diff --git a/Splitter-UI/Models/PreviewData.cs b/Splitter-UI/Models/PreviewData.cs
index ea76d07..9d41762 100644
--- a/Splitter-UI/Models/PreviewData.cs
+++ b/Splitter-UI/Models/PreviewData.cs
@@ -3,13 +3,13 @@
 public class PreviewData
 {
     public Avalonia.Media.Imaging.Bitmap? Frame          { get; }
-    public IReadOnlyList<OpenCvSharp.Rect> DetectedBoxes { get; }
+    public IReadOnlyList<DetectedPerson> DetectedBoxes { get; }
     public Rect? CropRect                                { get; }
     public Point2f GravitateTo                           { get; }
     public TimeSpan Position                             { get; }
     public int? Rotate                                   { get; }
 
-    public PreviewData(Avalonia.Media.Imaging.Bitmap? frame, IReadOnlyList<OpenCvSharp.Rect> boxes, Rect? crop, Point2f gravitateTo, TimeSpan position, int? rotate)
+    public PreviewData(Avalonia.Media.Imaging.Bitmap? frame, IReadOnlyList<DetectedPerson> boxes, Rect? crop, Point2f gravitateTo, TimeSpan position, int? rotate)
     {
         Frame         = frame;
         DetectedBoxes = boxes;
diff --git a/Splitter-UI/Program.cs b/Splitter-UI/Program.cs
index dd8f420..7bc20f8 100644
--- a/Splitter-UI/Program.cs
+++ b/Splitter-UI/Program.cs
@@ -39,19 +39,16 @@ internal sealed class Program
         services.AddSingleton<YoloV10ObjectDetector>();
         services.AddSingleton<OSNetEmbeddingExtractor>();
         services.AddSingleton<IObjectTracker, ObjectTracker>();
-        services.AddSingleton(x => new SingleThreadedDetector<UltraFaceDetector>(x.GetRequiredService<UltraFaceDetector>()));
-        services.AddSingleton(x => new SingleThreadedDetector<YoloV10ObjectDetector>(x.GetRequiredService<YoloV10ObjectDetector>()));
-        services.AddSingleton(x => new SingleThreadedDetector<DummyDetector>(x.GetRequiredService<DummyDetector>()));
+        services.AddKeyedSingleton<IObjectDetector>("face", (x,_) => new SingleThreadedDetector<UltraFaceDetector>(x.GetRequiredService<UltraFaceDetector>()));
+        services.AddKeyedSingleton<IObjectDetector>("body", (x,_) => new SingleThreadedDetector<YoloV10ObjectDetector>(x.GetRequiredService<YoloV10ObjectDetector>()));
+        services.AddKeyedSingleton<IObjectDetector>("none", (x,_) => new SingleThreadedDetector<DummyDetector>(x.GetRequiredService<DummyDetector>()));
         services.AddSingleton<IEmbeddingExtractor>(x => new SingleThreadedEmbeddingExtractor<OSNetEmbeddingExtractor>(x.GetRequiredService<OSNetEmbeddingExtractor>()));
-        services.AddSingleton<Func<string, IObjectDetector>>( x => detectorName =>
+        services.AddSingleton<Func<string, IObjectDetector>>(x => detectorName => x.GetKeyedService<IObjectDetector>(detectorName) ?? new DummyDetector());
+        services.AddSingleton<Func<string, IObjectTracker>>(x => detectorName =>
         {
-            return detectorName switch
-            {
-                "face" => x.GetRequiredService<SingleThreadedDetector<UltraFaceDetector>>(),
-                "body" => x.GetRequiredService<SingleThreadedDetector<YoloV10ObjectDetector>>(),
-                "none" => x.GetRequiredService<SingleThreadedDetector<DummyDetector>>(),
-                _ => new DummyDetector()
-            };
+            var detectorFactory = x.GetRequiredService<Func<string, IObjectDetector>>();
+            var extractor       = x.GetRequiredService<IEmbeddingExtractor>();
+            return new ObjectTracker(detectorFactory(detectorName), extractor);
         });
         services.AddSingleton<ILogger, GlobalLogger>();
         services.AddSingleton<IJobProcessor, JobProcessor>();
diff --git a/Splitter-UI/ViewModels/InspectorPaneViewModel.cs b/Splitter-UI/ViewModels/InspectorPaneViewModel.cs
index 726faf8..7aba1b5 100644
--- a/Splitter-UI/ViewModels/InspectorPaneViewModel.cs
+++ b/Splitter-UI/ViewModels/InspectorPaneViewModel.cs
@@ -30,22 +30,7 @@ public partial class InspectorPaneViewModel : ObservableObject
             return;
 
