29.97 versus 29.970030 [Archive]

poisondeathray

9th February 2015, 04:38

Is there some particular reason why DGindex reads .vob files as 29.970030 or 23.9760024 FPS instead of 29.97 or 23.976?

Because that's the real framerate for NTSC

"29.97" is an approximation of 30000/1001

"23.976" is an approximation of 24000/1001

Katie Boundary

9th February 2015, 08:49

Fascinating. Why were those values chosen?

filler56789

9th February 2015, 09:44

Probably you'd better ask the developer directly:

http://rationalqm.us/board/index.php

Just be careful and don't be misled by their domain name...
humans are VERY irrational,
principally the ones who claim to be
"more rational" than the rest of the world :p

feisty2

9th February 2015, 10:35

30 to 30/1.001 was set to avoid frequency interferences in ntsc system
24/1.001 got this weird stuff from the legacy analog ntsc system

Sharc

9th February 2015, 10:39

Fascinating. Why were those values chosen?
Ease of technical (harware) implementation to generate these slightly lower framerates, at the time when color TV was introduced.
See for example:
http://theautomaticfilmmaker.com/blog/2009/2/23/about-frame-rates-or-why-2997.html

pandy

9th February 2015, 10:43

Fascinating. Why were those values chosen?

http://en.wikipedia.org/wiki/Colorburst#Rationale_for_NTSC_Color_burst_frequency

But shortly - to provide limited (or rather to improve) separation between luminance and chrominance spectrum (and audio).

Similar approach is in PAL (25Hz offset introduced to improve spectrum separation between chrominance and luminance).

Katie Boundary

9th February 2015, 19:54

wonkey_monkey

9th February 2015, 21:51

Hindsight is 20:20.

Kill Hitler? Nah. If I get my grubby little mitts on a time machine, I'm going back to stop them inventing interlacing.

Sharc

10th February 2015, 00:05

......and extremely stupid decisions that were made in order to mitigate the effects of previous extremely stupid decisions....

Apparently you feel entitled to judge that TV technology has been developed by monkeys in the past .....

Katie Boundary

10th February 2015, 00:31

All I'm saying is that, if a technology has only been around for 10 years but standards will be around forever, future-proofing should be a higher priority than backward-compatibility. Never create permanent problems in order to solve temporary ones.

Apparently you feel entitled to judge that TV technology has been developed by monkeys in the past .....

Not all TV technology, just NTSC. I have quite a lot of respect for PAL/SECAM.

wonkey_monkey

10th February 2015, 01:19

future-proofing should be a higher priority than backward-compatibility

"Making future maths slightly easier on the poor humans" isn't really future proofing - there's no real show stopper involved in having a slightly different framerate.

Katie Boundary

10th February 2015, 02:41

"Making future maths slightly easier on the poor humans" isn't really future proofing - there's no real show stopper involved in having a slightly different framerate.

It forces us to either decimate frames or add a few milliseconds to the running time, and if the latter is chosen, then the audio has to be stretched out too, slightly lowering its pitch or tone or whatever. It also screwed up the entire point of having a 60 hz refresh rate to begin with.

Whatever, question has been answered, time to apply some ointment for my butthurt and get on with life.

pandy

10th February 2015, 09:08

Okay so it apparently has something to do with "intermodulation distortion" and how visual information was carried by an AM signal but audio was carried by an FM signal, and extremely stupid decisions that were made in order to mitigate the effects of previous extremely stupid decisions.

Reading the history of the NTSC standard reminds me of the story of the old lady who swallowed a fly.

Not particularly - all this things are to provide backward compatibility with Gray(B/W) TV and at the same time introduce color.
Remember that 2(3) different signals (video) are sent at the same time, add to this synchronization and audio then it will be very complex system designed so cleverly with very limited technology available those times.

All I'm saying is that, if a technology has only been around for 10 years but standards will be around forever, future-proofing should be a higher priority than backward-compatibility. Never create permanent problems in order to solve temporary ones.
Not all TV technology, just NTSC. I have quite a lot of respect for PAL/SECAM.

Well - NTSC is not so bad and i don't see anything described by You - writing this as electronics engineer - NTSC/PAL/SECAM are proof that they was designed as future proof systems - it is hard imagine such clever approach to solve so many problems nowadays with such limited amount of materials/components - we are plainly to stupid...

wonkey_monkey

10th February 2015, 19:38

It forces us to either decimate frames or add a few milliseconds to the running time

Forces who to add milliseconeds to the running time of what? Most video captured with the final intent of having it broadcast on TV will be done at the correct rate, or if not, as you point out, it can be converted with no noticeable impact.

