feat: Add media foundation backend

Directory.Build.props

@@ -18,7 +18,7 @@
     <RootNamespace>FlashCap</RootNamespace>
     <ProduceReferenceAssembly>false</ProduceReferenceAssembly>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
-    <NoWarn>$(NoWarn);CS1570;CS1591;CA1416;CS8981;NETSDK1215</NoWarn>
+    <NoWarn>$(NoWarn);CS1570;CS1591;CS8981;NETSDK1215</NoWarn>
 
     <Product>FlashCap</Product>
     <Trademark>FlashCap</Trademark>

FlashCap.Core/CaptureDeviceDescriptor.cs

@@ -23,6 +23,7 @@ public enum DeviceTypes
     DirectShow,
     V4L2,
     AVFoundation,
+    MediaFoundation,
 }
 
 public enum TranscodeFormats

FlashCap.Core/CaptureDevices.cs

@@ -13,11 +13,23 @@
 using FlashCap.Internal;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Runtime.CompilerServices;
+using System.Runtime.Versioning;
 
 namespace FlashCap;
 
+/// <summary>
+/// By default, the following backends are considered for <see cref="OnEnumerateDescriptors"/>:
+/// <list type= "bullet">
+/// <item><description><see cref="DirectShowDevices"/> (windows)</description></item>
+/// <item><description><see cref="VideoForWindowsDevices"/> (windows)</description></item>
+/// <item><description><c>MediaFoundationDevices</c> (Windows 7 or greater) - Supported on net48, netstandard2.0 or greater, .NET 5.0 or greater</description></item>
+/// <item><description><see cref="V4L2Devices"/> (linux)</description></item>
+/// <item><description><see cref="AVFoundationDevices"/> (macOs)</description></item>
+/// </list>
+/// </summary>
 public class CaptureDevices
 {
     protected readonly BufferPool DefaultBufferPool;
@@ -26,24 +38,37 @@ public CaptureDevices() :
         this(new DefaultBufferPool())
     {
     }
-
-    public CaptureDevices(BufferPool defaultBufferPool) =>
-        this.DefaultBufferPool = defaultBufferPool;
 
-    protected virtual IEnumerable<CaptureDeviceDescriptor> OnEnumerateDescriptors() =>
-        NativeMethods.CurrentPlatform switch
+    public CaptureDevices(BufferPool defaultBufferPool)
+    {
+        DefaultBufferPool = defaultBufferPool;
+    }
+
+    [RequiresUnreferencedCode("OnEnumerateDescriptors adds DirectShow which requires unreferenced code. Use platform-specific Devices directly.")]
+    protected virtual IEnumerable<CaptureDeviceDescriptor> OnEnumerateDescriptors()
+    {
+        if (NativeMethods.IsWindows())
         {
-            NativeMethods.Platforms.Windows =>
-                new DirectShowDevices(this.DefaultBufferPool).OnEnumerateDescriptors().
-                Concat(new VideoForWindowsDevices(this.DefaultBufferPool).OnEnumerateDescriptors()),
-            NativeMethods.Platforms.Linux =>
-                new V4L2Devices().OnEnumerateDescriptors(),
-            NativeMethods.Platforms.MacOS =>
-                new AVFoundationDevices().OnEnumerateDescriptors(),
-            _ =>
-                ArrayEx.Empty<CaptureDeviceDescriptor>(),
-        };
+            var descriptors = new DirectShowDevices(this.DefaultBufferPool).OnEnumerateDescriptors();
+            descriptors = descriptors.Concat(new VideoForWindowsDevices(this.DefaultBufferPool).OnEnumerateDescriptors());
+#if FLASHCAP_MEDIAFOUNDATION
+            if (NativeMethods.IsWindowsVersionAtLeast(6, 1))
+                descriptors = descriptors.Concat(new MediaFoundationDevices(this.DefaultBufferPool).OnEnumerateDescriptors());
+#endif
+            return descriptors;
+        }
+        if (NativeMethods.IsLinux())
+        {
+            return new V4L2Devices().OnEnumerateDescriptors();
+        }
+        if (NativeMethods.IsMacOS())
+        {
+            return new AVFoundationDevices().OnEnumerateDescriptors();
+        }
+        return ArrayEx.Empty<CaptureDeviceDescriptor>();
+    }
 
