diff --git a/apps/client/lib/modules/translation/controllers/translation_controller.dart b/apps/client/lib/modules/translation/controllers/translation_controller.dart
index f8add2d7..1d7a7b95 100644
--- a/apps/client/lib/modules/translation/controllers/translation_controller.dart
+++ b/apps/client/lib/modules/translation/controllers/translation_controller.dart
@@ -11,7 +11,6 @@ import 'package:floating_ui_plugin/native_plugin.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:permission_handler/permission_handler.dart';
 import 'package:device_info_plus/device_info_plus.dart';
-import 'package:pip/pip.dart';
 import 'package:eaimar/data/services/qq_music.dart';
 import '../../../data/services/ast_service.dart';
 import '../../../data/services/server_translation_service.dart';
@@ -99,13 +98,7 @@ class TranslationController extends GetxController with WidgetsBindingObserver {
   // 安卓悬浮窗管理器
   late final FloatingWindowManager _floatingWindowManager;
   // 苹果悬浮窗管理器
-  late final Pip _pip;
   late final NativePlugin _nativePlugin;
-  int _pipContentView = 0;
-  static const int _pipPreferredWidth = 375;
-  static const int _pipCompactPreferredHeight = 72;
-  static const int _pipExpandedPreferredHeight = 220;
-  bool _isPipExpanded = false;
 
   // ==================== 悬浮窗相关 ====================
   final isFloatingWindowEnabled = false.obs; // 悬浮窗状态
@@ -266,28 +259,14 @@ class TranslationController extends GetxController with WidgetsBindingObserver {
 
   /// 初始化苹果悬浮窗管理器
   Future<void> initPlatformState() async {
-    _pip = Pip();
     _nativePlugin = NativePlugin();
-    try {
-      isFloatingWindowEnabled.value = await _pip.isActived();
-      await _pip.registerStateChangedObserver(
-        PipStateChangedObserver(
-          onPipStateChanged: (state, error) {
-            isFloatingWindowEnabled.value = state == PipState.pipStateStarted;
-
-            if (state == PipState.pipStateFailed) {
-              _isPipExpanded = false;
-              _pip.dispose();
-              unawaited(_releasePipContentView());
-            } else if (state == PipState.pipStateStopped) {
-              _isPipExpanded = false;
-            }
-          },
-        ),
-      );
-    } on PlatformException {
-      isFloatingWindowEnabled.value = false;
-    }
+    if (!Platform.isIOS) return;
+    // ⚠️ 不再走 pub 包 `pip`。它给小窗喂的是一整块纯黑像素，真正的字幕卡片
+    // 靠把 contentView 搬进「keyWindow」来显示，而 PiP 窗口由系统进程托管、
+    // 根本不在 App 的窗口列表里 —— 于是字幕落在 App 自己身上（还盖住整屏），
+    // 小窗里只有一块黑的。现在改成自绘：把字幕画进 CVPixelBuffer 逐帧喂给
+    // AVSampleBufferDisplayLayer，小窗显示的就是它（见原生 SubtitlePipController）。
+    isFloatingWindowEnabled.value = await SubtitlePip.isActive();
   }
 
   /// 切换悬浮窗功能
@@ -296,9 +275,8 @@ class TranslationController extends GetxController with WidgetsBindingObserver {
       if (Platform.isAndroid) {
         await _disableFloatingWindow();
       } else if (Platform.isIOS) {
-        _isPipExpanded = false;
-        await _pip.dispose();
-        await _releasePipContentView();
+        await SubtitlePip.stop();
+        isFloatingWindowEnabled.value = false;
       }
     } else {
       if (Platform.isAndroid) {
@@ -309,51 +287,37 @@ class TranslationController extends GetxController with WidgetsBindingObserver {
     }
   }
 
-  PipOptions _buildIosPipOptions({required int preferredHeight}) {
-    return PipOptions(
-      autoEnterEnabled: true,
-      aspectRatioX: _pipPreferredWidth,
