CONSUMER APPLICATIONS OF THE IEEE 1394 SERIAL BUS,
`AND A 1394/DV VIDEO EDITING SYSTEM
`
`Alan T. Wetzel, Michael R. Schell*
`
`Texas Instruments, Inc., Dallas, Tx.
`*Interactive Images, Inc., Colorado Springs, Co.
`
`Copyright 1996 by The Institute of Electrical and Electronic Engineers, Inc.
`
`Reprinted by permission of the IEEE.
`
`This paper was prepared for and presented at the International Conference on Consumer
`Electronics held in Chicago, Ill., June 1996, conference session WPM-6, Intelligent Home
`Networks.
`
`Page 1 of 12
`
`HTC EXHIBIT 1035
`HTC America, Inc. v. Virginia Innovation Sciences, Inc.
`IPR2017-00874
`
`

`

`CONSUMER APPLICATIONS OF THE IEEE 1394 SERIAL BUS,
`AND A 1394/DV VIDEO EDITING SYSTEM
`
`Alan T. Wetzel, Michael R. Schell*
`
`Texas Instrmnents, Inc., Dallas, Tx.
`*Interactive Images, Inc., Colorado Springs, Co.
`
`ABSTRACT
`
`The IEEE 1394-1995 High Performance
`Serial Bus [1] has been created with
`consumer use in mind. Some of the more
`important features of the base standard
`are
`reviewed.· Enhancements
`and
`additions to the standard to support new
`consumer applications, such as MPEG-2
`transport and the new Digital Video (DV)
`tape format, are described. Consumer DV
`products incorporating 1394 are now on
`the market, more have been announced,
`and related developments portend even
`more in the future. The HD-DVC "DV'' 1_2]
`system has
`features which
`have
`significant advantages for video editing
`systems. The 1394 interface used by DV
`equipment brings many benefits to a
`video editing system. A PC based
`nonlinear video
`editing
`system
`is
`described, which takes advantage of the
`combination of DV and 1394 features in a
`high
`performance,
`low
`cost
`implementation.
`
`WHY CONSUMERS WILL BE WINNERS
`WITH 1394
`
`quality
`digital
`Superior
`performance at low cost
`
`and
`
`The most obvious benefit seen by consumers
`in the shift to digital technologies is the
`improvement in quality. This has been true
`for some time with audio CDs, as well as the
`
`newer DBS systems. This is now becoming
`true again with the new HD-DVC "DV"
`tape systems. The digital
`( digital video)
`recording and playback, combined with the
`digital 1394 interface, completely eliminates
`the noise pick-up and signal losses that occur
`in analog systems and interconnects. The
`digital
`record/playback avoids
`the audio
`flutter and video picture jitter that is common
`in present analog systems. The 1394/DV
`combination also provides for virtually lossless
`audio'video editing and dubbing. This
`recognition of the superior quality of the all(cid:173)
`digital
`systems
`has
`resulted
`in
`an
`unprecedented demand for products.
`
`The 1394 serial bus interface is designed to
`support these digital devices, both from the
`user experience and feature/ cost points of
`view. The 1394 interface has been completely
`implemented in generic digital ASIC CMOS
`integration
`processes. Multiple
`silicon
`possibilities
`exist,
`from
`today's
`first
`generation, multi-chip architectures, to single(cid:173)
`integration (zero additional
`chips, to full
`chips) into other ASIC chips. Full ASIC
`integration is a key benefit to reducing circuit
`board space requirements in space critiral
`applications. As the silicon processes evolve to
`smaller feature sizes, the area required to
`implement the 1394 logic will also decrease.
`
`Hassle-free hook-up
`
`The first, and perhaps only, 1394 item that a
`consumer is likely to encounter is the plug and
`cable. A user-friendly connector and cabling
`system is fundamental to 1394. The cable
`
`Page 2 of 12
`
`

