CD-i FAQ 2020 | Back to Index
Section 7. CD-i Authoring
7.1 How is CD-i authoring generally done?
CD-i authoring involves several steps, most of which should be followed in order, some of which can be done at the same time. Generally, one starts with the design phase. The producer of a disc decides what it should be all about, how the interactivity will take place, what screens the user will see, what audio will be used, etcetera. Then, the assets (audio and video material) will be created. These are usually made using regular video and audio editing software, and then converted into CD-i's audio and video formats. Now, the program code should be written, or -in case a high-level authoring tool is being used- the assets should be placed in their correct order. The program code or scripts then need to be converted to CD-i's real time disc format, this process is usually called disc building (see What is disc building?). This disc building then results in a disc image which can be played back using an Emulator (see What is a CD-i Emulator?), recorded onto a CD-Recordable or sent to a manufacturing plant for replication.
7.2 What is disc building?
A critical step in the development of a CD-i title is the so-called disc building process. Because of the fact that CD-i almost entirely depends on its real time behaviour (see What is a real-time system? in section 3 of this FAQ), it is very important that the audio and video are placed in the correct way on the disc. Unlike other non-realtime systems like PCs with a CD-ROM drive which can store large amounts of audio and video data in memory for later playback (and hence requiring more complicated and expensive systems), a CD-i player reproduces the audio and video data in realtime when it is being read from the disc. To accomplish the seemingly “same time” retrieval of audio and video, CD-i uses a clever sector format (see What is sector interleaving? in section 3 of this FAQ) to store various kinds of data in a single data stream.
Naturally, this process of placing all the information bits in the correct order is not done manually (although it remains the CD-i producer's responsibility to investigate whether the choice of the amount and quality of audio and video will fit in the data stream). The process of the creation of a file that holds the contents of a CD-i disc is called disc building. The resulting file is usually called a CD-i Disc Image. The Disc Image can be played back using an Emulator (see What is a CD-i Emulator?) or recorded on a CD-R to check whether it behaves on an actual CD-i player as expected.
7.3 What is a CD-i authoring or development player?
A CD-i authoring player is a CD-i player that can play CD-i discs in a normal way, but which has some additional functionality especially added for CD-i authoring purposes. An authoring player can for example be connected to an Emulator (see What is a CD-i Emulator?) for the retrieval of data as if it was being read from a CD. Furthermore, an authoring player provides for a SCSI-port to connect SCSI devices like harddisks and a CD-Recorder and a coaxial ethernet connector to hook it up to a local network.
There were two different models of CD-i authoring players from Philips. The first model was the CDI 180/181/182 modular CD-i system (which was also the first CD-i system ever released). The CDI-182 Expansion Module added the authoring capabilities (the SCSI port, the ethernet port, a parallel port and 1 MB of extra RAM) to the generic system. Later, the CDI 605/00 replaced this system as an all-in-one authoring player. The CDI 605 contained 5 MB of RAM, ethernet, SCSI, parallel, extra serial ports and several diagnostic and emulation tools stored in ROM. Since both of these players could not be expanded with a Digital Video cartridge, a new version of the CDI 605 was released as CDI 605T/20 which provided space for a dedicated Digital Video extension board.
Refer to Philips professional and authoring CD-i players in the Complete CD-i Players Overview on this web site for a comparison.
7.4 What is a CD-i Emulator?
A CD-i Emulator is a piece of hardware that contains a large harddisk and control circuitry to provide a stream of audio, video and program data to a CD-i authoring player in exactly the same way as if it was being read from a CD. The Emulator takes care of interleaving the data, creating the sector format and providing the feed of data according to the specification as laid down in the Green Book. When a CD-i Disc Image is being created, it can be read by the Emulator and played through the CD-i authoring player for testing purposes. You need to either do this, or make a one-off on CD-R for testing, because you can't test CD-i's realtime behaviour at programming level (the audio, video and program data is not interleaved yet at that time). Since CD-R and dedicated WORM systems that could create CD-compatible discs (such as the Yamaha WORM system) were just beginning to appear when this CD-i authoring hardware became available (early 90s), and a blank disc costed around US$ 50 a piece, a CD-i Emulator was a very economical solution for studios.
