fix: use microseconds as a Timestamp value

Assets/MediaPipe/Examples/Graphs/OfficialDemo/Scripts/OfficialDemoAndroid.cs

@@ -3,6 +3,8 @@
 using System.Linq;
 using UnityEngine;
 
+using Stopwatch = System.Diagnostics.Stopwatch;
+
 public class OfficialDemoAndroid : DemoGraph {
   const string outputStream = "output_video";
 
@@ -26,6 +28,7 @@ public class OfficialDemoAndroid : DemoGraph {
     sinkNode.InputSidePacket.Add($"DESTINATION:{destinationBufferName}");
 
     graph = new CalculatorGraph(calculatorGraphConfig);
+    stopwatch = new Stopwatch();
   }
 
   public override Status StartRun() {
@@ -45,6 +48,7 @@ public class OfficialDemoAndroid : DemoGraph {
     gpuHelper.RunInGlContext(BuildDestination).AssertOk();
     sidePacket.Emplace(destinationBufferName, outputPacket);
 
+    stopwatch.Start();
     return graph.StartRun(sidePacket);
   }
 

Assets/MediaPipe/Examples/Graphs/OfficialDemo/Scripts/OfficialDemoIOS.cs

@@ -10,10 +10,6 @@ public class OfficialDemoIOS : DemoGraph {
   private SidePacket sidePacket;
 
   public override Status StartRun() {
-    throw new NotSupportedException();
-  }
-
-  public override Status StartRun(Texture texture) {
     Debug.Log("This graph is for testing official examples. You can customize the graph by editing `official_demo_dekstop_gpu.txt` (default is `hand_tracking_mobile.pbtxt`)");
 
     outputStreamPoller = graph.AddOutputStreamPoller<ImageFrame>(outputStream).ConsumeValueOrDie();

Assets/MediaPipe/Examples/Scripts/DemoGraph.cs

@@ -3,11 +3,13 @@
 using System.Collections.Generic;
 using UnityEngine;
 
+using Stopwatch = System.Diagnostics.Stopwatch;
+
 public abstract class DemoGraph : MonoBehaviour, IDemoGraph<TextureFrame> {
   [SerializeField] protected TextAsset config = null;
 
   protected const string inputStream = "input_video";
-  protected int timestampValue;
+  protected Stopwatch stopwatch;
   protected static CalculatorGraph graph;
   protected static GlCalculatorHelper gpuHelper;
 
@@ -20,6 +22,10 @@ public abstract class DemoGraph : MonoBehaviour, IDemoGraph<TextureFrame> {
 
   protected virtual void OnDestroy() {
     Stop();
+
+    if (stopwatch != null && stopwatch.IsRunning) {
+      stopwatch.Stop();
+    }
   }
 
   public virtual void Initialize() {
@@ -28,7 +34,7 @@ public abstract class DemoGraph : MonoBehaviour, IDemoGraph<TextureFrame> {
     }
 
     graph = new CalculatorGraph(config.text);
-    timestampValue = System.Environment.TickCount & System.Int32.MaxValue;
+    stopwatch = new Stopwatch();
   }
 
   public void Initialize(GpuResources gpuResources, GlCalculatorHelper gpuHelper) {
@@ -40,11 +46,12 @@ public abstract class DemoGraph : MonoBehaviour, IDemoGraph<TextureFrame> {
 
   public abstract Status StartRun();
   public virtual Status StartRun(Texture texture) {
+    stopwatch.Start();
     return StartRun();
   }
 
   public Status PushInput(TextureFrame textureFrame) {
-    var timestamp = new Timestamp(++timestampValue);
+    var timestamp = GetCurrentTimestamp();
 
 #if !UNITY_ANDROID
     var imageFrame = new ImageFrame(
@@ -87,13 +94,18 @@ public abstract class DemoGraph : MonoBehaviour, IDemoGraph<TextureFrame> {
   public abstract void RenderOutput(WebCamScreenController screenController, TextureFrame textureFrame);
 
   public void Stop() {
-    if (graph != null) {
-      var status = graph.CloseAllPacketSources();
+    if (graph == null) { return; }
+
+    using (var status = graph.CloseAllPacketSources()) {
+      if (!status.ok) {
+        Debug.LogError(status.ToString());
+      }
+    }
 
+    using (var status = graph.WaitUntilDone()) {
       if (!status.ok) {
         Debug.LogError(status.ToString());
       }
-      graph.WaitUntilDone().AssertOk();
     }
   }
 
@@ -130,4 +142,13 @@ public abstract class DemoGraph : MonoBehaviour, IDemoGraph<TextureFrame> {
   protected bool IsGpuEnabled() {
     return gpuHelper != null;
   }
+
+  Timestamp GetCurrentTimestamp() {
+    if (stopwatch == null || !stopwatch.IsRunning) {
+      return Timestamp.Unset();
+    }
+
+    var microseconds = (stopwatch.ElapsedTicks) / (TimeSpan.TicksPerMillisecond / 1000);
+    return new Timestamp(microseconds);
+  }
 }