diff --git a/tools/chatgui-android/audio-probe/src/main/AndroidManifest.xml b/tools/chatgui-android/audio-probe/src/main/AndroidManifest.xml
index 64915f63..96d24743 100644
--- a/tools/chatgui-android/audio-probe/src/main/AndroidManifest.xml
+++ b/tools/chatgui-android/audio-probe/src/main/AndroidManifest.xml
@@ -2,6 +2,7 @@
     <uses-permission android:name="android.permission.RECORD_AUDIO" />
     <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
     <application android:label="uTun audio probe" android:theme="@android:style/Theme.Material.Light.NoActionBar" android:allowBackup="false">
+        <activity android:name=".VideoSurfaceProbeActivity" android:exported="true" android:configChanges="orientation|screenSize" />
         <activity android:name=".ProbeActivity" android:exported="true" android:configChanges="orientation|screenSize">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
diff --git a/tools/chatgui-android/audio-probe/src/main/java/com/utun/audioprobe/VideoSurfaceProbeActivity.java b/tools/chatgui-android/audio-probe/src/main/java/com/utun/audioprobe/VideoSurfaceProbeActivity.java
new file mode 100644
index 00000000..7100dee5
--- /dev/null
+++ b/tools/chatgui-android/audio-probe/src/main/java/com/utun/audioprobe/VideoSurfaceProbeActivity.java
@@ -0,0 +1,139 @@
+package com.utun.audioprobe;
+
+import android.app.Activity;
+import android.graphics.SurfaceTexture;
+import android.opengl.EGL14;
+import android.opengl.EGLConfig;
+import android.opengl.EGLContext;
+import android.opengl.EGLDisplay;
+import android.opengl.EGLExt;
+import android.opengl.EGLSurface;
+import android.opengl.GLES20;
+import android.os.Bundle;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.util.Log;
+import android.view.Surface;
+import android.view.TextureView;
+import android.view.ViewTreeObserver;
+import android.view.WindowManager;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/** Настоящий TextureView/EGL, один кадр до ACK. Без камеры, сети и основного приложения.
+ * am start -n com.utun.audioprobe/.VideoSurfaceProbeActivity --ei fps 60 --ez legacy false
+ * legacy регистрирует commit во время draw; fixed — в preDraw, как видеозвонок.
+ * Постороннее UI-обновление каждые 500мс воспроизводит зависимость от статистики звонка. */
+public final class VideoSurfaceProbeActivity extends Activity implements TextureView.SurfaceTextureListener, ViewTreeObserver.OnPreDrawListener {
+    private static final String TAG = "VideoSurfaceProbe";
+    private final Handler main = new Handler();
+    private final HandlerThread producer = new HandlerThread("video-surface-probe");
+    private Handler render;
+    private TextureView view;
+    private ViewTreeObserver observer;
+    private EGLDisplay display = EGL14.EGL_NO_DISPLAY;
+    private EGLContext context = EGL14.EGL_NO_CONTEXT;
+    private EGLSurface window = EGL14.EGL_NO_SURFACE;
+    private Surface surface;
+    private SurfaceTexture texture;
+    private volatile boolean cancelled;
+    private volatile long expectedPts = -1, submittedAt;
+    private final AtomicInteger submitted = new AtomicInteger();
+    private int acknowledged, updates, mismatches, lastReported;
+    private int fps;
+    private boolean legacy;
+    private long started, ackMaxUs;
+
+    @Override public void onCreate(Bundle saved) {
+        super.onCreate(saved);
+        fps = getIntent().getIntExtra("fps", 60); legacy = getIntent().getBooleanExtra("legacy", false);
+        if (fps != 30 && fps != 60) { Log.e(TAG, "Unsupported fps=" + fps); finish(); return; }
+        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+        producer.start(); render = new Handler(producer.getLooper());
+        view = new TextureView(this); view.setSurfaceTextureListener(this); setContentView(view);
+        Log.i(TAG, "start legacy=" + legacy + " fps=" + fps + " hardware=" + getWindow().getAttributes().flags);
+    }
+
+    @Override public void onSurfaceTextureAvailable(SurfaceTexture next, int width, int height) {
+        texture = next; next.setDefaultBufferSize(640, 360); surface = new Surface(next);
+        observer = view.getViewTreeObserver(); observer.addOnPreDrawListener(this);
+        render.post(() -> {
+            try {
+                display = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
+                int[] version = new int[2]; check(EGL14.eglInitialize(display, version, 0, version, 1), "initialize");
+                int[] attributes = {EGL14.EGL_RENDERABLE_TYPE, EGL14.EGL_OPENGL_ES2_BIT, EGL14.EGL_SURFACE_TYPE, EGL14.EGL_WINDOW_BIT,
+                    EGL14.EGL_RED_SIZE, 8, EGL14.EGL_GREEN_SIZE, 8, EGL14.EGL_BLUE_SIZE, 8, EGL14.EGL_NONE};
