A mixed mode CD is a

Compact Disc The compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony to store and play digital audio recordings. In August 1982, the first compact disc was manufactured. It was then released in O ...

which contains both data and audio in one session.PCMAG.com Mixed Mode CD Definition
/ref> Typically the first track is a data track while the rest are audio tracks. The most common use for mixed mode CDs is to add CD-quality audio to

video game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This feedba ...

s on a CD. The term "enhanced CD" is sometimes used to refer to mixed mode CDs,Enhanced CD Formats
/ref> though it is most commonly used to refer to either a more general category of formats that mix audio and data tracks, or to the particular

Enhanced Music CD The Blue Book is a compact disc standard developed in 1995 by Philips and Sony. It defines the Enhanced Music CD format (E-CD, also known as CD-Extra, CD-Plus and CD+), which combines audio tracks and data tracks on the same disc. The format was ...

format.

Overview

Mixed mode CDs are implicitly described in the original

CD-ROM A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains data. Computers can read—but not write or erase—CD-ROMs. Some CDs, called enhanced CDs, hold both com ...

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 manufactured prior to the mid-to-late-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 both data and audio tracks. As a result, it attempts to play back the data file as an audio recording, converting the encoded data into incongruous noise that can exceed the limitations of commercial speakers. 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 The Compact Disc-Interactive (CD-I, later CD-i) is a Digital media, digital optical disc data storage device, data storage format that was mostly developed and marketed by Dutch company Philips. It was created as an extension of Compact Disc Di ...

, CD-i Ready, and

Enhanced CD Enhanced CD is a certification mark of the Recording Industry Association of America for various technologies that combine audio and computer data for use in both Compact Disc and CD-ROM players. Formats that fall under the "enhanced CD" ...

s (both Blue Book-standard and non-standard enhanced CDs). In the case of the latter, 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 Mega-CD/Sega CD and NEC PC Engine CD/TurboGrafx CD are mixed mode CDs. Several games for the PC,

Amiga Amiga is a family of personal computers introduced by Commodore International, Commodore in 1985. The original model is one of a number of mid-1980s computers with 16- or 32-bit processors, 256 KB or more of RAM, mouse-based GUIs, and sign ...

, PlayStation, Sega Saturn, and Dreamcast are mixed mode CDs as well. Games ported from

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined ...

or cartridge media to a CD would often have the music replaced with (Red Book) audio CD tracks, using the mixed-mode format. As an alternative, some games embed video and audio in

data files and tend not to use CD audio tracks in the game, usually taking advantage of XA interleaving. This was the norm for and including Full-motion video (FMV) games, as the CD drive speed and system RAM size were not adequate to pre-load the video from the disc completely into RAM before playing it, so it had to be played (streamed) directly from the disc, and the CD drive could not read two tracks (a data track containing the video, and an audio track) at the same time. A short Red Book audio track was sometimes included with non-mixed-mode games anyway, so that when these discs are played in a CD player, the player will reproduce a recorded warning announcement, typically stating that the disc is not meant to be run in an audio CD player before instructing the listener to eject the disc immediately. Bonus audio tracks might also be included on the disc as Easter eggs for the player to find when the game software is not running.An example is the last track on the '' Sewer Shark'' pack-in game CD for the Sega CD, which is a sort of audio " vanity plate" for Digital Pictures, the producers of the game.

References

{{Rainbow Books Compact disc pl:Mixed-Mode