Ay yi yi. Where do we start on this one.
The beginning, always at the\h beginning. In this instance,\h\h
that beginning is 1940. Honestly, why do\h I do this to myself. I could just say,\h\h
it’s 1080P because of this. But no, no, no, I\h have to create an entire history lesson. FML.
But before I get started, there a couple\h of ways you can support the channel;
The first is to grab my latest book,\h Nostalgia Nerd's Gadgets Gizmos and\h\h
Gimmicks. An essential guide to\h personal take through the ages.
The second is Patreon. There'll you find\h various tiers, including early access,\h\h
producer credits, and a whole lot more.
Of course, just watching is support enough,\h so without further ado, let's back back to it.
In 1940, The National Television Committee\h was established by the United States Federal\h\h
Communication Commission, and it had one purpose.\h To resolve the conflicts between private companies\h\h
who were attempting to deliver television\h across the nation. In 1939 RCA had already\h\h
begun broadcasting their NBC TV Network across\h New York and Los Angeles, which relied on bulky\h\h
Television Receivers produced by General Electric\h and designed to receive the 441 lines broadcast\h\h
by NBC. However, Dumont, one of the pioneers\h in extending the life of Cathode Ray Tubes had\h\h
their own television station, W2XVT, and were\h campaigning to increase the number of broadcast\h\h
scanlines to between 605 and 800, greatly\h improving the resolution of TV pictures.\h\h
The Committee would settle for a compromise\h suggested by the Radio Manufacturers Association\h\h
of 525 (or 486 visible) scanlines, split into two\h interlaced fields of 262.5 lines, 30 times per\h\h
second. Adopted nationwide, this would remain\h the black and white television standard until\h\h
1953 when the NTSC color television standard was\h introduced, reducing the scanning frequency to\h\h
29.970 frames per second, with the remaining\h bandwidth used to carry the color signal.
Other parts of the world would have their\h own shit going on. For example, in the UK\h\h
and other parts of Europe, our PAL system was\h devised to improve on the shortcomings of NTSC,\h\h
with one of those being an increased vertical\h resolution to 625 lines, with 576 visible lines,\h\h
and like NTSC the rest reserved for retrace\h and sync data. Although usually broadcast at\h\h
a slightly lower frame rate of 25 per second,\h due to differences in our electrical systems.
These standards would persist, pushing signals\h to our 4:3 televisions for the remainder of the\h\h
century. However, in the 1970s a new form of\h technology popped up, and it had the arduous\h\h
task of interfacing with television sets that\h were not really designed for it’s arrival.
Ahhh yes, the home computer. Humble yet powerful.\h Limited yet mind blowing in it’s potential.
Machines like the Vic-20, Sinclair ZX80 and\h even game consoles like the Atari VCS, had to\h\h
effectively act as mini TV broadcasting stations\h so they could display pictures on your television\h\h
set, but they had to rely on a few tricks to\h make this possible, and importantly, usable.
Although standards like NTSC and PAL had a set\h number of vertical lines, they really didn’t have\h\h
any fixed horizontal resolution, it was only\h limited by the signal bandwidth and ability\h\h
of the TV receiver. The lines you see going\h up and down here are just the aperture grill,\h\h
or shadow mask behind the screen used to target\h the CRT gun, and although this dot pitch has\h\h
an effect on the perceived picture quality, it’s\h not tied the actual signal. For practical senses,\h\h
there were standards, which equated to\h around 338TVL for NTSC and 403TVL for PAL,\h\h
TVL standing for Television Lines, defined as the\h number of vertical lines that can be discerned.\h\h
It’s not the amount of vertical information that\h is broadcast as it’s just a continuous stream,\h\h
it’s more a limitation of the signal bandwidth,\h fidelity and the TV receiver. Interestingly, the\h\h
human eye is more sensitive to vertical resolution\h than horiztonal, so although this is lower than\h\h
you might expect, it was helped in part by the\h natural anti-aliasing effect of CRT screens.