`

`and durable
`small
`feature
`assemblies
`oonnectors. The plugs and sockets are
`designed for ease of use. The shape of the
`oonnector nose and socket opening provide
`unambiguous
`tactile
`feedback,
`which
`facilitates frustration-free blind insertion. A
`very flexible cable,
`less than %.
`inch in
`diameter, is standard This system has been
`evolved from the child-proof oonnectors used
`by the Ninetendo Game Boy.
`
`The seoond thing that a oonsumer is likely to
`notice about the 1394 interoonnect system is
`the freedom from oonnection oonstraints.
`Because 1394 is a bus, with all devices
`sharing the same transmission domain, it is
`irrelevant as to which way the different pieces
`of equipment are oonnected together. Because
`all the digital signals for a particular piece of
`equipment can be carried on the same 1394
`cable, only one oonnection is required for any
`unit. There is no in-out or up-down direction
`sense in 1394, so the oonnectors at each end of
`the cable will generally be the same. And it
`makes no difference which socket is used on a
`particular device,
`since
`they are
`all
`equivalent.
`
`One of the many things the oonsumer will
`probably not notice
`is
`the automatic
`oonfiguration and management that is built in
`to 1394. The user does not have to set any
`oonfiguration switches because the node IDs
`are assigned automatically during 1394 bus
`initialization. And no special device needs to
`be provided or designated as a central
`oontroller or bus manager.
`
`CONSUMER ORIENTED FEATURES OF
`THE IEEE 1394 SYSTEM
`
`The 1394 connector and cabling
`system
`
`systems are
`Two oonnector and cable
`presently defined The original 6-pin/6-
`oonductor style oontains two shielded twisted
`pairs for data, plus another pair for optional
`power and ground The 6-pin system uses a
`
`detent or optional latching retention system.
`A newer and smaller 4-pin/ 4-oonductor system
`was developed for use on digital camoorders
`and other size sensitive applications. It has
`the two twisted pairs for data signaling, but
`eliminates the optional power and ground
`pair. Both cables have overall shielding. The
`oonnectors for the two cable systems are
`shown in Fig 1.
`
`Fig 1: The 1394 connectors
`
`Unconstrained interconnect
`
`The topology of a 1394 bus may be a simple
`daisy-chain, a tree, a star, or a oombination of
`these. The 1394 standard indicates that the
`most widely separated devices should have no
`more than 16 cable hops between them, but in
`reality the generous margins designed in to
`the 1394 system ensures that nothing breaks
`even if this limit is exceeded
`
`Automatic configuration
`
`During initialization, each device on the 1394
`bus takes a turn to announce its oonfiguration
`and capabilities, and acquires a unique node
`ID. This process of bus enumeration and
`device ID assignments is handled oompletely
`automatically, and provides support for Plug(cid:173)
`and-Play oompatibility.
`
`All 1394 devices have the capability of being
`the root, which is a simple function to resolve
`
`Page 3 of 12
`
`

