MeetEval is an open-source toolkit to evaluate all kinds of meeting transcription systems. It provides a unified interface for the computation of commonly used Word Error Rates (WERs), specifically cpWER, ORC-WER and MIMO-WER along other WER definitions. We extend the cpWER computation by a temporal constraint to ensure that only words are identified as correct when the temporal alignment is plausible. This leads to a better quality of the matching of the hypothesis string to the reference string that more closely resembles the actual transcription quality, and a system is penalized if it provides poor time annotations. Since word-level timing information is often not available, we present a way to approximate exact word-level timings from segment-level timings (e.g., a sentence) and show that the approximation leads to a similar WER as a matching with exact word-level annotations. At the same time, the time constraint leads to a speedup of the matching algorithm, which outweighs the additional overhead caused by processing the time stamps.

翻译：MeetEval是一个用于评估各类会议转写系统的开源工具包。它提供了统一接口以计算常用词错误率，具体包括cpWER、ORC-WER、MIMO-WER及其他WER定义。我们在cpWER计算中引入时间约束，确保仅当时间对齐合理时才判定词语正确。这一改进使得假设字符串与参考字符串的匹配质量更接近实际转写质量，且若系统提供劣质时间标注则会受到惩罚。鉴于词级时间信息通常不可获取，我们提出一种从片段级时间信息（如句子）近似精确词级时间的方法，并证明该近似方法可得到与精确词级标注匹配相近的WER。同时，时间约束实现了匹配算法的加速，其性能提升足以抵消处理时间戳带来的额外开销。