-      aspectRatioY: preferredHeight,
-      sourceRectHintLeft: 0,
-      sourceRectHintTop: 0,
-      sourceRectHintRight: 0,
-      sourceRectHintBottom: 0,
-      seamlessResizeEnabled: true,
-      useExternalStateMonitor: true,
-      externalStateMonitorInterval: 100,
-      contentView: _pipContentView,
-      preferredContentWidth: _pipPreferredWidth,
-      preferredContentHeight: preferredHeight,
-      controlStyle: 2,
-    );
+  Future<void> _startPip() async {
+    final ok = await SubtitlePip.start();
+    isFloatingWindowEnabled.value = ok;
+    if (!ok) {
+      Logger.w('Translation', '字幕小窗启动失败（系统拒绝或本机不支持画中画）');
+      return;
+    }
+    // 起来之后把当前样式补一次，否则用户上次调的透明度/宽度这一轮不生效
+    await SubtitlePip.setStyle(
+        opacity: pipOpacity.value, widthScale: pipWidthScale.value);
   }
 
-  /// 释放 PiP 的字幕视图，并且**必须把 id 清零**，下次开启时重新 new 一个。
+  /// 字幕小窗的样式。**都会持久化**，下次进来沿用。
   ///
-  /// ⚠️ 不清零的话会复用一个已经被 pip 插件搬进 App keyWindow、
-  /// 而且再也摘不下来的 view：插件的 restoreContentViewIfNeeded 在
-  /// `originalParentView == nil` 时直接 return，而这个 view 是我们凭空
-  /// new 出来的、从来没有过 superview，所以那个还原分支永远走不到。
-  /// 结果就是关掉弹幕之后它仍然铺在屏幕上（现在至少不吃触摸了，但仍然多余）。
-  Future<void> _releasePipContentView() async {
-    if (_pipContentView == 0) return;
-    final int viewId = _pipContentView;
-    _pipContentView = 0;
-    try {
-      await _nativePlugin.disposePipContentView(viewId);
-    } catch (e) {
-      Logger.warning('释放 PiP 字幕视图失败（不影响退出弹幕）: $e');
-    }
+  /// ⚠️ [pipOpacity] 改的是卡片自己的底色，**不是**「透过小窗看见下面的 App」。
+  /// iOS 的 PiP 窗口本身不透明，系统没有开放任何让它半透明的接口。
+  /// 真要少挡内容只能把小窗做小（widthScale）或用系统手势把它拖到别处。
+  ///
+  /// ⚠️ [pipWidthScale] 改的是**画布宽高比**。小窗的实际大小由用户捏合手势
+  /// 决定，App 无权直接设定；换比例会让系统按新形状重新布局。
+  final RxDouble pipOpacity = 0.9.obs;
+  final RxDouble pipWidthScale = 1.0.obs;
+
+  Future<void> setPipOpacity(double v) async {
+    pipOpacity.value = v.clamp(0.2, 1.0);
+    await SubtitlePip.setStyle(opacity: pipOpacity.value);
   }
 
-  Future<void> _startPip() async {
-    if (_pipContentView == 0) {
-      _pipContentView = await _nativePlugin.createPipContentView();
-    }
-    _isPipExpanded = false;
-    await _pip.setup(
-        _buildIosPipOptions(preferredHeight: _pipCompactPreferredHeight));
-    await _pip.start();
+  Future<void> setPipWidthScale(double v) async {
+    pipWidthScale.value = v.clamp(0.5, 2.0);
+    await SubtitlePip.setStyle(widthScale: pipWidthScale.value);
   }
 
   /// 启用悬浮窗功能
@@ -427,23 +391,13 @@ class TranslationController extends GetxController with WidgetsBindingObserver {
       );
       await _floatingWindowManager.updateFloatingWindowContent(data);
     } else if (Platform.isIOS) {
-      final hasContent = item.sourceText.trim().isNotEmpty ||
-          item.translatedText.trim().isNotEmpty;
-      if (hasContent && !_isPipExpanded) {
-        final ok = await _pip.setup(
-            _buildIosPipOptions(preferredHeight: _pipExpandedPreferredHeight));
-        if (ok) _isPipExpanded = true;
-      } else if (!hasContent && _isPipExpanded) {
-        final ok = await _pip.setup(
-            _buildIosPipOptions(preferredHeight: _pipCompactPreferredHeight));
-        if (ok) _isPipExpanded = false;
-      }
-      await _nativePlugin.updatePipContentView({
-        'viewId': _pipContentView,
-        'cn': item.sourceText,
-        'en': item.translatedText,
-        'lang': '$sourceLanguageName -> $targetLanguageName',
-      });
