Haydn: Part 1 (#2007)

* Haydn: Part 1

Based on my reverse of audio 11.0.0.

As always, core implementation under LGPLv3 for the same reasons as for Amadeus.

This place the bases of a more flexible audio system while making audout & audin accurate.

This have the following improvements:
- Complete reimplementation of audout and audin.
- Audin currently only have a dummy backend.
- Dramatically reduce CPU usage by up to 50% in common cases (SoundIO and OpenAL).
- Audio Renderer now can output to 5.1 devices when supported.
- Audio Renderer init its backend on demand instead of keeping two up all the time.
- All backends implementation are now in their own project.
- Ryujinx.Audio.Renderer was renamed Ryujinx.Audio and was refactored because of this.

As a note, games having issues with OpenAL haven't improved and will not
because of OpenAL design (stopping when buffers finish playing causing
possible audio "pops" when buffers are very small).

* Update for latest hexkyz's edits on Switchbrew

* audren: Rollback channel configuration changes

* Address gdkchan's comments

* Fix typo in OpenAL backend driver

* Address last comments

* Fix a nit

* Address gdkchan's comments

Ryujinx.Audio/Renderer/Dsp/Command/DownMixSurroundToStereoCommand.cs

@@ -0,0 +1,89 @@
+//
+// Copyright (c) 2019-2021 Ryujinx
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+
+using System;
+using System.Runtime.CompilerServices;
+
+namespace Ryujinx.Audio.Renderer.Dsp.Command
+{
+    public class DownMixSurroundToStereoCommand : ICommand
+    {
+        public bool Enabled { get; set; }
+
+        public int NodeId { get; }
+
+        public CommandType CommandType => CommandType.DownMixSurroundToStereo;
+
+        public ulong EstimatedProcessingTime { get; set; }
+
+        public ushort[] InputBufferIndices { get; }
+        public ushort[] OutputBufferIndices { get; }
+
+        public float[] Coefficients { get; }
+
+        public DownMixSurroundToStereoCommand(uint bufferOffset, Span<byte> inputBufferOffset, Span<byte> outputBufferOffset, ReadOnlySpan<float> downMixParameter, int nodeId)
+        {
+            Enabled = true;
+            NodeId = nodeId;
+
+            InputBufferIndices = new ushort[Constants.VoiceChannelCountMax];
+            OutputBufferIndices = new ushort[Constants.VoiceChannelCountMax];
+
+            for (int i = 0; i < Constants.VoiceChannelCountMax; i++)
+            {
+                InputBufferIndices[i] = (ushort)(bufferOffset + inputBufferOffset[i]);
+                OutputBufferIndices[i] = (ushort)(bufferOffset + outputBufferOffset[i]);
+            }
+
+            Coefficients = downMixParameter.ToArray();
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static float DownMixSurroundToStereo(ReadOnlySpan<float> coefficients, float back, float lfe, float center, float front)
+        {
+            return FloatingPointHelper.RoundUp(coefficients[3] * back + coefficients[2] * lfe + coefficients[1] * center + coefficients[0] * front);
+        }
+
+        public void Process(CommandList context)
+        {
+            ReadOnlySpan<float> frontLeft = context.GetBuffer(InputBufferIndices[0]);
+            ReadOnlySpan<float> frontRight = context.GetBuffer(InputBufferIndices[1]);
+            ReadOnlySpan<float> frontCenter = context.GetBuffer(InputBufferIndices[2]);
+            ReadOnlySpan<float> lowFrequency = context.GetBuffer(InputBufferIndices[3]);
+            ReadOnlySpan<float> backLeft = context.GetBuffer(InputBufferIndices[4]);
+            ReadOnlySpan<float> backRight = context.GetBuffer(InputBufferIndices[5]);
+
+            Span<float> stereoLeft = context.GetBuffer(OutputBufferIndices[0]);
+            Span<float> stereoRight = context.GetBuffer(OutputBufferIndices[1]);
+            Span<float> unused2 = context.GetBuffer(OutputBufferIndices[2]);
+            Span<float> unused3 = context.GetBuffer(OutputBufferIndices[3]);
+            Span<float> unused4 = context.GetBuffer(OutputBufferIndices[4]);
+            Span<float> unused5 = context.GetBuffer(OutputBufferIndices[5]);
+
+            for (int i = 0; i < context.SampleCount; i++)
+            {
+                stereoLeft[i] = DownMixSurroundToStereo(Coefficients, backLeft[i], lowFrequency[i], frontCenter[i], frontLeft[i]);
+                stereoRight[i] = DownMixSurroundToStereo(Coefficients, backRight[i], lowFrequency[i], frontCenter[i], frontRight[i]);
+            }
+
+            unused2.Fill(0);
+            unused3.Fill(0);
+            unused4.Fill(0);
+            unused5.Fill(0);
+        }
+    }
+}