It could be a lot worse (http://en.wikipedia.org/wiki/576i#PAL_speed-up).

foxyshadis

11th February 2015, 00:02

Well - NTSC is not so bad and i don't see anything described by You - writing this as electronics engineer - NTSC/PAL/SECAM are proof that they was designed as future proof systems - it is hard imagine such clever approach to solve so many problems nowadays with such limited amount of materials/components - we are plainly to stupid...

Well, NTSC framerate isn't so bad. NTSC color was horrifyingly bad and impossible to standardize, only beaten by VHS being even worse, and I'm glad that era is behind us now.

nhakobian

11th February 2015, 04:00

Well, NTSC framerate isn't so bad. NTSC color was horrifyingly bad and impossible to standardize, only beaten by VHS being even worse, and I'm glad that era is behind us now.

Agreed.

The decisions were made back when reverse compatibility was a necessity. If they kept coming out with new formats every few years, people would not have been able to afford the technology, and when all of a sudden their old TV stopped working, why should they go and get a new one if the same thing was to happen?

The issue was primarily an economic decision. One that has haunted us until recently (and in some areas still do). It was a horrible decision from a technical standpoint, but I think they would have had a much harder time having people adopt a new technology if they had changed it as frequently as they could have.

pandy

11th February 2015, 11:20

Well, NTSC framerate isn't so bad. NTSC color was horrifyingly bad and impossible to standardize, only beaten by VHS being even worse, and I'm glad that era is behind us now.

Remember that NTSC is created in time where memories are made as analog delay lines (and computers rarely have more than few hundreds of memory bits) and that PAL is fully based on NTSC with few improvements and it took 10 years to invent and test those improvements... SECAM is different story (and in practice worse than PAL).

NTSC problems are related to components limitations not to NTSC itself (or theory of work).

Katie Boundary

13th February 2015, 05:21

all this things are to provide backward compatibility with Gray(B/W) TV and at the same time introduce color.

I know that, and I'm saying that was a bad call.

NTSC/PAL/SECAM are proof that they was designed as future proof systems

:confused:

Forces who to add milliseconeds to the running time of what?

who: Anyone trying to convert film footage to something NTSC-compatible

what: anything originally shot at 24 FPS

The decisions were made back when reverse compatibility was a necessity. If they kept coming out with new formats every few years, people would not have been able to afford the technology

But it wouldn't have been every few years. It would have been once in the entire history of TV.

Sharc

13th February 2015, 10:13

"Future-proof" is a marketing gimmick rather than anything else. Backward compatibility - at least supporting a smooth transition - is an economic and commercial necessity, and more even a social obligation. It has been a huge challenge at all times. Also to mention that PAL inherited the basic concept from NTSC but learned from the experience and apparent deficiencies of NTSC.
Imagine that in the 50/60ies industry and standarization bodies would have been striving for a standard which would now allow a hassle-free transition to 3D color TV broadcasting, with the quality people may expect in say 2020, well coordinated with the development of the movie industry, given the technology constraints of the 50/60ies and the state-of-the art of 2020. We would probably still be waiting for the 1st practical and affordable TV.
I am not aware of any technical solution which is not a compromise between a pile of conflicting requirements, wishes and imaginations. It's the same in 2015 as in 1960, I guess ...

Katie Boundary

13th February 2015, 11:48

Imagine that in the 50/60ies industry and standarization bodies would have been striving for a standard which would now allow a hassle-free transition to 3D color TV broadcasting, with the quality people may expect in say 2020, well coordinated with the development of the movie industry, given the technology constraints of the 50/60ies and the state-of-the art of 2020. We would probably still be waiting for the 1st practical and affordable TV.

Yeah because a 24 hz refresh rate and RGB signal are just soooo much more technologically advanced than what we have now :rolleyes:

hello_hello

15th February 2015, 04:39

I know that, and I'm saying that was a bad call.

Every house in the U.S with a TV has a black and white set and when the transition to colour takes place you think the better call would have been to make every existing TV obsolete? What fantasy world do you live in?

These days Bluray supports 24fps, and it's been around for eight or nine years. You're arguing about an older standard.