         foreach (JobViewModel job in Files.Where(x => !ReferenceEquals(x, Selected)))
-        {
-            job.Detect                 = Selected.Detect;
-            job.Rotate                 = Selected.Rotate;
-            job.CropText               = Selected.CropText;
-            job.ForceFixed             = Selected.ForceFixed;
-            job.GravitateText          = Selected.GravitateText;
-            job.Mask                   = Selected.Mask;
-            job.OutputFolder           = Selected.OutputFolder;
-            job.OverrideTargetDuration = Selected.OverrideTargetDuration;
-            job.PassthroughText        = Selected.PassthroughText;
-            job.Enhance                = Selected.Enhance;
-            
-            job.ParametersList.Clear();
-            foreach (var param in Selected.ParametersList)
-                job.ParametersList.Add(param);
-        }
+            job.CopyFrom(Selected);
     }
 
     public IRelayCommand RotateLeftCommand { get; }
diff --git a/Splitter-UI/ViewModels/JobViewModel.cs b/Splitter-UI/ViewModels/JobViewModel.cs
index 493c542..f192fa7 100644
--- a/Splitter-UI/ViewModels/JobViewModel.cs
+++ b/Splitter-UI/ViewModels/JobViewModel.cs
@@ -28,7 +28,7 @@ public partial class JobViewModel : ObservableObject
 
     private readonly IThumbnailService             _thumbnails;
     private readonly DispatcherTimer               _debounceTimer;
-    private readonly Func<string, IObjectDetector> _detectorFactory;
+    private readonly Func<string, IObjectTracker>  _trackerFactory;
     private readonly ILogger                       _log;
 
     public string FileName => Path.GetFileName(Job.InputFile);
@@ -220,6 +220,19 @@ public partial class JobViewModel : ObservableObject
         }
     }
 
+    public ulong? DetectId
+    {
+        get => Job.DetectId;
+        set
+        {
+            if (DetectId == value)
+                return;
+            Job.DetectId = value;
+            OnPropertyChanged();
+            Task.Run(CreatePreview);
+        }
+    }
+
     public double? OverrideTargetDuration
     {
         get => Job.OverrideTargetDuration;
@@ -231,11 +244,12 @@ public partial class JobViewModel : ObservableObject
             OnPropertyChanged();
         }
     }
-    public JobViewModel(SingleJob job, IThumbnailService thumbnails, Func<string, IObjectDetector> detectorFactory, ILogger log)
+
+    public JobViewModel(SingleJob job, IThumbnailService thumbnails, Func<string, IObjectTracker> trackerFactory, ILogger log)
     {
         Job              = job;
         _thumbnails      = thumbnails;
-        _detectorFactory = detectorFactory;
+        _trackerFactory = trackerFactory;
         _log             = log;
 
         ParametersList.Add(new ParameterEntry("DropoutToleranceFrames"      , ""));
@@ -271,6 +285,12 @@ public partial class JobViewModel : ObservableObject
         _debounceTimer.Tick += DebounceTimerTick;
     }
 
+    public void CopyFrom(JobViewModel src)
+    {
+        Job.CopyFrom(src.Job);
+        OnPropertyChanged(string.Empty); // Refresh all properties
+    }
+
     public async Task CreatePreview()
     {
         if ( Probe == null)
@@ -289,7 +309,7 @@ public partial class JobViewModel : ObservableObject
 
             Preview      = new PreviewData(frame, [], null, Job.GravitateTo, pos, Job.Rotate);
 
-            var detector = _detectorFactory(Job.Detect ?? "");
+            var tracker = _trackerFactory(Job.Detect ?? "");
             var j = new SingleTask
             (
                 Job             : Job,
@@ -301,31 +321,26 @@ public partial class JobViewModel : ObservableObject
                 SegmentLength   : 1, // 1 second segment for detection
                 ProcessorFactory: _ => throw new NotImplementedException()
             );
-            var detections = detector.DetectAll(j, frame.ToMatContinuous());
+
+            var (detections, primaryDetection) = tracker.SelectTrackedObject(j, frame.ToMatContinuous(), j.Job.GravitateTo);
 
             Rect? crop = null;
-            if (detections.Count > 0)
-            {
-                var primaryDetection = detections
-                    .OrderByDescending(d => d.Box.Height * d.Box.Width)
-                    .FirstOrDefault();
+            var w = Probe.Width;
+            var h = Probe.Height;
 
-                var w = Probe.Width;
-                var h = Probe.Height;
+            var cropWidth  = Job.Crop?.width  ?? CommandLine.DefaultW;
+            var cropHeight = Job.Crop?.height ?? CommandLine.DefaultH;
 
