CMX 600
Encyclopedia
The CMX 600 was the very first non-linear video editing system
. It was introduced in 1971 by CMX Systems
, a joint venture between CBS
and Memorex
. CMX referred to it as a "RAVE", or Random Access Video Editor.
The 600 had a console with 2 black & white monitors built in, as well as a light pen
used to control the system. The right monitor, which played the preview video, was used by the editor to make cuts and edit decisions, by using the light pen to select from options which were superimposed as text over the preview video. The left monitor was used to display the edited video.
It recorded and played back black-and-white "skip-field
" video in analog on specially modified disk pack
drives (supplied by Memorex, and which were commonly used to store data digitally on mainframe computers of the time) that were the size of washing machines. The audio was recorded digitally using PCM, and was recorded by being inserted in the "back porch" of the horizontal blanking interval pulses of the video. This audio was somewhat poor, due to a large amount of jitter
occurring from the signal being played back from the disk packs. The video was also of less than stellar quality, due to it being recorded in skip-field mode (which was done to extend recording time on the disk packs). But all of this did not matter, since the 600's main purpose was solely for off-line editing, in order to create an Edit Decision List
(EDL) for later on-line editing.
The 600 was paired with the CMX-200, which took the EDL information from the 600, and used it to control several VTRs to auto-assemble the video program in the on-line editing stage. The 200 used a Teletype
Model 33 ASR terminal to input EDL information.
The editing console was interfaced to two equipment racks
of support equipment (which were usually located remotely in another room from the console). The first rack contained the interface electronics for the system, monitoring equipment, and a Digital
PDP-11
minicomputer
with 32 kilobytes of RAM, which controlled the system. The second rack contained all the audio & video electronics, and the "Skip-Field Recorder", which took in video & audio for editing from a VTR
, and then recorded such to one or several disk pack drives interfaced to the 600. The CMX 600 could support up to six disk pack drives, for a total recording time of 27 minutes. Each disk pack could record up to 5.4 minutes of NTSC
video, or 4.5 minutes of PAL
video.
The CMX 600 was a system quite ahead of the technology of the time, and was quite expensive, costing about $250,000 USD at its introduction. About 6 systems were manufactured, and were used to edit several television shows and commercials.
Non-linear editing system
In video, a non-linear editing system is a video editing or audio editing digital audio workstation system which can perform random access non-destructive editing on the source material...
. It was introduced in 1971 by CMX Systems
CMX Systems
CMX Editing Systems was a company founded jointly by CBS and Memorex, that developed some of the very first computerized systems for linear and non-linear editing of videotape for post production...
, a joint venture between CBS
CBS
CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...
and Memorex
Memorex
Memorex began as a computer tape producer and expanded to become a major IBM plug compatible peripheral supplier. It is now a consumer electronics brand of Imation specializing in disk recordable media for CD and DVD drives, flash memory, computer accessories and other electronics.Established in...
. CMX referred to it as a "RAVE", or Random Access Video Editor.
The 600 had a console with 2 black & white monitors built in, as well as a light pen
Light pen
A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy...
used to control the system. The right monitor, which played the preview video, was used by the editor to make cuts and edit decisions, by using the light pen to select from options which were superimposed as text over the preview video. The left monitor was used to display the edited video.
It recorded and played back black-and-white "skip-field
Skip field
In video, skip field recording is a process in which only one field of video is recorded in order to conserve recording media space. For some kinds of recording, the quality loss of not using both fields of video is fairly negligible, it results in the loss of half of possible vertical video...
" video in analog on specially modified disk pack
Disk pack
A Disk pack is a layered grouping of hard disk platters . A disk pack is the core component of a hard disk drive. In modern hard disks, the disk pack is permanently sealed inside the drive...
drives (supplied by Memorex, and which were commonly used to store data digitally on mainframe computers of the time) that were the size of washing machines. The audio was recorded digitally using PCM, and was recorded by being inserted in the "back porch" of the horizontal blanking interval pulses of the video. This audio was somewhat poor, due to a large amount of jitter
Jitter
Jitter is the undesired deviation from true periodicity of an assumed periodic signal in electronics and telecommunications, often in relation to a reference clock source. Jitter may be observed in characteristics such as the frequency of successive pulses, the signal amplitude, or phase of...
occurring from the signal being played back from the disk packs. The video was also of less than stellar quality, due to it being recorded in skip-field mode (which was done to extend recording time on the disk packs). But all of this did not matter, since the 600's main purpose was solely for off-line editing, in order to create an Edit Decision List
Edit decision list
An edit decision list or EDL used in the post-production process of film editing and video editing. The list contains an ordered list of reel and timecode data representing where each video clip can be obtained in order to conform the final cut....
(EDL) for later on-line editing.
The 600 was paired with the CMX-200, which took the EDL information from the 600, and used it to control several VTRs to auto-assemble the video program in the on-line editing stage. The 200 used a Teletype
Teletype Corporation
The Teletype Corporation, a part of American Telephone and Telegraph Company's Western Electric manufacturing arm since 1930, came into being in 1928 when the Morkrum-Kleinschmidt Company changed its name to the name of its trademark equipment...
Model 33 ASR terminal to input EDL information.
The editing console was interfaced to two equipment racks
19-inch rack
A 19-inch rack is a standardized frame or enclosure for mounting multiple equipment modules. Each module has a front panel that is wide, including edges or ears that protrude on each side which allow the module to be fastened to the rack frame with screws.-Overview and history:Equipment designed...
of support equipment (which were usually located remotely in another room from the console). The first rack contained the interface electronics for the system, monitoring equipment, and a Digital
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
with 32 kilobytes of RAM, which controlled the system. The second rack contained all the audio & video electronics, and the "Skip-Field Recorder", which took in video & audio for editing from a VTR
Video tape recorder
A video tape recorder is a tape recorder that can record video material, usually on a magnetic tape. VTRs originated as individual tape reels, serving as a replacement for motion picture film stock and making recording for television applications cheaper and quicker. An improved form included the...
, and then recorded such to one or several disk pack drives interfaced to the 600. The CMX 600 could support up to six disk pack drives, for a total recording time of 27 minutes. Each disk pack could record up to 5.4 minutes of NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
video, or 4.5 minutes of PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
video.
The CMX 600 was a system quite ahead of the technology of the time, and was quite expensive, costing about $250,000 USD at its introduction. About 6 systems were manufactured, and were used to edit several television shows and commercials.
External links
- A page about the CMX 600, with a demo video available for viewing (Archived copy from archive.org)
- (The demo video mentioned in the above link, on YouTube)