Why is TV 29.97 frames per second?
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- čas přidán 20. 06. 2024
- I look at the historical quirks which gave us TV at 29.97 frames per second. In North America at least. It's a comfortable 25 fps in Europe.
More on that thing I mentioned at the end of the video here:
/ standupmaths
Here is the spherical video I was making with Henry Segerman which made me research NTSC frame rates in the first place:
• The Spherical Droste E...
Yes, technically, if you divide 4,500,000 by 286 you get a horizontal frequency of 15,734.26573 lines per second. That matches a frame rate of 29.97002997002997… and so old TVs used 30/1.001 = 29.97002997002997…
CORRECTIONS:
- A lot of people pointing out that increasing the number of horizontal lines without increasing the bandwidth would be a loss of resolution. Which is a good point.
Music by Howard Carter
Design by Simon Wright
MATT PARKER: Stand-up Mathematician
Website: standupmaths.com/
Patreon: / standupmaths
Nerdy maths toys: mathsgear.co.uk/ - Zábava
I love when someone finds something that is not on the internet and makes it their job to put it on the internet, I try to do it myself, great video!
+Cody'sLab It's why we do what we do. And now the internet knows that the toilet is a terrible option when you have surplus mercury to dispose of.
@@butwhy4579 And you ruined it
@@butwhy4579 no
Delet ur comments then
pprmograficp
Great explanation. Me and my 2.97 friends thoroughly enjoyed it.
Bryan Vas cannibalism
@@jeromej1234 r/cursedcomments
You have friends? Lucky.
What did you do to Jerry?
@Bryan Vas you mean, what happened to the remaining 0.027 of a friend don't you?
I've always thought RCA engineers did a pretty genius job adding color to the B&W signal without making non-color TVs obsolete.
Dave Holden yeah it is amazing how they pulled that one out their arse...I remember NTSC stood for never the same colour, SECAM Stood for system enitirely contrary to the American method, and PAL... peace at last....
NTSC: Never Twice the Same Color
You are absolutely correct! It was not perfect, but and outstanding job of integrating old technology.
I think they did the best to make the smooth transition from B&W to Color. If they changed the frequency or the amount of horizontal lines, it would make all B&W TV sets unusable, I guess. Some CRT expert here can comment for us!?
@@pangwa82 Yes, you are correct. If they changed any aspect of the existing waveform standard, they'd 'break' all existing TVs. Not only could they not change anything already working, but they had to *add* color to the existing standards, *without* it affecting B+W TVs.
For those that don't know, the overlaid much higher frequency wave on top of the B+W wave. B+W TVs weren't affected by these newly added waves superimposed onto the B+W signal. The addition was a 'color burst' at the start of each line of horizontal B+W data, and then the color carrier was made to be out of phase with the color burst, and the 360˚ phase were assigned to colors! That is, at point A, the color wave is the same as the color burst, and so the TV shows red. At point B, the wave is 180˚ out of phase with red, and the TV shows red's opposite color, cyan. Meanwhile the amplitude of the original B+W wave is STILL telling the TV how *bright* to make that pixel.
It's amazing what engineers accomplished without computers and modern electronics!
Next, can you do a video on why hotdog packages don’t match the number of buns in bun packages? I imagine it has something to do with the different resonate frequencies of the two foods.
you deserve more hype
Greg Belcher I figure the difference between the number of hot dogs in one package and the number of hot dog buns is because the companies that make them want you to buy more and if you buy 1 package of 10 dogs and one package of 8 buns, when they are all used, you have 2 left over dogs. If you want to use the last 2 dogs, then you might want to buy more buns, but then you would have 8 leftover dogs and the cycle of buying dogs and buns continues until you reach a common multiple of both dogs and buns, which is 40 dogs and 40 buns. For using even numbers of dogs and buns, there are no two better reasonable numbers for small packages of dogs and buns unless they are the same number, but the companies want to maximize their profits by keeping the customer buying dogs and buns.
I think 10 packs of hot dogs and 8 of buns should get you there right?
@@demodemo5146 or 5 and 4.
The reason they don't match is due to the metric system. The companies making hot dogs readily took to metric's base 10 system while those baking buns stubbornly held onto the ridiculous imperial standards.
No... I'm not being serious... why would you even ask that?
So many weird standards in the U.S. Sometimes I wonder if a dozen eggs isn't really 11.951 of them.
Nevermind the whole "bakers dozen" thing
+Kitsuneoni bakers dozen has been around for thousands of years. It has nothing to do with America
I don't get the use of a non-metric system in this day and age though
You do, since you use hours, days, weeks, months, and years. It'd make more sense if an hour were 100 minutes, a day were 10 hours, a week were 10 days and a year were 10 weeks. Metric time does exist, but since we're all pretty much used to our weird system of measuring time, we just choose to stick with that.
Our current system uses highly composite numbers which are more versatile though
My goodness you put a ton of effort into this video! I love how the motion graphics are in time with you speaking! Super well explained!
+Make Something Thanks! I was very pleased with the tech set-up required. Can't believe it all worked!
Any chance of a stand up gig here in Australia? :-)
Love your sense of humour, Brit humour and Aussie is seemingly closer than the US.
The huge irony is that NTSC does not have line by line phase reversal - aka Phase Alternating Line aka PAL. From memory the rest about adding the colourburst is correct, but that isnt, its the colourburst itself, it doesnt phase reverse. @Standupmaths - im kind of amazed you didnt mention even NASA would use the freq of the colourburst as a freq reference. I read a great anecdote where a TV station had their rubidium clock break down and had to return to an oven compensated xtal, and then was contacted by them asking what had happened to the signal and subsequently supplied with a ceasium clock for their colourburst :)
It was really nice
To be precise, for NTSC 4.5 MHz is the frequency difference between the video carrier and the audio carrier for each (6-MHz) channel. IIRC, the reason that this value could not be changed (leading to the math discussed by Matt) was that if you moved the audio carrier (say to keep 30 frames per second with 525 lines per frame as well as the half-integer requirements), the audio demodulators of the existing B&W TVs would be unable to correctly demodulate the audio. Analog TV audio for NTSC was frequency-modulated (as well as pre-distorted, but that’s a topic for another discussion), and I believe that the analog circuitry used at the time could not tolerate much error in the location of the audio carrier. The video demodulation, on the other hand, could tolerate a much larger relative change without needing redesign (say 30 Hz to 29.97 Hz, or around 1%).