`

`bus arbitration requests and grants. This
`means that no special device must be included
`to initialize or manage the operation of any
`1394 bus. This is a significant difference from
`some other busses which require a central
`processor
`running
`dedicated
`real-time
`processes for management and control. In a
`similar
`fashion,
`any
`isochronous-capable
`consumer device
`is able to function as the
`cycle master, which regulates the isochronous
`cycles.
`
`The distributed intelligence that handles the
`initial configuration and root arbitration
`functions is contained entirely within the 1394
`physical layer. This allows a device to be an
`active member of a bus even if its higher layer
`(link and above) functions are not active. By
`eliminating the need for higher layer activity
`the process is much faster, and power saving
`strategies
`can
`be
`realized
`The
`implementation of
`these physical
`layer
`functions is purposefully
`simple enough to
`allow it to be built as a small state machine.
`Hardware implementation also contributes to
`the speed of configuration. Because most of
`the 1394 functionality is implemented in
`silicon, the cost for 1394 will continue to drop
`as die size scales down with smaller process
`sizes.
`
`Isochronous "real-time" channels
`
`Besides scaling the 1394 implementation costs
`with each successive generation of silicon
`processes, the 1394 system provides a special
`feature to minimize the system complexity
`and costs. This feature is isochronous data
`transport.
`
`The 1394 Serial Bus provides two distinct
`modes of operation,
`asynchronous and
`isochronous. The bus alternates between
`these
`two modes
`of operation, with
`isochronous operation taking precedence over
`asynchronous corrnnunication.
`Isochronous
`operation occurs at a cycle rate of 8,000 times
`per second
`
`Under normal circumstances the isochronous
`operation may take up to 80% (100 µsec) of
`the available cycle time, reserving at least
`20%
`for
`asynchronous
`traffic.
`The
`asynchronous data delivery and verification is
`assured by an acknowledge and retry protocol,
`and is normally used for control, status, and
`accuracy-critical data.
`
`Isochronous data delivery is a 'just in time"
`type of service. Data is broadcast on assigned
`channels with guaranteed bandwidth or time
`allocations. Delivery of preallocated real time
`data packets, at a uniform rate, is built into
`the 1394 protocol.
`
`isochronous channels may be
`Up to 64
`allocated on the 1394 Serial Bus. All allocated
`channels can send their data during each
`isochronous cycle. Only one device may
`transmit data on a given channel, but any
`number of devices may listen to a particular
`channel.
`
`A major advantage of isochronous transport is
`that a much smaller FIFO is required for
`buffering the video and audio data before and
`after transmission across
`the 1394 bus.
`Because the bandwidth and latency are
`guaranteed, the 1394 interface silicon can use
`a minimally-sized FIFO memory, which
`reduces the die size and the ultimate product
`cost
`to
`the consumer. Non-isochronous
`transport systems require significantly larger
`FIFO memories to accorrnnodate the wide
`swings in data-rates or transport delays.
`
`ENHANCEMENTS AND EXTENSIONS
`TO IEEE 1394
`
`MPEG-2 transport
`
`ISO/IEC
`The MPEG-2 System standard,
`that
`the
`13818-1, Part 1
`[3] assumes
`transmission system for transporting packets
`has a constant delay characteristic. The
`maximum deviation or jitter allowed is 500
`limit
`is a
`significant
`nanoseconds. This
`
`Page 4 of 12
`
`

`

`to any shared a~ss system,
`challenge
`including 1394.
`
`to
`Two primary factors may contribute
`variations
`in delivery delay of 1394
`isochronous packets: 1) Delays in starting an
`isochronous cycle, and, 2) Changes in the
`order
`in which channels
`(packets) are
`transmitted Cycle start delays can be caused
`by an asynchronous transaction being active
`at the time when cycle start should occur.
`With a maximum sized asynchronous packet
`this
`delay
`can be
`approximately 7 5
`microseoonds. The ordering of isochronous
`channels in any particular cycle is unlikely to
`change unless there is a change in bus
`oonfiguration, or in bus utilization. The worst
`case would be for a channel's packet to move
`between the beginning and end of the 100
`microseoond
`transmission window of the
`isochronous cycle.
`
`jitter
`this MPEG-2
`to meet
`In order
`requirement, a technique was developed that
`allows cancellation of almost all of the 1394
`induced packet delivery jitter. This technique
`takes advantage of the fact that all nodes
`participating in isochronous traffic share a
`oonnnon time reference. The cycle start
`packets that signal the beginning of an
`isochronous cycle also include the current
`value of the master clock. This clock is based
`on the basic 1394 reference frequency of
`24.576 MHz.
`
`When an MPEG-2 transport packet is received
`by a 1394 device, the current 1394 system
`time value is prefixed to the transport packet.
`This time stamp is one quacllet, or four bytes
`of data. At the receiving end of the 1394
`transport system, the 13 94 time stamp is
`ren10ved, and is oompared to the current
`system time. By passing the transport packets
`to the destination device at a oonstant offset
`from system time, the original temporal
`relationship between the packets will be
`restored This eliminates 1394 transport jitter
`to the resolution of two 1394 clock periods, or
`2 x 1/(24.576 x 10A6) = 81.41 nanoseoonds.
`
`A proposed addition to the MPEG2 standards,
`Extensions for real time interfaces for system
`deooders [4] has clarified transport stream
`jitter measurements and suggested a more
`generous limit. The new transport jitter limit
`is 25 microseoonds, measured peak-to-average
`(or 50 µsec peak-peak). The 1394 time
`stamping system provides jitter cancellation
`capabilities that acoount for less than 1/6 of
`1% of this proposed limit, so 1394-induced
`jitter effectively can be ignored
`
`The CIP header system
`
`As part of the development of the 1394 time
`stamping and jitter canceling functions, a
`standardized formatting of the data was
`developed. This has been named the Connnon
`Isochronous Packet, or CIP, header. The CIP
`header is an extensible format that can be
`adapted for future applications as they arise.
`Today there are sets defined for the SD, HD
`and SDL formats of the DV tape systems,
`along with MPEG-2 transport packets as used
`by the DVB and ATV digital television
`systems. These formats are defined in the HD
`DVC "Blue Book"
`
`In addition to the previously described time
`stamping function, the CIP header system
`also supports a number of other system
`functions. The two most notable of these are
`the Plug Control Register, or PCR, and the
`Function Control Protoool, or FCP. The
`specifications for both of these, together with
`the. associated Connection Management
`Protoool (CMP), also are oovered in the HD(cid:173)
`DVC "Blue Book"
`
`The purpose of PCR/CMP is to provide a
`method for oontrolling the virtual oonnection
`between transmitting and receiving devices on
`a 1394- bus. Two primary functions are: 1) To
`prevent
`active oonnections
`from being
`accidentally broken, and 2) To permit
`broadcasting devices with no listeners to be
`turned off.
`In the first case, a listener can
`register with the sender, and the sender
`knows not to stop as long as the oonnection is
`
`Page 5 of 12
`
`