Two versions of the Emulator were being sold by OptImage. Both of them contained at least a 1.2 GB harddisk (enough to keep all data of a disc in its original form and the required space for a full CD-i Disc Image). The Emulator was based on the same version of OS-9 that is used in CD-i players, and they contained 2 MB of memory. The first model was generally referred to as E1 (probably Edition 1), it runs on a 20 MHz 68020 and contained a floppy disk drive which was needed for a disk to boot the system up, and a lot of connectors at the back. The E2, which was released some years later and runs on a 24 MHz 68340, lacked the floppy disk drive since all required software was stored in ROM, and it had a more convenient way of connecting to the CD-i authoring player.
Both versions of the Emulator can also be used for the emulation of other CD-i compatible disc formats like Photo-CD and Video-CD. Some Video-CD studios were known to use a CD-i development player and an Emulator in their quality checks.
7.5 Do I need special hardware to make a CD-i title?
In theory: no. If you have the appropriate CD-i authoring software that runs on a PC (like the legacy Presentation CD or ShowBuilder products for 16-bit Windows, both available from the PC/Windows downloads page at this website), you can produce a CD-i title entirely without any additional hardware. Bear in mind however, that the results from these authoring tools are very linear and without much interactive features. Even if you had a tool that provided a way of creating a more complex CD-i title on a PC, you still wouldn't be able to test the behaviour of it on a CD-i player, since the tools did not provide for "emulation" of a CD-i title on the computer. A CD-R would need to be recorded at the various development stages, which could be inconvenient and expensive.
Almost all consumer and professional CD-i titles were created with either low level authoring tools on a PC, Macintosh, Sun or OS-9 system which was connected to a CD-i development player and emulator, or entirely on a CD-i development player using a high-level authoring tool like MediaMogul. Refer to What CD-i authoring tools were available? for more information about the available tools.
7.6 What is OptImage?
OptImage was the name of the largest company that sold CD-i authoring solutions in the form of hardware and software products and development support. It was set up by Philips, Microware (the creator of the OS-9 operating system used in CD-i) and Sun Microsystems (creator of high-end workstations that were used in CD-i development a lot) in the late 80s. They developed various tools, and from the early 90s Philips and Microware became the sole owners of the company. In 1995, OptImage became a wholly owned subsidiary of Philips Media, with Philips now owning 100% of the company.
OptImage created the tools with which nearly all CD-i titles were created. Although other companies created CD-i tools as well, none of them became as popular and widely used as OptImage's Balboa Runtime Libraries and MediaMogul.
Other companies that created CD-i authoring software besides OptImage were Multimedia Technology Center with their Windows-based CDMotion for CD-i and ViaCD-i authoring tools, and Script Systems with their ABCD-i package.
7.7 What CD-i authoring tools were available?
A wide variety of authoring tools were available from OptImage alone. The authoring software was divided into high-level and low-level tools. High-level meant that a whole lot of the technical aspects are being taken care of by the system, leaving the developer to only concentrate on the creative part of the development process, and low-level tools which required a lot more technical knowledge from the programmer but which allowed for a much wider variety of possibilities. Besides these tools, a lot of additional software was available, such as tools for converting PC audio and video formats into CD-i format.
Some of the best-known authoring tools are:
OptImage created the Balboa Runtime Libraries for programmers who use C. Balboa provides a lot of custom written parts of software for CD-i, such as routines for accessing CD-i's video and audio features, visual effects, and MPEG Digital Video. The libraries could be included in the final end product. Using a combination of a C compiler for OS-9 and the Balboa libraries, the most advanced CD-i titles (such as highly interactive and complicated games) could be created. Most of the consumer CD-i titles were made using Balboa.
MediaMogul was a high-level authoring tool that was especially designed with the non-programmer in mind. It runs entirely on an authoring CD-i player like the CDI 180 and the CDI 605, the only requirement for operation was the connection to a harddisk. No further additional hardware or software (besides some video or audio conversion utilities on the PC) were needed to make CD-i titles with MediaMogul. MediaMogul is based on a timeline which has rows for audio, video and program commands, so that the user can build the application using a very intuitive chronological interface. The software could be extended with an unlimited amount of plug-ins, which were available from OptImage as well as from other companies (of which Interactive Resources, Inc. of Iowa was the most well-known) to provide for such features as playing MPEG Digital Video, controlling other devices like printers or bar code readers, etcetera. Although MediaMogul does not allow for the same complexity as Balboa, excellent interactive titles could be produced with it. MediaMogul is especially useful for the creation of professional applications.
