UK 405 line system + FR 819 line system : no videotape system ever existed for these formats?

[Steve Roberts]

UK 405 line system + FRENCH 819 line system : no videotape system ever
existed for these formats?

Sorry to jump onto the back of your post Martin, but the original
hasn't hit our server yet.

Yes, 405 line Ampex 2" quad existed and there are still loads of tapes
around. Until recently we were playing them out for archival purposes
on an Ampex VR2000 machine, via a modified timebase corrector and
aspect ratio converter to do the conversion from 405-->625.

Steve


The Doctor Who Restoration Team Website
http://www.restoration-team.co.uk

[Steve Roberts]

via a modified timebase corrector and aspect ratio converter
to do the conversion from 405-->625.

There is 5:4 aspect ratio material from after 1950 ?

The aspect ratio onverter was used to unsqueeze the image from the
modified TBC. The TBC basically wrote the 405 line frame into the top
of a 625 line framestore, then the ARC was used to correct the aspect
and position.

Steve

The Doctor Who Restoration Team Website
http://www.restoration-team.co.uk

[Phil]

Ampexes used a drum with four heads rotating vertically,

thus writing each frame in four slightly angled stripes as the tape ran
past it: the three joins were often just visible. (Modern machines use
^^^^^^^^^^^^^^^^^^^^^^^^^^^
the angled drum with two heads, the same principle as domestic video
recorders).

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Phil: NO - multi segmented tracks on ALL DIGITAL formats (and BCN
Format before them)

Phil: Each pass of the head only recorded 16 or 20 lines and the
characteristic features of 'quad banding' were velocity errors,
slant or scalloping: \ or ( or ) or / (corrected at the left edge each
line, but increasing to the right) due to head-tip penetration errors /
differences from the original recording, and last-line errors as these
couldn't be corrected because there wasn't another line to refer to (it
belonged to the next head every 16 or 20 lines) - this, seen in PAL-simple
showed as phase errors on the 16th/20th line.
Line by line correction of colour saturation etc came in with the AVR2
AMTEC then COLORTEC then VELOCITY corrector in VR2000s
The joins were visible - perhaps more so nowadays as those used to lining
them up are long gone to other employment.

There was also the Rank Cintel /IVC 9000 which was a 1.7" slant track
recording on 2" tape - used at Birmingham and other distant places 8-)

[Steve Roberts]

On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

You couldn't record 405 line on a 625 line recorder, it wouldn't work,
there were no domestic 405 line VCR's made (it was too early) but
commercial machines were available.

Au contraire on both counts, Nigel!

You most certainly can record and replay 405 line TV on a domestic 625
line VHS, because I've done it! The field period is 20mS on both
formats, so the rotary heads spin at the same speed. The VHS doesn't
mind how many lines are included in that period.

There were domestic 405 line reel-to-reel VTR's - the Sony CV2000
being the most well-known and popular one. You could buy a matching
monitor and camera for it, to allow you to go out and shoot your own
videos.

The BBC originally used to convert
between standards (405/525/625) by playing it back on a monitor and
recording from a camera aimed at the monitor.

That was true of very early 525/625 conversions, but not 405/625, as
this could be done using simple electronic line stores and averaging,
even in the early days.

Steve


The Doctor Who Restoration Team Website
http://www.restoration-team.co.uk

[Martin Underwood]

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

You couldn't record 405 line on a 625 line recorder, it wouldn't work,
there were no domestic 405 line VCR's made (it was too early) but
commercial machines were available.

Au contraire on both counts, Nigel!
You most certainly can record and replay 405 line TV on a domestic 625
line VHS, because I've done it! The field period is 20mS on both
formats, so the rotary heads spin at the same speed. The VHS doesn't
mind how many lines are included in that period.

Exactly the point that I was making: I'm glad someone's come to my defence
and convinced me that I wasn't making it up!

Post by Steve Roberts
There were domestic 405 line reel-to-reel VTR's - the Sony CV2000
being the most well-known and popular one. You could buy a matching
monitor and camera for it, to allow you to go out and shoot your own
videos.

I remember this: I think it recorded on 1/4" audio tape - it certainly
*looked* narrower than 1/2" VHS tape, but I could be wrong. The VCR had a
very obvious circular cover over the head, with a semi-circular guide around
which the tape was wrapped. Stability of the picture was atrocious: at best
the picture wobbled and shimmered - and if you breathed on the VCR (let
alone jogging it or carrying it), the picture broke up completely.

Post by Steve Roberts

The BBC originally used to convert
between standards (405/525/625) by playing it back on a monitor and
recording from a camera aimed at the monitor.