`

`active. In the second case, a broadcasting
`device is
`able to tell when there are no
`listeners, so it can stop sending and release its
`allocated bandwidth and channel.
`
`The Function Control Protocol (FCP) and its
`related AV/C Command and Transaction Set
`provide for a standardized register location
`where information can be obtained as to what
`control
`languages are understood by a
`particular device. At present two values are
`defined, one for the AV/C language used by
`DV tape systems, and the other for the
`Common Application Language
`(CAL) of
`CEBus.
`
`The relation between the 1394 protocol stack
`and the HDDV-DVC layers is shown in Fig 2.
`The areas delineated by the dashed lines
`designate the sections of the "Blue Book" that
`
`deal with the 1394 interface.
`
`Longer and faster
`
`The specifications for the cables used in 1394
`are based on electrical performance. An
`example given as a reference in the standard
`is suitable for use over the full range of
`signaling speeds (100 Mbit/s base rate, plus
`the 200 and 400 Mbit/sec options) at a length
`of up to 4.5 meters. A slightly larger and lower
`loss cable has been developed which may be
`used to increase the distance per hop into the
`15-20 meter range.
`
`Restricting the maximum signaling frequency
`also allows a given cable to be used at a
`greater length. For consumer use, the 200
`Mbit/sec optional speed appears to provide
`more than adequate performance and has
`
`Recording
`Format
`SD-DVCR
`Data
`Sequence
`
`HD-DVCR
`Recording
`Format
`HD-DVCR
`Data
`Sequence
`
`SDL-DVCR
`Recording
`Format
`SDL-DVCR
`Data
`Sequence
`
`DVB
`Recording
`Format
`
`ATV
`Recording
`Format
`
`MPEG data
`sequence
`
`Set for Digital Interface l SD-DVCR
`
`Specifications of
`Consumer-Use
`Digital VCRs
`
`Specification of A VIC
`Command and Transaction
`___ A __ _
`
`I
`
`'
`
`AV/C
`Command and
`Transaction Set
`
`: Part 2
`
`--··- ·-----
`................. --··· ····-
`--------··
`. .
`....._ ____ ___.: :
`: :
`.......... ,
`
`: : Part 3
`
`: : Part 5
`
`:
`
`.
`:
`: : SDL-DVCR
`: : HD-DVCR
`:
`• • Transmission • • Transmission •
`
`:
`
`: Part 4
`
`··-·- ..........
`, ...... ____ ___.
`·----· -····'
`
`,
`
`' . . . . . . .
`
`,
`
`' . . . . . . . . .
`
`#
`
`6. Real time data
`transmission protocol
`
`1394
`Protocol
`Stack
`
`8. Connection
`Management
`Protocol
`7. Plug
`Control
`Registers
`
`4. Transaction Layer
`
`3. Link Layer
`
`2. Physical Layer
`
`•
`'·····-·····················-········--·-------------#
`
`'
`
`8---------------------·-
`Specifications of
`Digital Interface for
`Consumer Electronic
`AudioNideo
`Equipment
`................
`I
`,
`•
`Part 1 Annex
`•
`•
`
`AV Cable/
`Connector
`
`Fig 2: Relation of 1394 Protocol Stack to HD-DVC Blue Book
`
`Page 6 of 12
`
`

