Specifications
CD-i FAQ 2000 Edition Revised February 21, 2001
Latest version and more CD-i info: http://www.icdia.org
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motion video can be played back. To achieve this, the cartridge is equiped with MPEG audio and
video decoding ICs, and an additional 1.5 MB of system RAM. This extra memory may also be
used to improve the perfomance of certain titles, for example by using it to store images that do
not need to be reloaded from the disc each time.
Although the Digital Video cartridge is in essence not a part of the Base Case CD-i specification,
it is the most important extension for the CD-i system that was ever introduced. The full motion
video extension is extensively specified as an optional extension from the March 1993 version
onwards of the Green Book. Roughly 75% of all CD-i titles require the cartridge to be installed.
Please note that a title should be made specifically for the Digital Video cartridge to use its
features, standard Base Case CD-i titles do not look any different, nor will the quality of audio and
video be improved, when a cartridge is installed in the player.
4.7.1 Is there a difference between the various Digital Video cartridges?
There were two models of the Digital Video cartridge available: the larger 22ER9141, and the
slightly smaller 22ER9956. The first model was used in the first batch of players (CDI 910, CDI
205, first versions of CDI 210, first versions of CDI 220 and the portable players CDI 310, CDI
350 and CDI 360), the second one is used in all other players. The new cartridge was introduced
in late 1994, to allow for a smaller design of a CD-i player (the CDI 450). By then it was possible
to reduce the size of the cartridge because of large scale integration of the various components.
In technical terms there is a small difference: the 22ER9141 delivers its video signal in an
analogue way into the player, the 22ER9956 produces a digital signal that is parsed to the
players internal DACs. In terms of performance there is absolutely no difference, all CD-i Digital
Video titles look exaclty the same with both cartridges.
Due to problems with of decoding MPEG video that was not 100% according to the specifications
using the first batch of 22ER9141 cartridges (errors in decoding, displaying of green "ghost
sprites" on screen), a second version with a different decoding IC which was more tolerant was
introduced slighly after. This new cartridge had /20 added to the type number indication, see
Overview of Digital Video cartridges at www.icdia.org for more information about all available
cartridges and compatibility issues. To check which cartridge should be used in a particular
player, please refer to the Comparison table of all Philips CD-i players at www.icdia.org.
4.7.2 Is the extra RAM used by non-DV titles?
Every Digital Video incorporates an additional 1.5 MB of RAM. This memory consists of 1 MB of
standard RAM, and 512 KB of decoding RAM for buffering data when decoding MPEG audio and
video. All of this memory can be used by a CD-i application to improve performace. For example,
a title can store data in RAM that does not to be reloaded from the disc each time. But since a
Base Case CD-i title must work on every CD-i player, even if no Digital Video cartridge is
available, the software must not depend on this extra RAM.
The best example of the usage of this extra RAM is the Photo-CD on CD-i application. When you
select the thumbnail overview of a Photo-CD disc, all of the thumbnails that are generated from
the pictures on the disc are stored in RAM. The more RAM that is available, the more thumbnails
that can be stored without reading the pictures from the disc again. So, Photo-CDs benefit in this
way from the Digital Video cartrigde. Besides this, I know of only one "Base Case" CD-i title (the
game Christmas Crisis) that uses the extra RAM to load soundmaps (audio effects). These
sounds can not be heared when no Digital Video cartridge is installed.
4.8 How much NV-RAM storage space does a CD-i player have?
According to the Green Book, every CD-i player should at least provide some way to store at
least 8 KB of data. In most players, this storage space is implemented as battery-powered NV-
RAM (Non-volatile Random Access Memory). The data is kept in this memory when the player is