That was true of very early 525/625 conversions, but not 405/625, as
this could be done using simple electronic line stores and averaging,
even in the early days.

That must have resulted in *horrible* moire fringes and 5 Hz flicker. I'm
too young to remember it being done - I presume nowadays that if any very
old 525 material is shown, it is converted a lot more professionally so one
would never see the effect nowadays.

Was there a simple relationship between the number of active lines for 405
and 625? Certainly 405/625 isn't a simple fraction. I'm not sure how many
active lines the 405 system had.

[R. Mark Clayton]

Post by Martin Underwood

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin
There were domestic 405 line reel-to-reel VTR's - the Sony CV2000
being the most well-known and popular one. You could buy a matching
monitor and camera for it, to allow you to go out and shoot your own
videos.

Yes I recall this from 1978. It was helical scan, but reel to reel.

Post by Martin Underwood
I remember this: I think it recorded on 1/4" audio tape - it certainly
*looked* narrower than 1/2" VHS tape, but I could be wrong. The VCR had a
very obvious circular cover over the head, with a semi-circular guide around
which the tape was wrapped.

IIRC the tape was ~1cm. The semi-circiular guide contained the slot thtough
which the rotating head scanned the tape.

Post by Martin Underwood
Stability of the picture was atrocious: at best
the picture wobbled and shimmered - and if you breathed on the VCR (let
alone jogging it or carrying it), the picture broke up completely.

Don't remember this rom camera te picture was quite stable.
snip

Post by Martin Underwood
Was there a simple relationship between the number of active lines for 405
and 625? Certainly 405/625 isn't a simple fraction. I'm not sure how many
active lines the 405 system had.

Probably not all the 625 have picture on them.

[Martin Underwood]

Post by R. Mark Clayton

Post by Martin Underwood

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

Was there a simple relationship between the number of active lines for 405
and 625? Certainly 405/625 isn't a simple fraction. I'm not sure how many
active lines the 405 system had.

Probably not all the 625 have picture on them.

No, I realise that - which is why I said *active* lines. I've since heard
that the number of active lines for the 405 system was 377. And I know that
for the 625 system it's 575. But neither 405/625 nor 377/575 is a nice round
fraction, which suggests that the averaging algorithm must have been
horrendous.

[Stephen]

Post by Martin Underwood

Post by R. Mark Clayton

Post by Martin Underwood

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

Was there a simple relationship between the number of active lines for
405 and 625? Certainly 405/625 isn't a simple fraction. I'm not sure
how many active lines the 405 system had.

Probably not all the 625 have picture on them.

No, I realise that - which is why I said *active* lines. I've since heard
that the number of active lines for the 405 system was 377. And I know
that for the 625 system it's 575. But neither 405/625 nor 377/575 is a
nice round fraction, which suggests that the averaging algorithm must have
been horrendous.

I thought the ratio was a simple 3 to 2, with 575 active lines in, 383
active lines out, and the excess lines blanked. The loss of a few lines
would not have been noticeable and would have made for a simple 3 to 2
electronic line store converter. I guess they stored 2 lines, dropped every
3rd line, and dropped an extra line, about 10 times per frame, whenever the
store would have overflowed. There would have been only 372 active lines on
the output because 625 has longer field blanking than 405, so there would
not have been any picture information in the line stores to fill any more
lines than this on the output side.

[Paul Sherwin]

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

The BBC originally used to convert
between standards (405/525/625) by playing it back on a monitor and
recording from a camera aimed at the monitor.

That was true of very early 525/625 conversions, but not 405/625, as
this could be done using simple electronic line stores and averaging,
even in the early days.

IIRC the RTE electronic standards converter blew up towards the end of
the 405 era in Ireland, and they ran for a couple of years in the 70s
with a 405 camera pointed at a 625 monitor. Of course, few people were
actually watching the 405 signal by then.

Best regards, Paul
--
Paul Sherwin Consulting http://paulsherwin.co.uk

[Andrew Morrison]

Post by Paul Sherwin

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

The BBC originally used to convert
between standards (405/525/625) by playing it back on a monitor and
recording from a camera aimed at the monitor.

That was true of very early 525/625 conversions, but not 405/625, as
this could be done using simple electronic line stores and averaging,
even in the early days.

IIRC the RTE electronic standards converter blew up towards the end of
the 405 era in Ireland, and they ran for a couple of years in the 70s
with a 405 camera pointed at a 625 monitor. Of course, few people were
actually watching the 405 signal by then.
Best regards, Paul
--
Paul Sherwin Consulting http://paulsherwin.co.uk

So, if the french secam system had 819 lines over the UK's 405 - over
double - then wouldn't have the quality been great ?