`

`been specified as the maximum signaling rate
`supported by the HD-DVC specification This
`also allows for smaller cables to be used for
`any particular distance.
`
`Even with these types of cable enhancements
`. and signaling rate compromises it is still
`difficult to extend the reach of a single 1394
`cable hop into the 25-50 meter range needed
`for a home or small office network The use of
`active signal repeaters is a simple solution for
`certain situations. A repeater is nothing more
`than a two port physical layer device, with no
`link or higher layers, that is a fully compliant
`node in the network However, the use of
`repeaters
`in permanently
`installed and
`inareessible wiring is problematic.
`
`A number of alternative physical layers and
`configurations have been examined for longer
`distances. One very important parameter that
`should be considered when increasing the
`distances within a single 1394 bus is the likely
`inclusion of a larger number of devices than
`would be found in a typical local equipment
`cluster. A larger number of devices on the bus
`raises the prospects for running out of
`isochronous bandwidth to support all the
`desired applications. Another consideration is
`the arbitration signaling and gap (idle) time.
`The longer the end-to-end distance, the longer
`one must wait
`for
`arbitration
`and
`acknowledgment
`round trip delays. Longer
`wait times translates to more timing overhead
`or lower efficiency.
`
`For these reasons it is believed that most
`longer distance 1394 networks will benefit
`from being arranged as separate (local cluster)
`busses connected by bridges or routers. Traffic
`belonging to one bus is not seen by any others
`unless specifically addressed to another bus.
`The performance of each separate local cluster
`bus may also be independently optimized
`
`The addressing scheme used in 1394 allocates
`10 bits for bus_ID, 6 bits for node_ID, and 48
`bits
`for
`internal device addresses. This
`translates to a maximum 1023 busses, each
`
`having up to 63 nodes (the all-l's addresses
`are reserved for broadcast purposes). The
`protocols
`for managing
`bridges was
`purposefully not included in the base IEEE
`standard in order to avoid unnecessary delays.
`Work to define bridging/routing started in
`1995 as a working group project within the
`1394 Trade Association [5]. It is expected to
`become an authorized project of the IEEE
`mid-year 1996 [6].
`
`One of the proposed features of the bridge
`definition work is the concept of an extended
`bridge. In its simplest implementation this
`could be a pair of ''half bridges" separated by
`some
`longer distance point-to-point
`link
`Possible links for the extended bridge include
`unshielded twisted pair (UTP), plastic optical
`(POF), coax, or wireless. Distance
`fiber
`capabilities are expected to be at least 50
`meters.
`
`In addition to this work to define bridges for
`1394, work has also started to define a new
`gigabit rate physical layer and protocol. This
`work also started as a working group within
`the 1394 Trade Association, and is also
`expected to become an authorized project of
`the IEEE mid-year 1996[7]. The gigabit
`physical layer and protocol will provide a
`backbone supporting multiple standard 1394
`busses through bridges. The goals are a
`minimum distance of 25 meters, and that the
`interface will look and behave the same to the
`user as the present 1394 bus.
`
`PRODUCTS USING 1394
`
`DV camcorders
`
`In the fall of 1995 Sony introduced two DV
`the DCR-VXl 000 and DCR(cid:173)
`camcorders,
`VX700. Both of these units meet the HD-DVC
`requirements for SD (525-60 and 625-50
`systems) format digital camcorders. Both
`models include a 1394 based DV digital
`interface. This allows for virtually lossless
`audidvideo dubbing and editing. Many other
`manufacturers also have
`introduced DV
`
`Page 7 of 12
`
`