+                EGLConfig[] config = new EGLConfig[1]; int[] count = new int[1];
+                check(EGL14.eglChooseConfig(display, attributes, 0, config, 0, 1, count, 0) && count[0] == 1, "config");
+                context = EGL14.eglCreateContext(display, config[0], EGL14.EGL_NO_CONTEXT,
+                    new int[]{EGL14.EGL_CONTEXT_CLIENT_VERSION, 2, EGL14.EGL_NONE}, 0);
+                check(context != EGL14.EGL_NO_CONTEXT, "context");
+                window = EGL14.eglCreateWindowSurface(display, config[0], surface, new int[]{EGL14.EGL_NONE}, 0);
+                check(window != EGL14.EGL_NO_SURFACE && EGL14.eglMakeCurrent(display, window, window, context), "surface");
+                started = System.nanoTime(); main.post(this::tick); send();
+            } catch (Exception e) { Log.e(TAG, "producer failed", e); main.post(this::finish); }
+        });
+    }
+
+    private void send() {
+        if (cancelled) return;
+        try {
+            int number = submitted.get(); long pts = 1_000_000L + number * 1_000_000L / fps;
+            GLES20.glClearColor((number % 3) / 2f, ((number + 1) % 3) / 2f, ((number + 2) % 3) / 2f, 1);
+            GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
+            expectedPts = pts; submittedAt = System.nanoTime(); submitted.incrementAndGet();
+            check(EGLExt.eglPresentationTimeANDROID(display, window, pts * 1000), "timestamp");
+            check(EGL14.eglSwapBuffers(display, window), "swap");
+        } catch (Exception e) { Log.e(TAG, "frame failed", e); main.post(this::finish); }
+    }
+
+    private void committed() {
+        if (cancelled || texture == null || expectedPts < 0) return;
+        long pts = texture.getTimestamp() / 1000;
+        if (pts != expectedPts) { mismatches++; Log.w(TAG, "timestamp actual=" + pts + " expected=" + expectedPts); return; }
+        expectedPts = -1; acknowledged++;
+        ackMaxUs = Math.max(ackMaxUs, (System.nanoTime() - submittedAt) / 1000);
+        long next = started + submitted.get() * 1_000_000_000L / fps;
+        render.postDelayed(this::send, Math.max(0, (next - System.nanoTime() + 999_999) / 1_000_000));
+    }
+
+    @Override public boolean onPreDraw() {
+        if (!cancelled && !legacy) view.getViewTreeObserver().registerFrameCommitCallback(this::committed);
+        return true;
+    }
+    @Override public void onSurfaceTextureUpdated(SurfaceTexture source) {
+        updates++;
+        if (legacy) view.getViewTreeObserver().registerFrameCommitCallback(this::committed);
+    }
+    @Override public void onSurfaceTextureSizeChanged(SurfaceTexture source, int width, int height) {}
+    @Override public boolean onSurfaceTextureDestroyed(SurfaceTexture source) {
+        if (observer != null && observer.isAlive()) observer.removeOnPreDrawListener(this);
+        observer = null; cancelled = true;
+        render.post(() -> {
+            EGL14.eglMakeCurrent(display, EGL14.EGL_NO_SURFACE, EGL14.EGL_NO_SURFACE, EGL14.EGL_NO_CONTEXT);
+            if (window != EGL14.EGL_NO_SURFACE) EGL14.eglDestroySurface(display, window);
+            if (context != EGL14.EGL_NO_CONTEXT) EGL14.eglDestroyContext(display, context);
+            if (display != EGL14.EGL_NO_DISPLAY) EGL14.eglTerminate(display);
+            surface.release(); source.release(); producer.quitSafely();
+        });
+        return false;
+    }
+
+    private void tick() {
+        if (cancelled) return;
+        long elapsed = System.nanoTime() - started;
+        Log.i(TAG, "progress legacy=" + legacy + " fps=" + fps + " elapsedMs=" + elapsed / 1_000_000 + " acknowledged=" + acknowledged
+            + " advanced=" + (acknowledged - lastReported) + " updates=" + updates + " ackMaxUs=" + ackMaxUs);
+        lastReported = acknowledged;
+        if (elapsed >= 8_000_000_000L) {
+            boolean valid = legacy ? acknowledged < 30 : acknowledged >= fps * 8 * 0.8 && mismatches == 0;
+            Log.i(TAG, "RESULT " + (valid ? "PASS" : "FAIL") + " legacy=" + legacy + " targetFps=" + fps + " submitted=" + submitted.get()
+                + " acknowledged=" + acknowledged + " updates=" + updates + " mismatches=" + mismatches + " ackMaxUs=" + ackMaxUs);
+            finish(); return;
+        }
+        view.invalidate(); main.postDelayed(this::tick, 500);
+    }
+    @Override protected void onStop() { cancelled = true; super.onStop(); }
+    private static void check(boolean condition, String stage) {
+        if (!condition) throw new IllegalStateException(stage + " EGL error=" + EGL14.eglGetError());
+    }
+}