+      // 收起/展开不再需要重新 setup：画布高度跟着卡片内容走，
+      // 宽高比一变系统就会把小窗重新布形状。
+      await SubtitlePip.update(
+        lang: '$sourceLanguageName -> $targetLanguageName',
+        cn: item.sourceText,
+        en: item.translatedText,
+      );
     }
   }
 
@@ -1123,10 +1077,7 @@ class TranslationController extends GetxController with WidgetsBindingObserver {
     if (Platform.isAndroid) {
       _disableFloatingWindow();
     } else if (Platform.isIOS) {
-      _pip.dispose();
-      if (_pipContentView != 0) {
-        _nativePlugin.disposePipContentView(_pipContentView);
-      }
+      unawaited(SubtitlePip.stop());
     }
 
     // 释放管理器资源
diff --git a/apps/client/local_plugins/floating_ui_plugin/ios/Classes/NativePlugin.swift b/apps/client/local_plugins/floating_ui_plugin/ios/Classes/NativePlugin.swift
index 55623908..1654105b 100644
--- a/apps/client/local_plugins/floating_ui_plugin/ios/Classes/NativePlugin.swift
+++ b/apps/client/local_plugins/floating_ui_plugin/ios/Classes/NativePlugin.swift
@@ -55,6 +55,53 @@ public class FloatingUiPlugin: NSObject, FlutterPlugin {
     case "getPlatformVersion":
       result("iOS " + UIDevice.current.systemVersion)
 
+    // ===== 字幕画中画（自绘）=====
+    //
+    // 与下面那套 createPipContentView/updatePipContentView 的区别：那一套依赖
+    // pub 包 `pip` 把 contentView 搬进 keyWindow，而 PiP 窗口根本不在 App 的
+    // 窗口列表里，字幕永远进不去小窗（详见 SubtitlePipController 的注释）。
+    // 这一套自己把字幕画进 CVPixelBuffer 喂给 AVSampleBufferDisplayLayer，
+    // 小窗显示的就是它。
+    case "subtitlePipStart":
+      if #available(iOS 15.0, *) {
+        Self.updateAudioSession()
+        result(SubtitlePipController.shared.start())
+      } else {
+        result(FlutterError(code: "UNSUPPORTED", message: "字幕小窗需要 iOS 15 及以上", details: nil))
+      }
+
+    case "subtitlePipStop":
+      if #available(iOS 15.0, *) {
+        SubtitlePipController.shared.stop()
+      }
+      result(nil)
+
+    case "subtitlePipUpdate":
+      if #available(iOS 15.0, *) {
+        let data = call.arguments as? [String: Any]
+        SubtitlePipController.shared.update(
+          lang: data?["lang"] as? String,
+          cn: data?["cn"] as? String,
+          en: data?["en"] as? String)
+      }
+      result(nil)
+
+    case "subtitlePipSetStyle":
+      if #available(iOS 15.0, *) {
+        let data = call.arguments as? [String: Any]
+        SubtitlePipController.shared.setStyle(
+          opacity: (data?["opacity"] as? NSNumber).map { CGFloat($0.doubleValue) },
+          widthScale: (data?["widthScale"] as? NSNumber).map { CGFloat($0.doubleValue) })
+      }
+      result(nil)
+
+    case "subtitlePipIsActive":
+      if #available(iOS 15.0, *) {
+        result(SubtitlePipController.shared.isActive)
+      } else {
+        result(false)
+      }
+
     case "createPipContentView":
       Self.updateAudioSession()
       let playerView = PlayerView()
diff --git a/apps/client/local_plugins/floating_ui_plugin/ios/Classes/PlayerView.swift b/apps/client/local_plugins/floating_ui_plugin/ios/Classes/PlayerView.swift
index 9b0b45b6..905ab062 100644
--- a/apps/client/local_plugins/floating_ui_plugin/ios/Classes/PlayerView.swift
+++ b/apps/client/local_plugins/floating_ui_plugin/ios/Classes/PlayerView.swift
@@ -11,6 +11,7 @@ public class PlayerView: UIView {
   /// 挂在 cardView 上、并且只把 cardView 钉在顶部，最坏情况也只是顶部一条字幕条。
   private let cardView: UIView = UIView()
   private var cardHeightConstraint: NSLayoutConstraint?
