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Knowledge Extraction from Video Training Material using Retrieval-Augmented Generation

Konstantina Roussou

Epubl LTU, 2026

Abstract

The increasing availability of video-based training material has created new challenges related to knowledge extraction, accessibility and information retrieval. While Automatic Speech Recognition (ASR) systems can transform speech into text, the resulting transcripts are often difficult to search and reuse efficiently. Retrieval-Augmented Generation (RAG) systems provide an opportunity to combine semantic retrieval and Large Language Models (LLMs) in order to support grounded question answering over unstructured transcript data. In this work, technical training videos were transcribed into text using the Whisper ASR model and processed through a RAG pipeline implemented using Langflow. The pipeline performed text splitting, embeddings generation, vector storage using Chroma DB, semantic retrieval and grounded answer generation, where multiple embedding and language model configurations were evaluated. Additionally, an evaluation pipeline based on an LLM-as-a-judge approach was implemented in order to assess the system performance quality. The evaluation framework analyzed metrics including faithfulness, context relevance, answer relevance, completeness, accuracy, hallucinations and retrieval failures across fifty evaluation questions. According to the experimental results, all configurations achieved high performance, particularly with respect to faithfulness and answer accuracy. Among the evaluated configurations, the Nomic-GPT implementation achieved the strongest…

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