I'm not sure where you got this from but it contradicts what the main problem the standard was trying to eliminate. The new subcarrier (3.583125 MHz, for color) had harmonics that interfered with the FM sound subcarrier (4.5 MHz) creating a constant buzz in the audio. By lowering the framerate along with the SC frequency the noise in the audio was reduced (beat frequency was now outside the audio bandwidth) and everyone signed off. Lots of compromises b/c no one wanted to reinvent the wheel with the color SC again.
Since it's not allowed to go outside the 4.5 MHz window, couldn't they just change the window slightly by moving it *_inwards_* instead?
Ah, 15,750 cps, I remember that number. The old "horizontal synch tone" I used to hear whenever the TV was on. My Dad declared I wasn't hearing it, of course what was really happening is *he* couldn't hear it.
I can still hear it at 58. I still watch a CRT TV.
Joe Shmoe and do you still wave your hand over the screen and feel the static electricity?
Yup. You got home late at night, you could hear if the TV was still on with the sound off, meant you were in trouble.....
Older people lose hearing of high frequencies
Man, I remember that. That barely audible high-pitched whine... been so long since I've used CRT TVs or monitors that I'd forgotten about that. That's so nostalgic... I remember staying up all night watching Doctor Who on PBS on my little hand-me-down 13" black & white TV sitting next to my bed... wow. Now I want to go watch Doctor Who. lol
I like how the Patreon screen totally screwed up the white balance. LOL
+Robert Baltrusch It takes a cut of my white balance.
Excellent video though. This is super relevant to the FPV hobby, and no one has covered it as well as you have.
Don't you mean exposure?
White balance is yellow/blue tint. Do you mean exposure, which controls the brightness of the video? ;)
Yes, I did mean exposure, and white balance. He's wearing a white shirt next to a white monitor, that's glowing white. But the exposure was most affected, you're correct.
The BIG MYSTERY is why, despite:
• The death of CRTs
• The death of NTSC
• The death of analogue broadcasting
• The death of "standard definition" video
• The introduction of 720p, 720i, 1080p, 1080i, 4K and 8K
• The death of VCRs
• The death of tape-based systems in video/TV production
...this ridiculous frame rate still exists. I beg EVERYONE in TV/video production, please ditch 29.97! It'd be exactly like a musician of today never recording a song over 4.5 minutes because otherwise it wouldn't fit on a 7" 45rpm single!
Limiting songs to 4.5 minutes constrains an entire art form. Having an awkward frame rate for your TV standard is a minor inconvenience to a tiny number of people. It's not "exactly like" it at all.
@@EebstertheGreat tbf how many songs are over 4.5 minutes. Only inconvenient to a small number of artists and barely any that would be played on the radio
@@isaac_aren In some genres, every song is over 4.5 minutes.
@@EebstertheGreat I wouldn't say the entire TV industry* is a "tiny number of people".
*I'm saying the entire TV industry, even though it's only America who uses these ludicrous frame rates because it's almost guaranteed that at some point, almost everyone working in TV will have to deal with some kind of video that originated in America.
@@tgktgkify It's not the entire TV industry who has to worry about the 0.1% difference in frame rate, just some techs in specific situations converting frame rates between formats. Everyone else involved (producers, actors, writers, cameramen, etc.) never have to think about it.
Something to note is that while NTSC is 525 lines, only 486 lines were actually used to visually show the image. The other 26 lines were used for vertical synchronization and retrace. Thats why SD digital is 480p, as thats equal to the actual visual representation of NTSC. PAL was about 600 lines of visible footage, so if you ever have on your hands a master tape of a European TV show, from BetaCam or something else, it makes more sense to up-convert it to 4:3 720p HD, or else you will be losing a bunch of quality.
Real SD digital is 486. DV is 480.
Exactly, I rather over sample the video and get as much information from the picture as possible even if 720P or 1080i seems overkill. Analog video does have high frequency peaks and the professional analog recording equipment could capture a lot of information. Watching old Dr. Who episodes on blu-ray shows how good PAL video was, as far as the in studio recording elements were. The outside scenes were usually done with film, and those were re-transferred from original footage if available.
@@randystuehm7924 It's 483.
I have just spent too much time searching for my reference material! What I found was that 525/30 according to the NTSC spec, has a total 40 lines of blanking and thus 485 lines of active picture per frame. 625/25 according to the EBU spec has 52 lines of blanking and thus 573 lines of active picture. In practice this might vary, usually by rounding down.
I did find two useful links. This one has a simple explanation of NTSC with some humour: www.sxlist.com/techref/io/video/ntsc.htm This one is more technical but has tables for everything, and links to more info than you would imagine: enacademic.com/dic.nsf/enwiki/14957 That one appears to be translated from German, so there are some quaint bits.
@@marcusdamberger Yes. BBC ALWAYS shot outdoors on 16MM film, and indoors in a TV studio on tape. You see this throughout the 1950 to around the 1990s, until decent tape-based recorders and cameras became cheaper than shooting processing and transferring film. Dr. Who is a great example, as is Monty Python
“PAL was better because it was higher resolution”. Not true. The reason was much more interesting. Colour information was coded in the phase of a sub carrier relative to a short burst of that subcarrier at the start of the line. The problem with NTSC was that the received signal could have phase errors due to things near the aerial blowing around in the wind. These phase errors would get turned into distracting colour (hue) errors. In PAL (Phase Alternate Line where the phase swung +/- 45 deg ) each tv line signal was stored in a delay line and averaged with the next line. The vector sum turned phase (hue) errors into amplitude (brightness) errors which were visually unnoticeable. That’s the real reason NTSC was mockingly called ‘Never the same colour’
Exactly. But what about SECAM?
Never Twice (the) Same Colour
I was at BBC Engineering Training Department Wood Norton in 1980 (a former stately home which doubled as UNIT Headquarters where Jon Pertwee first appeared as Doctor Who). Our lecturer, Pete Harris, had a humorous take on how the pros & cons of the three colour systems related to their names. NTSC was a beautiful work of genius but it suffered from one major problem - hue errors. (Thus American TVs all needed a 'Hue' control.) SECAM (Séquentiel Couleur À Mémoire) was fantastic for transmission (and protecting French manufacturing on the orders of Charles de Gaulle) but was mind-numbingly useless in the studio. PAL (Phase Alternating Line), however, took the otherwise excellent NTSC, built on the American experience and elegantly solved the hue problem. Thus, we had the three designations:
NTSC: Never Twice Same Colour
SECAM: Système Extraordinaire Contre les Américains
PAL: Perfect At Last!