`

`camcorders, and several have announced that
`futtrre units will
`include
`the 1394/DV
`interface.
`
`DV VCR tape decks
`
`In April 1996 Sony introduced its DHR-1000
`digital VCR deck companion to its DV
`camcorders. This unit, currently available in
`Etrrope, includes a single front-panel 1394/DV
`connector.
`
`D-VHSVCR
`
`JVC has announced the finalization of the
`specifications for D-VHS, Standard Mode ~].
`1394 has been adopted as the digital interface
`for this system. This technology offers bit
`stream recording of compressed digital data in
`a variety of formats, such as those used by
`Digital Broadcast Satellites (DBS).
`
`Desktop camera
`
`Sony has introduced the CCM-DS250 desktop
`video camera [9] which utilizes a single
`standard (6-pin) 1394 cable to provide the
`complete camera connection to a PC adapter
`card. The camera is powered through the 1394
`cable. Camera connnand and status messages
`are
`carried
`as
`asynchronous
`packets
`interleaved with the isochronous packets of
`uncompressed video data. This camera
`supports a wide range of operating modes
`with options for resolution, frame rate, and
`color depth. A 100 Mbit/ sec 13 94 interface
`easily supports this camera operating in a 320
`x 240, 30 frames/sec, 16 bit/pixel (YUV 4:2:2)
`mode. The connnand and register format
`specifications have been documented by a
`working group of the 1394 Trade Association.
`
`Digital video editing system
`
`miro Computer Products AG has announced
`[10]
`a
`licensing agreement with Sony
`Corporation to develop 1394 based desk-top
`video editing products for the PC. This action
`is "designed to bridge the gap between the
`
`highly successful DV format camcorders and
`the non-linear editing world of desktop video."
`
`Truevision has announced a DVCPRO version
`of TARGA 2000 RTX digital video engine [11]
`that includes a 1394 interface. DVCPRO is
`Panasonic Broadcast & Television Systems
`Company's implementation of DV with a
`different recording (but not data) format. The
`new adapter card provides non-linear editing
`and real time 2D effects processing of DV(cid:173)
`encoded data on a desktop system.
`
`Digital still image capture board
`
`Sony has introduced a digital still image video
`capttrre board, the DVBK-1000 [12], as a
`companion to its DV camcorders. This ISA
`adapter card featmes a 13 94 interface to
`Sony's consumer DV camcorders.
`
`Set top boxes and digital television
`
`The Digital Audio Visual Interface Council
`(DAVIC) has been working to define a
`connnon set top box architecttrre. A technical
`subcommittee of DAVIC is considering the
`addition of 1394 as the "external AO" interface
`for the DAVIC 1.1 specification The Digital
`Video Broadcasting (DVB) Project is defining
`standards for digital television broadcasts,
`and a subcommittee is considering 1394 for
`the digital interface to digital televisions and
`peripherals. The EIA R-4.1 subcommittee of
`the R-4 Television systems committee has
`selected 1394 as the basis for the digital
`interface
`for US-ATV digital
`television
`systems. All of the above items are drafts or
`work in progress, so should not be assumed to
`be finalized A
`recent specification from
`TELE-TV for a set top box
`includes a
`reference to the DA VIC architecttrre, and
`includes a requirement for a 1394 interface.
`
`PCs and motherboards
`
`Several major manufacttrrers of computers
`and related hardware and software have
`announced support of 1394 [13]: Adaptec,
`
`Page 8 of 12
`
`