-                var cropWidth  = Job.Crop?.width  ?? CommandLine.DefaultW;
-                var cropHeight = Job.Crop?.height ?? CommandLine.DefaultH;
+            var p = primaryDetection?.Center ?? new Point2f(w * Job.GravitateTo.X, h * Job.GravitateTo.Y);
 
-                var cx = primaryDetection.Center.X - cropWidth  / 2f;
-                var cy = primaryDetection.Center.Y - cropHeight / 2f;
+            var cx = p.X - cropWidth  / 2f;
+            var cy = p.Y - cropHeight / 2f;
 
-                var r = new Rect(cx, cy, cropWidth, cropHeight);
+            var r = new Rect(cx, cy, cropWidth, cropHeight);
 
-                crop = ClampCrop(r, w, h);
-            }
+            crop = ClampCrop(r, w, h);
 
-            var boxes = detections.Select(x => x.Box).ToList();
-            Preview = new PreviewData(frame, boxes, crop, Job.GravitateTo, pos, Job.Rotate);
+            Preview = new PreviewData(frame, detections ?? [], crop, Job.GravitateTo, pos, Job.Rotate);
         }
         catch (Exception ex)
         {
diff --git a/Splitter-UI/ViewModels/PreviewPaneViewModel.cs b/Splitter-UI/ViewModels/PreviewPaneViewModel.cs
index 8a45d73..58c1b2e 100644
--- a/Splitter-UI/ViewModels/PreviewPaneViewModel.cs
+++ b/Splitter-UI/ViewModels/PreviewPaneViewModel.cs
@@ -35,6 +35,18 @@ public partial class PreviewPaneViewModel : ObservableObject
         }
     }
 
+    public ulong? TrackedId
+    {
+        get => Selected?.DetectId;
+        set
+        {
+            if (Selected == null)
+                return;
+            Selected.DetectId = value;
+            OnPropertyChanged(nameof(TrackedId));
+        }
+    }
+
     partial void OnSelectedChanged(JobViewModel? oldValue, JobViewModel? newValue)
     {
         if (oldValue != null)
@@ -46,6 +58,8 @@ public partial class PreviewPaneViewModel : ObservableObject
         OnPropertyChanged(nameof(Preview));
         OnPropertyChanged(nameof(Sar));
         OnPropertyChanged(nameof(Rotate));
+        OnPropertyChanged(nameof(TrackedId));
+        OnPropertyChanged(nameof(DetectAbove));
     }
 
     private void SelectedPropertyChanged(object? sender, PropertyChangedEventArgs e)
diff --git a/Splitter-UI/Views/InspectorPane.axaml b/Splitter-UI/Views/InspectorPane.axaml
index 3b0cd7f..6e5d301 100644
--- a/Splitter-UI/Views/InspectorPane.axaml
+++ b/Splitter-UI/Views/InspectorPane.axaml
@@ -9,6 +9,21 @@ x:DataType="vm:InspectorPaneViewModel">
         <ScrollViewer>
             <StackPanel Spacing="2">
 
+                <StackPanel Orientation="Horizontal"
+                            HorizontalAlignment="Right"
+                            Spacing="8"
+                            Margin="0,10,0,0">
+
+                    <Button Content="Apply to Selected"
+                            Command="{Binding ApplyOverridesCommand}"/>
+
+                    <Button Content="Transform all"
+                            Background="#AA0000"
+                            Foreground="White"
+                            Command="{Binding TransformAllCommand}"/>
+
+                </StackPanel>
+                
                 <TextBlock Text="Parameters" FontSize="10" Margin="0,0,0,10" FontWeight="Bold"/>
 
                 <!-- InputFile -->
@@ -111,6 +126,12 @@ x:DataType="vm:InspectorPaneViewModel">
                     <TextBox Text="{Binding Selected.DetectAbove}" Width="160"/>
                 </StackPanel>
 
+                <!-- DetectId -->
+                <StackPanel Orientation="Horizontal" Spacing="8">
+                    <TextBlock Text="Object to track" Width="120"/>
+                    <TextBox Text="{Binding Selected.DetectId}" Width="160"/>
+                </StackPanel>
+
                 <!-- OverrideTargetDuration -->
                 <StackPanel Orientation="Horizontal" Spacing="8">
                     <TextBlock Text="Target Duration" Width="120"/>
@@ -182,22 +203,6 @@ x:DataType="vm:InspectorPaneViewModel">
                     <TextBox Text="{Binding Selected.PassthroughText}" Width="260"/>
                 </StackPanel>
 
