TV Home Forum

The TV Question Amnesty Thread

A thread to ask questions about things you want to know about television but were too afraid to ask (March 2019)

This site closed in March 2021 and is now a read-only archive
SC
Si-Co
Inspired by discussion in the ITV Strike thread:

Various “ VT machines” and types of tape have been mentioned. Can anyone explain briefly, or confirm that the 1” or 2” “tapes” mentioned were “reels” that were stored in a round case? And BetaSP/BetaCam resembled more closely a home video cassette that was loaded differently onto a machine? Just a brief layman’s explanation needed about what was what.

When a programme was recorded on VT instead of film did the various cameras link up to a VT machine that recorded the output onto a reel-style tape. Were smaller tapes ever used (that fitted into a camera) for say, a news report footage or interviewing people in the street, where it wasn’t practical to have an OB truck?

Also - comparing professional tapes with home VHSs etc, the tapes used didn’t seem to suffer damage from constant/repetitive rewinding/FFing of a particular segment the way a VHS would. VHS tapes didn’t seem to like you constantly rewatching a favourite scene - Interference would appear as if the tape had became creased/damaged.

I know there are examples of archive shows suffering dropouts and “sound lines” etc over time, but I doubt this is the same thing.
PP
Po6xyPop77
Which continuity announcer on a UK PSB has lasted the longest?
MA
Markymark
Si-Co posted:
Inspired by discussion in the ITV Strike thread:

Various “VT machines” and types of tape have been mentioned. Can anyone explain briefly, or confirm that the 1” or 2” “tapes” mentioned were “reels” that were stored in a round case? And BetaSP/BetaCam resembled more closely a home video cassette that was loaded differently onto a machine? Just a brief layman’s explanation needed about what was what.



1 and 2 inch (or Quad, short for Quadaplex) VTRs were indeed open reel formats. The Quad machines were huge, and ran on compressed air (for the tape guiding)

Quad
https://www.youtube.com/watch?v=zHDU1wXw1sU

1 inch
https://www.youtube.com/watch?v=ZCLpNvBwHsM

From the late 70s, tape cassette formats started to appear, U-Matic
was used for news gathering. This used 3/4 inch tape, quality was poor,
so was not used (in the UK) for anything other than news.

From the early to mid 80s, BetaCam was used. This used exactly the same 1/2 inch
tape cassettes as the domestic BetaMax format, but that's where any similarities ended.
It used a component recording system (keeping colour and b/w signals separated) which greatly
increased the quality. Still only used for news. BetaCam SP came along in the late 80s, and that started to be used for non news. In 1993 Digital BetaCam was launched, that used 2:1 ish compression. During the late 80s/ early 90s other digital tape formats were launched, D2, D3, D5, which were used, but DigiBeta became the most widely used.

Further info
http://www.tech-notes.tv/Standards-Practices/TVTapeformats.htm

And the various flavours of Betacam
https://en.wikipedia.org/wiki/Betacam

Si-Co posted:

When a programme was recorded on VT instead of film did the various cameras link up to a VT machine that recorded the output onto a reel-style tape. Were smaller tapes ever used (that fitted into a camera) for say, a news report footage or interviewing people in the street, where it wasn’t practical to have an OB truck?



The key term is PSC production. Portable Single Camera. In the 70s, there were some productions made this way, mostly a single video camera, feeding into a portable VTR. This developed into the 90s using single camcorders, predominately DigiBeta

Si-Co posted:
Also - comparing professional tapes with home VHSs etc, the tapes used didn’t seem to suffer damage from constant/repetitive rewinding/FFing of a particular segment the way a VHS would. VHS tapes didn’t seem to like you constantly rewatching a favourite scene - Interference would appear as if the tape had became creased/damaged.