Although analogue signals, or CRT displays for\h that matter, didn’t have a fixed horizontal\h\h
resolution, a computer, being digital can.\h However, a computer, especially at the time,\h\h
had a limited amount of RAM, and therefore\h the number of pixels and thusly resolution\h\h
it could display were limited. Many computers of\h the time would therefore display in something like\h\h
160×200 or 320×200; far lower than\h could be discerned on your set,\h\h
whilst also forgoing interlaced scanning to\h save memory and processing time, which also\h\h
meant they only had access to half the screens\h vertical resolution, each pixel taking up two\h\h
vertical lines. In the sense of a computer then,\h a pixel is a logical, rather than physical unit;\h\h
the smallest addressable block on screen, as\h defined by the machine’s ROM and screen mode.\h\h
You could in theory have a 1×1 resolution screen,\h that’s just one single colour addressable block.
As more powerful computers came along, with more\h memory and faster processors, their abilities to\h\h
display higher resolutions increased, and although\h machines like the Amiga could display pretty high\h\h
resolutions through a TV set, the number of\h vertical lines was a hard limit, which when\h\h
interlaced would be particularly flickery, and\h the horizontal fidelity was keyed to bandwidth,\h\h
the dot pitch of the shadow mask (basically a set\h of holes that the CRT gun would fire through) and\h\h
phosphor density; which could vary from\h set to set. Therefore dedicated computer\h\h
monitors would become more widely adopted.\h Something that professional machines,\h\h
such as IBM PC compatibles had already\h been using since their inception.
Unlike television signals, monitor signals were\h progressive. Meaning each line was drawn in order,\h\h
with no interlacing, giving a more stable image.\h Also, unlike televisions, monitors could have\h\h
their own refresh rates and the ability to scan\h the image onto the screen at different rates,\h\h
allowing for different resolutions. Compared to\h our modern LCD monitors, CRT monitors didn’t have\h\h
a set number of physical pixels, but they still\h had a maximum number of pixels they could draw on\h\h
screen, limited by the video card, their hardware\h the screens shadow mask and phosphor density.
Early PC graphics standards would more of less\h mimic the resolutions of TV based systems,\h\h
but by 1987, something more usable was\h required, and so IBM introduced the\h\h
VGA monitor and VGA graphics card with their\h PS/2 line of computers, offering a resolution\h\h
of 640×480. Within three years, this was\h the standard display type among PC users,\h\h
which was quickly improved upon by third party\h manufacturers into a de-facto standard that\h\h
became known as Super VGA. But just like the\h TV broadcasters before, lack of compatibility\h\h
between these graphics cards and screens meant\h something needed to be done to ensure they could\h\h
be universally programmed for. This time, it was\h The Video Electronics Standards Association that\h\h
would create a common software interface for all\h cards which confirmed to their VBE specification.
This and subsequent specifications would\h standardise the following resolutions;
800×600, 1024×768 (also known as XGA) and finally\h 1280×1024 (also known as Super XGA). A natural\h\h
step up in resolution, that all conformed to\h the 4:3 viewing ratio of monitors at the time.
However, whilst computers were doing their own\h thing, the TV boffins were not at rest, and\h\h
anyone who has watched my video on aspect ratios\h will know where this part of the tale begins.
1972
Waaaayy back in 1972, Japan proposed a new CCIR\h Study Program to work on an analog high definition\h\h
television system. Utilising 2D filtering,\h dot interlacing, motion-vector compensation,\h\h
line sequential colour encoding and time\h compression, it managed to cram a 20MHz bandwidth\h\h
source signal into just 8.1MHz. However, creating\h all this took time, and signals wouldn’t begin\h\h
broadcasting until December 1988. The initial\h aspect ratio for this Hi-Vision system was 2:1.
However, around the same time, Sony released this.
This is the HDM3830 Colour\h Monitor and it’s a beast.
This CRT not only has a 38″ visible picture,\h but it can take a 1080i input. Yup, you could\h\h
plug a PS5 into this thing and play until your\h heart’s content. It also has a 16:9 aspect ratio\h\h
that….. ok let’s stop there a\h second. I’ve covered aspect ratios,\h\h
but this TV could take 1080i… in 1988…\h that’s crazy, right? Well yes and no.
In 1974, Work on the CCIR Study Program\h for High Definition Television had led\h\h
to a number of groups and other International\h initiatives, one of which was that in March 1977\h\h
the Society of Motion Picture and Television\h Engineers in America had begun development\h\h
of a digital television interface standard. By\h 1979 a standard had been drafted that allowed\h\h
the NTSC television signal to be sampled as a\h single composite colour signal. Over in Europe,\h\h
The European Broadcasting Union issued a document\h at around the same time recommending a component\h\h
television production standard, and it was\h quickly realised that the community would\h\h
be best served by a single set of standards\h that could be applied to NTSC, PAL and SECAM.