The wind did not cause hue errors in NTSC. The color subcarrier and the main carrier may shift together a little but, but, since the color subcarrier is detected as the difference between the carrier and the subcarrier (a much smaller figure than the main carrier), hue shifts did not occur.
If the picture is heavily affected by dynamic multipath (e.g. trees blowing in a storm) can cause a loss in horizontal synchronization. When the back porch color pilot is freed from the synch, anything that occurs in the horizontal retrace becomes a false color reference.
@@1L6E6VHF That's not entirely correct. It's not a question of subcarrier and "main carrier". The colour information was sent on a subcarrier (a sine wave added to the video signal - 3.58MHz in NTSC and 4.433MHz in PAL). The instantaneous saturation & hue of the picture were given respectively by the amplitude of this wave and its phase angle with respect to a fixed reference. The angle of the fixed reference was communicated to the TV set by a short sample of about ten cycles of subcarrier at the beginning of each television line (the Colour Burst) and then maintained throughout the duration of the line by the BLO (Burst-Locked Oscillator) inside the TV.
Early television engineers were damned smart. Make the best out of a crappy situation due to the limitations of physics and find a solution. And they did it by using their brains and education with good old pencil and paper. Hat off to them!
Well they sure as hell weren't any ordinary people..... most of them were former Nazi scientists!
Euzifyy How do you know that?
Johnny Appleseed Color TV first appeared in the early 1950's and the second world war finished in the 1940's
It looks like I found my lost twin.
Euzifyy Everyone's a Nazi scientist these days. What's new?
The video is pretty interesting but I must highlight that building up the presentation on that screen had to be a tedious job, so congratulations for all the time you and your team took for preparing the whole explanation!
+kundogb Thanks! But this video was just me. If my patreon goes well I might be able to get my team involved.
Very impressive. Great presentation. Big fan. Thanks for making math/maths (and old TVs) so much more understandable.
Nice. I remember changing my DVD player output from PAL to NTSC, and see the screen blink, colours go haywire and picture area shortened vertically. This video explains it clearly.
“When you do things right, people won’t be sure you’ve done anything at all”. Godly advice, if I do say so myself. ;)
That is from Futurama. I saw it a few hours ago.
From what I remember from working in broadcast TV, the reason they stuck with this as a standard was for backwards compatibility. They wanted to still be able to broadcast the same signal so it works on the millions of black and white TVs that were already sold to consumers, and to enable TV stations who invested millions to not have to scrap everything and start over.
How many people are still using black and white tvs in almost 2023
@@Xnoob545 Plus this is specifically for analoge signal. So why people insisting on using 23,976 and 29,97 fps for digital content, I don't get.
That line through the patreon logo that’s _ever_ so slowly moving down the screen is the _definition_ of rounding error.
Growing up in this digital age, where FPS is usually expressed as an integer, I never knew why my video editing software always defaulted to such a specific decimal value. The answer was much more fascinating than I expected. Thanks for the info!
As a curiosity, Brazil used a NTSC-PAL hybrid called PAL-M, which featured 525 lines, exact 30 fps, and the PAL color encoding scheme with almost the same chroma carrier frequency as NTSC.
Exactly! It would be great if Matt made a video about it. PAL-M merged 30 FPS with perfect colour reproduction.
Yes very similar but being PAL there had to be a quarter-line offset so the frequency changed. Another difference between PAL-M and European PAL is that there in no 30Hz subcarrier offset (25Hz is used in Europe). This offset was an afterthought by Dr Bruch and has caused us heartache in Europe with editing.
@@dhaen Ah! The glorious days of eight-field editing!
This is really cool and interesting!
I do enjoy your content Matt.
+Vicvic W Thanks, it's fun to make! And now I have a spare TV…
Well congratulations matt 😊
By the way, I love your vids
pls keep making amazing content like this...
I know this NTSC-pun: NeverTheSameColor
😂
how do you get 152,265 subscribers precisely
"Standards have to be continuous . . . for some definition of continuous."
Gotta remember that one.
In fact, in the UK, the black and white system (which used 405 lines, thus incompatible with colour) wasn't switched off until 1985.
First timer here at your channel and love how you explained it (very clearl) and the exactly timed animations on the CRT. Well done! This is an excellent example that a (minimal looking) video like this can be informative, fun to watch without the need of fancy stuff around. Really like it.
What superb exposition! This is a complex subject, which has puzzled me for years, and you made it crystal clear. Bravo!
Great video, and very informative. I have long wondered but never bothered to check.
(Phase reversal requires that the phase of the wavefunction describing the signal be adjusted by precisely one half of a wavelength for each color frame, hence the need for an integer multiple.)
+TomatoBreadOrgasm I started reading about it because it sounded interesting but realised it was slightly too off-topic for the video.
standupmaths Well it didn't diminish the quality of a great video, in my opinion.
+standupmaths, are you implying that maths is off topic?
wow. I could never expect an oldschool TV to be usable to achieve a well edited youtube video. nicely done parker :)
I'm looking forward for that BTS video :D
Video editing is a magical thing.
It might actually be some kind of computer monitor. It's at least a high end Trinitron.
RogerWilco I'm positive it's a tv monitor. he probably has a wacky adapter to convert from a pc/circuit board HDMI/VGA to the tv format
look right at the end when the Patrion logo is on the CRT you can see a black stripe slowly edging downwards - a mismatch between 29.97 and 30, Close enough to be usabe
Wonderful explanation, and the “beam graphics” demonstrated on your CRT really clarifies how the sweep, scan, and interlace produce the raster. It’s amazing how these vestigial technologies spill over to complicate modern methods...
Excellently informative and engaging. I was hooked to the end!
That's a good explanation except for fact that it's not 100% technically accurate. 29.97fps * 525 lines * 286 is actually equal to 4,499,995.5. Although we nominally refer to the NTSC framerate as 29.97, that's actually just an aproximation. The true framerate is actually 30/1.001, or about 29.97002997002997... When you plug 30/1.001 into your equation, you get EXACTLY 4,500,000Hz.
Neat.
It's nice explanation but based on wrong facts. PAL channel is wide enough that you don't need to mess with Δ2 = ODD2 * fh/2. Sound use FM modulation, so there is no way to interlace sound spectrum and chroma spectrum, so exact Δ2 doesn't help much. In Europe we have 5,5MHz, 6,0MHz and 6,5MHz sound IF (Δ2 is different) and all systems use the same PAL 4,43MHz frequency.
