Edit controllers and VTRs with built-in controllers
Valeriy Golubkov

Though edit VTRs are not the subject of this review, we think it is possible to make a short presentation about video taper recorders' built-in edit controllers.

Though non-linear edit is getting more and more popular, many edit arias still remain traditionally linear. One of the advantages of linear edit is possibility of operating with unlimited video material, i.e. any moment it is possible to stop editing and change the tapes in VTRs. Edit controller, managing practically all its devices, plays one of the most important roles in edit areas.

RM-G820 by JVC and BVE-2000 by Sony controllers support pre-read function allowing simple edit system to perform edit operations that require three machines.

There are several kinds of control: with the help of RS-422 or RS-232 interface, LANC interface or using start/stop (GPI) control.

Search of the necessary video fragment is performed with the help of one or two jog/shuttle wheels (depending on the controller's model).

For edit control and providing synchronous operating of devices, SMPTE time code is mainly used: LTC (Longitudinal Time Code) or VITC (Vertical Interval Time Code). LTC reading is not reliable at low playback speed, at Pause mode of static picture playback the reading being impossible at all. VITC may be read at low playback speed and during static picture, but it may not be read during high playback speed.

Sometimes, edit is performed by CTL. In this case, edit accuracy is lower than during operating with SMPTE code. For example, in case RM-G820E controller operates with LTC and VITC edit accuracy makes +/- 0 frames, and if it operates with CTL edit accuracy is not more than +/- 2 frames.

The Table displays main peculiarities of the most popular controllers.

• D-9 format - BR-D92E and BR-D95E edit VTRs.
• DVCAM format - DSR-2000P edit VTR.
• DVCRO format - AJ-D850 edit VTR.
• DVCRO50 format - AJ-D960 edit VTRs.

Two-post DVCPRO system with the integrated Panasonic controller

DSR-2000P by Sony - is a VTR designed for professional record and edit, fully compatible by playback with all DV (25 Mbit/s) formats, including DVCPRO. It has 2 audio channels 16 bit/48 kHz. Standard RS-422 control interface allows editing records from different tapes. Additional DSBK-190 board allows i.Link (IEEE 1394) interfacing. DSR-2000P's front panel contains jog/shuttle wheel allowing direct editing on two VTRs (without extended controller). Besides, additional extension set of control front panel (DSBK-200) allows performing remote control of edit system, operating under i.Link standard, within up to 10m.

Owing to wide range of speed control at slow-motion playback mode (-1x...1x) DSR-2000P provides smooth sound track search, similar to that existing in analog VTRs. This allows quick edit marking, listening good-quality sound. DSR-2000 employs Non-tracking technology, that uses additional heads in video heads' unit, owing to which it is possible to play the cassette having abnormal geometry of tracks' distribution on the tape (this refers both to tapes' physical problems: trapped edges, stretched tape, and incorrect record made on old or low-quality video camera).

BR-D92E VTR by JVC is designed for operating and usage in production High-End studios. Obliquely opening front panel with built-in controller provides quick access to all functions. The penal contains all function regulations: encoders of four 16bit/48 kHz audio channels' levels (separate for recording and playback), tracking preset and control, menu control buttons, display counter. It is possible to use preview mode when operating with built-in controller (swap editing). Preroll time may be set within a range of 0...15 s.

Range of speed control in slow-motion playback mode makes -1/3x...+1/3x.

Access to corrector of time distortion provides phase control of subcarrier and video signal, level of video signal, phase and level of color signal.

Professional BR-D95E VTR of D9 format is a new model of JVC. In addition to stated above characteristics, it is equipped with temporary compression and extension function, allowing changing the tape's speed within +/-10% with audio tone height and picture frame frequency remaining the same. This function is indispensable for mastering, when it is necessary to save strictly the fixed duration of program.

Availability of standard control interfaces (RS-422 serial, 25-pin parallel, and RS-232 serial) and inputs/outputs allows using DVCPRO AJ-D850 by Panasonic in any studio configurations. The VTR features built-in two-machine edit controller; audio split marking keys; digital slow motion within the range of -0.43x ... +0.75x; recording two digital audio channels of 16 bit/48 kHz. The VTR plays tapes of DV, DVCAM format (mini is played using adapter).

AJ-D960 VTR by Panasonic is designed for operating in on-line mode and any other professional edit tasks, in particular, for employing in edit pairs controlled by own edit controller. It is capable of digital slow motion playback within the range of -1x...+2x relatively to normal speed. The VTR records and plays tapes of DVCPRO and DVCRPO 50 formats. It features 4 cleaning heads for edit operations of video and audio insert; recording of 4 digital audio channels of 16 bit/48 kHz; RS-422 and RS-232 control serial and 25-pin parallel interfaces.

Besides stated above professional VTR with built-in controllers, it is necessary to note semi-professional VTRs' models, having built-in edit controller. These are Panasonic AG-DV2700 and JVC SR-VS20.

AG-DV2700 VTR of DV format by Panasonic has built-in wireless two-machine controller, 5-pin and LANC control edit interfaces. A wide set of edit operations, such as split edit, assemble edit, is available.

SR-VS20 VTR by JVC differs from other recorders by the fact that there are two VTRs of different formats (S-VHS deck and DV deck) in one housing. Built-in controller allows performing assemble-type edit with the use of transition effects (from DV to S-VHS deck), insert-type simultaneous edit of video and audio from external VTR (only for S-VHS deck), insert-type edit of video from external VTR (for DV deck).

Era Company.