Reading, Writing, Sharing, and Interacting with the World through Video
Organizations: University of Oxford · NUS · NTU · University of California, Merced
Abstract
Video foundation models have advanced rapidly in understanding and generating visual sequences, while video world models seek to capture the underlying dynamics of the world they depict. Despite their different objectives, both concern the relationship between video observations and an evolving world. This survey adopts world modeling as a unifying lens for examining these developments. Viewing an observed video as a partial, lossy, and temporally ordered projection of a latent temporal world, we organize the literature around four complementary operations: reading infers world properties from observed video; writing synthesizes video from specified or learned world conditions; sharing integrates understanding and generation through common modeling mechanisms; and interacting predicts and updates world states under actions and evolving observations. This perspective distinguishes temporal coherence in observed or generated sequences from consistency in the underlying world state. Across tasks, representations, models, datasets, and benchmarks, we trace a shift in emphasis from clip-level recognition and perceptual fidelity toward persistent state, controllable evolution, physical and causal validity, and evaluation grounded in interaction and downstream decisions, and we distill the open challenges that follow.
Figures & tables
| Symbol | Meaning | Introduced in |
|---|---|---|
| World and video | ||
| video time; is the number of frames | Section 3.1 | |
| , | latent temporal world and its state space | Definition |
| world dynamics | Definition | |
| action or external intervention; may be absent | Definition | |
| observed video and its frames | Definition | |
| Operation | 1. Plausible output | 2. Faithful to evidence or conditions | 3. Consistent world state | 4. Decision utility |
|---|---|---|---|---|
| Reading | correct labels and answers on clips Kay et al.,2017 ; Fu et al.,2025 | answers depend on the video, with shortcuts controlled Ok & Lee,2025 ; Song et al.,2026 ; Krojer et al.,2025 | state kept across occlusion, revisits, and streams Ma et al.,2026 ; Li et al.,2026i ; Liu et al.,2026d | evidence supports agent or driving decisions An et al.,2026 ; Sima et al.,2024 |
| Writing | perceptual quality and temporal coherence Huang et al.,2024a | adherence to text, motion, and reference conditions Sun et al.,2025 ; Chu et al.,2025 | world consistency (Definition ): identity, layout, physics Bansal et al.,2026 ; Motamed et al.,2026 | generated data or plans improve downstream models Jang et al.,2025 ; Shang et al.,2026 |
| Sharing | both directions work in one system Li et al.,2024a ; Zheng et al.,2025 | integrated, source-faithful transformations Wei et al.,2026b ; Liu et al.,2025d | measured transfer under matched data, capacity, and compute Fu et al.,2026a ; Poppi et al.,2026 | shared prediction improves planning or action Lu et al.,2025 ; Wang et al.,2026b |
| Interacting | plausible predicted frames or features | predicted changes follow fixed or online controls Arai et al.,2024 ; Fang et al.,2026 | persistent state and valid responses to interventions Ye et al.,2026 ; Chen et al.,2026a ; Li et al.,2025b ; Cai et al.,2026 | better planning, policy training, or policy ranking Quevedo et al.,2026 ; Zhang et al.,2026d ; Shang et al.,2026 |
| Dimension | State property / readout | Benchmarks |
|---|---|---|
| Semantic | Actions/events; clip–text matching | Kinetics Kay et al., 2017 , MSR-VTT Xu et al., 2016 , VATEX Wang et al., 2019 , ActivityNet-QA Yu et al.,2019 |
| Semantic | VideoQA with temporal and knowledge demands | Video-MME series Fu et al., 2025 ; Fu et al., 2026 , MMBench-Video Fang et al., 2024 , MMVU Zhao et al., 2025a , Video-MMMU Hu et al.,2026c |
| Semantic | Evidence support; hallucination/omission | VideoHallucer Wang et al., 2024g , EventHallusion Zhang et al., 2024 , ARGUS Rawal et al.,2025 |
