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是一个开源工具包，用于评估各类会议转录系统。该工具包提供统一接口，可计算常用词错误率（WER），包括cpWER、ORC WER、MIMO WER及其他WER定义。我们通过引入时间约束扩展cpWER计算方法，仅当时间对齐合理时才将词汇判定为正确，从而使假设字符串与参考字符串的匹配更接近实际转录质量，并对提供低质量时间标注的系统施加惩罚。由于词汇级时间信息通常不可获取，我们提出一种从片段级时间（如句子）近似计算精确词汇级时间的方法，并证明该近似方法产生的WER与使用精确词汇级标注的匹配结果相近。与此同时，时间约束可加速匹配算法，其效率提升足以抵消处理时间戳带来的额外计算开销。