Letters

The i-Visto Gateway XG—Uncompressed HDTV Multiple
Transmission Technology for 10-Gbit/s Networks
Takeaki Mochida†, Tetsuo Kawano, Tsuyoshi Ogura,and Keiji HaradaAbstract
The i-Visto gateway XG is a new product for the i-Visto (Internet video studio system for high-definition television (HDTV) production) system developed by NTT Laboratories. It can transmit multiple
HDTV streams using a 10-Gbit/s network interface. We used the i-Visto gateway XG in two field tests:
multiple HDTV transmission between Osaka and Tokyo over the JGNII network and a local demonstration at an NTT Group exhibition. This article describes the new functions of the i-Visto gateway XG, theresults of the field tests, and our future plans.

1. Development background
The i-Visto (Internet video studio system for highdefinition television (HDTV) production) is an Internet-based video production-support system for professional use developed by NTT Laboratories. It con-sists of six main products (Fig. 1). (1) The i-Visto
gateway performs conversion between digital video
signals and Internet protocol (IP) streams. (2) The iVisto HDTV camera is an HDTV camera that can bedirectly connected to an IP network. (3) The i-Visto
media server is a network-attached video server that

i-Visto HDTV cameramHD

streamtrea

Optical IP network

SD s

i-Visto media converter

HD-SDI

Hard diskdrive

HDTV equipment
i-Visto switch
SD-SDI
SDTV equipment

i-Visto media server

i-Visto gateway

HD: high definition
SD: standard definition
SDI: serial digital interface

i-Visto manager

Fig. 1. The i-Visto product lineup.
† NTT Network Service Systems Laboratories
Musashino-shi, 180-8585 Japan
E-mail: i-visto@core.ecl.net

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NTT Technical ReviewLetters

can handle uncompressed HDTV streams. (4) The iVisto media converter converts video from one format to another in real time (e.g., from HDTV toSDTV (high definition to standard definition television)). (5) The i-Visto switch is an OC-48-basedlayer-2 switch. (6) The i-Visto manager manages andcontrols i-Visto products via an IP network.
Field tests have shown that these products can provide quality sufficient for commercial broadcasting.
However, various transmission technologies that
reduce the cost of video transmission services haverecently been making their appearance (e.g., coarsewavelength division multiplexing (CWDM)). Consequently, finding ways to make i-Visto a more economical system have become important. In response,
we have developed the i-Visto gateway XG (Fig. 2),
which is an upgraded version of the previous i-Vistogateway. It reduces network-related costs in the following ways.
(1) The i-Visto gateway XG supports Ethernet.
This lets us use wide-area Ethernet services,which are cheaper than transmission services
based on asynchronous transfer mode (ATM) or

synchronous transfer mode (STM). The previous i-Visto gateway supported only STM.
(2) The i-Visto gateway XG can handle multiple
HD-SDI or SD-SDI (high/standard definition
serial digital interface) signals. The previous iVisto gateway could handle only one digital
video signal.
2. Functions
The i-Visto gateway XG guarantees backward compatibility with the previous i-Visto gateway. Table 1
shows how the functions of the i-Visto gateway havebeen enhanced in the i-Visto gateway XG. Theseenhancements are described in more detail below.
2.1 Multiplexed transmission of video streams
The i-Visto gateway XG can transmit multiple
video streams over an IP network. It can convert HDSDI and SD-SDI video streams input from multiple
video interfaces to IP packets in real time, then multiplex and transmit these packets via a network interface (Fig. 3). The destination i-Visto gateway XG ofFig. 2. External view of i-Visto gateway XG.
Table 1. Main functions of i-Visto gateway XG.

Network interfaces
Maximum number of video
streams (multiplicity)
IP packet length
Supported data (other than video)

i-Visto gateway XG

i-Visto gateway

10-Gbit/s Ethernet,
1-Gbit/s Ethernet,
POS/POS++ (max. 10 Gbit/s)

POS/POS++ (max. 2.4 Gbit/s)

3

11500 bytes to 64 KB

64 KB

RS232c (for control), IP tunneling

RS232c (for control)

POS: packet over SONET/SDH
POS++: multiple access protocol over SONET/SDH
SONET: synchronous optical network
SDH: synchronous digital hierarchy

Vol. 3 No. 4 Apr. 2005

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HD-SDI stream..
.

Time axis
IP conversion..
.
Identifies destination
gateway by address

Identifies stream
by port number

IP header UDP header RTP header Video data

IPmultiplexer

IP header UDP header RTP header Video data
Shows video frame
identifier, relative position
SD-SDI stream within frame, etc.
..
.
..
.

Networkinterface

Datatotransmit..
.