PAL creator Walter Bruch choose chroma frequency other way - PAL use the same horizontal (15625 Hz) and vertical (50Hz) frequency like B/W standard, but chroma frequency was shifted - fv/2 was added to minimize artefacts. In fact in PAL it must be ODD * fh/4 (because of PAL phase alternating line by line) + fv/2. Exactly: 1135 * (15625Hz/4) + (50Hz/2) = 4,43361875MHz
So PAL never used chroma frequency ODD * fh/2 ! It was only used in experiments with NTSC based system in Europe in early 60's.
+xsc1000 The explanation is specifically pertaining to the North American NTSC standard. PAL was developed after NTSC so the engineers were able to avoid many of the inherent flaws that plagued us here in the USA.
You count 6MHz bandwith for PAL for Δ2, but in fact it is 5,5MHz in original German version, 6MHz in British version and 6,5MHz in eastern Europe version.
If NTSC changed horizontal lines to 625 (like you offer), none of B/W set would be compatible because of horizontal oscillator changed frequency. Also horizontal resolution would be low. You can count bandwith you need for Y (luma) signal by this equation: B= 625 (horizontal lines) * 625 * 4/3 (vertical lines) * 30 (framerate) /2 (two pixels create sine wave period) = 7,8MHz. But you have < 3.5 MHz for luma in NTSC, so horizontal resolution would be less than half the vertical resolution.
"The true framerate is actually 30/1.001, or about 29.97002997002997..."
So NTSC TVs are more accurate timekeepers than atomic clocks?
I am telecommunications engineer and I never had so good explanation of the whole thing like you did right there in this video. Not to mention how entertaining it was. And a good hearted joke from my side... I learned in school that NTSC stands for 'Never The Same Color' and PAL stands for 'Perfect At Last' ;)
And the French SECAM system stood for "Something Entirely Contrary to the American Method"...
@@bobweiss8682 System Entirely Contrary to the American Method. I used to know how to write this in French, but can't find the note I wrote back in the late 70s!
This was remarkably well explained. Thank you SO much for this, standupmaths!! 😍👌 I've learned so, so much from this.
Great little animations on your ‘tv’ there. Excellent work.
When I worked in a post production house in Hollywood, the saying was:
NTSC = Never The Same Color
Also, in order for timecode on broadcast videotapes to make sense with the 29.97 framerate, they developed "drop-frame timecode," typically denoted with a semicolon or period after the seconds [HH:MM:SS;FF]. For every minute not ending in a zero, two frames were skipped in the timecode. If they hadn't done this, then every hour of timecode would have an additional 3.6 seconds of real time.
Yeah, I've researched this because why not-yeah, "because why not" is why I research most of the things that I do.
So 00:00;00 is a real timecode, as are 00:00;01, 10:00;00, and 10:00;01, but 01:00;00 just doesn't exist, and neither does 01:00;01, or 01:00;02 or 01:00;03 in the case of 59.94fps.
This drops 18 frames (29.97fps) or 36 frames (59.94fps) every 10 minutes (18000 frames in 30fps or 36000 frames in 60fps), leading to a frame rate of 17982 or 35964 frames per 10 minutes, or 29.97 or 59.94 exactly. NTSC is actually 29.970029 970029 97... frames per second, which means that timecodes with the SMPTE drop-frame correction still drop a frame every few hours.
@@meta04 I remember this too well, it is burnt into my memory. Generating SMPTE on a brain dead 8bit.
Who on earth is going to notice the extra 3.6 seconds of real time? Also, you still end up with the problem that every hour of timecode is short 3.6 milliseconds of real time (4500000/(525*286) isn't exactly 29.97)
@@Anonymous-df8it We're talking about TV networks who sold advertising space by the second, so they needed to be precise in how everything was measured. Also editors would often have to deal with audio coming from different sources, so having the sync drift by 3.6 seconds per hour would be catastrophic. Those are just two of many reasons why precise timecode was important.
@@lednerg Why isn't 3.6 milliseconds per hour catastrophic?
why the hell is this video 50fps
Yeah, why not 59.94
The PAL standard frame rate is 25 so double that to 50 for modern high frame rate PAL.
My guess is so that its FPS is multiple of the CRT screen he has there, so that no flicker is visible.
Because as he said in europe CRT uses 25FPS so filming it at 30 or 60 would cause problems, but as 25 is a factor of 50 it works
sorry. premature comment.
The first video I ever watched of you Matt, I love your videos and now I'm a massive fan! Thank you for all the nerdiness!
One of the most interesting presentation methods I have ever seen on youtube :D Good job!
Cool graphics. I wonder how you did it.
sane
You can just hook a pc up to the tv, as long you have the cables. PC monitors used to be CRT
of course but what is displayed didn't create itself. I guess After Effects. Whatever program, very nicelly done.
He did a behind the scenes on this
Probably like a powerpoint presentation and a remote on hand or on foot. And yes i'm answering to 10 month old question lol.
The most amazing thing in this video was seeing a CRT television........
My sister who is pre 10, has never seen a CRT computer monitor.
Sony Trinitrons are generally very good ones, I'd have kept it too. I use mine to play arcade games.
I still have a CRT television, fully functional
Kind of an odd fact but Super Smash Bros Melee on the gamecube is primarily played on CRT tvs because there is less lag. In fact watch any ametur to professional SSBM match and they are playing on CRT tvs. They are in very high demand right now among the Melee community as good ones are becoming harder to find
*COUGH COUGH* 144hz 1MS Response Time BenQ screens *COUGH COUGH*
Excellent timing at the end with the frame roll ! loved it.
Thank you very much indeed. You were able to provide what you had promised in the beginning: a nice, coherent and concise explanation ...
Matt i read your book, and i really enjoyed it. So i think that a good petreon reward would be a few more chapters to read. C:
+Mads Philipsen I'm writing a new book now. I could release some chapters early to patreon supporters?
Me too
It would be really cool if it was like a chapter pr month.
+standupmaths Stuff to Create and Have in the 5th Dimensoon
Mr Calligraphy If you've read the book you know it already talks about really high dimensions too.
I always assumed it was a rounding problem when converting from imperial time to metric time.
LOL, best comment.
Does anyone know if the 29.97 frames per (metric) seconds is an integer when converted to the imperial feet-fahrenheit time unit?
Ummm, the current definition of the second was the result of a collaboration between the British National Physics Laboratory (NPL) and the United States Naval Observatory in the late 1950's. (You might be able to guess the nationalities of those two institutions.) The effort was aimed at defining the atomic (silicon) second to match as nearly as possible the 1898 definition of the ephemeris second, as given by Simon Newcomb, Newfoundland born director of the United States Naval Observatory, employing the lunar theory of British born Yale professor Ernest William Brown. The modern second is pretty much an Anglo-American project.