-                <StackPanel Orientation="Horizontal"
-                            HorizontalAlignment="Right"
-                            Spacing="8"
-                            Margin="0,10,0,0">
-
-                    <Button Content="Apply to Selected"
-                            Command="{Binding ApplyOverridesCommand}"/>
-
-                    <Button Content="Transform all"
-                            Background="#AA0000"
-                            Foreground="White"
-                            Command="{Binding TransformAllCommand}"/>
-
-                </StackPanel>
-
-
             </StackPanel>
         </ScrollViewer>
     </Border>
diff --git a/Splitter-UI/Views/MainWindow.axaml b/Splitter-UI/Views/MainWindow.axaml
index cd6f25d..3e07b53 100644
--- a/Splitter-UI/Views/MainWindow.axaml
+++ b/Splitter-UI/Views/MainWindow.axaml
@@ -8,7 +8,7 @@
     x:DataType="vm:MainViewModel"
     x:Name="Root"
     Width="1800"
-    Height="830"
+    Height="870"
     Title="Splitter UI"
     Icon="avares://Splitter-UI/Assets/splitter.png">
 
diff --git a/Splitter-UI/Views/PreviewCanvas.cs b/Splitter-UI/Views/PreviewCanvas.cs
index 8fea4c8..d8234ee 100644
--- a/Splitter-UI/Views/PreviewCanvas.cs
+++ b/Splitter-UI/Views/PreviewCanvas.cs
@@ -1,4 +1,5 @@
 using System.ComponentModel;
+using System.Globalization;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Input;
@@ -17,10 +18,10 @@ public sealed class PreviewCanvas : Control
         AvaloniaProperty.Register<PreviewCanvas, int>(nameof(RotateAngle));
     public static readonly StyledProperty<Point2f> GravitateToProperty =
         AvaloniaProperty.Register<PreviewCanvas, Point2f>(nameof(GravitateTo));
-
-    // normalized 0..1 from top of frame
     public static readonly StyledProperty<float> DetectAboveProperty =
         AvaloniaProperty.Register<PreviewCanvas, float>(nameof(DetectAbove), 0.2f);
+    public static readonly StyledProperty<ulong?> DetectIdProperty =
+        AvaloniaProperty.Register<PreviewCanvas, ulong?>(nameof(DetectId));
 
     public PreviewData? Preview
     {
@@ -47,6 +48,12 @@ public sealed class PreviewCanvas : Control
         set => SetValue(GravitateToProperty, value);
     }
 
+    public ulong? DetectId
+    {
+        get => GetValue(DetectIdProperty);
+        set => SetValue(DetectIdProperty, value);
+    }
+
     // DetectAbove is normalized (0..1) from top
     public float DetectAbove
     {
@@ -181,30 +188,22 @@ public sealed class PreviewCanvas : Control
             h * scale);
     }
 
-    // ------------------------------------------------------------
-    // Hit test for gravitate point (normalized)
-    // ------------------------------------------------------------
-
-    private bool HitGravitate(Avalonia.Point p, out Point2f value)
+    private void GetAspects(
+        PreviewData preview,
+        out int rawW,
+        out int rawH,
+        out int rotate,
+        out float pixelAspect,
+        out double scale,
+        out double offsetX,
+        out double offsetY)
     {
-        value = default;
+        rawW = preview.Frame!.PixelSize.Width;
+        rawH = preview.Frame.PixelSize.Height;
+        rotate = RotateAngle;
 
-        var preview = Preview;
-        if (preview?.Frame is null)
-            return false;
-
-        var g = GravitateTo;
-
-        var rawW = preview.Frame.PixelSize.Width;
-        var rawH = preview.Frame.PixelSize.Height;
-
-        // normalized → pixel
-        double px = g.X * rawW;
-        double py = g.Y * rawH;
-
-        var rotate = RotateAngle;
         var sar = Sar ?? new Point2f(1, 1);
-        var pixelAspect = sar.X / sar.Y;
+        pixelAspect = sar.X / sar.Y;
 
         var dispW = Bounds.Width;
         var dispH = Bounds.Height;
@@ -221,9 +220,32 @@ public sealed class PreviewCanvas : Control
             displayH = rawH * pixelAspect;
         }
 