[Stephen Neal]

Andrew Morrison wrote:
[snip]

Post by Andrew Morrison
So, if the french secam system had 819 lines over the UK's 405 - over
double - then wouldn't have the quality been great ?

This wasn't SECAM - AIUI SECAM was/is the line sequential FM based
subcarrier colour system. (Sequential Couleur Avec Memoire - Sequential
colour with memory)

I expect the 819 system could have been good in picture quality terms live -
it had a wide vision bandwith? - but I suspect any Quad VTR designed to
operate on it must have softened it a bit?

Steve

[Andrew Morrison]

Post by Stephen Neal
[snip]

Post by Andrew Morrison
So, if the french secam system had 819 lines over the UK's 405 - over
double - then wouldn't have the quality been great ?

This wasn't SECAM - AIUI SECAM was/is the line sequential FM based
subcarrier colour system. (Sequential Couleur Avec Memoire - Sequential
colour with memory)
I expect the 819 system could have been good in picture quality terms live -
it had a wide vision bandwith? - but I suspect any Quad VTR designed to
operate on it must have softened it a bit?
Steve

Of course SECAM wasn't in use then - your right. SECAM was developed for
colour. D'oh !

[PeterW]

Post by Stephen Neal

Post by Stephen Neal
[snip]

Post by Andrew Morrison
So, if the french secam system had 819 lines over the UK's 405 - over
double - then wouldn't have the quality been great ?

This wasn't SECAM - AIUI SECAM was/is the line sequential FM based
subcarrier colour system. (Sequential Couleur Avec Memoire - Sequential
colour with memory)
I expect the 819 system could have been good in picture quality terms

live -

Post by Stephen Neal
it had a wide vision bandwith? - but I suspect any Quad VTR designed to
operate on it must have softened it a bit?
Steve

Of course SECAM wasn't in use then - your right. SECAM was developed for
colour. D'oh !

I remember seeing 819 back in the '70s in France. It was a very fine
quality picture but I think rather prone to interference as everything
(sound & vision) was AM (perhaps even double-sideband I think!) and IIRC it
was positive modulation like 405-line in the UK, so car-ignition
interference was white spots unlike System-I 625 where the vision
modulation is negative (black interference) with FM sound.

The TV had a big changeover switch for 625, like the dual-standard 625/405
Bush sets in Ireland in the 60's.

Peter

[Stephen Neal]

Post by PeterW

Post by Stephen Neal

Post by Stephen Neal
[snip]

Post by Andrew Morrison
So, if the french secam system had 819 lines over the UK's 405 - over
double - then wouldn't have the quality been great ?

This wasn't SECAM - AIUI SECAM was/is the line sequential FM based
subcarrier colour system. (Sequential Couleur Avec Memoire - Sequential
colour with memory)
I expect the 819 system could have been good in picture quality terms

live -

Post by Stephen Neal
it had a wide vision bandwith? - but I suspect any Quad VTR designed to
operate on it must have softened it a bit?
Steve

Of course SECAM wasn't in use then - your right. SECAM was developed for
colour. D'oh !

I remember seeing 819 back in the '70s in France. It was a very fine
quality picture but I think rather prone to interference as everything
(sound & vision) was AM (perhaps even double-sideband I think!) and IIRC it
was positive modulation like 405-line in the UK, so car-ignition
interference was white spots unlike System-I 625 where the vision
modulation is negative (black interference) with FM sound.

Yep - and the French still use positive modulation and AM sound (though now
joined by NICAM I believe) for their SECAM L transmissions!

I suspect that by the 70s production was in 625 lines with conversion to 819
lines taking place at the transmitter?

Steve

[John]

Post by PeterW
I remember seeing 819 back in the '70s in France. It was a very fine
quality picture but I think rather prone to interference as everything
(sound & vision) was AM (perhaps even double-sideband I think!) and IIRC it
was positive modulation like 405-line in the UK, so car-ignition
interference was white spots unlike System-I 625 where the vision
modulation is negative (black interference) with FM sound.

Looking through an old TV Engineering book.

System E
Line Numbers = 819
Overall channel bandwidth = 14 MHz.
Vision Bandwidth = 10 MHz.
Sound to Vision spacing = 11.15 MHz.
Vision Modulation = Positive.
Sound Modulation = AM.

Two channel in Band I and nine in Band III which were interlaced.

John

[James Follett]

X-No-Archive: yes

Post by Andrew Morrison
So, if the french secam system had 819 lines over the UK's 405 - over
double - then wouldn't have the quality been great ?

It was, but many French got pissed off with the need for two TV sets in
their living rooms.

[The Technical Manager]

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

You couldn't record 405 line on a 625 line recorder, it wouldn't work,
there were no domestic 405 line VCR's made (it was too early) but
commercial machines were available.

