VideoLat: An Extensible Tool for Multimedia Delay Measurements

When using a videoconferencing system there will always be a delay from sender to receiver. Such delays affect human communication, and therefore knowing the delay is a major factor in judging the expected quality of experience of the conferencing system. Additionally, for implementors, tuning the system to reduce delay requires an ability to effectively and easily gather delay metrics on a potentially wide range of settings. In order to support this process, we make available a system called videoLat. VideoLat provides an innovative approach to understand glass-to-glass video delays and speaker-to-microphone delays. VideoLat can be used as-is to do audio and video roundtrip delays of black box systems, but by making it available as open source we want to enable people to extend and modify it for different scenarios, such as measuring one-way delays or delay of camera switching.