JVC Compu Link, a brief history of time and space

JVC Compu Link (also called SYNCHRO 'terminal') was a simple point to point or later disjointed daisy chain method of connecting many Audio (only) devices together in a chain of devices.Initially TAPE (Cassette), CD (player) and MD - MiniDisc (recordable) to each other and to an AMP (AM/FM Receiver, Amplfier, Source switcher with IR remote receiver).

The protocol seems to be based on a 8 bit data frame with stop (or possibly a Parity) bit, at 100 or 110 baud (bps) in which 3 bits represent a Device, and four bits represent a state or 'command' from or to an addressed device. The intial cable was described as a [monoaural Ring/Tip miniplug] carrying logic levels of 5 volts or 0 volts refrenced to Ring ground. And normally [High] meaning a Pull-Up resistor was used to maintain a reference when not transmitting data.

Compu Link had (four) generations starting from about the year 1991.

Compu Link - I (version 1) was described as having the ability to emit or receive a [Start or Source] command along the connection to other devices. If [Play] was pressed on an Audio device it would emit a [Switch to Source command indicating itself, to an assumed AMP connected through the Compu Link connection] the AMP would then switch its Source to the Device requesting attention and shutdown any other playing Source. Alternatively an AMP could issue a [Start or Play] command to a particular Device naming it in the first three bits of the data frame.

Compu Link - II (version 2) was described as having the same capabilities but layering on additional features, there by maintaining backwards support for previous Compu Link - 1 Devices connected to Compu Link - II terminal ports.

Compu Link - III (version 3) gained [Stand By] or [On/Off] feature allowing the AMP to place a device into an On or Off mode called Stand By.

Compu Link - IV (version 4) gained the ability to coordinate Record/Pause and Playback between Audio components, in which a recorder was loaded with blank media, record and pause buttons pressed and then a seperate source signal component was set to play, it would inform the AMP to switch to it as the source.. the AMP would inform the recorder that playback had begun and release the pause to begin recording.

The Compu Link terminal ports, or mini-plugs were mono-aural (only one Ring, so only one signal path per connection) and to connect one to an AMP only one per device was required, however to daisy chain from for example a TAPE, to CD player and then to an AMP the CD player would be expected to have two Compu Link terminals, one could be used for connection to the TAPE device and would convey its signals to the CD player which would also be connected by its second Comp Link terminal to the AMP.

Early AMPs were mostly AM/FM radio receivers which shared their speaker connections and allowed switching the source, later including advanced audio mixers for equalization and mixing signals. Compu Link made them intelligent and able to respond and command various Audio connected components. Including acting as a Master IR remote receiver which could relay commands from the IR remote along the Compu Link connections to the various Audio Devices with a single remote. note: it did not relay demodulated "IR" codes, as with some other manufacturers, rather it issued legitimate Compu Link protocol codes targeted for that type of connected Audio device.

When MD - "mini-disc" player/recorders came along the ability to copy and record signals to digitial media opened up the ability to Read and Write [TEXT] from areas of the Disc. For this a new version  of Compu Link called [TEXT Compu Link] using "bi-aural" mini-plugs or [Tip, Ring, Ring]  was created and made using a {green colored} jacket. Early AMPs supporting this displayed the TEXT on Vacuum Fluorscent Display tubes called (VFD). Later Audio/Video AMPs would display TEXT Compu Link in TV On Screen Displays integrated in the video display menus on the TV. Early methods of entering TEXT were performed using a Qwerty alphanumeric keyboard in the remote, and were later replaced by On Screen Display navigation of a Video keyboard on the TV screen using remote control arrow keys.

When Video source became available and an Audio/Video switcher was added to the AMP another new version of Compu Link called [AV Compu Link] using another set of mini plugs was created. There were three (I, II, III) versions of AV Compu Link. In addition TVs were given AV Compu Link terminal ports, and or Compu Link EX terminal ports. The functions included a similar ability to set the Video Source of the AMP (now called generically the Receiver) either by turning on a Video source, or by turning on the TV. The "Receiver" would then use the commands from the Video sourcer or the TV to set the appropriate paths for video and audio through the receiver to the TV for playback. Like MD, this began with VCR, DVD sources and progressed through recordable versions.

