In message <5b28be12a5charles@candehope.me.uk> at Fri, 26 Jan 2024
12:00:06, charles <charles@candehope.me.uk> writes
In article <l1hed2Fg967U1@mid.individual.net>,[]
John Williamson <johnwilliamson@btinternet.com> wrote:
Quad head video is very intolerant of incorrect tape speed, so even
slight corruption of the sync pulses will cause all sorts of problems.
This is why it can not be used for things like still frames and slow
motion.
Not quite true. BBC Designs Dept developed a slow motion facility for quad >machines. It was used in the 1966 World Cup coverage
I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?
On 25/01/2024 18:08, J. P. Gilliver wrote:
https://www.youtube.com/watch?v=dCOcmGyqnLU - 2:51 in.
Banded into about four horizontal, fairly static bars. And then briefly
at the end of the bad patch - about 3:05 - a large number of bars.
The show is 1978, so I presume well after 2" formats were in general
use; of course, who knows what it's been stored on subsequently. Audio solid throughout.
Not being in the profession, I can't really guess - other than that I
can't think of any mechanism whereby this distortion could have come
from a domestic machine. (Though from the bandwidth, I think it's been stored on one at the final level - though one in excellent condition.)
Quad tape was in regular use until the mid 1980s, and the four bars are
a common fault. Somebody will likely be along shortly to explain how it happened here.
The recording has also been through a domestic system, probably VHS,
which has left the trademark noise bar from a poorly aligned machine or
dirt on the head drum at the bottom of the picture. That may also be
where the total breakdown of the picture into noise bars came from, indicating that the edge of the tape may have been damaged, causing loss
of sync.
In message <l1hi0vFgv3vU1@mid.individual.net> at Fri, 26 Jan 2024
11:06:07, John Williamson <johnwilliamson@btinternet.com> writes
On 26/01/2024 10:59, J. P. Gilliver wrote:
Wow, that's quite fast! I can see that it will indeed cross many tracks, >> if it gets to a poor speed (or stops).
I've just seen the typo. Early machines ran at 15 ips, later ones at 7.5.
In message <l1h7ilFeuknU1@mid.individual.net> at Fri, 26 Jan 2024
08:07:50, John Williamson <johnwilliamson@btinternet.com> writes
On 25/01/2024 21:10, J. P. Gilliver wrote:
ss of sync.
Just before or after the noise, there were multiple picture bars - 10 to >> 13 I would say.
As the sync pulses degrade, the rest of the circuitry tries to keep
things running, then gives up until the pulses come back. You can see
the start of the breakup as the colour problems get worse, and the
image starts breaking up inside each bar. My guess would be damage to
the edge of the quad tape due to poor storage or a problem with a
previous playback.
I can understand the four-banding - AIUI, there are four head passes to
a field? - but the 15- or 16-banding (I've been back to count)? Is that
that, as things fall apart, the heads pass across adjacent tracks? 16
(or even 4 each main band, though the 16 look even and not grouped into
4) seems quite a lot of mistracking.
On 27/01/2024 12:48, Mark Carver wrote:
On 26/01/2024 14:37, Bill Posters wrote:
On Fri Jan 26 13:37:38 2024 "J. P. Gilliver" wrote:
I thought the "instant replay" - used for sporting events, football
goals mainly - used a spinning magnetic disc (capable of storing, I
don't know, a second or less)?
Ampex HS-100, 36 seconds PAL, 30 seconds NTSC
Yep, only ever I gather three in the UK, the Beeb had one, LWT had
another, and the third was owned by a facilites house in Soho ?
As few as that? I imagined that they were an integral part of any
scanner van that was used for sports where action replays were needed.
Or are you saying that there were many other models of slo-mo, and that
it is specifically the Ampex HS-100 of which there were only three
instances in the UK?
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