`

`IBM PC Company,
`Inc..,
`Cirrus Logic
`Microsoft Corp., Sun Microsystems, and Texas
`Instruments Mobile Computing Business.
`
`At the April 1, 1996, WinHEC (Windows
`Hardware Engineering Conference) Microsoft
`Corp. announced the Simply Interactive PC
`(SIPC) [14] which will allow the PC platform
`to be
`the
`"center of entertainment,
`communications and productivity in both
`home and office." One of the keys technologies
`to SIPC is 13 94, which will provide users with
`low-cost,
`easy-to-install
`peripherals.
`Endorsement for SIPC [15] has been given by
`Adaptec
`Inc.., Compaq Computer Corp.,
`Gateway 2000 Inc.., Hewlett-Packard Co.,
`Intel Corp., and Toshiba Corp.
`
`Apple Computer has announced [16] that its
`Pippin 1997 reference platform will include
`1394 for consumer product connectivity. Apple
`also plans
`to include 1394 on selected
`computer systems in 1997, and across the
`entire product line in 1998. The Mac OS is
`expected to include 1394 support in the first
`half of 1997.
`
`1394/DV VIDEO EDITING
`
`The advantages of 1394/DV in video
`editing
`
`1394 and the DV (Digital Video) standard
`promise to revolutionize video editing over the
`next 3-5 years. Compared to the current
`analog/ JPEG video editing systems now
`widely used, 1394/DV offers superior video
`quality at a lower, constant data-rate, smaller
`tape size, fewer tape drop-outs, built-in data
`archiving,
`guaranteed
`audio-video
`virtual
`elimination
`of
`synchronization,
`dropped frames, and file interchangeability.
`These advantages hold
`the promise of
`bringing professional digital video editing to
`the high-volume consumer market.
`
`DV, a new video compression standard, does
`not contain the bi-directional and predictive
`frames of MPEG-2, so editing boundaries may
`
`be at any frame. DV produces a fixed data(cid:173)
`rate of approximately 3.6 MBytes/sec,
`utilizing a fixed 5: 1 compression based on
`4:1:1 YUV video sampling. DV compression
`relies on discrete cosine transform like JPEG
`and MPEG, but adds the enhancement of field
`interpolation on
`low-motion scenes. This
`interpolation, as well as other enhancements,
`produces video which many observers say is
`equivalent to Sony Betacam SP which has
`been JPEG compressed at 2.5:1. Therefore,
`DV produces equivalent video quality to
`JPEG, but at about a 30% lower data-rate.
`
`The DV data is stored on a new, smaller
`evaporated-metal tape specifically designed
`for digital data. This new tape uses a 10
`micron track (versus VHS at 50 microns) and
`can store 60 minutes of video and audio ( over
`15 GBytes of data) on a tape. which is about
`7 5 % the size of an 8mm cassette. Prior to
`writing to this DV tape, error detection and
`correction bits are added to the data stream.
`Additionally, the digital data is interleaved
`across the tape within a single frame. These
`techniques greatly reduced dropouts and other
`tape artifacts commonly found in 8mm and
`other analog formats.
`
`In addition to excellent video and audio
`quality, the 1394/DV system provides built-in
`data archiving. After creating a video tape
`using a typical analog/ JPEG system the editor
`may wish to save the video clips on a digital
`tape for
`long-term archiving. This often
`requires the added cost of a high capacity tape
`drive (e.g. Exabyte) and tape. With a 1394/DV
`system the user can simply use the built-in
`digital storage capability of the DV cassette
`for archiving.
`
`(3.6
`data-rate
`digital
`constant
`The
`MBytes/sec) of the 1394/DV system eliminates
`the problems associated with JPEG data-rate
`bursts. JPEG is a "constant quality, variable
`data-rate" algorithm. The compressed data(cid:173)
`rate from a JPEG system can easily vary by a
`factor of 4:1, depending on the complexity of
`the image. These data-rate bursts cause
`
`Page 9 of 12
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`