The Compu Link family of protocols were a Home Theatre set of protocols to coordinate signal source and choice using a central Master device called the AMP or Receiver which could also consolidate the remotes into one remote for the Receiver to control all of the other Audio and Video components to the Speaker and/or the TV display device.

JVC JLIP (Joint Level Interface Protocol) - J-Terminal

The JVC JLIP protocol was a circa 1996 pseudo serial protocol over an RS232 connection between devices and a PC serial port. Capable of send and receive of targeted master slave communications.

It is possible the name "Joint Level" - "Interface Protocol" refers to the use of "Junction Boxes" to share a single Serial connection with a PC among many J-terminal or JLIP enabled devices. Each connection between a J-terminal device and a PC was intended to be "point to point" however, to share that connection a breakout box or "device" with two or more simultaneous connections to the same Serial uplink to the PC were necessary. Thus to arbitrate between two or more simultaneously connected devices when passing messages each device must be assigned a unique Identifier or "ID" and that must be encapsulated in the protocol used at the "Joint Level". Since the "Junction Boxes" are essentially passive and contain no intelligent routing decision engines, each device itself must perform the decision or inspection of each message packet in order to determine when or if a particular message packet is intended for itself or is part of an ongoing conversation between itself and the PC. -- an equally descriptive title could have been "Junction Box Interface Protocol" however it is likely the protocol was developed before the junction boxes and hence the naming refers to an as yet to be defined interface device to accomodate the protocol.

It was used as an alternative to the IEEE1394 or "Firewire" standard as a proposed method of locally networking a number of audio/video and multimedia printer and video frame capture devices with point to point connections.

Because it was a master/slave systems targets are treated as resources addressed individually by the master (PC) using embedded "ID" codes in the frames used to pass messages to and from the targeted slave devices connected to the bus or the PC over the electrical signaling connection. These "IDs" were often self-assigned from within the menus or user interfaces inside the JLIP devices themselves with faceplate buttons or onscreen menu options using the devices IR remote. For example VCRs with a JLIP port (aka.. a 'J-terminal') had an onscreen menu location for manually 'setting' the JLIP ('ID') value.

Each frame of the JLIP protocol consisted of 11 bytes with a checksum at the end to help managed frame or packet corruption during transmission or reception. Various return bytes would acknowledge receipt of the command or status.

The protocol was not widely published and only deciphered by observation a few times. It was in fact a Patented and Proprietary protocol that belonged exclusively to JVC.

The "uses" to which this protocol was put were several:

1. for managing camcorder or vcr playback and record and positioning for assemble and insert editing (dubbing) with a second playback or recording deck, if used with a special capture box to pass video through to an ouput and then input into the recording video deck, transitions and screen wipes could be inserted into the video stream.
2. for coordinating audio/video equipment like camcorders or vcrs in order capture still frames and upload them to a PC or print them to special photo paper

Camcorders often came with several 'ports' including JLIP electrical ports, PC serial ports ran at traditional RS-232 full voltage swings of 12 volts +/- while JLIP ports ran at newer smaller device TTL small voltage swings of 5 volts +/- 0 volts. A JLIP to PC cable therefore needed a voltage level converter to allow a JLIP device to communicate with a PC. However a JLIP port enabled device could also have a second JLIP port in order to daisy chain the device with up to 50 or 63 other daisy chained devices..(these "splitter" boxes were called "JLIP junction boxes".. only a very few were ever made) this was similar to the way a USB port, hub and device daisy chains would be possible later. When connecting a JLIP device to a JLIP device a special canble with no level converter could be used. A special PC to JLIP port cable contained a level converter and was only needed with the first JLIP device in a chain. A JLIP device which connected to other JLIP devices downstream was called a 'Junction Box' somewhat similar to the terminology used with USB hubs today. Unlike USB however, power was not conveyed from the PC to the JLIP device and all such JLIP devices and JLIP Junction boxes had to be 'self' powered.