+  private var cardBottomConstraint: NSLayoutConstraint?
   private let titleLabel: UILabel = UILabel()
   private let langLabel: UILabel = UILabel()
   private let langContainer: UIView = UIView()
@@ -156,6 +157,46 @@ public class PlayerView: UIView {
     ])
   }
 
+  // MARK: - 供 PiP 离屏渲染使用
+
+  /// 当前内容需要的画布尺寸（宽度给定，高度由展开/收起状态决定）。
+  ///
+  /// PiP 小窗的宽高比由我们喂进去的 pixel buffer 尺寸决定，所以这个值变了，
+  /// 系统的小窗也会跟着变形状 —— 「有内容时变高、没内容时收成一条」就是
+  /// 靠它实现的。
+  public func canvasSize(width: CGFloat) -> CGSize {
+    CGSize(width: width, height: isExpanded ? expandedPreferredHeight : compactPreferredHeight)
+  }
+
+  /// 卡片背景的不透明度（0~1）。
+  ///
+  /// ⚠️ 这**不是**「透过弹幕看到下面的 App」。iOS 的 PiP 窗口本身是不透明的，
+  /// 系统不给任何接口让它变成半透明——alpha 只是让卡片在小窗自己那块黑底上
+  /// 显得深一点浅一点。真正减少遮挡只能靠把小窗做小、或者挪到别处。
+  public func setBackgroundAlpha(_ alpha: CGFloat) {
+    let a = max(0, min(1, alpha))
+    cardView.backgroundColor = UIColor(red: 40.0 / 255.0,
+                                       green: 40.0 / 255.0,
+                                       blue: 40.0 / 255.0,
+                                       alpha: a)
+    cardView.layer.borderColor = UIColor(white: 1.0, alpha: 46.0 / 255.0 * a).cgColor
+  }
+
+  /// 让 cardView 铺满整个 view —— 离屏渲染时画布就是卡片，不需要顶部对齐。
+  public func setFillsBounds(_ fills: Bool) {
+    cardHeightConstraint?.isActive = !fills
+    if fills {
+      if cardBottomConstraint == nil {
+        cardBottomConstraint = cardView.bottomAnchor.constraint(equalTo: bottomAnchor)
+      }
+      cardBottomConstraint?.isActive = true
+    } else {
+      cardBottomConstraint?.isActive = false
+      cardHeightConstraint?.isActive = true
+    }
+    setNeedsLayout()
+  }
+
   public func play() {
   }
 
diff --git a/apps/client/local_plugins/floating_ui_plugin/ios/Classes/SubtitlePipController.swift b/apps/client/local_plugins/floating_ui_plugin/ios/Classes/SubtitlePipController.swift
new file mode 100644
index 00000000..d38f195d
--- /dev/null
+++ b/apps/client/local_plugins/floating_ui_plugin/ios/Classes/SubtitlePipController.swift
@@ -0,0 +1,294 @@
+import AVFoundation
+import AVKit
+import UIKit
+
+/// 自己实现的字幕画中画。
+///
+/// ## 为什么不用 pub 上的 `pip` 包
+/// 那个包给 PiP 喂的是**一整块纯黑像素**（PipView.m 里 `pixel = 0xFF000000`
+/// 填满 pixelBuffer），只是个占位帧；真正的字幕卡片它是靠
+/// `insertContentViewIfNeeded` 塞进「keyWindow」的。而 PiP 窗口由系统进程托管、
+/// **不在 `UIApplication.connectedScenes` 的窗口列表里**，那个 keyWindow 永远
+/// 是 App 自己的窗口。结果就是：字幕落在 App 自己身上（还盖住整个屏幕），
+/// PiP 小窗里只有一块黑的。用户看到的「弹幕上没有翻译内容」就是这么来的。
+///
+/// 正确做法只有一条：**自己把字幕画进 CVPixelBuffer，逐帧喂给
+/// AVSampleBufferDisplayLayer**。小窗显示的就是这个 layer 的内容。
+///
+/// ## ⚠️ 关于透明度
+/// iOS 的 PiP 窗口本身不透明，系统没有任何接口能让它变成半透明。
+/// [setStyle] 里的 opacity 只作用于卡片自己的底色（在小窗那块黑底之上），
+/// **做不到透过小窗看见下面的 App**。要少挡内容只能把小窗做小，
+/// 或者用系统手势把它拖到别处 / 收到屏幕边缘。
+///
+/// ## ⚠️ 关于大小
+/// PiP 小窗的尺寸由用户捏合手势控制，App 无权直接设定；我们能决定的是