By January 1980 a SMPTE Task Force was\h setup to ensure compatibility across\h\h
all systems. Any transmission, either through the\h air, or via the suggested new connection standards\h\h
needs a frequency, and to get that frequency\h we need to take our analog signal and convert\h\h
it. Remember our Television Lines number, well\h this needed to be sampled to make it digital,\h\h
this sampling rate is known as the number of\h samples per active line, and how many samples\h\h
we take depends on the signal sampling frequency.\h For example a signal sampled at 6.75MHz would give\h\h
360 samples per active line. A signal sampled at\h double that rate would give double the samples\h\h
per line. At this point of negotiations the\h stipulations were that European community wanted\h\h
a luminance signal sampling frequency lower than\h 14.318MHz, whilst America wanted more than 12MHz.
To accommodate all European standards for\h active line periods, it was further put forward\h\h
that the number of samples per line should be\h greater than 715.5. With 720 being 6-factorial,\h\h
allowing for many small factors, it seemed the\h ideal number. This is much higher than the TVL\h\h
numbers I mentioned earlier, but remember\h TVL doesn’t relate to much data there is,\h\h
it’s simply what is discernible on screen,\h and really shows how much of the image was\h\h
lost due to analog transmission bandwidth and\h TV receivers. That’s in part why a DVD image\h\h
looks so much clearer than an analogue image of\h the same source material. So, in the business of\h\h
converting an analog signal to digital, we’re\h pulling a defined number of horizonal samples,\h\h
which is then normalised to our number of vertical\h lines, so as to retain the 4:3 image format.
It was therefore suggested that a 3 x\h 4.5MHz sampling frequency should be used,\h\h
equating to 13.5MHz. This makes sense as\h both NTSC and PAL line frequencies can be\h\h
synchronised to 4.5MHz, and therefore any\h multiple thereof. This frequency delivered\h\h
720 samples per active line, accommodating the\h needs of both European and American systems,\h\h
and allowing our TV Lines to be\h defined in acceptable digital clarity.
By February 1981, this component recording\h technology was effectively born, with the EBU\h\h
demonstrating component coded systems in January\h 1981 to the International Broadcasting Authority,\h\h
followed by the Bureau of the Technical\h Committee in San Francisco a month later.\h\h
These demonstrations were supported by\h companies including ABC Television, CBS,\h\h
RCA Laboratories and Sony Corporation. By\h Autumn 1981, NHK in Japan, the EBU in Europe\h\h
and SMPTE in America had agreed on the 13.5MHz\h 4:2:2 component digital recording standard.
By 1982, this had been put forward in SMPTE\h 125 and ITU Recommendation 601, which defined\h\h
how to encode interlaced analog video signals into\h digital video form. It also recommended that “The\h\h
horizontal resolution for HDTV [should] be twice\h that of conventional television systems”. If you\h\h
take 720 samples per active line, that gives us\h a horizontal sample rate, or resolution of 1440.
Fast forward a few years to 1984, and a gentleman\h by the name of Kerns H. Powers was working on the\h\h
problem of standardising the image formats used\h in our homes and in our cinemas. Ultimately,\h\h
he laid out all the main existing film and\h broadcasting ratios out in front of him,\h\h
overlapping their centre points, to\h give us the aspect ratio of 16:9.
Now expanding a 4:3 screen out to 16:9 requires\h one third more samples than a 4:3 picture ratio.\h\h
So if we take our 1440 and adjust the count for a\h 16:9 ratio, we get 1920 samples per active line.
Things are starting to take shape. Literally.
In 1987, the ITU were still not entirely\h convinced and were faffing about with\h\h
screen ratios. Having defined the following\h parameters for their first HDTV recommendation;
Active lines: 1152
Field rate: 50Hz
Scanning Method: Progressive
Aspect Ratio: 19:9
Samples per active line: 1920 for luminance.
