Building the New In-Vehicle Entertainment Network

Contributed by:
Akio Nezu
Fujitsu Microelectronics America, Inc.

It doesn’t take much imagination any more to envision a whole new entertainment network in a car, truck or SUV. In fact, automakers intent on presenting consumers with the newest and most innovative A/V features are working now on rear seat and passenger side networks that will bring multimedia throughout the vehicle.

But multiple videos require plenty of bandwidth, and high quality and reliability are crucial to optimize the media experience for the user. So the first step in getting these networks into place is standardization, a baseline protocol that automakers and their OEMs can work with in their product development. The 1394 Automotive network protocol provides the bandwidth required for these in-vehicle multimedia applications.

There are several advantages of using the IEEE 1394 technology for vehicle infotainment applications. The standard provides a minimum bit rate of 400 Megabits/second; that's higher than any alternative standard such as Ethernet or MOST – the Media Oriented Systems Transport. In addition, the technology is in place to move 1394 to 800 Megabits/second, making it scalable and versatile, and preserving the value of 1394-equipped product investment as speed and bandwidth increase that is also fully compatible with 400 Megabits/second products.

Also, the 1394 standard is supported by a robust community of developers and by a strong group of third party software developers. Many 1394 supporting partners are available, with support from virtually every operating system. And because 1394 can be configured as a multiplexing network, multiple video and audio streams can be transmitted simultaneously over the same physical layer. As a result, the vehicle network can carry complex information over a single cable, reducing wiring-harness complexity and weight.

With 400 Mbps now available for audio and video transmission over either copper or plastic fiber around the car, truck or SUV, the network can link multiple communication channels on one wire harness. The 1394 standard enables many audio streams of compact disc audio along with multiple streams of DVD.

Closed area implementation may vary, and may be different for consumer application cases, but the network could easily include DVD players, PCs, handheld products, games and other peripherals -- and 1394 allows multiplexed transmission of audio and image content, that are divided and transmitted simultaneously on different channels.

This is achieved using either isochronous (real-time) channels, which are available to guarantee a defined bandwidth and a specific latency for the payload, or with asynchronous channels, which usually are set up to move user commands. Video and associated audio content move through isochronous channels along with any audio signals synchronized to the image data at the receiving end to the rear seat entertainment application.

At Fujitsu we decided to develop the 1394-compliant controller series, which has been designed as a single chip solution with both physical and data link layers in one sliver of silicon, just for these rear-seat entertainment systems, for example. The newest member of this family is the MB88388A, a controller that supports newly defined BT.601 compressed video on 1394 protocol supported by the 1394 Trade Association. The controller complies with the Digital Transmission Copy Protection (DTCP), which has been developed to pre-empt illegal copying. This is an important benefit that assures support from content providers who want to protect copyrights. In addition, Fujitsu's BT.601 video interface and I2S interface includes streaming capability. Fujitsu's 1394-compliant controller significantly reduces the host processor's overhead. That means system design can deliver a very efficient video and audio network system without the huge cost of the host processor, or an existing host processor to handle 1394 controller with minimum overhead. Major automotive manufacturers are beginning to put the system into place now.

The MB88388A is the industry’s first device to support very high data rate vehicle navigation imaging using the 1394 automotive standard. It implements the Fujitsu proprietary SmartCODEC, a video codec specified under the 1394 international standard for in-vehicle video transmission. SmartCODEC, which was developed by Fujitsu Laboratories Ltd., can transmit compressed digital video without perceptible latencies. It is specially designed to be sure that there are no multiple video stream bottlenecks in the 1394-based system.

SmartCODEC can be implemented in the form of a controller that's capable of transmitting DVD-Video, digital TV, and navigation images without any external MPEG encoders and decoders. It does not require any special equipment, but digital video interface that the raw data in the form of YUV digital signals and RGB digital signals is compressed by a new, faster codec algorithm that compresses the raw data to one-third of its original size in 2 to 3 milliseconds.  The SmartCODEC algorithm also has been designed to meet real time demands while opening opportunities for conventional systems that support simple video interfaces, as well as increasing requirements of in-vehicle camera systems.

Briefly, here is how the ideal 1394-automotive device should function, as we see it. There should be three different paths for transmission and reception of payload data and commands, with BT.601 interface for video and I2S interface for audio that route data through the DTCP unit towards the local application. From there, two bridges connect to the link layer implementation of the 1394 controller. The transport stream moves to the double-port physical layer implementation. These ports drive the lines to the next node, while supporting bus speeds that match the various physical layer specifications of the 1394 standard, up to 400 Megabits/second in the physical layer. A 'PHY/LINK layer control' block ensures that the complete 1394 data stream is copied in full duplex between both ports.

Networks based on the IDB-1394 standard can be used in ring, bus, or tree structures for the wire harness wiring, instead of numerous point-to-point connections or separate routing for command transfer and analog audio. That’s one reason why 1394 is so efficient for these implementations. Another is the extensive bandwidth that’s enhanced by Fujitsu's SmartCODEC technology provided -- typical bandwidth allocations in the rear seat entertainment supported by the Fujitsu controllers require only approximately 25 percent of the available single isochronous channel bandwidth of an S400 class 1394-Automotive network. So there’s plenty left to add multiple video images onto the network, or to add PCs, storage peripherals, or handhelds.

For a more complete look at the Fujitsu 1394-compliant controller technology visit this link: http://www.fujitsu.com/us/services/edevices/microelectronics/idb1394/