Film and TV Technician (1957)

264 FILM & TV TECHNICIAN May 1958 TED LANGLEY Senior Cameraman B.B.C. Television Service introduces VERA 'yHE latest addition to the B.B.C. * Recording Equipment, the Video Electronic Recording Apparatus, VERA for short, is being installed at Lime Grove and will be ready for service very soon. A demonstration was given on Panorama on Monday, April 14th, the vision signals being recorded on the prototype apparatus at the B.B.C.'s Research Department at Nightingale Square. Normally Telerecordings are done by filming the picture from a Cathode Ray Tube. The film is then sent to the Laboratories in the usual way for processing. This takes anything up to twenty-four hours for urgent prints. If the film is topical and urgently required the negative can be used for transmission and phasereversal applied in the video channel. By using magnetic tape, this can be recorded and transmitted in a few minutes, in other words, in the time it takes to re-wind the tape back to the start position. For News and programmes like Panorama and Sportsview VERA is a Godsend. The tape travels through the heads at 200 inches per second or 1,000 feet per minute and the runup time is approximately twenty seconds. It is possible to monitor vision and sound whilst recording is in progress. Twenty-thousand feet reels are used which give nearly twenty minutes recording. Three tracks are used on i-inch un-sprocketed tape. Of these, two are for vision and one for sound. The video waveform ( picture i is divided into two frequency bands, one frequency band per track. It is believed that the upper frequency band is heterodyned to produce a lower band of frequencies for easier recording. This would be converted back to the original frequency band on reproduction. Magnetic tape can be wiped and used again and again and as there is no processing involved the cost of recording a programme on VERA is much less than a recording on film. Contributions to or from Eurovision are catered for by the converter at Swingate, which consists of a display (TV cathode ray tube) with a static Television camera working at the required line frefrequency focused on it. Programmes recorded on VERA could only be offered abroad via this facility. In other words, the tape cannot be sent abroad for transmission by a foreign station. Even if the foreign station had a VERA, they would still need a converter to convert the recording to their own line frequency. Therefore, programmes recorded on VERA would have to be transferred to film for sale abroad. Ampex System It might be interesting to mention the Ampex system which is used in the U.S.A. This uses a slow tape speed and a system of rotating heads which lay the recorded video information across, rather than along, the tape. A drawback of this system is that the same heads must be used for recording and playback. VERA recordings are not bound by this critical requirement. Magnetic tape cannot be stored for long periods without gradual loss of the higher frequencies and there is also the possibility of print-through. Great care must be exercised at all times to keep the tape away from magnetic fields such as generators, etc. Full technical information on editing is not yet available. In the case of a play being recorded there are sometimes a few re-takes necessary after transmission has taken place, due, perhaps, to an artist fluffing lines, someone making a noise, a cameraman, producer or sound mixer making an operational error. This necessitates editing but this presents no problems with film. Editing high speed tape, however, would appear to present some problems and would require a high degree of concentration, probably behind locked doors ! It could be done by wiping the faulty sequences, but what is there to guarantee that the retake time is exactly that of the original and will fit perfectly the wiped portion? Also, although the recording can be monitored during editing and the wipe switch pressed at the correct moment, there will be nothing on the monitor to indicate when to release the wipe key at the end of the sequence, with the consequent danger of wiping beyond the required point. Editing by transfer of essential material to another machine, stopping at the point of retake, doing the retake on the transfer machine, then carrying on with the transfer from the original machine, might appear to be a solution. Unfortunately, synchrnisation of the two machines would be absolutely essential and this would be virtually impossible because the run-up time varies. Cutting and Joining Cutting and joining would be the best method, using a frequency blip above the audio range superimposed on the sound track to mark the splicing point. This blip would be heard as a whistle when the tape was played back slowly. The splice would probably cause a change of syncs on transmission which would be visible as a momentary line twitter or a frame roll but this would not be serious. It remains to be seen whether eventually all telerecordings will be done on VERA. I do not think so because material for archives or other similar requirements will onlj retain its original quality over tin' years if done on film, and programmes for sale abroad also need to be done on film for reasons already given.