Jim DeCamp, you know hes joking right?
On youTube (and especially numberphile) one can never be certain. I guess I took nationalistic umbrage, given that the definition of the second, at least since the late 19th Century has been pretty much a U.S. project, with substantial help from the UK's NPL.
I suppose you're going to tell me that we're nitwits for not using a rational and sane AC frequency like 50 Hz, or a "more efficient" mains voltage like 220V.
The editing on this video is remarkable
The content was super interesting AND I loved the section at the tail end :D
>29.97 fps
>inches, feet, yards, miles
>month/day/year
>fahrenheit
>handegg
*_UNITED STATES OF MERICUH_*
You forgot paper standards.
An insult to the word "standard", really ...
Well Fahrenheit is used as a general sense of how hot something is. " It's 30 degrees? Oh that's cold. It's 100 degrees, 100 is a lot, so its really hot." Ask water how hot it feels and you get Celsius. Simplicity.
Horny Fruit Flies writes:
">29.97 fps
>inches, feet, yards, miles
>month/day/year
>fahrenheit
>handegg
UNITED STATES OF MERICUH"
Well, MERICUH is not how it's spelled, so that's not a valid complaint! (^_^)
I thought the video explained why we have 29.97 fps. Bad luck, basically, and a desire to maintain backward compatibility. The numbers just happened to work out better in Europe.
As for units, you use the right ones for the job (just like tools!). Feet are useful for high-energy physicists because light travels 1 ft. in 1 ns. So this is useful for estimating delays from cables.
Month/day/year. You find day/month/year better? The best is really the ISO format: yyyy-mm-dd. And I wish the world would switch to that, but current date formats are like QWERTY: too deeply ingrained. I myself find writing m/d/y natural, just from growing up in America.
Fahrenheit. I think this is more fitting for normal use. A Celsius degree is a little too large when used for indoor and outdoor temperature. Fahrenheit makes a weather map better, too. An area of 20's C would be too wide. Fahrenheit gives you "better resolution" while still working with integers. Scientists outside of the weather business typically use Kelvins and Celsius. You use the right units (tools) for the right job!
Handegg? OK, I looked it up. To each his own.
If you favor metric, or SI, units, I can tell you all sorts of non-metric or non-SI units that are used by scientists: atmospheres, G-forces, parsecs, feet (already mentioned), hell, let me just quote an old post of mine from another website:
"Speaking of units, scientists frequently use non-metric units: light-year, parsec, astronomical unit (equal to the radius of the earth's orbit), (an) atmosphere (a unit of pressure, though more for convenience when precision is not paramount), G forces, electron volt, barn (a barn is 10^(-24) cm^2), fermi (which is 10^(-13) cm). These last two are based on a metric unit, but so is the inch (defined as 2.54 cm), so it's just as "bad", sort of). The electrical charge of particles, in many cases, is more conveniently measured in multiples of that of a proton, as in the charge on an electron (which would be -1), or quarks, which, depending on which quark you're dealing with, is +/- 1/3 or +/- 2/3 of that amount of charge. There's also a foot (of cable, or patch cord, if you will), which is how far light and electricity) travel in one nanosecond. This is useful in high-energy physics experiments for estimating delays. I believe calories are still used by some, though I'm not really sure. Add to all this units of time: years, months, weeks, and days are not metric units, yet scientists use days and years, at least. The dinosaurs were wiped out 65,000,000 years ago. No one converts that to seconds. Angstroms are still used (based on a metric unit, though). There are probably more.
Bottom line: Use the units that are appropriate for the job."
I never got the argument that Fahrenheit gives you better resolution. Why would you ever need slightly better resolution for Temperature, and if you do: Why not use the Celsius value with another digit?
Also, the estimate that light travels 1 feet per ns is just that; an estimate. The estimate has an error of about 1.7 %. Pretty sure mostly American or English engineers use it, and for any serious calculations you'd use meters.
We use the units we're used to. It's an important part of our culture.
Unfortunately, changing the number of horizontal lines in a North American TV picture from 525 to 625 would have destroyed backwards compatibility with the existing black and white sets.
Not really, vintage tv´s had vertical, width, horizontal controls to ajust the picture on the tube
It was more easy to implement.back in those days.
I remember a guy in Portugal receiving by sky skip a freak signal of Brazilian tv that came in,and all he did was ajust his 625 50hz tv to 525 line 60hz on a small portable black and white set. using the vertical width controls
Brazil does use PAL but on 525 60hz
But the tv been an old b/w did not have to deal with other things of the signal.
The video is on youtube
Yeah, but every time you change channel? Some channels (some SHOWS) were B&W, others color. They coexisted.
Brazil also uses PAL.
@@voorhes80
PAL-M 525 60hz
@@angelsmith1761 You are assuming that existing TV's had horizontal and vertical frequency controls that would have sufficient range to make such large frequency adjustments and that the circuits would still have performed properly with such a large deviation from what they were originally designed to work at.
Wow this video was amazing. Thank you for explaining it so perfectly 🔥
Wow. Amazingly thorough info there. Thanks
It's awesome when you work through equations like this :) I especially like that, instead of a blackboard, you utilised a television.
It's a parker framerate.
parker framerate*
@@martinator9480 you're right, I fixed it
@@martinator9480 What was the original?
Really cool format!
So informative. What a great video. Thanks!
"Why is TV 29.97 frames per second?"
because peasantry
***** edgeyMcangister
But it updates 59.94 times per second. That's why games still run at 60fps on CRT TVs.
If someone is more informed than me, please feel free to correct me, but I believe that the 60FPS (and 50 for PAL) is only the first round of scanning (meaning half the scanlines). When you combine the two different scans in order to have a "full image", it totals to 30FPS.
So, 60FPS for one out of two scan cycles, 30FPS for two out of two scan cycles.
Karolos Triantafyllou Sorry, no. The "frame" as described by NTSC/ATSC or other interlaced formats is actually a combination of two different images (these are called fields). NTSC has 59.94 distinct images (fields) per second. The 30 frames per second idea a very bad naming scheme.
SNESIvan
So the naming convention is untrue? Interesting. Could you point me to somewhere were I could read more about it? It seems interesting.
The whole point of NTSC color tv was to put in a standard in which people who still owned black and white sets (vast majority) could still see color broadcasts and color tvs could still see black and white broadcasts, this was referred to as "compatable color". If they were to have adjusted the horizontal lines like you suggest the would have made a signal that no tv could display, therefore defeating the whole point of their efforts. In Europe, when PAL was introduced, anyone still using the old 405 line black and white sets, just didnt get to see the new color shows and anyone who had a color tv couldnt see the old programs.