So, when Sony released HDM3830, they were pretty\h much taking a punt. Based on the SMPTE’s work,\h\h
the technology for component connections had been\h finalised, but globally High Definition TV had not\h\h
completely been defined. Japan was pushing\h out it’s experimental Hi-Vision HDTV system\h\h
which delivered 1035 lines of visible\h screen data with 1920 samples per line,\h\h
but there was no guarantee this would stick\h around. The fact that this thing can take 1080i\h\h
signals is really testament to the work that\h the ITU and SMPTE had done on standardisation.
It wouldn’t be until 1990 at the\h 17th CCIR Plenary Assembly that ITU\h\h
recommendation 709 was approved which\h defined a picture ratio of 16:9 along\h\h
with our 1920 samples per active line.\h However, at this stage the total number\h\h
of agreed vertical lines still varied\h to allow for international variations.
Something worth considering at this\h point is that neither NTSC nor PAL\h\h
pixels are square. I say pixels for want\h of a better word, but ultimately we’re\h\h
talking about TV Lines or sample width vs.\h the vertical line height. NTSC pixels are\h\h
narrower than they are high, allowing for the\h 720×486 aspect ratio… whilst PAL pixels are\h\h
wider than they are high, allowing for the\h 720×576 aspect ratio. It’s what allows both\h\h
formats to be different ratios themselves,\h but yet fit in the same aspect screen ratio.
It’s here where we jump back to the\h computing community, who had one wish.\h\h
Well I imagine they had hundreds, but in\h terms of pixels, they wanted one thing.
S Q U A R E P I X E L S.
and that’s because computers, well, they\h already used square pixels. Your average\h\h
PC display in the States was the same\h as your average PC display in the UK. No\h\h
fuss. Just perfection which allowed our fabulous\h resolutions to exist in harmony and abundance.
It’s also because editing NTSC and PAL video in\h a PC without standard pixel sizes is a menace.
So, if you take our 1920 samples per line,\h and convert them into the world of PCs,\h\h
you effectively get 1920 pixels. If you\h work out how many square pixels you’d\h\h
then need to then fill the vertical\h space of a 16:9 screen, you get 1080.
!BINGO!
1920×1080….. our HD resolution is born, and\h although it wasn’t commonplace anywhere yet.\h\h
It made sense from a manufacturers point of view,\h and it made sense from a standardisation point\h\h
of view. Especially when you consider that\h the LCD screens about to hit the market had\h\h
a defined number of physical pixels as opposed\h to the more versatile whims of a CRT. Meaning\h\h
that a pixel in your computer’s memory can\h actually equate to a physical pixel on screen.
It wouldn’t be until the year 2000 that\h Recommendation ITU BT.709 was approved that set\h\h
our HD resolution and our screen ratio, allowing\h manufacturers to produce equipment at a lower\h\h
cost, and for broadcasters to work towards\h common HDTV program production standards.
Our 720P screens also followed this same rule. 720\h horizontal pixels x 4/3 resolution improvement,\h\h
adjusted for 16:9 equated to 1280 x 720. Offering\h a cost effective step into the world of full HD,\h\h
and a noticeable step up in quality\h from standard resolution video.
As for 1080i, well, again, it worked well as a\h stop gap, and did the whole interlace thing that\h\h
our standards and we had been used to, but\h progressive scanning was always the future.
It would take about 10 years for HD 16:9\h displays to be adopted universally by both\h\h
the computing world and TV world. PC owners\h went through a variety of resolutions between\h\h
the millennium and 2010, with 1024×768 being the\h most common at the dawn, before an abundance of\h\h
5:4 LCD screens made 1280×1024 more popular,\h followed by 1440×900 on16:10 displays which\h\h
were more prevalent until economies of scale meant\h that standardisation between computer screens and\h\h
TVs made much more sense. Ultimately, it also\h allowed graphics cards and their cost to catch\h\h
up to the point where a 1920×1080 desktop\h and gaming resolution made much more sense.
But it will always be strange to me that although\h computer resolutions led the way for so long,\h\h
it would be the weird, cumbersome\h and disparate world of television\h\h
broadcasting that ultimately\h took the lead and steered us on.
It may have taken 70 years, but\h standardisation finally came. Just about.
Everything else that came after, 4K, 8K, well\h it’s all born from this original HD standard.
Until next time, I’ve been Nostalgia Nerd.
Toodleoo.