This paper was written in January 1996 by Gary Hoffman

IEEE 1394, the A/V Digital Interface of Choice

IEEE 1394 is an international standard, low-cost digital interface that will integrate entertainment, communication, and computing electronics into consumer multimedia. Originated by Apple Computer as a desktop LAN and developed by the IEEE 1394 working group, IEEE 1394 is:

Serial Bus Management provides overall configuration control of the serial bus in the form of optimizing arbitration timing, guarantee of adequate electrical power for all devices on the bus, assignment of which IEEE 1394 device is the cycle master, assignment of isochronous channel ID, and notification of errors. Bus management is built upon IEEE 1212 standard register architecture.

There are two types of IEEE 1394 data transfer: asynchronous and isochronous. Asynchronous transport is the traditional computer memory-mapped, load and store interface. Data requests are sent to a specific address and an acknowledgment is returned.

In addition to an architecture that scales with silicon technology, IEEE 1394 features a unique isochronous data channel interface. Isochronous data channels provide guaranteed data transport at a pre-determined rate. This is especially important for time-critical multimedia data where just-in-time delivery eliminates the need for costly buffering.

Much like LANs and WANs, IEEE 1394 is defined by the high level application interfaces that use it, not a single physical implementation. Therefore as new silicon technologies allow high higher speeds, longer distances, and alternate media, IEEE 1394 will scale to enable new applications.

Perhaps most important for use as the digital interface for consumer electronics is that IEEE 1394 is a peer-to-peer interface. This allows not only dubbing from one camcorder to another without a computer, but allows multiple computers to share a given camcorder without any special support in the camcorders or computers.

All of these features of IEEE 1394 are key reasons why it has become the A/V Digital Interface of Choice.

IEEE 1394 in the Industry

Initially, IEEE 1394 will be the computer attachment of digital cameras and digital video applications. IEEE 1394 is the lowest-cost digital interface available for audio/video applications. New audio/video applications such as digital television, Multimedia CDROM (MMCD), and home networks are the first market for IEEE 1394.

IEEE 1394 has been accepted as the standard digital interface by the Digital VCR Conference (DVC). This standard has been proposed to the IEC to publish as an international standard. The EIA 4.1 subcommittee has voted for IEEE 1394 as the point-to-point interface for digital TV as well as the multi-point interface for entertainment systems. The European Digital Video Broadcasters (DVB) have endorsed IEEE 1394 as their digital television interface as well. Several of these companies have proposed IEEE 1394 to the VESA (Video Experts Standards Association) for the digital home network media of choice.

From a video editing point of view, IEEE 1394 enabled cameras removes the need for costly analog video computer frame buffers to capture digital video. The video is converted to its digital form when captured at the camera. DVC Camcorders not only delivers Beta SP quality at a fraction of the camera cost, but professional computer interfaces at the price of a 100Mb Ethernet adapter.

Later, IEEE 1394 will gradually have application opportunities to improve upon existing interfaces such as SCSI. IEEE 1394 offers higher speed, lower cost, and is more user friendly than most existing interfaces. SCSI products such as scanners, CD-ROMs, disk drives, and printers are examples of devices that would be enhanced by migrating to IEEE 1394.

The 1394 Trade Association also is working with other standards groups and electronics associations as IEEE 1394 becomes useful for them. The American National Standards Institute (ANSI) has defined Serial Bus Protocol (SBP) to encapsulate SCSI-3 for IEEE 1394. Several TA companies have proposed IEEE 1394 to the VESA Home Network working group as the preferred digital home network medium.

In the 1394 Trade Association and the IEEE 1394.1 study group many new extensions to IEEE 1394 are being mapped out. Extensions include:

Note: since the writing of this paper, the 1394 Trade Association has separated these extensions into individual study groups. For example,

  • IEEE 1394.1 is the supplement to 1394
  • IEEE 1394.2 is the gigabit extension
  • IEEE 1394.3 is the definition of bus bridges
  • Supporters

    Sony has launched the IEEE 1394 serial bus as the digital A/V bus with the introduction of their DCR-VX1000 and DCR-VX700 digital camcorders. In the six months since their introduction, they have taken the prosumer video world by storm. Sony is also expected to ship high volume DS-250 desktop cameras in 1996. The DS-250 gets data, command and control, and power over the single IEEE 1394 computer cable.

    Texas Instruments has announced IEEE 1394 chips for applications from cameras to host computer interfaces and from printers to notebook computers. TI is expected to release a notebook computer with IEEE 1394 on the motherboard in 1996.

