Many friends may not have heard of FFmpeg, but you must have used one of these software: Baofeng Yingyin, QQ Yingyin, KMP, GOM Player, PotPlayer (2010), KMPlayer. FFmpeg is open source software, and software that uses FFmpeg in accordance with the agreement must also be open source. However, these audio and video software do not comply with the agreement, so they were put on FFmpeg's "blacklist".