Quadruplex Videotape - Edit Control

Edit Control

• At first, editing was accomplished by physically cutting and splicing the 2" magnetic tape. The tape was "developed" using fine iron powder suspended in a liquid solvent, a solution marketed as "Edivue" Magnetic Developer. Using a special splicing block (such as the then-industry standard "Smith Splicer") equipped with a microscope to view the developed tracks, the editor could then see their patterns and then cut between them. Some 2" splicing blocks instead used a read-only tape head connected to an oscilloscope that enabled the editor to electronically view cue tones or the control track pulses on the tape to determine where the tape should be cut. See linear video editing for details.
• Ampex developed its breakthrough Editec system in 1963; by recording cue tones on the tape, the editor could make frame-accurate edits.
• RCA had an "Electronic Splicer" in their TR-4/5 and TR-22 VTRs for frame-accurate edits.
• In 1967, EECO created and introduced the EECO-900 edit controller, which used their proprietary "On-Time" time code (the later and more standard SMPTE time code had not yet been developed), which was used in conjunction with the Quad machines of the time, and was the successor to Ampex's Editec. The EECO-900 and "On-Time" timecode were developed from EECO's previous work and products developed for NASA for logging and timecoding of their telemetry tapes during space missions.
• In 1971, CMX, a collaborative between CBS and Memorex, introduced the first computer-based edit controller using SMPTE time code for editing. The CMX 200 could control both the source (A-roll) and record (B-Roll) Quad VTRs. CMX continued to make more powerful edit controllers capable of controlling more VTRs and peripheral devices, such as switchers, DVEs and character generators.
• In 1976, Robert Bosch GmbH introduced the "Mach One" list-management edit controller, a lower-cost (and less powerful) post-production alternative to CMX edit controllers. At the time, both CMX and Bosch edit controllers utilized similar DEC computers as their basic hardware.
• As 1" Type B and 1" Type C VTRs came on the market, list-management editing bays sometimes used a combination of both 1" and 2" VTRs; however, 2" VTRs soon began to disappear from both broadcast and post-production facilities, as the newer 1" machines were smaller, more dependable, used tape that was far less expensive to purchase, and were capable of recording stereo audio tracks.