BUT System Description for CHiME-9 MCoRec Challenge

Fuente: arXiv
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Autori principali: Klement, Dominik, Polok, Alexander, Phong, Nguyen Hai, Singh, Prachi, Burget, Lukáš
Natura: Preprint
Pubblicazione: 2026
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author Klement, Dominik
Polok, Alexander
Phong, Nguyen Hai
Singh, Prachi
Burget, Lukáš
author_facet Klement, Dominik
Polok, Alexander
Phong, Nguyen Hai
Singh, Prachi
Burget, Lukáš
contents Multi-talker automatic speech recognition (ASR) in conversational recordings remains an open problem, particularly in scenarios with large portion of overlapping speech where identifying and transcribing a target speaker is difficult from audio alone. Visual cues can help resolve speaker ambiguity, yet their integration into long-context audio-visual (AV) ASR systems has been limited. The CHiME-9 MCoRec task addresses this challenge by requiring transcription of audio-visual recordings of heavily-overlapped parallel conversations, followed by clustering the participants into conversational groups. In this work, we present the BUT system based on a long-context target-speaker AV-ASR model capable of processing long-form recordings in a single decoding pass. Our architecture conditions a pre-trained NVIDIA Parakeet-v2 ASR model on visual representations from a pre-trained AV-HuBERT model. To cluster participants into conversation groups, we employ Qwen3.5-122B LLM to estimate transcript topic similarity followed by hierarchical agglomerative clustering. On the MCoRec development set, the proposed system achieves 33.7% WER and a clustering F1 score of 0.97, improving over the official baseline by 16.2% WER and 0.15 F1 absolute. On the eval set, our team ranked second, being 0.16% WER and 0.5% F1 worse than the best system.
format Preprint
id arxiv_https___arxiv_org_abs_2604_27436
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle BUT System Description for CHiME-9 MCoRec Challenge
Klement, Dominik
Polok, Alexander
Phong, Nguyen Hai
Singh, Prachi
Burget, Lukáš
Audio and Speech Processing
Image and Video Processing
Multi-talker automatic speech recognition (ASR) in conversational recordings remains an open problem, particularly in scenarios with large portion of overlapping speech where identifying and transcribing a target speaker is difficult from audio alone. Visual cues can help resolve speaker ambiguity, yet their integration into long-context audio-visual (AV) ASR systems has been limited. The CHiME-9 MCoRec task addresses this challenge by requiring transcription of audio-visual recordings of heavily-overlapped parallel conversations, followed by clustering the participants into conversational groups. In this work, we present the BUT system based on a long-context target-speaker AV-ASR model capable of processing long-form recordings in a single decoding pass. Our architecture conditions a pre-trained NVIDIA Parakeet-v2 ASR model on visual representations from a pre-trained AV-HuBERT model. To cluster participants into conversation groups, we employ Qwen3.5-122B LLM to estimate transcript topic similarity followed by hierarchical agglomerative clustering. On the MCoRec development set, the proposed system achieves 33.7% WER and a clustering F1 score of 0.97, improving over the official baseline by 16.2% WER and 0.15 F1 absolute. On the eval set, our team ranked second, being 0.16% WER and 0.5% F1 worse than the best system.
title BUT System Description for CHiME-9 MCoRec Challenge
topic Audio and Speech Processing
Image and Video Processing
url https://arxiv.org/abs/2604.27436