Time axis
IP conversion

RTP: realtime transport protocol

Fig. 3. Example of IP conversion and IP multiplexing of HD-SDI and SD-SDI video streams.

each of the video streams is specified by the destination IP address.
In reverse, it can also receive IP packets from a network interface and reconfigure individual digital
video streams from them, then output them from corresponding video interfaces. According to the videostream identification data included in IP packets, itidentifies the corresponding video stream for eacharriving IP packet. Specifically, a destination port
number of UDP (user datagram protocol) is used.
The i-Visto gateway XG supports both IPv4*1 andIPv6*2. It also supports 1-to-N video distribution
using IP multicasting.
In handling multiple video streams, i-Visto gateway
XG can separately initiate or halt the transmission ofeach video stream and can separately monitor its
transmission status.
Information attributed to each video stream such as
the source/destination IP address, video format, andother control data can be managed in an integrated
fashion using configuration files within the i-Visto
gateway XG. This makes it easy to refer to and modify this information.
2.2 Support for 10-Gbit/s and 1-Gbit/s Ethernet
interfaces
While the previous i-Visto gateway supported network interfaces up to 2.4-Gbit/s (OC-48), i-Visto*1 IPv4: The current IP standard (version 4) used by the Internet featuring an address length of 32 bits.
*2 IPv6: Next-generation IP standard (version 6) featuring an address
length of 128 bits.

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gateway XG supports 10-Gbit/s Ethernet. Moreover,the previous one transmitted HDTV streams using
only 64-KB IP packets, while the latter can additionally transmit HDTV streams over networks using a
1500-byte MTU (maximum transfer unit) because its
higher IP-SDI conversion performance lets it handle
such short MTUs. Needless to say, it supports Ethernet networks with larger MTUs such as 9 KB commonly referred to as a “jumbo frame”.
The i-Visto gateway XG also supports the trunking
transmission*3 scheme. It can transmit an HD-SDI
signal requiring a bandwidth of about 1.6 Gbit/s byusing two 1-Gbit/s Ethernet interfaces.
2.3 General-purpose-data transmission mode
In addition to video streams themselves, the IP conversion function used by this system supports thetransmission of data related to the streams and general-purpose data as well. This is an extension of theprevious i-Visto gateway function that allows IP multiplexing of an i-Visto HDTV-camera remote-control
signal with a video stream.
In more detail, the i-Visto gateway XG has a function for encapsulating Ethernet frames input from an
Ethernet interface or a POS (packet over SONET/SDH) interface plus IP or control signals input froma serial port to achieve tunneling-type transmission. It
also has a function for routing IP. In any case, IP-multiplexed transmission can be performed using the*3 trunking transmission: A transmission system that treats multiple
network interfaces as a single virtual interface.

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Letters

NTT WEST
Dojima Building (Osaka)

i-VistoHD-SDI source 1 gateway XG(generator)

NTT Communications
Otemachi Building (Tokyo)

JGNII network
10 Gbit/s

i-Vistogateway XG

HD monitor 1VLAN 1 (IPv4)
HD-SDI source 2(video server)

HD-SDI source 3(video tape)HD monitor 2

VLAN2 (IPv6)
i-Vistogateway XG

i-Vistogateway XG
10-Gbit/s
Ethernetswitch

10-Gbit/s
EthernetswitchHD monitor 3

About 500 kmFig. 4. System configuration for long-distance transmission field tests.

same network interface as used for the IP-converted
video-stream data.
2.4 Maximum number of installed interfaces
An i-Visto gateway XG can house up to six cards
for video and network interfaces. This provides flexibility in configuring the relationship between video
streams and IP such as when multiple video streams
are being transmitted and received from corresponding network interfaces.
3. Long-distance transmission field tests
To evaluate the performance of the i-Visto gateway
XG, field tests of HDTV uncompressed video transmission were conducted by NTT Communications,NTT West, and Asahi Broadcasting Corporation incollaboration with CKP*5 on the JGNII*6 10-Gbit/s
Ethernet network. As shown in Fig. 4, an IPv4 virtual local area network (VLAN) and an IPv6 VLAN
were constructed on JGNII 10-Gbit/s Ethernet lines
between Tokyo and Osaka, a distance of about 500
km. In each VLAN, a total of three uncompressed
HDTV streams including commercial broadcastingmaterial were IP multiplexed and transmitted. During
the transmission, video quality and operation stabili*5 CKP: Cyber Kansai Project; Chairman: Hideo Miyahara (President, Osaka University)*6 JGNII: An extension of the JGN (Japan Gigabit Network) testbed
network for R&D featuring ultrahigh transmission speeds andadvanced functions. It began operating in April 2004 under thesupervision of the National Institute of Information and Communications Technology (NiCT, President: Makoto Nagao).

