Mixed Mode CD

Overview

Mixed mode CDs are implicitly described in the original CD-ROM standard (the Yellow Book, later standardized as ISO/IEC 10149 and ECMA-130), which allows a CD-ROM to contain only data tracks, or data tracks and audio tracks. The CD-ROM standard, however, does not mention the term "mixed mode", nor does it describe any particular order of data and audio tracks on the disc. Since the original CD-ROM standard did not support multiple sessions, mixed mode CDs are created using only one session.

Some CD players from the 1990s have trouble with the mixed mode CD format because the first track, which contains data, might be "played", resulting in screeching which, at worst, might damage speakers. This is caused by the player not recognizing the "data" flag bit for the track that distinguishes it from an audio track; these players were designed for audio CDs only, with no provisions to handle CD-ROMs with data and audio tracks. Newer audio CD players do check for data tracks and (at least) mute the track if it contains data and not audio.

Several newer formats were created to improve the usability of CDs with audio and data tracks in audio CD players; these formats include CD-i, CD-i Ready and the Enhanced Music CD format. In the case of the Enhanced Music CD format (also known as CD Extra/CD Plus), audio tracks are placed in one session before the data tracks, which are stored in a second session. This avoids the problem with the data track for most audio players, since they will only be able to recognize the first session.

Use in video games

Most games released for the Sega Mega Drive/Sega CD and NEC PC Engine CD/TurboGrafx CD were mixed mode CDs. Several games for the PC and the Playstation were mixed mode CDs as well. Games ported from floppy disks or a cartridges to a CD would often replace the music with audio CD tracks. Full-motion video (FMV) games, however, usually embbeded video and audio in CD-ROM data files and tend not to use audio tracks in the game. A short audio track would be included with FMV games anyway so that when these discs were played in a CD player the audio track would utter a warning like "This disc is for use in the Sega CD system only."

Computer applications

Computer games

PlayStation games

Other console games