All color TV Systems (NTSC, PAL, SECAM) had to be backwards compatible to black and white TV standard. It would have been too costly to broadcast the same content simultaneously with two different standards. At introduction of color TV most pople still had b/w TV sets and only a few shows were actually transmitted in color.
@@oldSwede65 Also most of Europe were broadcasting 625/50 before they started broadcasting in colour! There was overlap with 405/50 staying on for some years until all the old VHF transmitters were replaced by UHF. The programmes they broadcast were the same, just in B&W. The BBC made everything in colour 625/50, and there were standards converters at TV Centre to down-convert to 405. I the French even had some 819/50 B&W transmissions running after they converted to 625.
NTSC = never the same colour twice ! Or so it was often described.
@@oldSwede65
And yet, the UK did exactly that for nearly 20 years (if you count the Trade Test Transmissions on BBC 2, which, though illegal to watch, were being seen nonetheless, as the law was virtually unenforceable).
The amazing side effect was that color signals gave better black and white images on black and white TV sets.
2:45 So THAT'S why running the vacuum always messed with the TV in the pre-LCD years! I've had that question since before I could just Google it, and forgot it by the time I could.
And now that I think of it, this makes me want to build a new alarm clock with an internal oscillator to get those likely seconds a year, from using the AC signal for timing, back.
The total time of a frame is enough to draw 525 lines on the screen, but that assumes you are dividing the frame time by the time to draw one horizontal scan line. However you have to also include the horizontal blank interval i.e. the time the beam is off so it can be repositioned at the start of the next scan line, as well as the vertical blank interval, i.e. the time the beam is off so it can be brought back to the top left corner of the picture from the bottom right and does this for each half frame. When those are taken into account, it turns out you only get 480 scan lines total. Horizontally, you can draw 320-350 alternating dark and light vertical lines giving you (in computer monitor terms) about 640-700 pixels on each scanline depending on how good your comb filters are. I know, 4 years late to the party, but there it is.
PAL is more cinematic!
you stole my words sir +Guitar Lesson
grande1899 omg 😲 YOU AGAIN
The lowest common multiple of PAL 50hz and movies 24hz is 600hz
The lowest common multiple of 60hz and 24hz is 120hz.
Sorry, PAL doesn't have enough prime factors in common with cinema for my taste.
Patrick Wise You're forgetting that as explained in the video, NTSC is actually 29.97 FPS an not 30/60. The lowest common multiple of 24 and 29.97 is 23976. Checkmate :^)
although what's funny about this, is that on UK TV, films, shot at 24fps aren't "mapped" (3:2 Pulldown i believe it's called) like on the NTSC system, we simply show 24fps at 25 fps. This is why if you check running times of movies shown on UK television it is about 4% shorter than the actual running time.
Also, now we are in the age of 1080P and soon 2160 P or even higher, why are we still having to even think about drop frames and 29.97 frame rates?
This was explained beautifully; I understood everything he said. Well done!
Great video. Awesome explanation.
I'm new to the channel. Great first video for me. And, you summed up a 15 week intro to tv course in 15 minutes... more clearly too. Thanks.🍻
'Ashuming'
where?`I didn't spot it :O
DoctorPC 9:50
Andro A Englishmen need speech therapy.
It sounds like he was a Kiwi before the British part of his accent.
Or sightly more aussie. The slurring in 'ashuming' is a classic speech laziness in both.
Also changing the number of lines in the signal would completely brick the older TVs, introducing an odd, skewed horizontal rollover as the greater number of horizontal lines would cram the same number of pixels into less horizontal space.
A small change to the number of lines would not have caused any particular difficulty with consumer video equipment. Until the late 1990s, most video game systems output video that was significantly different from what the NTSC specified, but TV mostly coped with it just fine.
Yes, a lot of early gaming and home computer systems produced signals that were more than a bit off, but the NTSC engineers were tasked with creating a standard that would be least disruptive and compatible with older B&W sets. Changing the vertical scan rate by a tenth of a percent was very likely to work on all receivers; changing the number of horizontal lines by 20% would have produced the artifacts seen with many games & computers, like jittery pictures, tearing, and flag waving.
I don't believe any of the European color standards were compatible with their earlier B&W signal. They saw the compromises the NTSC engineers made and decided to just abandon the old standard and start over for a better color picture, also a reasonable engineering decision, but it forced customers to replace their sets.
All the European colour standards were fully compatible/transparent and usable on older B&W TVs. No sets needed to be replaced (until digital broadcasts came about, but that was much more recent).
90 seconds into the video and I'm blown away by the wicked in-camera special effects
Thank you so much for this beautiful breakdown :)
How did it feel to intentionally misspell the word colour as a British person?
+VeryUnfriendlySpoon It felt dirty.
standupmaths
As a Canadian I have to deal with that dirty feeling very often.
It's not misspelled. It's a different dialect.
Gregory Kanniard its misspelled
Jackson Kennedy different dialects spell things differently. Believe it or not, Europeans spell some things very different than originally intended. Just like Americans
Linus where are you
why would he be here?
meloD30 Linus posted on twitter
Excellent history lesson! As a former resident under NTSC, and also wondering how in the world 29.97 ever existed, I found your video very interesting and exciting! I'm exploring the possibilities of video production and editing in post. Thanks. RS.
Wow, this was really well done! Kudos Matt, I've enjoyed some of your stuff before and watched this video after export my own CZcams video at 29.97 fps and wondering why, haha!
Sadly this is one of the problems being early when adopting new technologies.
It can be difficult to tell exactly what you need, how to create something, and so on. This often ends up in you finding out what you should have changed.
But, by then the old systems are already in place and you can't just shut them all off.
How is that sadly in this case? Whoever decided that near-30 fps is enough made a tech that lasted 40-ish years and near no one ever said it's a problem or even acknowledged. On the other hand now we have opened pandora's box where most people are moving toward 60fps while at the same time there are already people who say 90 or 120 or 140+ is the minimum desired level. Leading to tech being deprecated often within a year while we are supposed to save resources and environment.
@@kallemetsahalme5701these are 2 very different things. It isnt exactly the fps that is the problem, but having to be compatible with b&w and make a smooth transition.
It is about getting the technology and not fully understanding it and planning it out that leads to problems. Luckily with tv it is just a debate, but with other things it has costed lives.
