Systems and methods provide for on-the-fly alteration of apparent playback rate for content sent to a client based on a request from the client to alter the playback speed of the content. The system and method can use existing, open protocols and the media files served are playable by standard media playback clients. The method includes receiving a request for media content from a client, including instructions for adjusting the number of frames of the requested content to affect an apparent change in the playback speed of the content. The adjustment to the frames may include inserting frames, removing frames, and/or inserting markers to trigger the client device to duplicate frames.