+/// **宽高比**（= 喂进去的 pixel buffer 的宽高比）。所以"放大缩小"在这里表现为
+/// 换一个画布比例，系统会按新比例重新布局小窗。
+@available(iOS 15.0, *)
+final class SubtitlePipController: NSObject {
+    static let shared = SubtitlePipController()
+
+    /// 承载 AVSampleBufferDisplayLayer 的宿主 view
+    private final class RenderView: UIView {
+        override class var layerClass: AnyClass { AVSampleBufferDisplayLayer.self }
+        var displayLayer: AVSampleBufferDisplayLayer {
+            // swiftlint:disable:next force_cast
+            layer as! AVSampleBufferDisplayLayer
+        }
+    }
+
+    private let renderView = RenderView()
+    private let card = PlayerView()
+    private var pip: AVPictureInPictureController?
+    private var timebase: CMTimebase?
+    private var heartbeat: Timer?
+
+    /// 画布宽度。高度由卡片当前是收起还是展开决定，见 PlayerView.canvasSize。
+    private var canvasWidth: CGFloat = 375
+    private var lastCanvasSize: CGSize = .zero
+
+    private(set) var isActive = false
+
+    private override init() {
+        super.init()
+        card.setFillsBounds(true)
+    }
+
+    // MARK: - 生命周期
+
+    @discardableResult
+    func start() -> Bool {
+        guard AVPictureInPictureController.isPictureInPictureSupported() else {
+            NSLog("[SubtitlePip] 本机不支持画中画")
+            return false
+        }
+        attachRenderViewIfNeeded()
+        setupTimebaseIfNeeded()
+        // 先推一帧再 start：AVPictureInPictureController 在没有任何已入队帧时
+        // 可能拒绝启动（内容源被判定为"没有内容"），表现是回调里直接 failed。
+        renderAndEnqueue(force: true)
+
+        if pip == nil {
+            let source = AVPictureInPictureController.ContentSource(
+                sampleBufferDisplayLayer: renderView.displayLayer,
+                playbackDelegate: self
+            )
+            let controller = AVPictureInPictureController(contentSource: source)
+            controller.delegate = self
+            // 字幕不是可拖动进度的媒体，去掉播放/快进那套控件
+            controller.requiresLinearPlayback = true
+            // 用户切走 App 时自动进小窗——这正是本功能的使用场景
+            controller.canStartPictureInPictureAutomaticallyFromInline = true
+            pip = controller
+        }
+        pip?.startPictureInPicture()
+
+        // 心跳：定期补一帧。
+        // ⚠️ 不能只在文案变化时推帧 —— 长时间没有新帧时
+        // AVSampleBufferDisplayLayer 可能被系统判定为停滞并清空，
+        // 表现是「翻译停一会儿，小窗就黑了」。
+        heartbeat?.invalidate()
+        heartbeat = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { [weak self] _ in
+            self?.renderAndEnqueue(force: false)
+        }
+        return true
+    }
+
+    func stop() {
+        heartbeat?.invalidate()
+        heartbeat = nil
+        pip?.stopPictureInPicture()
+        renderView.removeFromSuperview()
+        isActive = false
+    }
+
+    // MARK: - 内容与样式
+
+    func update(lang: String?, cn: String?, en: String?) {