-        var scale = Math.Min(dispW / displayW, dispH / displayH);
-        var offsetX = (dispW - displayW * scale) / 2;
-        var offsetY = (dispH - displayH * scale) / 2;
+        scale = Math.Min(dispW / displayW, dispH / displayH);
+        offsetX = (dispW - displayW * scale) / 2;
+        offsetY = (dispH - displayH * scale) / 2;
+    }
+
+    // ------------------------------------------------------------
+    // Hit test for gravitate point (normalized)
+    // ------------------------------------------------------------
+
+    private bool HitGravitate(Avalonia.Point p, out Point2f value)
+    {
+        value = default;
+
+        var preview = Preview;
+        if (preview?.Frame is null)
+            return false;
+
+        var g = GravitateTo;
+
+        int rawW, rawH, rotate;
+        float pixelAspect;
+        double scale, offsetX, offsetY;
+        GetAspects(preview, out rawW, out rawH, out rotate, out pixelAspect, out scale, out offsetX, out offsetY);
+
+        double px = g.X * rawW;
+        double py = g.Y * rawH;
 
         var (cx, cy) = TransformPoint(
             px, py,
@@ -254,31 +276,10 @@ public sealed class PreviewCanvas : Control
         if (preview?.Frame is null)
             return false;
 
-        var rawW = preview.Frame.PixelSize.Width;
-        var rawH = preview.Frame.PixelSize.Height;
-
-        var rotate = RotateAngle;
-        var sar = Sar ?? new Point2f(1, 1);
-        var pixelAspect = sar.X / sar.Y;
-
-        var dispW = Bounds.Width;
-        var dispH = Bounds.Height;
-
-        double displayW, displayH;
-        if (rotate == 0 || rotate == 180)
-        {
-            displayW = rawW * pixelAspect;
-            displayH = rawH;
-        }
-        else
-        {
-            displayW = rawW;
-            displayH = rawH * pixelAspect;
-        }
-
-        var scale = Math.Min(dispW / displayW, dispH / displayH);
-        var offsetX = (dispW - displayW * scale) / 2;
-        var offsetY = (dispH - displayH * scale) / 2;
+        int rawW, rawH, rotate;
+        float pixelAspect;
+        double scale, offsetX, offsetY;
+        GetAspects(preview, out rawW, out rawH, out rotate, out pixelAspect, out scale, out offsetX, out offsetY);
 
         var da = DetectAbove;
         var py = da * rawH;
@@ -301,6 +302,42 @@ public sealed class PreviewCanvas : Control
         return hit;
     }
 
+    // ------------------------------------------------------------
+    // Hit test for detected boxes
+    // ------------------------------------------------------------
+    private bool HitDetectedBox(Avalonia.Point p, out ulong? value)
+    {
+        value = null;
+
+        var preview = Preview;
+        if (preview?.Frame is null)
+            return false;
+
+        int rawW, rawH, rotate;
+        float pixelAspect;
+        double scale, offsetX, offsetY;
+        GetAspects(preview, out rawW, out rawH, out rotate, out pixelAspect, out scale, out offsetX, out offsetY);
+
+        var frame = preview.Frame;
+        foreach (var box in preview.DetectedBoxes)
+        {
+            var rect = TransformRect(
+                box.Box.X, box.Box.Y, box.Box.Width, box.Box.Height,
+                frame.PixelSize.Width, frame.PixelSize.Height,
+                offsetX, offsetY, scale,
+                RotateAngle,
+                Sar?.X / Sar?.Y ?? 1);
+
+            if (rect.Contains(p))
+            {
+                value = box.Id;
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     // ------------------------------------------------------------
     // Pointer events
     // ------------------------------------------------------------
@@ -324,6 +361,12 @@ public sealed class PreviewCanvas : Control
             _dragStartCanvas = p;
             _dragStartDetectAbove = da; // normalized
             e.Pointer.Capture(this);
+            return;
+        }
+
+        if (HitDetectedBox(p, out var id))
+        {
+            DetectId = id;
         }
     }
 
@@ -337,29 +380,10 @@ public sealed class PreviewCanvas : Control
         var dxCanvas = p.X - _dragStartCanvas.X;
         var dyCanvas = p.Y - _dragStartCanvas.Y;
 
-        var rawW = preview.Frame.PixelSize.Width;
-        var rawH = preview.Frame.PixelSize.Height;
-
-        var rotate = RotateAngle;
-        var sar = Sar ?? new Point2f(1, 1);
-        var pixelAspect = sar.X / sar.Y;
-
-        var dispW = Bounds.Width;
-        var dispH = Bounds.Height;
-
-        double displayW, displayH;
-        if (rotate == 0 || rotate == 180)
-        {
-            displayW = rawW * pixelAspect;
-            displayH = rawH;
-        }
-        else
-        {
-            displayW = rawW;
-            displayH = rawH * pixelAspect;
-        }
-
-        var scale = Math.Min(dispW / displayW, dispH / displayH);
+        int rawW, rawH, rotate;
+        float pixelAspect;
+        double scale, offsetX, offsetY;
+        GetAspects(preview, out rawW, out rawH, out rotate, out pixelAspect, out scale, out offsetX, out offsetY);
 
         var dx = dxCanvas / scale;
         var dy = dyCanvas / scale;
@@ -480,7 +504,6 @@ public sealed class PreviewCanvas : Control
     {
         var g = GravitateTo;
 
