Merged PR 22155: Checking new videoformatav1 API into 2025-10b-release branch

This is picking up changes in main since the release branch was created.

Author: drewbatgit

windows.applicationmodel/package_effectiveexternallocation.md

@@ -34,4 +34,3 @@ To set the external folder, use one of the following combinations of [PackageMan
 [AddPackageByUriAsync](../windows.management.deployment/packagemanager_addpackagebyuriasync_797417417.md),[RegisterPackageByUriAsync](../windows.management.deployment/packagemanager_registerpackagebyuriasync_1415074502.md),[StagePackageByUriAsync](../windows.management.deployment/packagemanager_stagepackagebyuriasync_446584280.md)
 
 ## -examples
-

windows.applicationmodel/package_effectivelocation.md

@@ -12,19 +12,18 @@ public StorageFolder EffectiveLocation { get; }
 
 ## -description
 
-Gets either the location of the installed folder or the mutable folder for the installed package, depending on whether the app is declared to be mutable in its package manifest.
+Gets the effective location for the installed package, depending on how the app is declared in its package manifest. For details, see **Remarks**.
 
 ## -property-value
 
-The location of the installed folder or the mutable folder for the installed package, depending on whether the app is declared to be mutable in its package manifest.
+The effective location for the installed package, depending on how the app is declared in its package manifest. For details, see **Remarks**.
 
 ## -remarks
 
-If the app is declared to be mutable by including the [windows.mutablePackageDirectories extension](/uwp/schemas/appxpackage/uapmanifestschema/element-desktop6-package-extension) in its package manifest, this property gets the mutable folder for the installed package (that is, the folder under C:\Program Files\ModifiableWindowsApps where users can add files that modify the app). If the app is not declared to be mutable, this property gets the same value as the [InstalledLocation](package_installedlocation.md) property. The mutable folder feature is currently available only for certain types of desktop PC games that are published by Microsoft and our partners, and it enables these types of games to support mods.
+If the package has a User-External location, then get that folder. Otherwise, if the package has a Machine-External location, then get that folder. Otherwise, if the package has a [Mutable location](/uwp/schemas/appxpackage/uapmanifestschema/element-desktop8-mutablepackagedirectories), then get the Mutable folder for the installed package (that is, the folder under `C:\Program Files\ModifiableWindowsApps` where users can add files that modify the app). Also see [Create a directory in any location based on packaged app directory](/windows/msix/manage/create-directory). Otherwise, get the same value as the [InstalledLocation](package_installedlocation.md) property. The mutable folder feature is currently available only for certain types of desktop PC games that are published by Microsoft and partners, and it enables those types of games to support modifications (mods).
 
 ## -see-also
 
 [MutableLocation](package_mutablelocation.md),[InstalledLocation](package_installedlocation.md)
 
 ## -examples
-

windows.applicationmodel/package_machineexternallocation.md

@@ -15,7 +15,7 @@ Gets the location of the machine-wide external folder specified in the package m
 
 ## -property-value
 
-The location of the machine-wide external folder specified in the package manifest for the current package.
+The location of the machine-wide external folder specified in the package manifest for the current package. If the package doesn't have the path requested, then gets `null`.
 
 ## -remarks
 

windows.applicationmodel/package_machineexternalpath.md

@@ -15,7 +15,7 @@ Gets the location of the machine-wide external folder specified in the package m
 
 ## -property-value
 
-The location of the machine-wide external folder specified in the package manifest for the current package.
+The location of the machine-wide external folder specified in the package manifest for the current package. If the package doesn't have the path requested, then gets an empty string.
 
 ## -remarks
 

windows.applicationmodel/package_userexternallocation.md

@@ -15,7 +15,7 @@ Gets the location of the per-user external folder specified in the package manif
 
 ## -property-value
 
-The location of the per-user external folder specified in the package manifest for the current package.
+The location of the per-user external folder specified in the package manifest for the current package. If the package doesn't have the path requested, then gets `null`.
 
 ## -remarks
 
@@ -34,4 +34,3 @@ To set the external folder, use one of the following combinations of [PackageMan
 [AddPackageByUriAsync](../windows.management.deployment/packagemanager_addpackagebyuriasync_797417417.md),[RegisterPackageByUriAsync](../windows.management.deployment/packagemanager_registerpackagebyuriasync_1415074502.md),[StagePackageByUriAsync](../windows.management.deployment/packagemanager_stagepackagebyuriasync_446584280.md)
 
 ## -examples
-

windows.applicationmodel/package_userexternalpath.md

@@ -15,7 +15,7 @@ Gets the path of the per-user external folder specified in the package manifest
 
 ## -property-value
 
-The path of the per-user external folder specified in the package manifest for the current package.
+The path of the per-user external folder specified in the package manifest for the current package. If the package doesn't have the path requested, then gets an empty string.
 
