviewContext ??= new BassPreviewContext(this);
-				return _currentPreviewContext;
-			}
-		}
-
 		private double[] _stemVolumes;
 
 		private int _opusHandle;
@@ -97,8 +88,8 @@ public void Initialize() {
 
 			Debug.Log($"BASS Successfully Initialized");
 			Debug.Log($"BASS: {Bass.Version}");
-			Debug.Log($"BASS.FX: {Bass.Version}");
-			Debug.Log($"BASS.Mix: {Bass.Version}");
+			Debug.Log($"BASS.FX: {BassFx.Version}");
+			Debug.Log($"BASS.Mix: {BassMix.Version}");
 
 			Debug.Log($"Update Period: {Bass.UpdatePeriod}");
 			Debug.Log($"Device Buffer Length: {Bass.DeviceBufferLength}");
@@ -163,7 +154,7 @@ public void LoadSfx() {
 			Debug.Log("Finished loading SFX");
 		}
 
-		public void LoadSong(ICollection<string> stems, bool isSpeedUp, params SongStem[] ignoreStems) {
+		public void LoadSong(ICollection<string> stems, float speed, params SongStem[] ignoreStems) {
 			Debug.Log("Loading song");
 			UnloadSong();
 
@@ -190,7 +181,7 @@ public void LoadSong(ICollection<string> stems, bool isSpeedUp, params SongStem[
 				}
 
 				var stemChannel = new BassStemChannel(this, stemPath, songStem);
-				if (stemChannel.Load(isSpeedUp, PlayMode.Play.speed) != 0) {
+				if (stemChannel.Load(speed) != 0) {
 					Debug.LogError($"Failed to load stem! {stemPath}");
 					Debug.LogError($"Bass Error: {Bass.LastError}");
 					continue;
@@ -216,17 +207,19 @@ public void LoadSong(ICollection<string> stems, bool isSpeedUp, params SongStem[
 			IsAudioLoaded = true;
 		}
 
-		public void LoadMogg(ExtractedConSongEntry exConSong, bool isSpeedUp, params SongStem[] ignoreStems) {
+		public void LoadMogg(ExtractedConSongEntry exConSong, float speed, params SongStem[] ignoreStems) {
 			Debug.Log("Loading mogg song");
 			UnloadSong();
 
+			// Process MOGG data
 			byte[] moggArray = exConSong.LoadMoggFile();
 
 			if (BitConverter.ToUInt32(moggArray, 0) != 0xA)
 				throw new Exception("Original unencrypted mogg replaced by an encrpyted mogg");
 
 			moggArray = moggArray[BitConverter.ToInt32(moggArray, 4)..];
 
+			// Initialize stream
 			int moggStreamHandle = Bass.CreateStream(moggArray, 0, moggArray.Length, BassFlags.Prescan | BassFlags.Decode | BassFlags.AsyncFile);
 			if (moggStreamHandle == 0) {
 				Debug.LogError($"Failed to load mogg file or position: {Bass.LastError}");
@@ -239,13 +232,52 @@ public void LoadMogg(ExtractedConSongEntry exConSong, bool isSpeedUp, params Son
 				exConSong.StemMaps.Remove(stem);
 			}
 
-			_mixer = new BassStemMixer(this, moggStreamHandle, exConSong.StemMaps, exConSong.MatrixRatios);
+			// Initialize mixer
+			_mixer = new BassMoggStemMixer(this, moggStreamHandle);
 			if (!_mixer.Create()) {
 				throw new Exception($"Failed to create mixer: {Bass.LastError}");
 			}
 
-			if (!_mixer.SetupMogg(isSpeedUp)) {
-				throw new Exception($"Failed to setup MOGG channels: {Bass.LastError}");
+			// Split stream into multiple channels
+			var stemMaps = exConSong.StemMaps;
+			var matrixRatios = exConSong.MatrixRatios;
+			var splitStreams = new int[matrixRatios.GetLength(0)];
+
+			var channelMap = new int[2];
+			channelMap[1] = -1;
+
+			for (var i = 0; i < splitStreams.Length; i++) {
+				channelMap[0] = i;
+
+				int splitHandle = BassMix.CreateSplitStream(moggStreamHandle, BassFlags.Decode | BassFlags.SplitPosition, channelMap);
+				if (splitHandle == 0) {
+					throw new Exception($"Failed to create MOGG stream handle: {Bass.LastError}");
+				}
+
+				splitStreams[i] = splitHandle;
+			}
+
+			// Set up channels
+			foreach ((var stem, int[] channelIndexes) in stemMaps) {
+				int[] channelStreams = channelIndexes.Select(i => splitStreams[i]).ToArray();
+
+				var matrixes = new List<float[]>();
+				foreach (var channelIndex in channelIndexes) {
+					var matrix = new float[2];
+					matrix[0] = matrixRatios[channelIndex, 0];
+					matrix[1] = matrixRatios[channelIndex, 1];
+					matrixes.Add(matrix);
+				}
+
+				var channel = new BassMoggStemChannel(this, stem, channelStreams, matrixes);
+				if (channel.Load(speed) < 0) {
+					throw new Exception($"Failed to load MOGG stem channel: {Bass.LastError}");
+				}
+
+				int code = _mixer.AddChannel(channel);
+				if (code != 0) {
+					throw new Exception($"Failed to add MOGG stem channel to mixer: {Bass.LastError}");
+				}
 			}
 
 			Debug.Log($"Loaded {_mixer.StemsLoaded} stems");
@@ -257,7 +289,7 @@ public void LoadMogg(ExtractedConSongEntry exConSong, bool isSpeedUp, params Son
 			IsAudioLoaded = true;
 		}
 
-		public void LoadCustomAudioFile(string audioPath) {
+		public void LoadCustomAudioFile(string audioPath, float speed) {
 			Debug.Log("Loading custom audio file");
 			UnloadSong();
 
@@ -267,7 +299,7 @@ public void LoadCustomAudioFile(string audioPath) {
 			}
 
 			var stemChannel = new BassStemChannel(this, audioPath, SongStem.Song);
-			if (stemChannel.Load(false, PlayMode.Play.speed) != 0) {
+			if (stemChannel.Load(speed) != 0) {
 				Debug.LogError($"Failed to load stem! {audioPath}");
 				Debug.LogError($"Bass Error: {Bass.LastError}");
 				return;
@@ -335,11 +367,6 @@ public void Pause() {
 			IsPlaying = _mixer.IsPlaying;
 		}
 
-		public void DisposePreviewContext() {
-			_currentPreviewContext?.Dispose();
-			_currentPreviewContext = null;
-		}
-
 		public void FadeIn(float maxVolume) {
 			Play(true);
 			if (IsPlaying) {

Assets/Script/Audio/Bass/BassHelpers.cs

@@ -3,7 +3,7 @@
 using ManagedBass.DirectX8;
 using ManagedBass.Fx;
 
-namespace YARG {
+namespace YARG.Audio.BASS {
 	public static class BassHelpers {
 
 		public const float SONG_VOLUME_MULTIPLIER = 0.7f;