Hybrid CD
Encyclopedia
A Hybrid disc is a CD-ROM
with additional types of data stored on it.
It may contain:
that has multiple file systems, so that it can be used on various system software, for example both Apple Macintosh and Microsoft Windows
based operating system
s.
A hybrid disc has multiple file system
s installed on it, typically ISO 9660
and HFS+ (or HFS
on older discs). The reason for the format is primarily that ISO 9660 has severe restrictions placed on filename
s (initially only 8 characters per file, and a depths of 8 directories, similar to the Microsoft
FAT
filesystem.) and lacks key structures present in Apple Computer
's HFS and HFS+ file systems. Another key factor is that ISO 9660 does not support resource fork
s, which is critical to Mac OS
' software design (Mac OS X
has removed much of the emphasis/need for resource forks in application design). Companies that released products for both DOS
(later Windows
) and Mac OS
(later Mac OS X
) could release a CD containing software for both, natively readable on either system. Data files can even be shared by both partitions, while keeping the platform specific data separate. In a true (or shared) hybrid HFS filesystem, files common to both the ISO 9660 and HFS partitions are stored only once, with the ISO 9660 partition pointing to file content in the HFS area (or vice versa). Blizzard Entertainment
has released most of their computer games on hybrid CDs. By default, Mac OS 9
and Mac OS X
burn hybrid discs.
A hybrid disc has an ISO 9660 primary volume descriptor, which makes it a valid ISO 9660 disc, and an Apple partition. It may also have an Apple partition map
, although this is not necessary. The ISO 9660 portion of the disc can co-exist with an Apple partition because the header areas which define the contents of the disc are located in different places. The ISO 9660 primary volume descriptor begins 32768 bytes (32KB) into the disc. If present, an Apple partition map begins 512 bytes into the disc; if there is no partition map, the header for an Apple HFS
partition (known as a Master Directory Block, or MDB) begins 1,024 bytes into the disc.
which also includes a data track
storing MP3
(or other digital audio compression format) copy of those CDDA tracks. Before the introduction and subsequent popularization of iTunes
and the iPod
, such discs were popular for sharing music on compact disc
without requiring the recipient to extract and encode the CDDA themselves — a technical and perhaps time-consuming process on older computing hardware. However, with the advent of faster computing hardware and vastly simplified automated extraction and encoding tools (e.g. iTunes, Rhythmbox
, etc.) and the lack of an automated hybrid feature in that very same software, popularity of such hybrid CD has subsequently declined. Furthermore, the legal status of such discs poses economic frictions
in that they may be interpreted as two copies of a copyright
ed work. However, such hybrid discs do remain in a commercial setting as a digital rights management
enforcement technique, where encrypted compressed copies of the digital audio are provided with proprietary software
for listening in a computer disc drive, while the CDDA is included for playback in stand-alone CD players.
CD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....
with additional types of data stored on it.
It may contain:
- Multiple file systems such as for both Microsoft WindowsMicrosoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
and Apple Macintosh based operating systemOperating systemAn operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s. - Additional security measures
- Audio CD with added data tracks
Multiple file systems
A Hybrid disc is a CD-ROMCD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....
that has multiple file systems, so that it can be used on various system software, for example both Apple Macintosh and Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
based operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s.
A hybrid disc has multiple file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
s installed on it, typically ISO 9660
ISO 9660
ISO 9660, also referred to as CDFS by some hardware and software providers, is a file system standard published by the International Organization for Standardization for optical disc media....
and HFS+ (or HFS
Hierarchical File System
Hierarchical File System is a file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs...
on older discs). The reason for the format is primarily that ISO 9660 has severe restrictions placed on filename
Filename
The filename is metadata about a file; a string used to uniquely identify a file stored on the file system. Different file systems impose different restrictions on length and allowed characters on filenames.A filename includes one or more of these components:...
s (initially only 8 characters per file, and a depths of 8 directories, similar to the Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
FAT
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
filesystem.) and lacks key structures present in Apple Computer
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
's HFS and HFS+ file systems. Another key factor is that ISO 9660 does not support resource fork
Resource fork
The resource fork is a construct of the Mac OS operating system used to store structured data in a file, alongside unstructured data stored within the data fork. A resource fork stores information in a specific form, such as icons, the shapes of windows, definitions of menus and their contents, and...