+        DispatchQueue.main.async { [weak self] in
+            guard let self = self else { return }
+            self.card.update(withLang: lang, cn: cn, en: en)
+            self.renderAndEnqueue(force: true)
+        }
+    }
+
+    /// [opacity] 卡片底色不透明度 0~1；[widthScale] 画布宽度相对基准 375 的倍数，
+    /// 通过改变宽高比让系统把小窗重新布成更宽/更窄的形状。
+    func setStyle(opacity: CGFloat?, widthScale: CGFloat?) {
+        DispatchQueue.main.async { [weak self] in
+            guard let self = self else { return }
+            if let opacity = opacity { self.card.setBackgroundAlpha(opacity) }
+            if let scale = widthScale {
+                self.canvasWidth = max(180, min(750, 375 * scale))
+            }
+            self.renderAndEnqueue(force: true)
+        }
+    }
+
+    // MARK: - 渲染
+
+    private func attachRenderViewIfNeeded() {
+        guard renderView.superview == nil else { return }
+        // ⚠️ 必须挂在真实的窗口层级里，且尺寸非零：脱离层级的 layer 不会被
+        // PiP 采纳，表现是 start 之后立刻回调 failed。做成几乎全透明即可，
+        // 它在 App 内不需要被看见。
+        guard let window = UIApplication.shared.connectedScenes
+            .compactMap({ $0 as? UIWindowScene })
+            .flatMap({ $0.windows })
+            .first(where: { $0.isKeyWindow }) ?? UIApplication.shared.windows.first else {
+            return
+        }
+        renderView.alpha = 0.01
+        renderView.isUserInteractionEnabled = false
+        renderView.frame = CGRect(x: 0, y: 0, width: 1, height: 1)
+        window.addSubview(renderView)
+    }
+
+    private func setupTimebaseIfNeeded() {
+        guard timebase == nil else { return }
+        var tb: CMTimebase?
+        CMTimebaseCreateWithSourceClock(allocator: kCFAllocatorDefault,
+                                        sourceClock: CMClockGetHostTimeClock(),
+                                        timebaseOut: &tb)
+        if let tb = tb {
+            CMTimebaseSetTime(tb, time: .zero)
+            CMTimebaseSetRate(tb, rate: 1.0)
+            renderView.displayLayer.controlTimebase = tb
+            timebase = tb
+        }
+    }
+
+    private func renderAndEnqueue(force: Bool) {
+        let size = card.canvasSize(width: canvasWidth)
+        if size != lastCanvasSize {
+            lastCanvasSize = size
+            card.frame = CGRect(origin: .zero, size: size)
+        }
+        card.setNeedsLayout()
+        card.layoutIfNeeded()
+
+        guard let pixelBuffer = makePixelBuffer(size: size),
+              let sample = makeSampleBuffer(pixelBuffer) else { return }
+        let layer = renderView.displayLayer
+        if layer.status == .failed { layer.flush() }
+        layer.enqueue(sample)
+    }
+
+    private func makePixelBuffer(size: CGSize) -> CVPixelBuffer? {
+        let w = max(2, Int(size.width))
+        let h = max(2, Int(size.height))
+        var pb: CVPixelBuffer?