`dropped video frames if the data-rate exceeds
`the capability of the disk 1/0 subsystem. On
`the other hand, the constant 3.6 MByte data(cid:173)
`rate of a 1394/DV system is well within the
`capabilities of a modern SCSI disk system,
`virtually eliminating dropped frames.
`
`Finally, 1394/DV systems will support file
`interchangeability.
`In most analog/ JPEG
`systems the JPEG data stream parameters
`are proprietary to a given manufacturer.
`However, the DV data stream is well defined
`and a widely areepted standard within all DV
`camcorder products. This includes Panasonic's
`DVCPRO and Sony's DVCam professional
`products. This means that video footage shot
`on a high end professional camcorder can be
`played or edited on a consumer DVCR tape
`deck or on a consumer 1394/DV editing
`system.
`
`''Blue Book"
`the DV
`Early drafts of
`specification defined the tape fonnat and the
`video compression algorithm, but not a digital
`interface or data transport protocols. While
`several digital video transport protocols such
`as parallel and serial Dl were well known,
`these protocols were soon recr>gnized as too
`complex and too expensive for a consumer
`application. 1394 with its bandwidth of 100
`Mbits/sec or greater, guaranteed isochronous
`delivery of data, low-cost interconnect and
`relatively simple silicon implementation was
`quickly identified as the best overall choice for
`the digital transport of DV data. Accordingly,
`1394 was added to the final 1996 ''Blue Book''
`specification and has been widely areepted as
`the digital standard for DV transport.
`
`A proposed 1394/DV editing card
`
`A software based 1394/DV editing system can
`be easily created on a Pentium class PC with
`the addition of a 1394 adapter card and a fast
`disk subsystem. A fast disk subsystem, such
`as SCSI,
`is required to meet
`the 3.6
`Mbytes/sec DV data-rate. While functional,
`such a system would be extremely slow as
`
`each video effect would be rendered entirely in
`software.
`
`Fig 3: A PC based 1394/DV video editing
`system
`
`The creation of a video effect, such as titling,
`picture-in-a-picture,
`dissolves
`or wipes,
`requires the decompression, and ultimately
`the re-compression of each video frame
`involved in the video effect. Each frame of
`rendered
`video
`typically
`requires
`the
`decompressions of two video source frames,
`and the re-compression of the final video
`frame.
`This
`decompression
`and
`re(cid:173)
`compression can be performed in hardware or
`software.
`
`the time
`In a software based solution,
`required for a decompression or compression
`of a frame of video is approximately one
`second. Each second of video is made up of 30
`frames of video. Therefore, producing a one
`second video effect will take about 90 seconds
`of CPU time just for the decompression and
`compression: Decompression of two source
`frames plus compression of the rendered
`frame. A hardware
`codec
`(compressor(cid:173)
`decompressor) card, on the other hand can
`perform each
`required
`compression or
`decompression
`in
`approximately
`33
`milliseconds
`-
`a 30X
`improvement over
`software.
`
`The diagram in Fig 4 shows a proposed
`hardware based 1394/DV adapter-codec. The
`product uses a 1394 link layer controller and
`physical layer interface to connect to the
`camcorder via a 1394 cable. The DV data is
`moved across the CPU bus via a PCI
`controller. A DV
`codec
`(DVCPRO or
`equivalent) chip set is used to compress or
`
`Page 10 of 12
`
`

`

`PCI
`Controller.._--+-_.,.
`
`PCI
`
`BUS
`
`1394 Inter-
`face
`
`Port 1
`
`Port2
`
`Port3
`
`Digital
`Video
`Bus
`
`Link
`Controller
`
`PHY Layer
`
`Serial Audio
`
`DVC
`Compression
`Chips et
`
`olor Space
`onverter
`<>RGB
`
`FPGA
`
`FIFO
`
`Fig4: 1394/DV adapter-codec block diagram
`
`decompress the DV data at full video rates of
`approximately 33 milliseconds per frame for
`rendering or display operations. The color
`space converter
`transforms between
`the
`uncompressed YUV video data from the color
`space of the camcorder to the RGB color space
`of the computer for rendering operations. The
`FIFO is used to buffer this RGB data prior to
`transport across the PCI bus.
`
`(Field
`FPGA
`an
`uses
`design
`This
`Programmable Gate Array) to control the flow
`of video and audio data within the card
`Additionally, the PCI controller must be bus
`master rapable
`to maximize
`PCI bus
`bandwidth and to minimize dependencies on
`the interrupt latency of the CPU. Ring zero
`software drivers are mandatory to enhance
`overall system perlormance. Actual render
`times using this hardware design is expected
`to be 30 to 40 times faster than a software
`only solution.
`
`The 1394/DV system is expected to become
`the de facto consumer video editing standard
`in the next 3-5 years. While software based
`editing
`solutions hold
`the promise of