| Spatial | Masks/tubes and identity continuity | DAVIS Pont-Tuset et al., 2017 , YouTube-VOS Xu et al., 2018 , Ref-YouTube-VOS Seo et al., 2020 , MeViS Ding et al., 2023 , MOTChallenge Milan et al., 2016 , LaSOT Fan et al., 2019 , VidSTG Zhang et al.,2020 |
| Spatial | Geometry, viewpoint, and observer/object motion | VSI-Bench Yang et al., 2025b , MMSI-Video-Bench Lin et al., 2025a , STI-Bench Li et al., 2025j , DSI-Bench Zhang et al., 2025i ; NuScenes-SpatialQA Tian et al.,2025 |
| Spatial | Out-of-view states and retained spatial context | SCP-Bench Zhao et al., 2026b , Beyond3D Ma et al., 2026 , OVO-S-Bench Li et al.,2026i |
| Model / training stage | Vision encoder | Connector / compression | LLM |
|---|---|---|---|
| Video-ChatGPT Maaz et al.,2024 Instruction tuning | ✗ CLIP ViT-L/14 | ✓ Spatiotemporal pooling; linear projector | ✗ Vicuna-7B |
| Video-LLaVA Lin et al.,2024 Instruction tuning | ✗ LanguageBind image/video encoders | ✓ Shared two-layer MLP | ✓ Vicuna-7B v1.5 |
| LLaMA-VID Li et al.,2024c Instruction tuning | ✗ EVA-G | ✓ Q-Former context query; context/content projection | ✓ Vicuna-7B/13B |
| LLaVA-OneVision Li et al.,2025 Stage 2: mixed modalities | ✓ SigLIP | ✓ Two-layer MLP; video pooling | ✓ Qwen2 |
| VideoLLaMA3 Zhang et al.,2025 Video-centric fine-tuning | ✓ SigLIP, dynamic resolution | ✓ Differential frame pruning; MLP | ✓ Qwen2.5 |
| Qwen2.5-VL Bai et al.,2025a Supervised fine-tuning | ✗ Window-attention ViT | ✓ merge; MLP | ✓ Qwen2.5 |
| Dataset | Scale | Description |
|---|---|---|
| Web-scale video–text pairs (alignment pretraining) | ||
| HowTo100M Miech et al.,2019 | 136M clips / 1.2M videos | instructional videos paired with automatically transcribed narration |
| WebVid-10M Bain et al.,2021 | 10.7M clips | stock-footage clips paired with alt-text descriptions |
| YT-Temporal-180M Zellers et al.,2021 | 180M segments / 6M videos | transcribed speech aligned with frames for temporal script knowledge |
| HD-VILA-100M Xue et al.,2022 | 103M clips / 3.3M videos | 371.5K hours of 720p video spanning 15 YouTube categories |
| InternVid Wang et al.,2024c | 234M clips / 7.1M videos | scalable model-generated captions with ViCLIP filtering; 760K hours |
| Model | Backbone | Organization | Memory / context | Operations |
|---|---|---|---|---|
| VideoAgent (long-form) Wang et al.,2024a | GPT-4 controller; LaViLa or CogAgent captioner | Single | Selected-frame captions | Frame retrieval; captioning |
| VideoAgent (memory) Fan et al.,2024 | GPT-4 controller | Single | Event captions; object tracks | Caption retrieval; video QA; temporal localization; object queries |
| VideoMind Liu et al.,2026i | Qwen2-VL + role LoRA | Multi-role | Grounded intervals; role context | Grounding; verification; answering |
| VideoMultiAgents Kugo et al.,2025 | GPT-4o roles; Gemini 2.0 Flash video tool | Multi-role | Role histories; scene graph | Caption analysis; scene-graph analysis; video QA |
| Ego-R1 Tian et al.,2026a | Qwen2.5-3B controller | Single | Timestamped summaries | Hierarchical retrieval; video QA; image QA |
| M3-Agent Long et al.,2026a | Qwen3 controller; Qwen2.5-Omni memory model | Single | Episodic + semantic memory | Memory retrieval; face/speaker identification |
| Benchmark | Task / data | Measures | Protocol |
|---|---|---|---|
| VideoSIAH-Eval Yang et al.,2026f | Sparse-evidence QA; 652 questions | Answer accuracy | Sparse/dense sampling; tool calling |
| LongVidSearch Yu et al.,2026 | Multi-hop retrieval; 3,000 questions / 447 videos | Answer accuracy; tool-call cost | Fixed tools; 2–4 hops; gold-evidence oracle |
| OmniInteract Lu et al.,2026a | Audiovisual streams; 1,430 response slots / 250 videos | IA-QTF1 a | Causal replay; interruptions; nested context |
| IPIBench Li et al.,2026d | Proactive monitoring; interleaved queries | Trigger timing; response correctness | Add/edit/cancel tasks; past frames only |
| VideoGAIA Zhang et al.,2026 | Video–web tasks; 271 tasks | pass@1, three-run mean | ReAct; 40-step budget |
| AgentVidBench An et al.,2026 | Multi-hop QA; 100 questions / 71 videos | Answer accuracy; trajectory scores b | Evidence milestones; judged trajectories |
| Resource | Condition | Scale | Annotations / construction |
|---|---|---|---|