+        let attrs: [String: Any] = [
+            kCVPixelBufferIOSurfacePropertiesKey as String: [String: Any]()
+        ]
+        guard CVPixelBufferCreate(kCFAllocatorDefault, w, h,
+                                  kCVPixelFormatType_32BGRA,
+                                  attrs as CFDictionary, &pb) == kCVReturnSuccess,
+              let pixelBuffer = pb else { return nil }
+
+        CVPixelBufferLockBaseAddress(pixelBuffer, [])
+        defer { CVPixelBufferUnlockBaseAddress(pixelBuffer, []) }
+        guard let base = CVPixelBufferGetBaseAddress(pixelBuffer) else { return nil }
+
+        guard let ctx = CGContext(
+            data: base,
+            width: w, height: h,
+            bitsPerComponent: 8,
+            bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBuffer),
+            space: CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedFirst.rawValue
+                | CGBitmapInfo.byteOrder32Little.rawValue
+        ) else { return nil }
+
+        ctx.clear(CGRect(x: 0, y: 0, width: w, height: h))
+        // ⚠️ UIKit 原点在左上、CoreGraphics 在左下。不翻这一下，字幕是上下颠倒的。
+        ctx.translateBy(x: 0, y: CGFloat(h))
+        ctx.scaleBy(x: 1, y: -1)
+        UIGraphicsPushContext(ctx)
+        card.layer.render(in: ctx)
+        UIGraphicsPopContext()
+        return pixelBuffer
+    }
+
+    private func makeSampleBuffer(_ pixelBuffer: CVPixelBuffer) -> CMSampleBuffer? {
+        var formatDesc: CMVideoFormatDescription?
+        guard CMVideoFormatDescriptionCreateForImageBuffer(
+            allocator: kCFAllocatorDefault,
+            imageBuffer: pixelBuffer,
+            formatDescriptionOut: &formatDesc) == noErr,
+            let desc = formatDesc else { return nil }
+
+        let now = timebase.map { CMTimebaseGetTime($0) } ?? .zero
+        var timing = CMSampleTimingInfo(
+            duration: CMTimeMakeWithSeconds(1, preferredTimescale: 600),
+            presentationTimeStamp: now,
+            decodeTimeStamp: .invalid
+        )
+        var sample: CMSampleBuffer?
+        guard CMSampleBufferCreateReadyWithImageBuffer(
+            allocator: kCFAllocatorDefault,
+            imageBuffer: pixelBuffer,
+            formatDescription: desc,
+            sampleTiming: &timing,
+            sampleBufferOut: &sample) == noErr else { return nil }
+        return sample
+    }
+}
+
+// MARK: - AVPictureInPictureControllerDelegate
+
+@available(iOS 15.0, *)
+extension SubtitlePipController: AVPictureInPictureControllerDelegate {
+    func pictureInPictureControllerDidStartPictureInPicture(
+        _ pictureInPictureController: AVPictureInPictureController) {
+        isActive = true
+        NSLog("[SubtitlePip] 已进入画中画")
+        renderAndEnqueue(force: true)
+    }
+
+    func pictureInPictureController(
+        _ pictureInPictureController: AVPictureInPictureController,
+        failedToStartPictureInPictureWithError error: Error) {
+        isActive = false
+        NSLog("[SubtitlePip] 进入画中画失败: %@", error.localizedDescription)
+    }
+
+    func pictureInPictureControllerDidStopPictureInPicture(
+        _ pictureInPictureController: AVPictureInPictureController) {
+        isActive = false
+        NSLog("[SubtitlePip] 已退出画中画")
+    }
+}
+
+// MARK: - AVPictureInPictureSampleBufferPlaybackDelegate
+
+@available(iOS 15.0, *)
+extension SubtitlePipController: AVPictureInPictureSampleBufferPlaybackDelegate {
