LVSum: A Benchmark for Timestamp-Aware Long Video Summarization
For researchers working on video understanding and MLLMs, this benchmark provides a standardized evaluation to address temporal fidelity in long video summarization.
LVSum is a benchmark for evaluating long video summarization with temporal alignment. Experiments reveal systematic gaps in temporal understanding among current MLLMs, establishing a foundation for advancing temporal reasoning.
Long video summarization presents significant challenges for current multimodal large language models (MLLMs), particularly in maintaining temporal fidelity over extended durations and producing summaries that are both semantically and temporally grounded. In this work, we present LVSum, a human-annotated benchmark designed specifically for evaluating long video summarization with fine-grained temporal alignment. LVSum comprises diverse long-form videos across 13 domains, each paired with human-generated summaries containing precise temporal references. We conduct a comprehensive evaluation of both proprietary and open-source MLLMs on LVSum, assessing performance using newly introduced LLM-based metrics for content relevance and modality coherence, alongside standard evaluation metrics. Our experiments reveal systematic gaps in temporal understanding among existing MLLMs and offer insights that establish a new foundation for advancing temporal reasoning in long video summarization.