-        // normalized → pixel
         var px = g.X * rawW;
         var py = g.Y * rawH;
 
@@ -516,18 +539,24 @@ public sealed class PreviewCanvas : Control
             return;
 
         var pen = new Pen(Brushes.Lime, 2);
+        var selectedPen = new Pen(Brushes.Magenta, 2);
 
-        foreach (var r in preview.DetectedBoxes)
+        var detected = preview.DetectedBoxes.ToList();
+
+        foreach (var r in detected)
         {
             var rr = TransformRect(
-                r.X, r.Y, r.Width, r.Height,
+                r.Box.X, r.Box.Y, r.Box.Width, r.Box.Height,
                 rawW, rawH,
                 offsetX, offsetY,
                 scale,
                 rotate,
                 pixelAspect);
 
-            context.DrawRectangle(null, pen, rr);
+            context.DrawRectangle(null, r.Id == DetectId ? selectedPen : pen, rr);
+            context.DrawText(
+                new FormattedText($"ID: {r.Id}", CultureInfo.CurrentCulture, FlowDirection.LeftToRight, Typeface.Default, 12, r.Id == DetectId ? Brushes.Magenta : Brushes.Lime),
+                new Avalonia.Point(rr.X + 5, rr.Y + 5));
         }
     }
 
diff --git a/Splitter-UI/Views/PreviewPane.axaml b/Splitter-UI/Views/PreviewPane.axaml
index e19f13c..aa776f0 100644
--- a/Splitter-UI/Views/PreviewPane.axaml
+++ b/Splitter-UI/Views/PreviewPane.axaml
@@ -16,6 +16,7 @@
                 RotateAngle="{Binding Rotate}"
                 GravitateTo="{Binding GravitateTo, Mode=TwoWay}"
                 DetectAbove="{Binding DetectAbove, Mode=TwoWay}"
+                DetectId="{Binding Selected.DetectId, Mode=TwoWay}"
                 />
 
             <Grid Grid.Row="1"
diff --git a/splitter-cli/CommandLine.cs b/splitter-cli/CommandLine.cs
index 4a3fa3b..81fbefc 100644
--- a/splitter-cli/CommandLine.cs
+++ b/splitter-cli/CommandLine.cs
@@ -86,6 +86,14 @@ public sealed class CommandLine
                 else
                     throw new FormatException($"Invalid --rotate value: {val}");
             }
+            else if (arg.StartsWith("--detect-id="))
+            {
+                var val = arg.Substring("--detect-id=".Length);
+                if (ulong.TryParse(val, out var detectId))
+                    Master.DetectId = detectId;
+                else
+                    throw new FormatException($"Invalid --detect-id value: {val}");
+            }
             else if (arg.StartsWith("--crop="))
             {
                 Master.Crop = ParseCrop(arg.Substring("--crop=".Length));
@@ -164,24 +172,11 @@ public sealed class CommandLine
 
         var files = inputFiles.SelectMany(x => FileMaskExpander.Expand(x));
 
-        Jobs = files.Select(x => new SingleJob
+        Jobs = files.Select(x =>
         {
-            InputFile              = x,
-            OutputFolder           = Master.OutputFolder,
-            Crop                   = Master.Crop,
-            GravitateTo            = Master.GravitateTo,
-            Mask                   = Master.Mask,
-            Debug                  = Master.Debug,
-            Detect                 = Master.Detect,
-            OverrideTargetDuration = Master.OverrideTargetDuration,
-            Passthrough            = Master.Passthrough,
-            PlainText              = Master.PlainText,
-            EstimateOnly           = Master.EstimateOnly,
-            ForceFixed             = Master.ForceFixed,
-            SingleThreaded         = Master.SingleThreaded,
-            Rotate                 = Master.Rotate,
-            RotateAuto             = Master.RotateAuto,
-            Parameters             = new Dictionary<string, string>(Master.Parameters)
+            var job = new SingleJob { InputFile = x };
+            Master.CopyTo(job);
+            return job;
         }).ToArray();
 
         if ( Jobs.Length == 0)
@@ -370,6 +365,11 @@ Options:
   --detect-above=<0-1>   Face or human detectors should only report detections if their upper bound starts below this threshold. 
                          This is a value between 0.0 and 1.0 mapped to 0..Height.
 