| Panda-70M Chen et al.,2024d | Text | 70.8M clips | Captions selected from multiple cross-modality teachers |
| Koala-36M Wang et al.,2025a | Text; motion, aesthetic, and clarity scores | 36M clips | Structured captions; Video Training Suitability Score (VTSS) filtering |
| OpenVid-1M Nan et al.,2025 | Text | 1M pairs; 433K HD subset | Captions with aesthetic, temporal, motion, and clarity filtering |
| UltraVideo Xue et al.,2025 | Text | 42K short; 17K long clips | 4K/8K footage; structured captions and summaries |
| RealEstate10K Zhou et al.,2018a | Reference image; camera parameters | 80K clips; 10M frames | Estimated camera intrinsics and poses for view synthesis |
| DL3DV-10K Ling et al.,2024 | Reference image; camera parameters | 10,510 videos; 51.2M frames | 4K multi-view scenes; camera intrinsics, poses, and scene-property labels |
| Evaluation aspect | Metrics and scorers | What is measured |
|---|---|---|
| Perceptual and temporal quality | ||
| Distributional quality | IS Salimans et al., 2016 , FID Heusel et al., 2017 , FVD Unterthiner et al., 2018 , tFVD Guo et al., 2026 , JEDi Luo et al.,2025 | classifier confidence/class coverage (IS); feature-distribution distances (FID/FVD/JEDi), not direct physical validity |
| Reference fidelity | PSNR, SSIM Wang et al., 2004 , LPIPS Zhang et al.,2018 | pixel, structural, or perceptual agreement with an aligned target; unsuitable as sole criteria for open-ended futures |
| Conditional diversity | DiVid descriptors Hu et al.,2026a | variation across repeated samples in semantics, style, subject, scene, motion, and camera, alongside faithfulness |
| Motion and temporal quality | FVMD Liu et al., 2024 , STREAM Kim et al.,2024 | motion-feature distributions and separated spatial/temporal quality; dependent on tracking or feature extraction |
| Condition fidelity | ||
| Benchmark | Condition | Evaluation target |
|---|---|---|
| VBench / EvalCrafter Huang et al.,2024a ; Liu et al.,2024c | Text | Frame appearance, temporal consistency, and text–video alignment |
| VBench++ Huang et al.,2026f | Text or reference image | Video appearance and motion; image–video subject/background consistency |
| FETV / T2V-CompBench Liu et al.,2023a ; Sun et al.,2025 | Text | Content coverage; attribute, action, motion, and relation composition |
| VMBench Ling et al.,2025 | Text | Object integrity, motion amplitude/smoothness, temporal coherence, and commonsense |
| MoveBench Chu et al.,2025 | Text; reference image; point tracks or masks | Trajectory adherence and motion consistency |
| OmniVBench Li et al.,2026e | Text; reference image or video | Reference fidelity, attribute binding, and separation of content, motion, and style |
| System | Architecture | Learning | Visual space | MLLM online | Modes T I V AV L |
|---|---|---|---|---|---|
| Diffusion over pixels or continuous latents | |||||
| Video Diffusion Models (text) Ho et al.,2022a | U-Net | Diffusion | Px | – | • – – – – |
| Video Diffusion Models (prediction) Ho et al.,2022a | U-Net | Diffusion | Px | – | – • • – – |
| Imagen Video Ho et al.,2022 | Cascaded U-Nets | Diffusion | Px | – | • – – – – |
| Make-A-Video Singer et al.,2023 | U-Net cascade | Diffusion | Px | – | • • • – – |
| Video LDM (text) Blattmann et al.,2023a | U-Net | Diffusion | VAE | – | • – – – – |
| Family | Where control enters | What is trained | Strengths | Limitations | Examples |
|---|---|---|---|---|---|
| Attention | Cross- and self-attention maps, replaced, reweighted, or reused from a source run | No separate control network | Local semantic edits that keep the source layout | Depends on learned correspondences; large motion and occlusion break them; strong map reuse blocks geometric change | Prompt-to-Prompt Hertz et al., 2023 , Video-P2P Liu et al., 2024a , FateZero Qi et al., 2023 , TokenFlow Geyer et al.,2024 |
| Adapter | Block features of a frozen backbone, through a side branch | Adapter or side network | Keeps the pretrained generator; encodes dense spatial and temporal structure | Needs paired control data; one branch per signal; separately trained adapters may conflict | ControlNet Zhang et al., 2023a , T2I-Adapter Mou et al., 2024 , MotionCtrl Wang et al., 2024i , VideoControlNet Hu & Xu, 2023 , VACE Jiang et al.,2025 |