@@kallemetsahalme5701
Your point is 100% correct. However, in this case it was a decision of backwards compatibility AND seamless change. Nothing really about frame rate itself. As no one will notice the -0.03
Also are people saying that like 90, 120, 144, etc. is the minimum desirable frame rate?
As I will be honest 60fps is perfectly fine, 120 fps is even better, and 240 fps is incredible.
It depends on application though. Gaming? 120 and above
Watching movies? 30 or 60
Animation? 30 is probably the best
Matt, I hear the clicking of a remote for that powerpoint. You didn't fool me.
+Lucy Tycho I might have a cheeky foot pedal…
This is mind boggling. Fantastic explanation.
Pretty fascinating to me. Great video!
When I see your hair I'm suddenly scared to get old
+Gian990 I serve as a warning of the inevitable passing of time.
standupmaths
(':
It's okay, all that hair you lose from your head will magically regrow all over your body.
There were several attempts at coming up with a color standard. Finally, it was realized that with the expense at the time of television in general--and especially the new color sets--you would have to make it "backwards compatible" to the existing B&W sets or you would be selling zero color TV sets and would fail. So they did, and made the best of a bad situation. PAL is superior in many respects--and is so because it started from scratch with the lessons learned by the compromises that had to be made in the North American system. Had that been a real option for the American engineers, they would have loved to start over and make a clean solution. But marketing always asks for miracles, and it's up to engineering to deliver them (compromised as they may be).
Have to add that at the time devices were meant to last forever. You could not simply ditch a B&W set because it's outdated due to a standard of color tv being introduced. Of course things have changed...
@@PR-fk5yb In the 1950s TVs were far more expensive relative to average earnings than they are now. Colour sets even more so. Although NTSC colour transmissions started in 1955 it wasn't until about a decade later that colour TVs outnumbered B&W ones in US homes.
@@PR-fk5yb Yeah, imagine if Apple had invented it.
@@zoewells3160 lol remember that story : What if Microsoft had invented the automobile? It would not work certain types of gas or it would suddenly stop on the highway for no reason then you would have to find the stop button in order to restart it... If Apple had invented the television... you would have to pay $$$ just to use the airwaves or you would have to pay an extra everytime you would change the channel...
@@PR-fk5yb This is also true, yes.
Thank you CZcams for suggesting me this video. Great work, dude. Thanks!
Wow, so glad I paid attention to the end of this video and got that sneak peek!
Always knew NTSC as "Never Twice the Same Color"... must be my european PALs that taught me this ;-]
NTSC: Never Twice Same Colour
SECAM: Systéme Extraordinaire Contre les Américains
PAL: Perfect At Last
PAL: Pretty Awful Looking
@@gerardjlaw "SECAM: Systéme Extraordinaire Contre les Américains"
That's good!
@@daveholden2711 Not my creation. I heard it from Pete Harris at BBC Engineering Training Department.
Did you, a Brit, just write colour without the u? :o
But including the u, there are six symbols, allowing you to make a colour rainbow, inside the word 'colour'!
How dare you write colour without the u?!
He's not a Brit.
+russ18uk really?
+russ18uk but he does use British english
Well, to be fair he was speaking about the American standard at that point.
He is actually an Australian (but living in the UK, though).
Great job!!!!! Great knowledge and very entertaining!
I would absolutely love to see more technical maths videos. I’ll repost this suggestion after I’ve subscribed to the Patreon.
If they had chosen to increase the line count to 625 instead, then the spectrum of the signal would have changed, adding more high frequencies, making it no longer fit into that 4.5 MHz window.
Perhaps. But the main reason for keeping 525, as many others have already noted here, is because most of the TVs out there were B&W (and there were lots and lots of them), and they could not adopt a standard that suddenly made everyone's TV become useless.
Yes, definitely. But even if they had decided to change the standard more thoroughly, they wouldn't have been able to for the reason I mentioned.
It could have been fitted into that window, but it would have required more aggressive low-pass filtering, which would have resulted in a blurrier picture.
Televisions of the early 1950s were really, REALLY forgiving as far as what they would accept as input. They all had H-hold and V-hold knobs that changed the timing of the signal. Even later TVs with only the V-hold could somewhat display 625 lines by adjusting the V-hold knob.
A 1950s TV could very easily be adjusted to display 625 lines, without losing any of the picture.
The biggest problem would've been that 625 lines would be quite blurry on American TVs. It would still have to fit into the same 6 MHz channel space that was originally designed for 441 lines in the 1930s.
I'm sure the people working on the standard would have used 625 lines if they knew for a fact that all existing TV's could handle it (even if they needed adjustment). The fact that they didn't shows that it wouldn't have worked. Perhaps because it'd be blurry, but I don't see all TV's being that forgiving. Remember that "most TV's will handle it" isn't good enough, you must guarantee that all will.
They did not just take 60 Hz to match the electricity outlet, since synchronization could be set to anything, they did it to avoid interference-flicker with studio lamps and lights that are also connected to 60 Hz outlets.
You just gotta love from back in the day when someone put the TV on, and your computer screen seemingly degaussed.
That's litteraly what Matt says though
I'm pretty sure that most TVs had their electron beam deflected by the environmental 60Hz electromagnetic noise, this would cause the screen to move vertically at the beat frequency between 60Hz and vertical scan rate. That would be quite annoying though I'm guessing 29.97 is close enough that a movement that takes 30 seconds to complete would not be noticeable.
Can you tell me why they didn't just rectify 60hz AC into DC? Seems like a lot of trouble for something that has such a simple solution.
@@CSGhostAnimation - Yes, Thomas Edison's plan of transmitting power as DC instead of AC would solve the problem. It would also create far bigger problems.
The problem is the current that's not inside your TV set. It creates a magnetic field that deflects the CRT electron beam. The frequency difference between the external magnetic field and the vertical scan rate is what you see as motion on the tube.
Excellent presentation.
That's on of the best, interesting and funny, videos I've seen in months.
They could not have made 30 x 625. That would have brought the horizontal frequency to 18750Hz, which is quite a leap from 15750. It would have broken compatibility with existing sets and other equipment. The change from 15750 to ~15734 worked because the analog electronics involved had some, say, "give". They could tolerate some variance up and down from the expected frequencies, but that much of a change would have been tolerated by very few existing sets, if any at all.
Also, even for those sets that would tolerate and display the new signal, most would probably suffer from some instability, and even those that were stable, would need to be serviced to get the new signal to display correctly, because the video signal doesn't contain driving signals for the deflection coils, but just pulses signaling when to return to the starting position to scan a new line or frame. Then, the electronics on the TV set, upon detecing that pulse, internally generate the sawtooth electric currents that actually drive the deflection coils. These are called flyback transformers. Those found on PC monitors with geometry controls can be adjusted pretty widely, but those on regular TV sets are specifically made for one and only one sawtooth wave lenght, which determines line lenght on the screen.