In theory a camcorder with both a PC port and a JLIP port could be used as a 'Junction Box'.

At this time USB was either too slow, too new, or not widely accepted and was not added to camcorders and other devices until many years later..

JVC released several standalone software/cable JLIP packages to partner with or use with equipment it made with a JLIP interface port. The JLIP port was identified by the stylized italic "J" symbol inside a purple box and later referred to retroactively as a [ "J-terminal" ] to more readily identify it as belonging to a class of commerical control ports similar to other commerical remote control management ports by other vendors like LANC, SLink, or AVCompulink

These were:

JLIP Player Pack - HS-V1UPC for Windows 3.1 on 3.5 inch floppy disk only
JLIP Capture Pack - HS-V16KIT for Windows 98/95 on CDROM disc only

("possible" release history)

HS-V1KIT  =  JLIP Video Movie Player Ver 1.0
HS-V3KIT  =  JLIP Video Capture Ver.2.0
HS-V5KIT  =  JLIP Video Producer Ver 1.1
HS-V7KIT  =  JLIP Video Capture Ver.2.1
HS-V9KIT  =  JLIP Video Capture Ver.3.0, JLIP Video Producer Ver.1.15
HS-V10KIT = JLIP Video Capture Ver.3.1, JLIP Video Producer Ver.1.15

HS-V11KIT = JLIP Video Capture Ver.3.1, JLIP Video Producer Ver 2.0

HS-V13KIT = JLIP Video Capture Ver.3.1, JLIP Video Producer Ver 2.0

HS-V14KIT = JLIP Video Capture Ver.3.1, JLIP Video Producer Ver 2.0
HS-V15KIT = JLIP Video Capture Ver.3.1, JLIP Video Producer Ver.2.0

Video Movie Player - was essentially an MCI interface for remotely pressing buttons and capturing to a video printer

Video Capturer - was esentially a Still Frame capture to BMP or JPEG with photo transfer over the JLIP serial connection to the PC

Video Producer - was essentially a Linear A/B Roll "Edit Decision List" video editor for dubbing segments from multiple sources to a single recorder

Picture Navigator was an early Photo Collection manager with an Album interface for filing captured stills.

Most of this made more sense when used with one or more Camcorders and VCRs to produce video on a limited budget and with an analog  linear editor system,The introduction of the DV firewire capture, transfer and whole digitial workflow a few years later would become more popular and replace it. This was an [entirely] Analog Linear Assemble workflow.

Which were basically for coordination and control of a remote controlled camcorder or vcr with a 'J-terminal' port. Capture was controlled after the media was properly positioned and triggered by a seperate signal to a video capture device like the Video Capture Box (which was also a J-terminal junction box from 1 to 2 JLIP ports) or the Video Multimedia Printer (which had only 1 JLIP port)

JLIP Video Capture Box - GV-CB3U for stills or clips to files for upload to the Internet
JLIP Multimedia Printer - GV-PT2U for video capture to paper for publication or archiving

Advanced JLIP control
The process of finding, capturing and printing video pictures is facilitated by JLIP (Joint Level Interface Protocol), designed by JVC to enable efficient bidirectional control of AV equipment as well as to provide computer connectivity. In addition, the GV-PT2 can be connected to such JLIP-ready video hardware as the CyberCam Series of digital camcorders--the popular GR-DV1 or the recently announced GR-DVM1D--and used in conjunction with special JLIP- based software to create an advanced multimedia system totally controlled from the computer. With the mouse, the user can control everything from camcorder playback to printer memory functions, enjoying such convenient features as Scene Playback, which facilitates finding and printing just the right picture. Also, after a video editing session, the edit-in points can all be printed automatically.
Printing from a video source
When connected to a VCR or camcorder, the GV-PT2 can store image data in its field/frame memory and print directly from that. Using either the printer's own control buttons or the remote control unit (supplied), the desired scene is selected. Prior to printing, the user can choose from a number of design elements to personalize any scene.