+    func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController,
+                                    setPlaying playing: Bool) {}
+
+    /// 返回无限区间 = 告诉系统这是直播流，小窗上就不会出现进度条和快进按钮。
+    func pictureInPictureControllerTimeRangeForPlayback(
+        _ pictureInPictureController: AVPictureInPictureController) -> CMTimeRange {
+        CMTimeRange(start: .negativeInfinity, duration: .positiveInfinity)
+    }
+
+    func pictureInPictureControllerIsPlaybackPaused(
+        _ pictureInPictureController: AVPictureInPictureController) -> Bool {
+        false
+    }
+
+    func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController,
+                                    didTransitionToRenderSize newRenderSize: CMVideoDimensions) {
+        // 用户捏合改了小窗大小。这里不改画布：画布比例是我们定的，
+        // 系统会自己把内容缩放到新尺寸。
+        NSLog("[SubtitlePip] 小窗尺寸变为 %dx%d", newRenderSize.width, newRenderSize.height)
+    }
+
+    func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController,
+                                    skipByInterval skipInterval: CMTime,
+                                    completion completionHandler: @escaping () -> Void) {
+        completionHandler()
+    }
+}
diff --git a/apps/client/local_plugins/floating_ui_plugin/lib/native_plugin.dart b/apps/client/local_plugins/floating_ui_plugin/lib/native_plugin.dart
index 3650779a..50c04d2e 100644
--- a/apps/client/local_plugins/floating_ui_plugin/lib/native_plugin.dart
+++ b/apps/client/local_plugins/floating_ui_plugin/lib/native_plugin.dart
@@ -78,3 +78,64 @@ class TranslationFloatingWindowApi {
     return channel.invokeMethod<void>('setPosition', {'x': x, 'y': y});
   }
 }
+
+/// 字幕画中画（iOS）。自绘内容喂给 AVSampleBufferDisplayLayer，
+/// 与 [NativePlugin.createPipContentView] 那套**不是**一回事：
+/// 那一套依赖 pub 包 `pip` 把 contentView 搬进 keyWindow，而 PiP 窗口不在
+/// App 的窗口列表里，字幕永远进不了小窗（原生侧 SubtitlePipController 有详述）。
+///
+/// Android 上全部是空操作 —— 那边用的是真正的系统悬浮窗。
+class SubtitlePip {
+  SubtitlePip._();
+
+  static const MethodChannel _channel = MethodChannel('native_plugin');
+
+  /// 进入画中画。返回 false 表示本机不支持或启动被系统拒绝。
+  static Future<bool> start() async {
+    try {
+      return (await _channel.invokeMethod<bool>('subtitlePipStart')) ?? false;
+    } catch (_) {
+      return false;
+    }
+  }
+
+  static Future<void> stop() async {
+    try {
+      await _channel.invokeMethod<void>('subtitlePipStop');
+    } catch (_) {}
+  }
+
+  /// 更新小窗里显示的内容。[lang] 是「源语言 → 目标语言」那一行。
+  static Future<void> update({String? lang, String? cn, String? en}) async {
+    try {
+      await _channel.invokeMethod<void>('subtitlePipUpdate', {
+        'lang': lang,
+        'cn': cn,
+        'en': en,
+      });
+    } catch (_) {}
+  }
+
+  /// [opacity] 卡片底色不透明度 0~1。
+  /// [widthScale] 画布宽度倍数（基准 375），改的是**宽高比**——
+  /// 小窗实际大小由用户捏合决定，App 无权直接设定。
+  ///
+  /// ⚠️ opacity 做不到「透过小窗看见下面的 App」：iOS 的 PiP 窗口本身不透明，
+  /// 系统没有开放任何接口。它只让卡片在小窗自己那块底上显得深浅不同。
+  static Future<void> setStyle({double? opacity, double? widthScale}) async {
+    try {
+      await _channel.invokeMethod<void>('subtitlePipSetStyle', {
+        if (opacity != null) 'opacity': opacity,
+        if (widthScale != null) 'widthScale': widthScale,
+      });
+    } catch (_) {}
+  }
+
+  static Future<bool> isActive() async {
+    try {
+      return (await _channel.invokeMethod<bool>('subtitlePipIsActive')) ?? false;
+    } catch (_) {
+      return false;
+    }
+  }
+}