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Video-CCAM: Enhancing Video-Language Understanding with Causal Cross-Attention Masks for Short and Long Videos

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arxiv 2408.14023 v1 pith:FFW334MD submitted 2024-08-26 cs.CV cs.AI

classification cs.CVcs.AI
keywords video-ccamvideoscross-attentionlongmodelsvisualunderstandingbenchmarks
verification ladder T0 review T1 audit T2 compute T3 formal
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abstract

Multi-modal large language models (MLLMs) have demonstrated considerable potential across various downstream tasks that require cross-domain knowledge. MLLMs capable of processing videos, known as Video-MLLMs, have attracted broad interest in video-language understanding. However, videos, especially long videos, contain more visual tokens than images, making them difficult for LLMs to process. Existing works either downsample visual features or extend the LLM context size, risking the loss of high-resolution information or slowing down inference speed. To address these limitations, we apply cross-attention layers in the intermediate projector between the visual encoder and the large language model (LLM). As the naive cross-attention mechanism is insensitive to temporal order, we further introduce causal cross-attention masks (CCAMs) within the cross-attention layers. This Video-MLLM, named Video-CCAM, is trained in a straightforward two-stage fashion: feature alignment and visual instruction tuning. We develop several Video-CCAM models based on LLMs of different sizes (4B, 9B, and 14B). Video-CCAM proves to be a robust Video-MLLM and shows outstanding performance from short videos to long ones. Among standard video benchmarks like MVBench and VideoChatGPT-QA, Video-CCAM shows outstanding performances (1st/2nd/3rd in MVBench and TGIF-QA, 2nd/3rd/4th in MSVD-QA, MSRVTT-QA, and ActivityNet-QA). In benchmarks encompassing long videos, Video-CCAM models can be directly adapted to long video understanding and still achieve exceptional scores despite being trained solely with images and 16-frame videos. Using 96 frames (6$\times$ the training number of frames), Video-CCAM models rank 1st/2nd/3rd in VideoVista and 1st/2nd/4th in MLVU among all open-source Video-MLLMs, respectively. The code is publicly available in \url{https://github.com/QQ-MM/Video-CCAM}.

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Forward citations

Cited by 15 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

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    cs.CV 2026-08 conditional novelty 6.0 of 10

    EviSelect uses the target multimodal model's internal attention as a prior to dynamically select frames, sampling rates, and resolutions, achieving about 50% token reduction and a 3.9x speedup with better benchmark accuracy.

  2. Efficient Frame Selection for Long Videos at Test Time with Attention-Based MLLM Selectors

    cs.CV 2026-07 conditional novelty 6.0 of 10

    Attention maps from a small MLLM can serve as a training-free, query-conditioned frame selector, improving long-video QA accuracy under fixed frame budgets.

  3. TimeThink: Reasoning with Time for Video LLMs

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    TimeThink adds step-wise temporal process rewards (max IoU of referenced intervals) to GRPO for Video-LLMs, improving grounding and reasoning over outcome-only RL baselines.

  4. Reasoning with Memory: A Temporal Granularity-Adaptive Framework for Training-Free Long Video Understanding

    cs.AI 2026-06 conditional novelty 6.0 of 10

    ReMem improves zero-shot long-video QA by combining LLM-based temporal granularity parsing, CLIP-based dual-semantic frame scoring, and structure-aware dynamic frame routing.

  5. Video-MTR: Reinforced Multi-Turn Reasoning for Long Video Understanding

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    A multi-turn reinforcement learning framework where a 7B video LLM iteratively retrieves relevant video segments, guided by a gated bi-level reward, achieves state-of-the-art accuracy on VideoMME, MLVU, and EgoSchema ...

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    LongAnimation uses a dynamic global-local memory, built from a long-video-understanding model's KV cache, to colorize animation sequences of about 500 frames with stable color consistency.

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    SparseMM shows that under 5% of attention heads carry visual understanding in MLLMs and uses OCR-derived head scores to allocate KV-cache budgets asymmetrically, preserving accuracy at low cache sizes.

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    ViaRL uses rule-based reinforcement learning to train a frame selector for video QA, improving Qwen2.5-VL on VideoMME, LVBench, and MLVU by several points.

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    A CLIP-scored, Gumbel-Max frame sampler with per-frame multi-resolution allocation improves long-video question answering in Video-LLMs under a fixed token budget.

  11. Task-Aware KV Compression For Cost-Effective Long Video Understanding

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    Video-X2L uses bi-level KV compression with task-aware selective reloading to improve long-video QA accuracy and reduce decode-time memory versus uniform KV compression.

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    Video-XL-2 cuts long-video inference cost with chunked pre-filling and query-gated dense-or-sparse KV reloading, reporting half the FLOPs and a third less decoding memory at roughly equal benchmark scores.

  13. FlexSelect: Flexible Token Selection for Efficient Long Video Understanding

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    FlexSelect selects a small fraction of query-relevant visual tokens using attention from an intermediate layer, improving long-video accuracy and inference speed across multiple VideoLLMs.

  14. VideoEval-Pro: Robust and Realistic Long Video Understanding Evaluation

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    An open-ended short-answer long-video benchmark, built by converting MCQ questions from four existing tests, shows large accuracy drops and different model rankings versus multiple-choice evaluation.

  15. LeanPO: Lean Preference Optimization for Likelihood Alignment in Video-LLMs

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    LeanPO improves Video-LLM alignment by using a reference-free average-likelihood reward, self-generated winning/losing pairs, and dynamic label smoothing, yielding gains on six video benchmarks.

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