 ## -remarks
 
@@ -34,4 +34,3 @@ To set the external folder, use one of the following combinations of [PackageMan
 [AddPackageByUriAsync](../windows.management.deployment/packagemanager_addpackagebyuriasync_797417417.md),[RegisterPackageByUriAsync](../windows.management.deployment/packagemanager_registerpackagebyuriasync_1415074502.md),[StagePackageByUriAsync](../windows.management.deployment/packagemanager_stagepackagebyuriasync_446584280.md)
 
 ## -examples
-

windows.media.core/codecsubtypes_videoformatav1.md

@@ -0,0 +1,29 @@
+---
+-api-id: P:Windows.Media.Core.CodecSubtypes.VideoFormatAv1
+-api-type: winrt property
+---
+
+# Windows.Media.Core.CodecSubtypes.VideoFormatAv1
+
+<!--
+public static string VideoFormatAv1 { get; }
+-->
+
+
+## -description
+
+Gets the string representation of the [GUID](/windows/win32/api/guiddef/ns-guiddef-guid) for the AV1 video subtype.
+
+## -property-value
+
+The string representation of the AV1 video subtype.
+
+## -remarks
+
+This GUID matches the value of the Media Foundation subtype [MFVideoFormat_AV1](/windows/win32/medfound/video-subtype-guids), defined using the FOURCC 'AV01'.
+
+## -see-also
+
+## -examples
+
+

windows.media.core/codecsubtypes_videoformatdv25.md

@@ -10,9 +10,11 @@ public string VideoFormatDV25 { get; }
 # Windows.Media.Core.CodecSubtypes.VideoFormatDV25
 
 ## -description
+
 Gets the string representation of the [GUID](/windows/win32/api/guiddef/ns-guiddef-guid) for the DVCPRO 25 (525-60 or 625-50) video subtype.
 
 ## -property-value
+
 The string representation of the GUID for the DVCPRO 25 (525-60 or 625-50) video subtype.
 
 ## -remarks

windows.storage.pickers/fileopenpicker.md

@@ -19,6 +19,9 @@ In a desktop app, before using an instance of this class in a way that displays
 
 To get started accessing files and folders file picker, see [Quickstart: Accessing files with File Pickers](/windows/uwp/files/quickstart-using-file-and-folder-pickers).
 
+> [!NOTE]
+> To use a file open picker in a WinUI app (or other desktop app), see the [FileOpenPicker class](/windows/windows-app-sdk/api/winrt/microsoft.windows.storage.pickers.fileopenpicker) documentation for the Windows App SDK.
+
 For information about how to use this API outside of UWP apps, see [Call interop APIs from a .NET app](/windows/apps/desktop/modernize/winrt-com-interop-csharp).
 
 ### Version history

windows.storage.pickers/filesavepicker.md

@@ -18,18 +18,26 @@ In a desktop app, before using an instance of this class in a way that displays
 ## -remarks
 
 > [!IMPORTANT]
-> You must use the [FileTypeChoices property](filesavepicker_filetypechoices.md) property to specify one or more file types before you call the PickSaveFileAsync method, or the picker will thrown an exception. 
+> You must use the [FileTypeChoices property](filesavepicker_filetypechoices.md) property to specify one or more file types before you call the **PickSaveFileAsync** method, or the picker will thrown an exception. 
 
 To learn how to save files through the file picker, see [How to save files through file pickers](/windows/uwp/files/quickstart-save-a-file-with-a-picker).
 
+> [!NOTE]
+> To use a file save picker in a WinUI app, see the [FileSavePicker class](/windows/windows-app-sdk/api/winrt/microsoft.windows.storage.pickers.filesavepicker) documentation for the Windows App SDK.
+
 To get started accessing files and folders file picker, see [Files, folders, and libraries ](/windows/uwp/files/index).
 
 > [!WARNING]
 > If you try to show the file picker while your app is snapped, the file picker will not be shown and an exception will be thrown. You can avoid this by making sure your app is not snapped or by unsnapping it before you call the file picker. The following code examples and the [File picker sample](https://github.com/microsoft/Windows-universal-samples/tree/master/Samples/FilePicker) show you how.
 
 ### In a desktop app that requires elevation
 
-In a desktop app (which includes WinUI 3 apps), you can use **FileSavePicker** (and other types from **Windows.Storage.Pickers**). But if the desktop app requires elevation to run, then you'll need a different approach (that's because these APIs aren't designed to be used in an elevated app). The code snippet below illustrates how you can use the [C#/Win32 P/Invoke Source Generator](https://github.com/microsoft/CsWin32) (CsWin32) to call the Win32 picking APIs instead. To learn how to use CsWin32, follow that link for the documentation.
+> [!IMPORTANT]
+> The file and folder picker APIs (Windows.Storage.Pickers) in the Windows SDK don't work when apps run as administrator (elevated mode). To address this gap, the [Microsoft.Windows.Storage.Pickers](/windows/windows-app-sdk/api/winrt/microsoft.windows.storage.pickers) APIs are added to the Windows App SDK and support file and folder selection in elevated mode. It's designed for desktop apps and uses a WindowId property to link the picker to its host window.
+>
+> If you must use the Windows.Storage.Pickers APIs in an elevated desktop app, you can follow example below.
+
+You can use **FileSavePicker** (and other types from **Windows.Storage.Pickers**) in a desktop app. However, if the desktop app requires elevation to run, then you'll need a different approach (that's because these APIs aren't designed to be used in an elevated app). The code snippet below illustrates how you can use the [C#/Win32 P/Invoke Source Generator](https://github.com/microsoft/CsWin32) (CsWin32) to call the Win32 picking APIs instead. To learn how to use CsWin32, follow that link for the documentation.
 
 ```csharp
 // NativeMethods.txt