CDMotion from Multimedia Technology Center was positioned as a competing product against MediaMogul. It was entirely Windows-based. No special hardware was required, and all video, audio and image conversion tools were built-in. Some people claim it was much more powerful and easier to use than MediaMogul.
Besides the authoring tools, OptImage also produced some utilities that could be used in conjunction with the programming tools, such as the Image and Audio Conversion Utilities for Windows and Macintosh (available on the PC/Windows downloads page at this website), MediaStockroom (which replaced the conversion utilities as a all-in-one package) and the CD-i plugins for Adobe Photoshop.
7.8 Who distributed the CD-i authoring tools?
In the later CD-i era, most of the CD-i authoring tools from Philips and OptImage were sold and supported by Cambridge Multimedia Ltd. from the UK and Rise International from the US. Cambridge Multimediawas a Philips value added reseller of CD-i players and authoring tools for Europe. Apart from selling tools and players, Cambridge delivered various services such as disc labeling and reproduction. Rise International was a Philips value added reseller of CD-i players and authoring tools for the Americas. The Philips and OptImage authoring tools are no longer officially available nor supported.
7.9 What is the easiest way to make a CD-i title?
Several PC-based development tools were created that did not require dedicated CD-i authoring hardware. Some of them were never formally finalized, or updated to work on current versions of Windows.
One of the employees of Cambridge Multimedia, Robin Burrows, was working a Windows 95 application, MoguLike, that allowed for the creation of MediaMogul compatible scripts without the need for MediaMogul itself. A demo version of this program can still be downloaded at the PC/Windows downloads page at this website. Unfortunately, you still need Script2Disc, the software that is needed to build a CD-i Disc Image from a MediaMogul script. This software was never formally finalized.
Another simple way of producing a CD-i compatible title was by using the Presentation CD driver for Windows 3.x that can still be downloaded at the PC/Windows downloads page at this website. Presentation CD is in essence a (Windows 3.x) printer driver that allows you to 'print' to a CD-i disc image format. All 'pages' will be added in sequence and are combined with a CD-i application. The created file can then be burnt onto a CD using a CD-Recording tool. The resulting disc is playable on a CD-i player. The driver only supported up to 16 colors due to a limitation in the Windows 3.x printer driver system.
A more sophisticated way of creating a CD-i title using a Windows 95 system however was probably the ShowBuilder package from Philips, that can still be downloaded at the PC/Windows downloads page at this website. It allowed you to create CD-i presetions using stills, audio and even MPEG Digital Video directly on a PC. The scripts you provide on the disc can even be changed at runtime on the CD-i player, allowing the user to create their own presentations using the audio, stills and video on the disc. ShowBuilder did not provide for truly interactive features besides creating a slideshow and browsing through its contents.
Of course, you can also make a Video-CD title to play on a CD-i player. Video-CD creation tools are much more widely available than dedicated CD-i creation tools, and a true White Book Video-CD disc can always be played on a CD-i player provided that the required CD-i application is included on the disc. Refer to How can I make a Video-CD? for more information.
7.10 How can I write a CD-i Disc Image file?
In essence, a CD-i disc image can be written using any CD-Recording application that supports writing Mode 2 CD-ROM/XA sectors (which is the sector format that was originally developed for CD-i). However, several different Disc Image file formats exist in the CD-i development space, because some of them include header information for all of the disc's sectors, while others leave the creation of such headers up to the CD-R software. Another issue is whether the authoring tool produces a scrambled or unscrambled Disc Image format. This can result in the fact that a particular CD-R tool can write CD-i Disc Images from one authoring package, but not from the other.
One tool that was known to support most of the CD-i Disc Image formats is Gear from Gear Software, Inc.
You should use the following settings when writing a CD-i disc:
CDI 2352 bytes per sector - 2 sec pregap - scrambled
for Disc Images generated by Script2Disc from MediaMogul and ShowBuilder Disc Images
CDXA 2352 bytes per sector - 2 sec pregap - scrambled
for Disc Images generated by Video-CD Toolkit
7.11 How can I make a Video-CD?
Specific tools are available that let you create Video-CDs that can be played back on Video-CD compatible devices such a most DVD and Blu-ray Disc players, and on CD-i players. Some standard CD-Recording tools include a module to create Video-CDs. Early programs with this capability included Adaptec Easy CD Creator, CeQuadrat WinOnCD and Nero Burning Rom.