    Molex has been shipping the first cables, connectors, and headers for use in products. Molex has played a key role by insuring that the entire mechanical and electrical designs are included in the IEEE standard. This allows all connector makers to bring totally compliant second-source products to market faster.

    Microsoft Corp. announced support of the IEEE 1394 serial bus interface standard in future releases of the Microsoft® Windows® family of operating systems. IEEE 1394 enables high-performance multimedia connections and control of business and consumer electronic devices such as camcorders, televisions, stereos, CD changers, set-top boxes, mixing consoles and music keyboards, as well as traditional PC devices such as hard drives, CD-ROM drives, printers and scanners, and docking stations for portable computers.

    In addition, Microsoft and Sony Electronics Inc. have signed a letter of intent to develop open device driver interfaces (DDIs), APIs and an open host controller interface for IEEE 1394. Microsoft has also signed a letter of intent with Compaq Computer Corp. to accelerate adoption of the IEEE 1394 high-speed serial interface as a standard in the PC industry. This includes defining an open host controller interface specification. Both of these efforts will be undertaken in cooperation with the 1394 Trade Association.

    Apple Computer has been OEMing IEEE 1394 link and PHY chip designs since 1994. Licensees include TI, Sony, Fujifilm, Symbios, and Adaptec. Howard Lee, Apple's Development VP, has stated that Apple will support IEEE 1394 via PCI adapters at the end of 1996 and will support IEEE 1394 on motherboards by the end of 1997.

    Sun Microsystems announced that it will support the IEEE 1394 serial bus interface standard, stating that IEEE 1394 is the most advanced, open standard for connecting computers with traditional computer peripherals as well as with consumer electronics products. Sun explained how excited its engineering staff had become with the ability of IEEE 1394 to accelerate the pace of digital "convergence" and add multimedia and image-intensive features to home and business systems. Sun is working with Apple, other members of the 1394 Trade Association, and the 1394.1 Study Group to define multi-gigabit IEEE 1394 implementations.

    Other recent announcements of support have come from Intel, IBM, SGS Thompson, and Compaq. Yamaha has proposed that IEEE 1394 could be the future of MIDI and digital audio. IEEE 1394 would be able to carry both MIDI command and control data as well as 32 channel digital audio on a single cable. Conner Peripherals announced at the January 1996 1394 Trade Association General Session that they would be developing disk drives for IEEE 1394. Conner is proposing to develop isochronous drives for A/V applications as well as traditional async SCSI drives.

    Skipstone, Inc. has been shipping developers toolkits since early 1995. These toolkits include PCI 100Mb mastering adapters and the Skipstone portable API for Windows and Mac. Skipstone will be shipping high volume, low cost 200Mb mastering adapters in mid-1996 with software to support the Sony digital camcorders and desktop cameras. Totally focused on IEEE 1394, Skipstone offers a roadmap of capability and performance for IEEE 1394 audio and video computer solutions.

    BTC will sample a digital video camera using the IEEE 1394 serial bus, with mass production planned for the fourth quarter of 1996. BTC is one of Taiwan's major keyboard producers.

    IEEE 1394 Future

    Based on the initial success of the Sony camcorders, other A/V products are expected to be introduced in 1996 and 1997. These introductions may include: DVD for television using the DVC HD format (MPEG2), DVD as a CDROM, desktop cameras, and color printers.

    ATM (Asynchronous Transfer Mode) and IEEE 1394 will drive each other's markets. ATM will become the world-wide voice/video/data public switched networks. However, ATM is too expensive for devices such as disk drives, cameras, and desktop computers. Therefore IEEE 1394 is a complementary interface as the device interface for ATM.

    Built firmly on a base of low cost implementations IEEE 1394 will become a high volume consumer electronics interface. Consumer electronics interfaces tend to be very long lived, plain old telephone (POTS) as we know it is over 100 years old, and audio/video coax interfaces date from World War II. Therefore with ability to span media and maintain software compatibility, IEEE 1394 should enjoy a very long life. If ATM, the next telephone system, lasts at least 100 years then IEEE 1394 will be there with it.

    Such a high volume interface that is fundamentally available to computers will enable many new applications. Not only will A/V data be available for computers to manipulate, but a use friendly command and control interface will span home, vehicle, office, and factory products. Barriers that exist will gradually be shattered by growth of IEEE 1394 roots.

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