+  --detect-id=<hex>      Object ID to track. This is a hexadecimal string that identifies a specific face or 
+                         person to track across segments. This is useful when you want to consistently track the same person 
+                         across all segments of a video, even if there are multiple people present.
+                         The ID can be obtained when running with --debug or from the debug overlay.
+
   --gravitate=<x:y>      Gravitate towards a specific point (x, y) in the video frame when tracking.
                          Coordinates are normalized (0.0 to 1.0).
                          Example: --gravitate=0.2:0.5 (gravitate towards left-center)
diff --git a/splitter-cli/SingleJob.cs b/splitter-cli/SingleJob.cs
index 33ba9df..f4d3238 100644
--- a/splitter-cli/SingleJob.cs
+++ b/splitter-cli/SingleJob.cs
@@ -54,6 +54,13 @@ public class SingleJob
     /// </summary>
     public float                      DetectAbove            { get; set; } = 0.7f;
     /// <summary>
+    /// Object ID to track. This is a hexadecimal string that identifies a specific face or 
+    /// person to track across segments. This is useful when you want to consistently track the same person
+    /// publacross all segments of a video, even if there are multiple people present
+    /// The ID can be obtained when running with --debug or from the debug overlay.
+    /// </summary>
+    public ulong?                     DetectId               { get; set; }
+    /// <summary>
     /// Set starget segments length explicitly. By default, the splitter calculates segment 
     /// lengths to be equal and not exceed 58 seconds.
     /// </summary>
@@ -128,4 +135,28 @@ public class SingleJob
         }
     }
 
+    public void CopyTo(SingleJob target)
+    {
+        target.OutputFolder           = OutputFolder;
+        target.Crop                   = Crop;
+        target.GravitateTo            = GravitateTo;
+        target.Mask                   = Mask;
+        target.Debug                  = Debug;
+        target.Detect                 = Detect;
+        target.ScoreThreshold         = ScoreThreshold;
+        target.DetectAbove            = DetectAbove;
+        target.DetectId               = DetectId;
+        target.OverrideTargetDuration = OverrideTargetDuration;
+        target.Passthrough            = Passthrough.ToArray();
+        target.PlainText              = PlainText;
+        target.EstimateOnly           = EstimateOnly;
+        target.ForceFixed             = ForceFixed;
+        target.SingleThreaded         = SingleThreaded;
+        target.Rotate                 = Rotate;
+        target.RotateAuto             = RotateAuto;
+        target.Parameters             = new Dictionary<string, string>(Parameters);
+        target.Enhance                = Enhance;
+    }
+
+    public void CopyFrom(SingleJob source) => source.CopyTo(this);
 }
diff --git a/splitter-cli/algo/IObjectTracker.cs b/splitter-cli/algo/IObjectTracker.cs
index b98121b..d1bee73 100644
--- a/splitter-cli/algo/IObjectTracker.cs
+++ b/splitter-cli/algo/IObjectTracker.cs
@@ -2,5 +2,5 @@
 
 public interface IObjectTracker
 {
-    (List<DetectedPerson>, DetectedPerson?) SelectTrackedObject(SingleTask job, Mat frameMat, Point2f? lastMeasurement);
+    (List<DetectedPerson> objects, DetectedPerson? primary) SelectTrackedObject(SingleTask job, Mat frameMat, Point2f? lastMeasurement);
 }
\ No newline at end of file
diff --git a/splitter-cli/algo/IdentityCache.cs b/splitter-cli/algo/IdentityCache.cs
new file mode 100644
index 0000000..c3c692f
--- /dev/null
+++ b/splitter-cli/algo/IdentityCache.cs
@@ -0,0 +1,78 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace splitter.algo;
+
+public sealed class IdentityCache
+{
+    private sealed class Identity
+    {
+        public ulong Id;
+        public float[] Embedding; // EMA
+        public int Samples;
+    }
+
+    private readonly List<Identity> _ids = new();
+    private ulong _nextId = 1;
+
+    private const float Threshold = 0.35f; // good for OSNet
+    private const float EmaAlpha = 0.2f;
+
+    public ulong ResolveId(float[] embedding)
+    {
+        if (_ids.Count == 0)
+            return CreateNew(embedding);
+
+        int bestIndex = -1;
+        float bestDist = float.MaxValue;
+
+        for (int i = 0; i < _ids.Count; i++)
+        {
+            float d = CosineDistance(_ids[i].Embedding, embedding);
+            if (d < bestDist)
+            {
+                bestDist = d;
+                bestIndex = i;
+            }
+        }
+
+        if (bestDist <= Threshold)
+        {
+            UpdateEma(_ids[bestIndex].Embedding, embedding);
+            _ids[bestIndex].Samples++;
+            return _ids[bestIndex].Id;
+        }
+
+        return CreateNew(embedding);
+    }
+
+    private ulong CreateNew(float[] embedding)
+    {
+        var id = _nextId++;
+
+        _ids.Add(new Identity
+        {
+            Id        = id,
+            Embedding = embedding.ToArray(),
+            Samples   = 1
+        });
+
+        return id;
+    }
+
+    private static float CosineDistance(float[] a, float[] b)
+    {
+        float dot = 0f;
+        for (int i = 0; i < a.Length; i++)
+            dot += a[i] * b[i];
+
+        return 1f - dot;
+    }
+
+    private static void UpdateEma(float[] ema, float[] v)
+    {
+        for (int i = 0; i < ema.Length; i++)
+            ema[i] = ema[i] * (1 - EmaAlpha) + v[i] * EmaAlpha;
+    }
+}
diff --git a/splitter-cli/algo/ObjectTracker.cs b/splitter-cli/algo/ObjectTracker.cs
index a6317ec..12cb151 100644
--- a/splitter-cli/algo/ObjectTracker.cs
+++ b/splitter-cli/algo/ObjectTracker.cs
@@ -2,17 +2,21 @@
 
