SFD

Sofdec, abbreviated as SFD, is a video container developed by CRI Middleware and used in Persona 3 and Persona 4. It uses MPEG video and ADX audio. It was succeeded by USM, which the series uses from Persona 4 Golden onwards. In the Persona games, the video track can be either MPEG1 or MPEG2 and is always 29.97 FPS. The audio track is always 48000 Hz stereo ADX. Most Persona 3 videos are 16:10 640x368 and get letterboxed in-engine. Some are made to display in 4:3 fullscreen, which use 640x448. All videos in Persona 4 are 4:3 640x448, except for its unused copy of the Persona 3 opening. They can be played outside of the game on MPV(found here), audio may glitch when skipping the video.

Modding
The length of the video files appears to be hardcoded into the executable. However, it is still possible to create custom video files equal in duration to the original.

DCMovieCreator
DCMovieCreator is official Dreamcast development software for Windows that provides full functionality for converting an AVI video file to an SFD with a straightforward, user-friendly GUI. There have been mixed reports of success with different AVI codecs, sometimes resulting in video playback ending earlier than normal ingame. The best known codec is the | TechSmith Screen Codec.

TMPGEnc 4.0 XPress
Some users have reported that TMPGEnc 4.0 XPress (found | here) provides better video quality (using VBR encoding). Rename the exported video to .m1v and use it as input for DCMovieCreator.