s, which is critical to Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
' software design (Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
has removed much of the emphasis/need for resource forks in application design). Companies that released products for both DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
(later Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
) and Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
(later Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
) could release a CD containing software for both, natively readable on either system. Data files can even be shared by both partitions, while keeping the platform specific data separate. In a true (or shared) hybrid HFS filesystem, files common to both the ISO 9660 and HFS partitions are stored only once, with the ISO 9660 partition pointing to file content in the HFS area (or vice versa). Blizzard Entertainment
Blizzard Entertainment
Blizzard Entertainment, Inc. is an American video game developer and publisher founded on February 8, 1991 under the name Silicon & Synapse by three graduates of UCLA, Michael Morhaime, Allen Adham and Frank Pearce and currently owned by French company Activision Blizzard...
has released most of their computer games on hybrid CDs. By default, Mac OS 9
Mac OS 9
Mac OS 9 is the final major release of Apple's Mac OS before the launch of Mac OS X. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as...
and Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
burn hybrid discs.
A hybrid disc has an ISO 9660 primary volume descriptor, which makes it a valid ISO 9660 disc, and an Apple partition. It may also have an Apple partition map
Apple Partition Map
Apple Partition Map is a partition scheme used to define the low-level organization of data on disks formatted for use with 68K and PowerPC Macintosh computers that was introduced with the Macintosh SE ....
, although this is not necessary. The ISO 9660 portion of the disc can co-exist with an Apple partition because the header areas which define the contents of the disc are located in different places. The ISO 9660 primary volume descriptor begins 32768 bytes (32KB) into the disc. If present, an Apple partition map begins 512 bytes into the disc; if there is no partition map, the header for an Apple HFS
Hierarchical File System
Hierarchical File System is a file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs...
partition (known as a Master Directory Block, or MDB) begins 1,024 bytes into the disc.
Additional security measures
Hybrid-CD also refers to the invention of a single CD with additional security measures. To replace the CD-soft R, such a CD combines in it a CD-ROM section and a CD-RW section. Utilizing this hardware, a single disk can have a software package written in the ROM (read only) section which cannot be changed. However, the RW (read-write) section can store user specific data.Audio CD with added data tracks
Hybrid-CD also refers to audio CDRed Book (audio CD standard)
Red Book is the standard for audio CDs . It is named after one of the Rainbow Books, a series of books that contain the technical specifications for all CD and CD-ROM formats.The first edition of the Red Book was released in 1980 by Philips and Sony; it was adopted by the Digital Audio Disc...
which also includes a data track
ISO 9660
ISO 9660, also referred to as CDFS by some hardware and software providers, is a file system standard published by the International Organization for Standardization for optical disc media....
storing MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
(or other digital audio compression format) copy of those CDDA tracks. Before the introduction and subsequent popularization of iTunes
ITunes
iTunes is a media player computer program, used for playing, downloading, and organizing digital music and video files on desktop computers. It can also manage contents on iPod, iPhone, iPod Touch and iPad....
and the iPod
IPod
iPod is a line of portable media players created and marketed by Apple Inc. The product line-up currently consists of the hard drive-based iPod Classic, the touchscreen iPod Touch, the compact iPod Nano, and the ultra-compact iPod Shuffle...
, such discs were popular for sharing music on compact disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
without requiring the recipient to extract and encode the CDDA themselves — a technical and perhaps time-consuming process on older computing hardware. However, with the advent of faster computing hardware and vastly simplified automated extraction and encoding tools (e.g. iTunes, Rhythmbox
Rhythmbox
Rhythmbox is an audio player that plays and helps organize digital music. Originally inspired by Apple's iTunes, it is free software, designed to work well under the GNOME Desktop using the GStreamer media framework. However, Rhythmbox functions on desktop environments other than GNOME.-Music...
, etc.) and the lack of an automated hybrid feature in that very same software, popularity of such hybrid CD has subsequently declined. Furthermore, the legal status of such discs poses economic frictions
Efficiency (economics)
In economics, the term economic efficiency refers to the use of resources so as to maximize the production of goods and services. An economic system is said to be more efficient than another if it can provide more goods and services for society without using more resources...
in that they may be interpreted as two copies of a copyright
Copyright
Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time...
ed work. However, such hybrid discs do remain in a commercial setting as a digital rights management
Digital rights management
Digital rights management is a class of access control technologies that are used by hardware manufacturers, publishers, copyright holders and individuals with the intent to limit the use of digital content and devices after sale. DRM is any technology that inhibits uses of digital content that...
enforcement technique, where encrypted compressed copies of the digital audio are provided with proprietary software
Proprietary software
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
for listening in a computer disc drive, while the CDDA is included for playback in stand-alone CD players.