The tapes were higher quality, and designed with that sort of use in mind. Also the tape transport systems in professional VTRs were also designed for that use, but ultimately, yes, you could wear the tape out
IS
Inspector Sands
Yes, I remember a standby tape for a daytime programme that was loaded and cued every day just in case. Eventually the heads wore a hole in the oxide at the cue point. The biggest issue with damaged tapes wasn't so much the damage to the tape but the debris it left as it passed the heads - 'head clog'

The other big difference between VHS and broadcast videotape was that once digital tape came along so did error correction. It then took a heck of a lot of tape damage or a massively clogged head to cause picture disturbance as the machine could work out what data was missing. It also gave you an indication of what errors it was encountering. The D3 tape format had a nice graphical display showing you the strength and quality of the video signal and level of errors to fret over while the tape was playing out on air
MA
Markymark
Yes, I remember a standby tape for a daytime programme that was loaded and cued every day just in case. Eventually the heads wore a hole in the oxide at the cue point. The biggest issue with damaged tapes wasn't so much the damage to the tape but the debris it left as it passed the heads - 'head clog'


Yes, and that would effectively 'kill' the VTR, until the clog was removed, usually by getting inside and manually cleaning it. There were lightly abrasive cleaning tapes for cassette based VTRs, to be used very sparingly that could clear a head clog, but better to open up, and deal with it manually.
SP
Steve in Pudsey
Apparently the first track on Radio 2's emergency DAT (Red Light Spells Danger Smile) used to come up on the playlist occasionally.

It was possible to tell the difference by a load a drop out at the beginning on the emergency DAT from where it had been sat cued up for months and the oxide was falling off the tape.
Inspector Sands and Night Thoughts gave kudos
MA
Markymark
Apparently the first track on Radio 2's emergency DAT (Red Light Spells Danger Smile) used to come up on the playlist occasionally.

It was possible to tell the difference by a load a drop out at the beginning on the emergency DAT from where it had been sat cued up for months and the oxide was falling off the tape.


I'm quite sure that DAT decks would spin the head drum down, if left in pause/standby for more than a <user definable> period ?
SP
Steve in Pudsey
That was from no less an authority than Charles Nove commenting on a John Myers blog post that I can't immediately find
HC
Hatton Cross
Apparently the first track on Radio 2's emergency DAT (Red Light Spells Danger Smile) used to come up on the playlist occasionally.

It was possible to tell the difference by a load a drop out at the beginning on the emergency DAT from where it had been sat cued up for months and the oxide was falling off the tape.


I'm quite sure that DAT decks would spin the head drum down, if left in pause/standby for more than a <user definable> period ?


Yes it was 15 minutes at my place. I was caught out by that occasionally.

I once put a new DAT cassette in the deck on Rec/Pause at 1.30pm to record the first hour of tx at 2 for logging/snoop purposes. 1.59pm unpaused tape, starts tech opping show. Checks at 2.35 during 2nd commercial break set, mouth dry when I see the counter time LCD on front of DAT machine still displaying 'Time elapsed 00:00'. Causally asks duty engineer, and 'oh yeah. The heads retract if paused for longer than 15 minutes' Confused
SP
Steve in Pudsey
Quote:

Charles Nove
July 31, 2013

For some years, the first up on Radio 2′s emergency DAT was Kenny and Dolly doing Islands In the Stream. The astute listener could tell if it was just a casual play of the song or the DAT by whether the first few seconds were full of digital glitches from where the DAT had been laced up so long the oxide was falling off the tape!

https://web.archive.org/web/20130809171051/http://myersmedia.co.uk/2013/first-song-on-a-back-up-tape/
JA
james-2001
I'm sure I've heard before, on some stations at least, once you have the backup tape playing it can be tricky to get it to go off.
MA
Markymark
Quote:

Charles Nove
July 31, 2013

For some years, the first up on Radio 2′s emergency DAT was Kenny and Dolly doing Islands In the Stream. The astute listener could tell if it was just a casual play of the song or the DAT by whether the first few seconds were full of digital glitches from where the DAT had been laced up so long the oxide was falling off the tape!

https://web.archive.org/web/20130809171051/http://myersmedia.co.uk/2013/first-song-on-a-back-up-tape/


It wouldn't have done the tape much good to be sat in the machine, laced up, with or without the head drum spinning, so there's plenty of validity in that story.

Newer posts