Basically, your +18kHz horizontal sync signal, if accepted at all by an existing TV set not specifically made for it (let's rememeber that the idea was to keep compatibility with older BW sets), would result in a picture that didn't fill the whole screen but left a portion of the right side of the screen completely black, because a new horizontal pulse would arrive before the flyback transformer could have driven the electron beam all the way to the right side of the screen.
Just tweak the Width and HPos potentiometers on the back.
@@jeepien Have you tried it with TV equipment of the time? I'm not saying I did, but it sounds like, if it was as easy as that, they would have done it, right? So, are you sure it would work?
@@radornkeldam No, I haven''t. Although it would in principle, it's quite likely that such a large change would push it outside the range of existing controls. Nothing is easy.
I did have TV equipment back when the NTSC change occurred, and it was completely undetectable on older B&W TV sets. The Vert and Horiz controls needed occasional adjustment anyway, and had no calibration of any kind, so any small change would not be noticed. You just turned the knobs till the picture held still.
@@jeepien Many - if not most - TVs back then used as adjustable coil in like with the yoke to change the width. And they didn't have a whole bunch of adjustment. They also didn't have a horizontal phase adjustment. You could adjust the centering magnets on the tube to some extent.
@@compu85 TV sets had "Horizontal hold" and "Vertical hold" controls. Just knobs, no numbers. You would adjust the horizontal until the picture stopped looking like a bunch of slanted lines and torn up garbage. You would adjust the vertical hold until the picture stopped rolling frames and locked on one stable frame. Once you got it close, the frequencies would lock to the sync pulses in the picture data, and everything would remain stable. A tiny difference between 30 and 29.97 would not be detectable by anyone with an analog TV set.
On the back of the set, through screwdriver sized holes, you would find rarely needed adjustments of Width Vertical position, and Vertical linearity. These were local adjustments unrelated to the signal. They just put the picture in the right place on the screen, and didn't need to change to match the signal.
Thing is, NTSC never used "line-by-line phase reversal", which was at the heart of PAL.
@Maxx Fleischer You must be referring to the fact that the phase of the colour burst signal is 180°.
So, what was the point of fiddling around with the numbers?
The difficulty of doing this demonstration is astonishing. Well done.
Great info. Thanks for the post.
How did movies end up with 23.976 then?
Movies are still 24 fps. But shown through NTSC you would have to make up for the last ≈6 fps to get to ≈30 fps.
With PAL they just sped the film up from 24 to 25 fps, but speeding it up to 30 fps would be too ridiculous.
Therefore they use 4 frames of 24 fps film to create 5 frames of NTSC video in a ridiculously complicated process called the Three-two pull down method. Read more here:
en.wikipedia.org/wiki/Three-two_pull_down
"Just sped up the film" That's a major change in the timing of a film. Great directors and actors pride themselves on good timing. There was no pitch correction (for many years) so the audio was screwed up, too.
2:3 pulldown is quite simple. Europe uses the truly ridiculous 2:2:2:2:2:2:2:2:2:2:2:3 (Euro) pulldown. Read more here:_en.wikipedia.org/wiki/Telecine#Frame_rate_differences
Chris W
well going from 24 to 23.976 is about 0.1% of the speed in difference. It's not good but can be ignored.
PauLtus B It's non-good when the audio starts to slide out of sync as it is 0.1% longer.
Chris W, wow that is a truly ridiculous method, especially regarding the fact that fps will be less critical in the future as linear television slowly fades out. I've never actually heard of this method as it seems to be quite new it but it does make sense.
I couldn't focus the whole video, I was too busy watching the red LED reflection on the monitor !
+Matthieu Sontag I nearly re-filmed with some tape over it!
Still one of my favorite videos. ty
Awesome, awesome work mate
NTSC actually stands for Never The Same Color
The problem with 25 fps is that it flickers like hell, specially in CRT monitors. It was impossible not to notice it back then.
Curiously enough, Telefunken developed the PAL-M back in the 70s. It has 60fps (not 59.97) and also features the phase alternating line (aka PAL) that made the European PAL famous for its color fidelity.
The system was only adopted by Brazil and worked pretty well.
To be fair, most European TVs would have compensated this flickering issue by using phosphors with more persistence (the glow lasts longer).
The problem with this, however, is that you would notice the persistent glow a lot more if you were watching a content with high contrast--for example, a helicopter searchlight beaming down from a dark sky, well, you'd notice a trail of glowing phosphors behind the searchlight a lot more with a PAL TV.
As for PC monitors though, the phosphors had even less persistence than an average TV, because they were generally supposed to be run at 70 Hz or higher. That's why running one of those at 50 Hz is just eye hurting!
You must have real trouble watching movies, then, because the cinema screen flashes 48 times per second, less than PAL’s 50 times per second.
I don't know of any theatre that uses CRT projectors or old-school film projectors anymore--at least around where I live--so I'm not sure if that's a big issue anymore since it seems the most common projection tech is based on displays that don't inherently flicker.
I can't really say I've ever noticed a 48 fps flicker on a recent movie night.
Even older movies didn't scan so their was no flicker. Fps in the theater is the whole frame at once. You only have 1 line between frames that interrupts the image. You don't have half of the image being scanned in at once then the other half.
No, that's not right. You cannot show a frame in theatres for a complete 1/24th second, because the film stock had to be pulled in place and then advanced to the next frame. The film transport would cause immense vertical motion blur (for regular 35mm projection). Theatres always used rotating shutters to hide the film transport motion. That was also done with the cameras. To make this rotation smooth, each of the 24 frames was interrupted twice. During one of the interruptions the frame was transported. This resulted in 48Hz for 24 frames :)
Later projectors used higher speeds, such as 72Hz or 96Hz (probably why nobody noticed flickering in the last decades).
Very good explanation!
so well presented!
10:46 is almost the Futurama God quote: “when you do things right, people won’t be sure you’ve done anything at all.”
Agree. I noticed that too.
Some people take this as standard for crafting anything in life.
That´s pure Lao-Tze.....right there.
Also, there is a problem with changing the horizontal rate. The flyback transformers of older BW tv's could not have handled the higher frequencies without being ruined.
I like that you put those number figures right IN the video ON your old TV in there, instead of just simulating it; we can see how genuine that is!
Really goog explanation. Thanks. :D