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

1 files changed, 60 insertions, 0 deletions

diff --git a/Ryujinx.Audio/Integration/IHardwareDevice.cs b/Ryujinx.Audio/Integration/IHardwareDevice.cs
new file mode 100644
index 00000000..0f67b2c8
--- /dev/null
+++ b/Ryujinx.Audio/Integration/IHardwareDevice.cs
@@ -0,0 +1,60 @@
+//
+// 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.Diagnostics;
+
+namespace Ryujinx.Audio.Integration
+{
+    /// <summary>
+    /// Represent an hardware device used in <see cref="Renderer.Dsp.Command.DeviceSinkCommand"/>
+    /// </summary>
+    public interface IHardwareDevice : IDisposable
+    {
+        /// <summary>
+        /// Get the supported sample rate of this device.
+        /// </summary>
+        /// <returns>The supported sample rate of this device.</returns>
+        uint GetSampleRate();
+
+        /// <summary>
+        /// Get the channel count supported by this device.
+        /// </summary>
+        /// <returns>The channel count supported by this device.</returns>
+        uint GetChannelCount();
+
+        /// <summary>
+        /// Appends new PCM16 samples to the device.
+        /// </summary>
+        /// <param name="data">The new PCM16 samples.</param>
+        /// <param name="channelCount">The number of channels.</param>
+        void AppendBuffer(ReadOnlySpan<short> data, uint channelCount);
+
+        /// <summary>
+        /// Check if the audio renderer needs to perform downmixing.
+        /// </summary>
+        /// <returns>True if downmixing is needed.</returns>
+        public bool NeedDownmixing()
+        {
+            uint channelCount = GetChannelCount();
+
+            Debug.Assert(channelCount > 0 && channelCount <= Constants.ChannelCountMax);
+
+            return channelCount != Constants.ChannelCountMax;
+        }
+    }
+}