Fix cannot apply filters to multiple windows, #4273

This commit will:
- Change FilterWindowController to use the active PlayerCore
- Change FilterWindowController.reloadTable to check if the active
  PlayerCore is shutting down
- Disable the ability to add a filter if the active core is stopping
- Change PlayerCore.playbackStopped to clear all audio and video filters

iina/Base.lproj/FilterWindowController.xib

@@ -8,6 +8,7 @@
     <objects>
         <customObject id="-2" userLabel="File's Owner" customClass="FilterWindowController" customModule="IINA" customModuleProvider="target">
             <connections>
+                <outlet property="addButton" destination="La1-eJ-8B2" id="R96-ah-Qy4"/>
                 <outlet property="currentFiltersTableView" destination="iTp-t4-bao" id="kgR-wA-2qY"/>
                 <outlet property="editFilterKeyRecordView" destination="dAY-w3-zCx" id="45M-ij-r6G"/>
                 <outlet property="editFilterKeyRecordViewLabel" destination="B5v-za-vBd" id="8JH-aQ-LQH"/>

iina/FilterWindowController.swift

@@ -34,6 +34,7 @@ class FilterWindowController: NSWindowController, NSWindowDelegate {
   @IBOutlet weak var editFilterKeyRecordView: KeyRecordView!
   @IBOutlet weak var editFilterKeyRecordViewLabel: NSTextField!
   @IBOutlet weak var removeButton: NSButton!
+  @IBOutlet weak var addButton: NSButton!
 
   var loaded = false
 
@@ -60,7 +61,7 @@ class FilterWindowController: NSWindowController, NSWindowDelegate {
     splitView.setPosition(splitView.frame.height - 140, ofDividerAt: 0)
 
     savedFilters = (Preference.array(for: filterType == MPVProperty.af ? .savedAudioFilters : .savedVideoFilters) ?? []).compactMap(SavedFilter.init(dict:))
-    filters = PlayerCore.active.mpv.getFilters(filterType)
+    filters = PlayerCore.lastActive.mpv.getFilters(filterType)
     currentFiltersTableView.reloadData()
     savedFiltersTableView.reloadData()
 
@@ -84,7 +85,13 @@ class FilterWindowController: NSWindowController, NSWindowDelegate {
 
   @objc
   func reloadTable() {
-    filters = PlayerCore.active.mpv.getFilters(filterType)
+    let pc = PlayerCore.lastActive
+    // When IINA is terminating player windows are closed, which causes the iinaMainWindowChanged
+    // notification to be posted and that results in the observer established above calling this
+    // method. Thus this method may be called after IINA has commanded mpv to shutdown. Once mpv has
+    // been told to shutdown mpv APIs must not be called as it can trigger a crash in mpv.
+    guard !pc.isShuttingDown, !pc.isShutdown else { return }
+    filters = pc.mpv.getFilters(filterType)
     filterIsSaved = [Bool](repeatElement(false, count: filters.count))
     savedFilters.forEach { savedFilter in
       if let asObject = MPVFilter(rawString: savedFilter.filterString),
@@ -97,10 +104,13 @@ class FilterWindowController: NSWindowController, NSWindowDelegate {
     }
     currentFiltersTableView.reloadData()
     savedFiltersTableView.reloadData()
+    // Once a player window is being closed the user must not be allowed to add a filter to the
+    // active player core if it is being stopped and about to be added to the player core cache.
+    addButton.isEnabled = !pc.isStopping && !pc.isStopped
   }
 
   func setFilters() {
-    PlayerCore.active.mpv.setFilters(filterType, filters: filters)
+    PlayerCore.lastActive.mpv.setFilters(filterType, filters: filters)
   }
 
   deinit {
@@ -109,12 +119,12 @@ class FilterWindowController: NSWindowController, NSWindowDelegate {
 
   func addFilter(_ filter: MPVFilter) -> Bool {
     if filterType == MPVProperty.vf {
-      guard PlayerCore.active.addVideoFilter(filter) else {
+      guard PlayerCore.lastActive.addVideoFilter(filter) else {
         Utility.showAlert("filter.incorrect", sheetWindow: window)
         return false
       }
     } else {
-      guard PlayerCore.active.addAudioFilter(filter) else {
+      guard PlayerCore.lastActive.addAudioFilter(filter) else {
         Utility.showAlert("filter.incorrect", sheetWindow: window)
         return false
       }
@@ -160,7 +170,7 @@ class FilterWindowController: NSWindowController, NSWindowDelegate {
   }
 
   @IBAction func removeFilterAction(_ sender: Any) {
-    let pc = PlayerCore.active
+    let pc = PlayerCore.lastActive
     let selectedRow = currentFiltersTableView.selectedRow
     if selectedRow >= 0 {
       let success: Bool
@@ -190,7 +200,7 @@ class FilterWindowController: NSWindowController, NSWindowDelegate {
   @IBAction func toggleSavedFilterAction(_ sender: NSButton) {
     let row = savedFiltersTableView.row(for: sender)
     let savedFilter = savedFilters[row]
-    let pc = PlayerCore.active
+    let pc = PlayerCore.lastActive
 
     // choose appropriate add/remove functions for .af/.vf
     var addFilterFunction: (String) -> Bool
@@ -503,7 +513,7 @@ class NewFilterSheetViewController: NSViewController, NSTableViewDelegate, NSTab
     }
     // create filter
     if filterWindow.addFilter(preset.transformer(instance)) {
-      PlayerCore.active.sendOSD(.addFilter(preset.localizedName))
+      PlayerCore.lastActive.sendOSD(.addFilter(preset.localizedName))
     }
   }
 

iina/PlayerCore.swift

@@ -138,6 +138,9 @@ class PlayerCore: NSObject {
   /// Whether shutdown of this player has completed (mpv has shutdown).
   var isShutdown = false
 
+  /// Whether stopping of this player has been initiated.
+  var isStopping = false
+
   /// Whether mpv playback has stopped and the media has been unloaded.
   var isStopped = true
 
@@ -590,6 +593,7 @@ class PlayerCore: NSObject {
     // initiated directly through mpv.
     guard !isStopped else { return }
     Logger.log("Stopping playback", subsystem: subsystem)
+    isStopping = true
     mpv.command(.stop)
   }
 
@@ -600,6 +604,11 @@ class PlayerCore: NSObject {
   func playbackStopped() {
     Logger.log("Playback has stopped", subsystem: subsystem)
     isStopped = true
+    isStopping = false
+    // Must clear audio and video filters or they will be applied to the next video if this core is
+    // reused.
+    mpv.command(.af, args: ["clr", ""], checkError: false)
+    mpv.command(.vf, args: ["clr", ""], checkError: false)
     postNotification(.iinaPlayerStopped)
   }
 
@@ -1392,6 +1401,7 @@ class PlayerCore: NSObject {
     triedUsingExactSeekForCurrentFile = false
     info.fileLoading = false
     info.haveDownloadedSub = false
+    isStopping = false
     isStopped = false
     checkUnsyncedWindowOptions()
     // generate thumbnails if window has loaded video