Animation artist Max Fleischer introduced a series of sing-along short cartoons called Screen Songs, which invited audiences to sing along to popular songs by "following the bouncing ball," which is similar to a modern karaoke machine. Early 'cartoons featured popular musicians performing their hit songs on camera in live-action segments during the cartoons. The early animated films by Walt Disney, such as the Silly Symphonies shorts and especially Fantasia, which featured several interpretations of classical pieces, were built around music.