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Granularity-Adaptive Spatial Evidence Tokenization for Video Question Answering
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Proposes a granularity-adaptive spatial evidence tokenization model for video QA that highlights question-relevant patches at low resolution, encodes only those patches at high resolution with masking acceleration, and compresses multi-granular tokens by question.
Problem
Video question answering models encode frames at fixed low resolution, losing fine-grained spatial detail, while existing high-resolution image LLMs encode entire high-res frames at high computational cost.
Approach
Use question-guided spatial activation at low resolution to select patches, map them to high-resolution frames via index querying, encode only the masked activated patches (with relative position embeddings), and select/compress tokens across granularities with a question-conditioned granularity compression module.
Key results
- Achieves 73.4% accuracy on MSVD-QA and 51.4% on ActivityNet-QA, outperforming listed 7B baselines in open-ended QA (Table 1).
- Reaches 45.1% average on MVBench, above VideoLLaVA (42.9) and LLaMA-VID (42.2) but below VideoChat2 (51.1) which uses far more instruction data.
- Reduces model complexity versus LLaMA-VID from 16.84 to 11.97 TMACs and 33.70 to 23.94 TFLOPs (Table 8).
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| add granularity weighting module (ablation) | Granularity-adaptive tokenization model · MSVD-QA | accuracy: 72.0 -> 73.4 | Helped |
| add granularity compression module (ablation) | Granularity-adaptive tokenization model · MSVD-QA | accuracy: 72.5 -> 73.4 | Helped |
| add multi-granularity tokenization module (ablation) | Granularity-adaptive tokenization model · MSVD-QA | accuracy: 71.9 -> 73.4 | Helped |
| add granularity weighting module (ablation) | Granularity-adaptive tokenization model · ActivityNet-QA | accuracy: 49.7 -> 51.4 | Helped |
| add granularity compression module (ablation) | Granularity-adaptive tokenization model · ActivityNet-QA | accuracy: 49.7 -> 51.4 | Helped |
| add multi-granularity tokenization module (ablation) | Granularity-adaptive tokenization model · ActivityNet-QA | accuracy: 49.8 -> 51.4 | Helped |
| add granularity weighting module (ablation) | Granularity-adaptive tokenization model · TGIF-QA | accuracy: 72.4 -> 74.9 | Helped |
| add granularity compression module (ablation) | Granularity-adaptive tokenization model · TGIF-QA | accuracy: 73.8 -> 74.9 | Helped |
| add multi-granularity tokenization module (ablation) | Granularity-adaptive tokenization model · TGIF-QA | accuracy: 74.0 -> 74.9 | Helped |
| use the proposed masking and acceleration strategy instead of encoding all high-resolution frame patches (ablation) | Granularity-adaptive tokenization model · ActivityNet-QA | TFLOPs: 53.40 -> 23.94 | Helped |
| use prompt PR #2 instead of PR #1 | Granularity-adaptive tokenization model · NExT-QA | accuracy: 64.0 -> 61.8 | Mixed |
| use system instruction INS #2 instead of INS #1 | Granularity-adaptive tokenization model · NExT-QA | accuracy: 62.8 -> 64.1 | Helped |
Surprising findings
- Model performance varies only slightly across different question prompts and system instructions, per the prompt ablation.
Limitations
- Relies on a pretrained frozen visual encoder and Q-Former, so resolution gains depend on these components.
- Evaluation relies on GPT-3.5 as judge for open-ended QA and text generation.
- Comparisons with some baselines (VideoChat2, VideoLLaMA2) are excluded or uneven due to differing training data scale.
Experimental setup
Datasets: MSVD-QA MSRVTT-QA ActivityNet-QA TGIF-QA Video-ChatGPT text generation benchmark NExT-QA STAR TVQA IntentQA EgoSchema MVBench
Benchmarks: MSVD-QA MSRVTT-QA ActivityNet-QA TGIF-QA Video-ChatGPT text generation benchmark NExT-QA STAR TVQA IntentQA EgoSchema MVBench
Metrics: accuracy score
Baselines: Video-LLaMA LLaMA-Adapter Video-ChatGPT Video-LLaVA LLaMA-VID Chat-UniVi VideoChat2 VideoLLaMA2 Monkey MiniGPT4-V
Builds on: LLaMA-VID Monkey InstructBLIP BLIP-2
Closest papers by meaning
- Language-aware Visual Semantic Distillation for Video Question Answering (CVPR 2024 · similarity 0.89)
- Tool-Augmented Spatiotemporal Reasoning for Streamlining Video Question Answering Task (NeurIPS 2025 · similarity 0.88)
- VideoEspresso: A Large-Scale Chain-of-Thought Dataset for Fine-Grained Video Reasoning via Core Frame Selection (CVPR 2025 · similarity 0.88)
- Video-Panda: Parameter-efficient Alignment for Encoder-free Video-Language Models (CVPR 2025 · similarity 0.87)
- Temporal Chain of Thought: Long-Video Understanding by Thinking in Frames (NeurIPS 2025 · similarity 0.86)
- Not Another Text Benchmark: Putting the “Visual" Back in Visual Question Answering for Large Video Models (NeurIPS 2026 · similarity 0.86)
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