| Latent space | Noisy latent or denoising trajectory: partial noising, inversion, or constructed and optimized latents | Nothing, or the base model for constructed conditions | Noise level sets fidelity against edit strength; accurate inversion preserves background, identity, and motion | Limited by what the latent retains; inversion errors accumulate into temporal drift | SDEdit Meng et al., 2022 , DDIM inversion Song et al., 2021 , Wan-Move Chu et al., 2025 , VLIPP Yang et al.,2025d |
| Concatenation / in-context | Model input, as extra channels or tokens, including in-context examples and retrieved evidence | The backbone and its condition encoders | Simple; many conditions combine in one sequence and one model | Training must teach the model to bind each token type; longer sequences raise attention cost; retrieved evidence can be wrong | SVD Blattmann et al., 2023 , VideoComposer Wang et al., 2023a , FullDiT Ju et al., 2025 , UNIC Ye et al., 2026a , PhysRAG Cheng et al.,2026a |
| Guidance | Sampling update at each denoising step | Nothing at test time; CFG needs condition dropout during training | Works at test time; can impose constraints absent from the training data | Extra model or gradient evaluations; high scales reduce diversity; only as good as the surrogate objective | CFG Ho & Salimans, 2022 , universal guidance Bansal et al., 2024 , FreeDoM Yu et al., 2023 , self-guidance Epstein et al.,2023 |
| Tuning | Model parameters or text embeddings | Embeddings, full or low-rank weights, or a hypernetwork that predicts them | Preserves a specific subject or style more faithfully than prompts | Needs adaptation data and compute; adds parameters; can bind the subject to reference poses, backgrounds, or motion | Textual Inversion Gal et al., 2023 , DreamBooth Ruiz et al., 2023 , LoRA Hu et al., 2022 , Tune-A-Video Wu et al., 2023 , Video2LoRA Wu et al.,2026d |
| System | Core | Read interface | Write / act interface | Training / notes | U G E |
|---|---|---|---|---|---|
| Discrete-token unification | |||||
| Emu3 Wang et al.,2024b | 8B Transformer | Spatiotemporal VQ | VQ decoder | Joint AR C | ✓ ✓ – |
| Emu3.5 Cui et al.,2025 | 34B Transformer | IBQ over frames | IBQ frame decoder; keyframe diffusion | AR + SFT + RL C | ✓ ✓ – |
| Video-LaVIT Jin et al.,2024a | Llama-2-7B | Keyframe + motion VQ | Codes diffusion decoders | Video–language AR C | ✓ ✓ – |
| Vega Wang et al.,2026e | Qwen2.5-3B | Tar semantic tokens | Tar Wan2.1 renderer | Semantic AR + FM C | ✓ ✓ – |
| VILA-U Wu et al.,2025e | Llama-2-7B + RQ depth | SigLIP/RQ tower | RQ RQ-VAE | Alignment + joint AR C | ✓ ✓ – |
| Evidence level | Required test | Benchmarks and probes | Video-native status |
|---|---|---|---|
| Level 1 Separate competence | evaluate understanding and generation separately | Video-MME Fu et al., 2025 , MVBench Li et al., 2024a , LongVideoBench Wu et al., 2024 , LVBench Wang et al., 2025c , MLVU Zhou et al., 2025b ; VBench Huang et al., 2024a , VBench-2.0 Zheng et al.,2025 | well established |
| Level 2 Integrated behavior | test integrated transformations and source/intent fidelity | UniVBench Wei et al., 2026b , UniM Li et al., 2026h ; agentic UniVA-Bench Liang et al., 2025a ; reasoning-conditioned RVE-Bench Liu et al., 2025d and VR-Bench Xing et al.,2026 | emerging video coverage |
| Level 3 Measured synergy | ablate cross-direction information or training under matched settings | Video controls: Lance task mixtures Fu et al., 2026a , ReViSE reward Liu et al., 2025d , CounterVid preferences Poppi et al., 2026 , UnifiedReward critic transfer Wang et al., 2025f , EWAM future-feature interventions Wang et al., 2026b . Image–text: RealUnify Shi et al., 2026b , UniSandbox Niu et al.,2025a | directional video evidence; general bidirectional tests remain limited |
| Open gap Video round trip | specify invariants, block answer leakage, and compare cycle / non-cycle controls | image-based precedents: UniCorn Fang et al., 2026a , CyCLeGen Shan et al.,2026 | no established video-native standard |
| Model / protocol | Prediction space | Transition protocol | |||