Vol. 3 No. 4 Apr. 2005

ty were examined.
The test was conducted for a period of five days.
During the test we monitored HDTV video quality,
the number of lost IP-packets, and transmission
delay. We did not observe any video-frame or packet
loss in any of the video streams. We also found thatthe transmission delay was at most equal to the time
taken to display two HDTV video-frames, which
does not present any problems in practical use. Fromthese results, we conclude that the i-Visto gateway
XG achieves stable high-speed uncompressed video
transmission between widely separated locations.
4. Demonstrations at NTT Group exhibition
As part of an effort to promote business for the iVisto gateway XG, demonstrations were performedat the R&D booth at an NTT exhibition called NTT
Group Collection in West 2004 held sequentially atexhibition halls in Fukuoka, Nagoya, and Osaka. As
shown in Fig. 5, the network configuration of thisdemonstration system connected three locations
within the exhibition hall by a 10-Gbit/s Ethernet
LAN. In contrast to the long-distance transmission
field test described above, the objective of thisdemonstration was to let users experience for themselves the sensation of high-quality remote communication in bidirectional HDTV transmission using
the i-Visto gateway XG.
In the demonstration, a satellite studio set up inside
the exhibition hall was first connected to the exhibition booth by a 10-Gbit/s Ethernet line, and HDTV
streams including audio were transmitted in both41

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Satellite studio

Exhibition boothMPEG
encoder

MPEG-compressedtransmission
Trafficstatistics
displayterminal

Video+ audio
i-Vistogateway XG

HDTV camera 1

Uncompressedtransmission
10-Gbit/s
Ethernet

HD monitor 2

Video+ audio

MPEGdecoderVideoHD monitor 1b

i-Vistogateway XG

Video+ audio

Ethernetswitch

HD monitor 1aVideo+ audio

About 50 m

HDTV camera 2

Video

i-Vistogateway XG

Uncompressedtransmission

HD monitor 3
Video

10-Gbit/s
Ethernet
Camera control
i-VistoHDTV camera 3
gateway XG
with control function

Camera-platform
control unit

About 100 m

Main stage
Video/audio wiring
and transmission direction

Network wiring
and transmission directon

Control-signaltransmission direction

Fig. 5. Demonstration system at an NTT Group exhibition (NTT Group Collection in West 2004).

directions. A narrator in the satellite studio could converse with people visiting the booth. For comparison
purposes, an HDTV video transmission system consisting of an MPEG-2 encoder and decoder was set up
in parallel. It was found that most visitors participating in the demonstration could sense little delay inuncompressed video transmission by the i-Visto gateway XG and that they could understand the need forsuch a system.
A parallel demonstration was also held in which iVisto gateway XG was used to remotely control anHDTV camera on the main stage from the exhibitionbooth in order to relay happenings there in real time.
No problems were experienced in operating this sys-42tem even for visitors that were familiar only withordinary broadcast cameras.
5. Future plans
The i-Visto gateway XG is scheduled to go on themarket in March 2005 to meet the demand for HDTV
distribution networks generated by the spread of digital terrestrial broadcasting. In the future, we plan toexpand its scope of application by making further
functional improvements such as adding a videoclock synchronization function and a video interface
for broadcasting use.

NTT Technical Review

Letters

Takeaki Mochida

Tsuyoshi Ogura

Second Promotion Project, NTT Network Service Systems Laboratories.
He received the B.E. and M.E. degrees in system engineering from Tohoku University,Sendai, Miyagi in 1993 and 1995, respectively.
He joined NTT in 1995. Currently, he is studying
transmission system architectures. He is a member of the Institute of Electronics, Information
and Communication Engineers (IEICE) of Japan.

NTT Network Innovation Laboratories.
He received the B.E. and M.E. degrees in system engineering from Kobe University, Kobe,Hyogo in 1992 and 1994, respectively. He joined
NTT Laboratories in 1994. Currently, he isstudying parallel processing system architecturesand Internet systems. He is a member of theInformation Processing Society of Japan.

Tetsuo Kawano

Keiji Harada

NTT Network Innovation Laboratories.
He received the B.E. degree from Kumamoto
University, Kumamoto in 1991 and the M.E.
degree from Kyushu University, Fukuoka in1993. He received the Ph.D. for his research onparallel processing computer architecture fromKyushu University in 1996. He joined NTT Laboratories in 1996. His research interests include
super-high-bandwidth stream processing andparallel processing computer architectures.

Second Promotion Project, NTT Network Service Systems Laboratories.
He received the B.E. degree in electrical engineering from Nagoya Institute of Technology,Nagoya, Aichi in 1987. He joined NTT Network
Systems Development Center in 1987 anddesigned many SDH network systems. Currently, he is studying optical network systems andInternet systems. He is a member of IEICE.

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