Video Production equipment like the Datavideo SE-200 could also use the JLIP port to take control and manage the queuing and edit decision lists possible with assemble and insert editing pseudo-non-linear editing while creating new video clips and sequences of video programming on VHS or other tape media.

Essentially it was a proprietary master/slave RS-232 protocol at (TTL level 5 volts) for addressing devices on a p-t-p or chained or shared serial bus for the purpose of remote control and triggering events like power on/off - play/record - start/stop. The JLIP user interface software presented a video control deck interface graphically which scanned the bus and identified connected devices and allowed selecting one to work with and send and receive messages to and from. Secondarily it could capture stills from a capture box and return those to data files on the PC over the JLIP serial connection, or send data to the frame buffer of a printer connected by the JLIP serial connection.

The JLIP communications protocol however was binary and checksumed so some sort of custom proprietary communications client had to be used other than a simple ascii terminal program.

A JLIP Debug progam was written and released to monitor and originate JLIP commands to and from devices connected to a PC

JLIPD 1.0 beta  released 2000-11-18

Documentation for the actual commands is hard to come by and often reverse engineered by observation of the interaction of a J-terminal connected JLIP device with JLIP control software.

JVC XV-D701 DVD player
Marantz 8300P D-VHS recorder

Helpful sites:


JLIP and the JLIP logo are registered trademarks of JVC


The JLIP Player Pack software was included on a 3.5 inch floppy diskette and bundled with a JLIP "junction box" and JLIP and PC cable(s) such that a PC could connect via a JLIP connector to the Junction Box and then split out into connections to two other JLIP devices with J-terminal ports. -- This would work to connect for example a camcorder (acting as video source) and a vcr (acting as video recorder). The JLIP Player software would then act as a software "Control Editor" which could queue up scenes on the camcorder and stage their playback to the paused vcr and "execute" the [dubbing] from the camcorder to the vcr. At points where a [tape switch] was necessary in the camcorder, in order to coordinate additional scene dubbings it would prompt for a new tape which would be manually swapped.

The JLIP Capture pack software was included on a CDROM disc and bundled with JLIP and PC cables but no junction box.  The junction box "splitter feature" was combined inside a separate "Capture Box" which was sold separately. Standalone the Capture pack could control one video source which may or may not include a junction box "like" feature of a a second J-terminal to connect additional JLIP devices. Confusingly this made many purchase combinations possible and worked the junction box feature downstream and into more dedicated function devices. A single PC could then install the Capture pack software and use that with other JLIP devices to manage them in other ways. For example the Capture pack included two software packages and the PC cable, JLIP cable and an Edit cable.

The first software package was intended to be used with a Video Capture box to queue up a video source like a camcorder and take still snapshots of the video and then upload those over its Serial connection to the PC to be stored and managed in a Photo Album. It never had the ability to capture video segments, but rather created index images of a sort. Likewise it could be used with a similar dye sublimation video capture and print device, which was designed to queue up a video source and take still snapshots of the video and hold those in printer memory for editing, uploading to the PC or printing them to special thermal paper.

The second software package was intended to be used as a more traditional assemble video editor with software decision list. It could mark In and Out for segements of a video source tape and create a decision list. Then the decision list could be edited offline to included transitions and wipes, if played through a special video capture box and dubbed to a video recorder, which was also controlled by the JLIP software a junction box or direct connection. Addtional video source tapes could be supported by adding a tape swap step in the edit decision list.

While archaic by todays standards with USB or even IEEE1394 "firewire" this took place in 1996 on Windows 3.1 and Windows 95/98 PCs, which was miraculous for the time.. and probably led to the eventual feature set that USB Serial connections would be known for a few years later. Certainly the Controller, Hub and Device hierarchy is quite familar, although JLIP did not include a shared power source and instead of high speed serial frames, relied upon the more traditional RS-232 start, stop, byte frame protocols with additional procedural protocols layered upon the original ASCII 8 bit free form protocol.