Au contraire on both counts, Nigel!
You most certainly can record and replay 405 line TV on a domestic 625
line VHS, because I've done it! The field period is 20mS on both
formats, so the rotary heads spin at the same speed. The VHS doesn't
mind how many lines are included in that period.

Older VHS video recorders can handle 405 line material with few problems.
The Ferguson Videostars or their JVC equivalents are good choices. Around
1988 there were changes in circuitry that prevent them from properly
recording and playing back of 405 line material. Possibly something to do
with Macrovision.

Post by Steve Roberts
There were domestic 405 line reel-to-reel VTR's - the Sony CV2000
being the most well-known and popular one. You could buy a matching
monitor and camera for it, to allow you to go out and shoot your own
videos.

I am sure that there was a VHS video recorder from the late 1970s that
could be used to record both 405 and 625 line broadcasts and playback to
both 405 and 625 line TVs.

[Stephen Neal]

Post by The Technical Manager

Post by Steve Roberts
On Tue, 8 Jul 2003 13:11:24 +0100, Nigel Goodwin

You couldn't record 405 line on a 625 line recorder, it wouldn't work,
there were no domestic 405 line VCR's made (it was too early) but
commercial machines were available.

Au contraire on both counts, Nigel!
You most certainly can record and replay 405 line TV on a domestic 625
line VHS, because I've done it! The field period is 20mS on both
formats, so the rotary heads spin at the same speed. The VHS doesn't
mind how many lines are included in that period.

Older VHS video recorders can handle 405 line material with few problems.
The Ferguson Videostars or their JVC equivalents are good choices. Around
1988 there were changes in circuitry that prevent them from properly
recording and playing back of 405 line material. Possibly something to do
with Macrovision.

Don't think it was related to Macrovision - I think it was the introduction
of VHS HQ. This uses line-delay techniques to "improve" the picture - and
as they line lengths are different in 405 and 625 it doesn't cope with 405
at all well. Personally I'm not sure HQ improves decent recordings at all -
it just seems to add artifical ringing-style edge... Certainly some of the
best pictures I have seen from a VHS VCR were recorded on an early 80s
Hitachi machine (first generation with electronic rather than piano key
controlled transport?) I suspect build quality and specs were higher then
(but then the machines cost massively more in relative terms?)

Even non-HQ VHS machines had problems with 405 recordings with drop out - as
the drop-out comps in VHS machines were based on line-delays (designed for
625 line recordings) Therefore drop-out comps made 405 recordings worse not
better. (I think 405 enthusiasts either use high quality tapes or disable
the DOCs on their VCRs?)

I wonder if anyone has produced a Video CD style MPEG recorder for 405 lines
? With more data available (no colour content) it could look quite good?


Steve

[Laurence Taylor]

[Newsgroups trimmed]

The only old VHS machine I saw that would have had trouble with different
line standards was a half inch reel-to-reel in the early 70s that a friend

VHS? Reel-to-reel??

bought a load of and was trying to sell because they were cheap. Turned out
that they only recorded one field and played it back twice by using a half
line dihedral offset, i.e. a physical offset from 180deg of the two video
heads. I think it had been made for 405 and would have needed a mechanical
modification for 625, hence the "bargain price".

I've never had trouble with 405-line recordings on VHS (apart from the
dropout compensator), but I believe that some old r-r machines (and, I
think, U-matic) used the line sync as a reference oscillator, so the
wrong line speed might have some strange results.

Of course, the old Philips 1500-series recorders would record
anything, as in the absence of decent sync, it locked to the mains!

rgds
LAurence

... "Bother" said Pooh, when Windows crashed again
begin the search for better software

[Ed Ellers]

Roderick Stewart wrote:

"The only old...machine I saw that would have had trouble with different
line standards was a half inch reel-to-reel in the early 70s that a friend
bought a load of and was trying to sell because they were cheap. Turned out
that they only recorded one field and played it back twice by using a half
line dihedral offset, i.e. a physical offset from 180deg of the two video
heads."

That was a common trick on 1/2" open-reel VTRs. The ill-fated Cartrivision
system in the U.S. was even worse -- it recorded one field out of *three,*
for a resulting frame rate of 20 fps. (The artifacting must have been
sickening when the source material was film, or converted PAL video for that
matter.)

[Roderick Stewart]

Post by Laurence Taylor

The only old VHS machine I saw that would have had trouble with different
line standards was a half inch reel-to-reel in the early 70s that a friend

VHS? Reel-to-reel??

OK, it was late, I was tired, I was thinking "helical scan" and wrote "VHS".

Rod.