Physical CableCARDs
The physical CableCARD that is inserted into the host device is a PCMCIA type II card which handles decryption of video, and making sure that only people that have paid for the channel may view it. This is also known as "conditional access module" function.
There are two kinds of physical CableCARDs:
- A "Single-stream" CableCARD (S-CARD) can decode a single channel at a time. The S-CARD specification was initially specified in the Host-POD Interface (SCTE 28) and POD Copy Protection System (SCTE 41) standards (often referred to as CableCARD 1.0) set of specifications.
- A "Multi-Stream" CableCARD (M-Card) can decode up to six channels simultaneously. Multi-Stream cards were specified in a separate document in 2003.
No actual M-Cards were released before CableCARD 2.0 was released which combined and enhanced the CableCARD 1.0 and Multi-Stream standards. M-Cards are backward compatible with current CableCARD devices. To older CableCARD devices that do not support multiple streams, the card appears to be a single stream card. CE companies have long wanted M-Cards for their CableCARD 1.0 host devices in order to compete with Cable company devices that use multiple tuners. This is important for products such as Moxi & TiVo CableCARD DVRs, televisions with picture-in-picture and CableCARD-equipped personal computers, which need to be able to record one show while the user is watching another. To enable this without an M-Card, these products would be required to use multiple S-CARDs.
A common misconception is that there is a CableCARD 2.0 physical card that will provide two way services which is not compatible with a UDCP (one-way) certified devices. This is not the case. OpenCable Host Devices (two-way) are able to use either S-CARDs or M-Cards. And older UDCP certified devices can also use either card (but unless they are M-UDCP won't be able to take advantage of multiple streams).
Interactive features such as Video on Demand rely on the CableCARD Host device being an OpenCable Host Device and have nothing to do with the physical card. This makes the common use of the phrase "CableCARD 2.0" as a requirement for video on demand misleading, since two way services have been provided with the actual cards from the very beginning.
Read more about this topic: CableCARD
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