+    [RequiresUnreferencedCode("OnEnumerateDescriptors adds DirectShow which requires unreferenced code. Use platform-specific Devices directly.")]
     internal IEnumerable<CaptureDeviceDescriptor> InternalEnumerateDescriptors() =>
         this.OnEnumerateDescriptors();
 }

FlashCap.Core/Devices/AVFoundationDevice.cs

@@ -12,6 +12,7 @@
 using System.Diagnostics;
 using System.Linq;
 using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
 using System.Threading;
 using System.Threading.Tasks;
 using FlashCap.Internal;
@@ -23,6 +24,7 @@
 
 namespace FlashCap.Devices;
 
+[SupportedOSPlatform("macos")]
 public sealed class AVFoundationDevice : CaptureDevice
 {
     private readonly string uniqueID;

FlashCap.Core/Devices/AVFoundationDeviceDescriptor.cs

@@ -8,11 +8,13 @@
 //
 ////////////////////////////////////////////////////////////////////////////
 
+using System.Runtime.Versioning;
 using System.Threading;
 using System.Threading.Tasks;
 
 namespace FlashCap.Devices;
 
+[SupportedOSPlatform("macos")]
 public sealed class AVFoundationDeviceDescriptor : CaptureDeviceDescriptor
 {
     private readonly string uniqueId;

FlashCap.Core/Devices/AVFoundationDevices.cs

@@ -10,14 +10,17 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using System.Runtime.Versioning;
 using System.Threading.Tasks;
 using FlashCap.Internal;
 using FlashCap.Utilities;
 using static FlashCap.Internal.AVFoundation.LibAVFoundation;
 
 namespace FlashCap.Devices;
 
+[SupportedOSPlatform("macos")]
 public sealed class AVFoundationDevices : CaptureDevices
 {
     public AVFoundationDevices() :
@@ -30,8 +33,14 @@ public AVFoundationDevices(BufferPool defaultBufferPool) :
     {
     }
 
+    [UnconditionalSuppressMessage("Trimming", "IL2046", Justification = "This backend does not require unreferenced code")]
     protected override IEnumerable<CaptureDeviceDescriptor> OnEnumerateDescriptors()
     {
+        if (!NativeMethods.IsMacOS())
+        {
+            throw new PlatformNotSupportedException("AVFoundation capture requires macOS.");
+        }
+
         if (AVCaptureDevice.GetAuthorizationStatus(AVMediaType.Video) != AVAuthorizationStatus.Authorized)
         {
             TaskCompletionSource<bool> tcs = new();

FlashCap.Core/Devices/DirectShowDevice.cs

@@ -10,14 +10,19 @@
 using FlashCap.Internal;
 using System;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
 using System.Threading;
 using System.Threading.Tasks;
 
 namespace FlashCap.Devices;
-
+#if NET6_0_OR_GREATER // Remove this when dropping net5.0. Its required because RequiresUnreferencedCode was not allowed on class level in net5.0
+[RequiresUnreferencedCode("Direct show depends on COM runtime generation and might require unreferenced code.")]
+#endif
+[SupportedOSPlatform("windows")]
 public sealed class DirectShowDevice :
     CaptureDevice
 {

FlashCap.Core/Devices/DirectShowDeviceDescriptor.cs

@@ -7,11 +7,17 @@
 //
 ////////////////////////////////////////////////////////////////////////////
 
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.Versioning;
 using System.Threading;
 using System.Threading.Tasks;
 
 namespace FlashCap.Devices;
 
+#if NET6_0_OR_GREATER // Remove this when dropping net5.0. Its required because RequiresUnreferencedCode was not allowed on class level in net5.0
+[RequiresUnreferencedCode("Direct show depends on COM runtime generation and might require unreferenced code.")]
+#endif
+[SupportedOSPlatform("windows")]
 public sealed class DirectShowDeviceDescriptor : CaptureDeviceDescriptor
 {
     private readonly string devicePath;

FlashCap.Core/Devices/DirectShowDevices.cs

@@ -10,10 +10,16 @@
 using FlashCap.Internal;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using System.Runtime.Versioning;
 
 namespace FlashCap.Devices;
 
+#if NET6_0_OR_GREATER // Remove this when dropping net5.0. Its required because RequiresUnreferencedCode was not allowed on class level in net5.0
+[RequiresUnreferencedCode("Direct show depends on COM runtime generation and might require unreferenced code.")]
+#endif
+[SupportedOSPlatform("windows")]
 public sealed class DirectShowDevices : CaptureDevices
 {
     public DirectShowDevices() :