fix: stream freeze when turning screen off and on with AVSB

VoidLink/Stream/VideoDecoderRenderer.m

@@ -297,7 +297,7 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
 - (void)renderFrame:(Frame *)frame atTime:(CMTime)targetTime {
     CMSampleBufferSetOutputPresentationTimeStamp(frame.sampleBuffer, targetTime);
 
-    if (frame.frameNumber == 1) {
+    if ([self->_displayLayer controlTimebase] == NULL) {
         // On first frame, set timebase to the initial presentation time.
         // This will let us present frames using the local clock (vsync pacing) or
         // the pts timestamps from the host.
@@ -310,6 +310,9 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
         CMTimebaseSetRate(timebase, 1.0);
 
         [self->_displayLayer setControlTimebase:timebase];
+        if (timebase) {
+            CFRelease(timebase);
+        }
         Log(LOG_I, @"Setting timebase for stream to %d / %d", pts.value, pts.timescale);
     }
 
@@ -821,7 +824,28 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
                             frameNumber:(int)frameNumber
                               frameType:(int)frameType
                         decodeStartTime:(CFTimeInterval)decodeStartTime {
-  if (frameType == FRAME_TYPE_IDR || _decompressionSession == nil) {
+  @synchronized(self) {
+        // If the decompression session is nil, we must decide what to do.
+        if (_decompressionSession == nil) {
+            // We can only create a session with an IDR frame.
+            if (frameType == FRAME_TYPE_IDR) {
+                // This is the startup path. Create the session now.
+                [self setupDecompressionSession];
+
+                // If session creation still fails, we cannot proceed.
+                if (_decompressionSession == nil) {
+                     Log(LOG_E, @"Failed to create initial decompression session with IDR frame.");
+                     return kVTInvalidSessionErr;
+                }
+            } else {
+                // This happens when resuming from background; we've reset the session
+                // and are waiting for a new IDR frame. Drop all other frames until it arrives.
+                return noErr;
+            }
+        }
+        // Also re-create the session if a new IDR frame arrives during an active stream,
+        // as it may contain updated video parameters (e.g., HDR toggled).
+        else if (frameType == FRAME_TYPE_IDR) {
             [self setupDecompressionSession];
         }
         
@@ -977,6 +1001,7 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
           });
 
       return status;
+  }
 }
 
 - (void)setHdrMode:(BOOL)enabled {
@@ -1130,25 +1155,38 @@ int DrSubmitDecodeUnit(PDECODE_UNIT decodeUnit);
 
 - (void)resetFramePacing {
     // Ensure this only runs for the AVSampleBuffer rendering backend and that the display link exists.
-    if (_renderingBackend == RENDER_AVSB && _displayLink) {
+    if (_renderingBackend == RENDER_AVSB) {
-        Log(LOG_I, @"Frame pacing is being reset to %d FPS...", self->_frameRate);
+        Log(LOG_I, @"Resetting video pipeline for AVSB renderer after resuming...");
 
-        // Toggling the paused state can help re-engage the display link with the
+        // 1. Reset the receiver layers on the main thread
-        // run loop correctly after the app resumes from a background state like PiP.
+        dispatch_async(dispatch_get_main_queue(), ^{
-        _displayLink.paused = YES;
+            // Reset the main display layer
-        
+            if (self->_displayLayer) {
-        // Re-apply the desired frame rate range. This is the critical hint for ProMotion
+                [self->_displayLayer flushAndRemoveImage];
-        // that may have been lost or ignored during the PiP transition.
+                [self->_displayLayer setControlTimebase:NULL];
-        if (@available(iOS 15.0, *)) {
-            _displayLink.preferredFrameRateRange = CAFrameRateRangeMake(self->_frameRate, self->_frameRate, self->_frameRate);
-        } else {
-            _displayLink.preferredFramesPerSecond = self->_frameRate;
             }
 
-        // Resume the display link immediately.
+            // FIX: Also reset the PiP layer if it exists
-        _displayLink.paused = NO;
+            if (self.pipLayer) {
+                [self.pipLayer flushAndRemoveImage];
+                [self.pipLayer setControlTimebase:NULL];
+            }
+        });
+
+        // 2. Reset the sender (the Decompression Session)
+        @synchronized(self) {
+            if (_decompressionSession != nil) {
+                VTDecompressionSessionInvalidate(_decompressionSession);
+                CFRelease(_decompressionSession);
+                _decompressionSession = nil;
+            }
+        }
+        
+        // 3. Request a new keyframe to restart the video stream cleanly
+        LiRequestIdrFrame();
     }
     else if (_renderingBackend == RENDER_METAL) {
+        // (The existing, correct logic for the Metal renderer remains here)
         Log(LOG_I, @"Resetting video pipeline for Metal renderer after resuming...");
 
         // 1. Reset the receiver (the PiP Layer) on the main thread