the epup-format is a tricky road. so a long time epub3 was the hope. now the time is come to fulfill the goal. epub3 in version 3.3 (incl support for webp & opus) is easy & useful.. maybe sumatra coulbe save epub (old) in modern epub3 (3.3)
the epup-format is a tricky road. so a long time epub3 was the hope. now the time is come to fulfill the goal. epub3 in version 3.3 (incl support for webp & opus) is easy & useful.. maybe sumatra coulbe save epub (old) in modern epub3 (3.3)