IDB-1394 and SmartCODEC enable in-vehicle video entertainment and information systems

A basic outline of these systems as envisioned by Nissan Corporation in its prototype in vehicle network is shown in Figure 1, which illustrates the network using the IDB-1394 standard. By providing bandwidth of up to 400 Megabits/second, IDB-1394 can meet the video and audio demands of the multimedia network.

Figure 1: network diagram from Molex

IDB-1394 is a network protocol that enables bandwidth required for these multimedia applications in the vehicle. The IEEE standard 1394b-2002 defines an extension from 100 Megabits/second to 400 Megabits/second for the physical layer, along with the ability to connect different system nodes at distances up to 100 meters without the need for repeaters. With almost 400 Mbps available, the network is capable of connecting numerous communication channels on a single wire harness, serving DVD players, PCs, handheld products, and related peripherals. IDB-1394 also allows multiplexed transmission of audio and image contents, which can be divided and transmitted simultaneously on different logical channels.

Concerning temporal options, the IDB-1394 protocol provides different types of transmission packet with isochronous (real-time) channels available to guarantee a defined bandwidth and latency for the payload; and asynchronous channels, which typically are used to move user commands. Video and its associated audio content are routed through isochronous channels along with any audio signals synchronized to the image data at the receiving node.

Any type of channel carries transport streams (TS) which can be in the form of raw or encoded data. (Encoding and decoding functions are not incorporated as part of the IDB-1394 standard; see below for the solution). Host processors are not required, as they almost always are with other standards such as USB. In IDB-1394, streaming enables a protocol handler independent of a host processor.

The network has a ring structure. Disconnecting any but one branch within the network will not lead to a system failure. Nor will it lead to any other sort of video delivery degradation. Thus, a reliable level of system availability is obtained as an intrinsic feature of the IDB-1394 network. In the demonstration network two DVD-streams coded as MPEG2-TS are fed into the network. They are available at any time for any receiving node, allowing random selection by a rear seat passenger.

The IDB-1394 controller
In order to implement the in-vehicle network, a specialized standards-based controller is required. Fujitsu has developed an IDB-1394 controller, designated the MB88387, which has been specifically designed for these rear-seat entertainment systems. It is a single chip solution that comprises physical layer and data link layer. It supports Audio/Video protocol processing including Digital Transmission Copy Protection (DTCP), which has been developed by industry leaders such as Sony, Intel and Hitachi industry, among others, to pre-empt illegal copying of copyrighted content.

The functions of the MB88387 IDB-controller are shown in the block diagram in Figure 2. Three different paths for the transmission and reception of payload data and commands are available. The arrow at the bottom of the diagram, identified as MPEG2-TS, illustrates the path of the video data transport stream (TS). It is typically encoded as MPEG2. The device provides two TS-interfaces for routing data through the DTCP unit towards the local application. From there forward, two bridges connect to the link layer implementation of the IDB-controller. Finally, the transport stream is routed to the double-port physical layer implementation.

Figure 2: MB88387 controller block

These 1394b-compliant ports drive the lines to the next node. They support bus speeds compliant with the various physical layer specifications of the 1394 standard, including S100, S200, and S400 physical layer specifications. The block named 'PHY/LINK layer control' ensures that the complete IDB-1394 data stream is copied in full duplex between both ports.

Networks based on the IDB-1394 standard require only a simple ring structure for the wire harness wiring. Other protocols generally require point-to-point connections or even separate routing for command transfer and analog audio. The versatility of IDB-1394 effectively renders these supplemental bus systems obsolete by the IDB-1394 specification.

Next: Using the IDB-1394 controller