Play sequencer in game low fps

lidingxing · August 17, 2023, 6:21am

sequencer_low_fps.rar (19.5 MB)
camera can smoothly move in eidtor sequencer,but in game mode,the fps is very low

janine · August 17, 2023, 1:30pm

We can’t really help you without more details. What versions of Unreal Engine and Cesium for Unreal are you using? What exactly is in your scene? If you’re using additional plugins or non-Cesium items, how do those affect performance?

lidingxing · August 18, 2023, 1:16am

you can see what i do in video,when i toggle my sequencer in game and sequence camera move fast,it will be low fps.i am not using any additional plugins or non-cesium items,the project is CesiumforUnrealSamples,the version is ue5.1,the map is 01_CesiumWorld

lidingxing · August 18, 2023, 9:00am

Video_move camera without sequence.rar (16.7 MB)
here is the another way i find,i can move player pawn in bluepint,it can move very smooth and high fps.
i want high fps when i play sequence just like moving with blueprint.

chenhui_xiao · August 23, 2023, 1:56am

i have same problem,it happened in play levelsequence.

Kevin_Ring · August 24, 2023, 12:43am

Cesium for Unreal detects when a sequence is active and it switches into an alternate mode where each render frame waits for all data to load before proceeding. This will indeed drop the frame rate, by a lot. The intention is that sequences are usually used to record videos, and it’s more important to get a high quality recording than it is to record the video quickly.

But it sounds like in your case you’re not using the sequence for video recording, but just to automate changes over time. So in that case, you’ll need to modify Cesium for Unreal itself in order to avoid the slowdown. The logic that detects and switches to special behavior in a sequence is here:

github.com

CesiumGS/cesium-unreal/blob/v1.29.0/Source/CesiumRuntime/Private/Cesium3DTileset.cpp#L572


      
                  CesiumToUnreal);
            }
          }
          
          // Called when the game starts or when spawned
          void ACesium3DTileset::BeginPlay() {
            Super::BeginPlay();
          
            this->LoadTileset();
          
            // Search for level sequence.
            for (auto sequenceActorIt = TActorIterator<ALevelSequenceActor>(GetWorld());
                 sequenceActorIt;
                 ++sequenceActorIt) {
              ALevelSequenceActor* sequenceActor = *sequenceActorIt;
          
              FScriptDelegate playMovieSequencerDelegate;
              playMovieSequencerDelegate.BindUFunction(this, FName("PlayMovieSequencer"));
              sequenceActor->GetSequencePlayer()->OnPlay.Add(playMovieSequencerDelegate);
          
              FScriptDelegate stopMovieSequencerDelegate;

github.com

CesiumGS/cesium-unreal/blob/v1.29.0/Source/CesiumRuntime/Private/Cesium3DTileset.cpp#L403


      
          }
          
          void ACesium3DTileset::SetPointCloudShading(
              FCesiumPointCloudShading InPointCloudShading) {
            if (PointCloudShading != InPointCloudShading) {
              PointCloudShading = InPointCloudShading;
              FCesiumGltfPointsSceneProxyUpdater::UpdateSettingsInProxies(this);
            }
          }
          
          void ACesium3DTileset::PlayMovieSequencer() {
            this->_beforeMoviePreloadAncestors = this->PreloadAncestors;
            this->_beforeMoviePreloadSiblings = this->PreloadSiblings;
            this->_beforeMovieLoadingDescendantLimit = this->LoadingDescendantLimit;
            this->_beforeMovieUseLodTransitions = this->UseLodTransitions;
          
            this->_captureMovieMode = true;
            this->PreloadAncestors = false;
            this->PreloadSiblings = false;
            this->LoadingDescendantLimit = 10000;
            this->UseLodTransitions = false;

I’m not sure if there’s a way to programmatically distinguish the video case versus the normal play case. If not, the next best thing is probably to add a user-configurable option on the Cesium3DTileset.

If you feel like trying this, we would welcome a pull request.

I wrote an issue to capture it:

github.com/CesiumGS/cesium-unreal

A LevelSequence tanks the frame rate even when it's not being used to render a video

opened 12:43AM - 24 Aug 23 UTC

kring

bug

Cesium for Unreal detects when a sequence is active and it switches into an alte…rnate mode where each render frame waits for all data to load before proceeding. This will definitely cause the frame rate to be lower, but the intention is that sequences are usually used to record videos, and it's more important to get a high quality recording than it is to record the video quickly. But a Level Sequence can also be used for general changes over time in a level, not just for recording videos. And in that scenario, this "wait for all the data each frame" logic is highly undesirable. I'm not sure if there's a way to programmatically distinguish the video case versus the normal play case. If not, the next best thing is probably to add a user-configurable option on the Cesium3DTileset.

lidingxing · August 24, 2023, 2:33am

thanks kevin,i find a way to avoid this problem.

just toggle “pause movie sequence” when start play sequence.

Kevin_Ring · August 24, 2023, 5:25am

Good find! I updated the issue to mention your workaround.

Blake_Victor · March 25, 2024, 9:04pm

Thank you so much for this. solved my issue, very simple.

Vincenzo_Casillo · February 4, 2025, 8:55am

Hi, how did u get the start play sequence event??

Topic		Replies	Views
Problems running a Level Sequencer in the scene Cesium for Unreal	5	106	August 22, 2024
Can this be used in sequencer? Cesium for Unreal	5	487	November 3, 2023
Cesium camera issue in sequencer Cesium for Unreal	6	220	November 9, 2023
Issues with sequencer Cesium for Unreal	5	492	November 14, 2023
Cesium causing Camera Render issues Cesium for Unreal	1	193	January 6, 2023

Play sequencer in game low fps

Related topics