 public class ObjectTracker(IObjectDetector _detector, IEmbeddingExtractor _embeddingExtractor) : IObjectTracker
 {
-    public (List<DetectedPerson> /*objects*/, DetectedPerson? /*primary*/) SelectTrackedObject(SingleTask job, Mat frameMat, Point2f? lastMeasurement)
+    private readonly IdentityCache _identityCache = new();
+
+    public (List<DetectedPerson> objects, DetectedPerson? primary) SelectTrackedObject(SingleTask job, Mat frameMat, Point2f? lastMeasurement)
     {
         var objects = _detector.DetectAll(job, frameMat) ?? [];
 
-        // Ignore detections starting in the lower 1/2 of the frame
-        objects = objects.Where(o => o.Center.Y <= frameMat.Height * job.Job.DetectAbove).ToList();
+        // filter by DetectAbove
+        objects = objects
+            .Where(o => o.Center.Y <= frameMat.Height * job.Job.DetectAbove)
+            .ToList();
 
-        // attach embeddings to all persons
+        // attach embeddings
         for (int i = 0; i < objects.Count; i++)
         {
-            var p = objects[i];   // copy struct
+            var p = objects[i];
 
             var rect = p.Box;
 
@@ -21,38 +25,32 @@ public class ObjectTracker(IObjectDetector _detector, IEmbeddingExtractor _embed
             rect.Width  = Math.Clamp(rect.Width, 1, frameMat.Width - rect.X);
             rect.Height = Math.Clamp(rect.Height, 1, frameMat.Height - rect.Y);
 
-            var embedding = _embeddingExtractor.Extract(frameMat, rect);
-            p.Id = HashEmbedding(embedding); // assign ID based on embedding hash
+            var embedding = _embeddingExtractor.Extract(frameMat, rect).ToArray(); // make a copy of the embedding array
+            p.Id = _identityCache.ResolveId(embedding);
 
-            objects[i] = p;       // write back
+            objects[i] = p;
         }
 
-        var primary = SelectPrimaryObject(objects, lastMeasurement);
+        // DeepSeek tracker assigns stable IDs
+        var primary = SelectPrimaryObject(objects, lastMeasurement, job.Job.DetectId);
         return (objects, primary);
     }
 
-    private static ulong HashEmbedding(float[] emb)
-    {
-        unchecked
-        {
-            ulong hash = 146527;
-            for (int i = 0; i < emb.Length; i++)
-            {
-                // convert float to int bits
-                uint bits = (uint)BitConverter.SingleToInt32Bits(emb[i]);
-                hash = (hash * 16777619) ^ bits;
-            }
-            return hash;
-        }
-    }
-
     private DetectedPerson? SelectPrimaryObject(
         List<DetectedPerson> foundObjects,
-        Point2f? previousCenter)
+        Point2f? previousCenter,
+        ulong? detectId)
     {
         if (foundObjects == null || foundObjects.Count == 0)
             return null;
 
+        if (detectId != null)
+        {
+            var match = foundObjects.FirstOrDefault(o => o.Id == detectId.Value);
+            if (match.Id != 0) // default struct has Id=0, so this means we found a match
+                return match;
+        }
+
         if (!previousCenter.HasValue)
         {
             var bestIndex = 0;