|---|---|---|---|---|---|
| Observe | Latent | Passive | Action | Interactive | |
| SV2P, action-free Babaeizadeh et al.,2018 | ✓ | – | ✓ | – | – |
| SV2P, fixed actions Babaeizadeh et al.,2018 | ✓ | – | – | ✓ | – |
| GAIA-1, driving controls Hu et al.,2023 | ✓ | – | – | ✓ | – |
| Vista Gao et al.,2024a | ✓ | – | – | ✓ | – |
| IRASim Zhu et al.,2025 | ✓ | – | – | ✓ | – |
| Method | Training mechanism | Intended effect |
|---|---|---|
| Teacher forcing | Clean ground-truth history; next-step prediction | Fit observed transitions; exposure mismatch remains |
| Diffusion Forcing Chen et al.,2024 | Independent noise levels across sequence elements | Denoise from histories with varying uncertainty |
| CausVid Yin et al.,2025 | DMD from a bidirectional teacher to a causal student | Few-step causal generation |
| Self-Forcing Huang et al.,2025a | Self-generated histories; video-level distribution matching | Align training context with autoregressive inference |
| Causal Forcing Zhu et al.,2026a | Causal-teacher ODE initialization followed by DMD on rollouts | Align initialization with causal prediction |
| Causal Forcing++ Zhao et al.,2026a | Causal consistency initialization followed by DMD | Reduce initialization cost for frame-wise few-step generation |
| Memory type | Stored state | Horizon scaling | Examples | Main limitation |
|---|---|---|---|---|
| Visual retrieval | frames, tokens, or anchors selected by similarity or pose | growing or capped archive | WorldMem Xiao et al., 2025a , RELIC Hong et al., 2025 , Context-as-Memory Yu et al., 2025a , AnchorWeave Wang et al., 2026h , SMI Yang et al., 2026d , Keepsake Al et al., 2026 (capped) | archives grow; eviction loses detail; false matches corrupt recall |
| Spatial caches | static maps, surfels, projected features, and reference views | grows with retained scene coverage | VMem Li et al., 2025g , Long-term Spatial Memory Wu et al., 2025c , Matrix-Game 3.5 Qian et al.,2026 | geometry errors persist; static caches alone do not model off-screen change |
| Planned dynamics with retrieval | object/camera trajectories, crops, and selected history | bounded selected context; growing video archive | WorldDirector Wang et al.,2026a | off-screen evolution is externally planned; chunks do not establish online interaction |
| Addressable KV summaries | recent window plus Field summaries or Landmark slots | fixed GPU cache; host scaling depends on writer | WorldTrace Wu et al., 2026b ; evaluated with LoopBench | host history grows by default; bounded aggregates lose information |
| Compressed context | selected chunks or summaries with unequal temporal budgets | bounded working context | StreamingT2V Henschel et al., 2025 , FramePack Zhang et al.,2025c | discarded detail requires another retained source or a new observation |
| Fixed-size memory | memory queries; spatial and spatiotemporal feature planes | fixed carrier; history budget accounted separately | Echo-Infinity Bian et al., 2026 , Owl-1 Huang et al., 2024 , GIM-World Wei et al., 2026c , Honeycomb Shi et al.,2026a | compression loses detail; state updates or history re-encoding add cost |
| Evaluation target | Benchmarks / protocols | Interpretation limit |
|---|---|---|
| Video plausibility | VBench Huang et al., 2024a , VBench++ Huang et al., 2026f , VBench-2.0 Zheng et al.,2025 | No closed-loop action or hidden-state test |
| Action response | ACT-Bench Arai et al., 2024 , iWorld-Bench Fang et al., 2026 , MiraBench Yang et al.,2026b | Action spaces and control interfaces differ |
| State persistence | MIND Ye et al., 2026 , MemoBench Chen et al., 2026a , LoopBench Wu et al.,2026b | Static revisits alone do not test off-screen dynamics |
| Interactive latency | Waypoint-1.5 Rajpal et al., 2026 and system protocols | Display, latent, and control rates differ |
| Physical validity | WorldModelBench Li et al., 2025b , Physics-IQ Motamed et al., 2026 , WorldBench Upadhyay et al., 2026 , CRONOS Begiristain et al., 2026 , What-If World Cai et al.,2026 | Intervention modalities differ |
| Scene / semantic consistency | EWMBench Yue et al.,2025 | Visual similarity alone does not establish state correctness |