It echoed many of the features of 10baseT Ethernet as well including limited station numbers and an initialization phase for identifying all stations on the local network of devices.


LRM-519 enabling S-Video recordings

The LRM-519 is an LG DVR recorder which used the Microsoft Guide service until it was discontinued. The initial setup of the LRM-519 used the Guide service as part of setting up Inputs and Channels from its NTSC tuner. Without the Guide service it is not possible to setup Inputs for S-Video or Composite.

However, a previously configured hard disk from an LRM-519 that was setup with Satellite Input before the Guide service was discontinued can be cloned and inserted in another LRM-519 to enable it to be used as an S-Video or Composite recorder.

Manual recordings from the Satellite inputs are recorded in MPEG2 format, which can then be sent to a PC file share.


empia 2861, Startech SVID2USB23 enabling audio capture

When installing the Startech SVID2USB23 which is a (composite or compound) USB device it "may" only expose (one 2861 device under "Sound, video and game controllers" within Device Manager ) [STOP] everything.. this is indicative of a Bigger Operating System problem under Windows 7.

The C:\Windows\inf\usb.inf file is ('missing') and it will not be detected as missing even with sfc scannow.

"The usb.inf file is also not one of the 3498 files that Windows File Protection looks after, so there is no backup copy on your system."

Many back up copies exist on your system, a file search for "usb.inf" with a tool like voidtools "Everything" will find them for you, and possibly Windows search targeting the C:\Windows subdirectory (although I gave up on Windows Search long ago and disabled it).

Simply copy one of the usb.inf "backups" into the C:\Windows\inf directory and unplug and re-plug in the 2861 device (SVID2USB23).

The first device that appears in the "Sound video and game controllers" represents the first Endpoint in the cable dongle, the video capture device.. the sound device is the second endpoint on the bus and fails to appear without usb.inf.

Once the usb.inf is in place the first endpoint will be detected as [ Imaging Device 2861 ] and the second endpoint as [ USB Audio ] and appears as [ Line (2861) ]  in the Windows Sound Audio Mixer "Recording Devices".. a correct "Update Driver" and installing the EMAudio driver will convert that into Sound device (2861 Audio)

VLC is one of a few programs which can properly enumerate USB Audio device as selectable Audio Input for recording or playback. Many legacy audio capture programs will simply list "Master Volume" and not give you a choice from all available audio sources. Without this level of control.. the Audio Input from the USB audio cannot be turned on or have its levels set.

The SVID2USB23 aslso has S-Video and Yellow Composite Video inputs.. if you recieve a black blank screen on recording it may need its crossbar video input switched over to the S-Video Input to cpature video signal.

More usb.inf info here:

USB Generic parent driver

And more specifically here



LRM-519, enabling SMB file share uploads

The LG LRM_519 is a DVD recorder with Tuner and record to HDD. It can also be configured to [Send to PC] recording if the Windows 7 machine has been configured to be a member of a Workgroup, not a Domain and HomeGroup filesharing is not turned on.

In addition, the IPSec MMC plug-in which can be exposed (only) by creating a new MMC console and then Adding the IIPSec plugin can host a rules called [ WND ] which will block SMB connections by default and enormously slow down "Kerberos" authenticated logins, or any password authenticated logins.. in fact it will stop "correct" username /password authenticated logins in many cases.

The problem appears to be enforcement of a "Kereberos" specifc rules that lingers after passing through a Domain joined phase.. or because of an erroneous windows patch, which happens quite often.

Rather than reinstalling the machine, created a new mmc.exe instance, add in the IPSec ruleset plugin (which is not the same thing as the Firewall IPSec plugin, nor is it the same thing as the IPSec VPN connection tool.. this is a legacy totally off the radar plugin, which also buries and does not expose is rules sets.. unless it is specifically exposed by digging in the IPSec plugin.. all rulesets appear blank until highlights, and the Inbound set is clicked on and then refreshed.. quite hidden.. quite bad programming.