For CD-i playback, it is very important that the Video-CD includes a CD-i application. Although this is a mandatory requirement of the White Book that should be included by all Video-CDs, many tools let you create a Video-CD without a CD-i application.
Other things to bear in mind while developing a Video-CD are:
- Make sure to what version of the White Book your disc should comply. Do you want to include Video-CD 2.0 interactive features and if so: does your playback device or software (e.g. the CD-i application) support this added functionality?
- What version of the CD-i application is included? Does it support the functions you want it to, for example Video-CD 2.0 menus and playlists?
- Do you want to customize the CD-i application by providing scan entrypoint files, subtitling, menu screens, backgrounds, etcetera? Does the Video-CD creation tool support for the adaptation of the CD-i application?
A good tool to use for making full White Book compliant Video-CDs was Nero Burning Rom version 5.0 and up (available from Nero AG). Nero allowed you to create Video-CD 2.0 titles that can even include still pictures (see question How can I play my pictures on my CD-i player? for more info). Bundled with Nero 5 is version 4.1.1 of the Philips Video-CD on CD-i application, resulting in full Video-CD 2.0 compatibility on CD-i players. Later versions of Nero removed the video disc functionality and moved some of them over to a seperate Nero Video application. Video-CD related features are no longer available in this program.
For more information about the various versions of the White Book Video-CD standard, the various CD-i applications, its versions, the customizations of the application and all other questions related to Video-CD on CD-i, please refer to section 6 of this FAQ: Video-CD on CD-i.
7.12 How can I make a Photo-CD?
The Photo-CD specification was proprietary to Philips and Kodak. The system was set up to provide extra sales opportunities for Kodak photo finishers, and not as a format to create at home. Partly because of contractual difficulties in obtaining a license for Photo-CD, most CD-Recording tools do not let you create a true Photo-CD that can be played on Photo-CD players and CD-i players. Especially the disc's image file format is heavily patented. This is why some tools let you place images in Photo-CD's codec format (Photo-YCC) on a CD-R, but they do not make these discs compatible with the Photo-CD standard (see Will CD-i play Picture-CD? in section 5 of this FAQ).
Kodak sold a CD-Recording application to create Photo-CDs, called Kodak Arange-it!. Note that the later, JPEG-based, Kodak Picture-CD format is not compatible with Photo-CD players nor CD-i players.
7.13 How can I play my pictures on my CD-i player?
As you can read in question 7.12, it is nearly impossible for the home user to make Photo-CDs. As an alternative, and using the appropriate software tools, you can create Video-CD 2.0 discs with still pictures, playable on a CD-i player. Using for example Nero Burning Rom version 5.0 and up, you could include still images in a Video-CD compilation. Video-CDs created with this software included the Philips Video-CD on CD-i 4.1.1 application. Later versions of Nero removed the video disc functionality and moved some of them over to a seperate Nero Video application. Video-CD related features are no longer available in this program.
In Nero 5.0, drag your JPG-files to the Video-CD section on the disc and they will be converted to MPEG stills. From version 5.5 onwards, Nero will include an index screen with thumbnails of all pictures that can be selected on the disc. The MPEG still pictures are encoded in high TV resolution (as long as the source pictures are in a high resolution), but they will be shown in a lower resolution when viewing the disc on a CD-i player. The pictures can then still be viewed in a higher resolution on for example DVD players that support Video-CD 2.0. Note that the CD-i player needs to be equipped with a Digital Video cartridge to view the MPEG stills, even though the disc might not contain moving video.
CeQuadrat/Roxio WinOnCD 3.7 and up offered similar functionality called the 'Photobook' feature, but although the program claims to make a Video-CD compliant disc, it does not include a CD-i application capable of showing these Video-CD 2.0 enhanced pictures.
Remember that in contrast to making a Photo-CD, placing pictures on a Video-CD is not a good solution for storing your archives of pictures. A Photo-CD contains pictures in a very high resolution (over 3000 x 2000 pixels) allowing you to make perfect prints of them, a Video-CD only stores the pictures in TV resolution. Always preserve the original files!
7.14 How can I make a CD+Graphics?
To create a CD+G (CD+Graphics) disc, you may use a dedicated CD+G authoring tool, such as CD+G Creator Pro or Power CD+G Burner. The functionality and options that are offered to be included on a disc (multiple language channels, color looping animations, etc.) vary between the various programs. Please note that you need a CD-Recorder capable of writing subcode to record CD+G data. Most, but not all, modern CD-recorders can do this.