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A compressed audio optical disc, MP3 CD, or MP3 CD-ROM or MP3 DVD is an optical disc (usually a CD-R, CD-RW, DVD-R or DVD-RW) that contains digital audio in the MP3 file format. Discs are written in the "Yellow Book" standard data format (used for CD-ROMs and DVD-ROMs), as opposed to the Red Book standard audio format (used for CD-DA audio CDs). Even modern day formats such as recordable Blu-Ray discs have also come in play for this concept. ==Description== Compressed audio files are supported by many modern CD players as well as DVD players. Disc players are capable of playing compressed formats, take for instance MP3, in which is the most commonly used format, and other formats such as Ogg Vorbis and the proprietary Windows Media Audio and ATRAC are also played as well. Because of audio data compression, optical discs do not have to spin all of the time, potentially saving battery power; however, decompressing the audio takes more processor time. The audio is buffered in random-access memory, which also provides protection against skipping. The number of files that a disc can hold depends on how the audio files are encoded and the length of the audio. A standard audio CD (74 minutes) can hold about 18 audio programs, a 650-MB data CD (equivalent to 74-minute audio CD) containing mid-quality (160-kb/s) audio files can hold approximately 9.5 hours of audio or about 138 audio tracks. ID3 tags stored in compressed audio files can be displayed by some players, and some players can search for audio files within directories on a compressed audio optical disc. There is no official standard for how audio files on a compressed audio optical CD are stored on discs. As such, the format expected by different players varies. This sometimes leads to incompatibilities and difficulty in playing discs, often because of filename length limits, sub-directory limits, number of files limits, and special character bugs. Sometimes, pressed CDs containing MP3s can be used, since some CD-ROM video games can act as an "MP3 CD" for some users. Some older classic CD-ROM games tend to use WAV files since WAV files were the biggest audio format throughout the 90s, in which WAV files on optical discs are also compatible with CD players which have Yellow Book CD-ROM support. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Compressed audio optical disc」の詳細全文を読む スポンサード リンク
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