Katie Boundary

15th February 2015, 07:39

Every house in the U.S with a TV has a black and white set and when the transition to colour takes place you think the better call would have been to make every existing TV obsolete?

Sure. Why not? We made the switch from VHS to DVD without killing the market for home movies...

hello_hello

15th February 2015, 10:05

Sure. Why not? We made the switch from VHS to DVD without killing the market for home movies...

And in the fantasy world you've created for yourself, that's the same thing?

I still have VHS player. It'll still play VHS tapes while connected to my Plasma TV just like a DVD player will still play DVDs and a Bluray player will play Bluray discs. It didn't stop working the minute the first DVD player was released.

Katie Boundary

15th February 2015, 10:30

And in the fantasy world you've created for yourself, that's the same thing?

I still have VHS player. It'll still play VHS tapes while connected to my Plasma TV just like a DVD player will still play DVDs and a Bluray player will play Bluray discs. It didn't stop working the minute the first DVD player was released.

Likewise, black-and-white TVs would have still been capable of playing black-and-white content after some programs were being broadcast in color.

hello_hello

15th February 2015, 10:55

Likewise, black-and-white TVs would have still been capable of playing black-and-white content after some programs were being broadcast in color.

And that's the same thing?
You're confident broadcasters could easily switch between broadcast methods according to whether a program was black and white or colour? What about black and white content with colour commercials?

Even today, movies are released in both DVD and Bluray format. The same thing happened during the transition from VHS to DVD. Likewise, nobody was instantly denied access to particular content when B/W transmission switched to colour.

Katie Boundary

15th February 2015, 19:40

And that's the same thing?
You're confident broadcasters could easily switch between broadcast methods according to whether a program was black and white or colour?

I'm sure they would have figured out something that worked better than what we ended up with.

wonkey_monkey

15th February 2015, 21:36

I'm sure they would have figured out something that worked better than what we ended up with.

Well, they didn't. So either they were all idiots, or they (they being all the many hundreds/thousands of professional TV broadcast engineers who played a part in making colour TV a reality) were actually smarter, and understood the situation far better, than you.

If the world were to continually put off their current best solutions in hopes of something better come along, we'd still be living in mud huts.

Katie Boundary

15th February 2015, 22:26

Well, they didn't. So either they were all idiots, or they (they being all the many hundreds/thousands of professional TV broadcast engineers who played a part in making colour TV a reality) were actually smarter, and understood the situation far better, than you.

Or you failed to correctly parse the conversation. Since 1:55 AM Pacific time today (i.e., the time of Hello's last post), "they" refers to the BROADCASTERS, not the engineers.

wonkey_monkey

15th February 2015, 23:17

Or you failed to correctly parse the conversation. Since 1:55 AM Pacific time today (i.e., the time of Hello's last post), "they" refers to the BROADCASTERS, not the engineers.

Are you really going to split that hair just for the sake of not being wrong about anything, ever? Re-read my post and replace "engineers" with "broadcasters," [an,idmbb-yjbpa] if you like. The point is still that you're not as qualified as you seem to think you are to second-guess the events of 60 years ago, just as those people weren't qualified to accurately predict the next 60 years of technical progress.

Reducing frame rates by a factor of 1001/1000 was almost certainly the best choice at the time. And, frankly, there's very little hardship in having to deal with 59.97 vs. 60.00.

hello_hello

16th February 2015, 00:21

I'm sure they would have figured out something that worked better than what we ended up with.
In this world of make-believe, could everything be made of chocolate?

Katie Boundary

16th February 2015, 01:50

Are you really going to split that hair just for the sake of not being wrong about anything, ever? Re-read my post and replace "engineers" with "broadcasters," [an,idmbb-yjbpa] if you like.

But they're two different groups. Conflating them would be like saying that Microsoft was responsible for the design of the Pentium 4 :/

there's very little hardship in having to deal with 59.97 vs. 60.00.

At that point, it wasn't about 59.97 vs. 60.00 so much as it was about 59.94 vs. 60.00 vs 24.00. Going with 59.94 just re-introduced an artifact that 60hz had been picked to eliminate, so there was no longer any reason to use anything remotely close to 60hz anymore except to maintain backward compatibility, but backward compatibility was causing other problems too.

Bloax

16th February 2015, 02:29

If anyone wants some good news then I'd like to point out that streaming videogames at integer framerates is an uprising industry.

As for the rest of the thread, it's a good idea to do certain things every now and then (http://i.imgur.com/p3ba7hU.gif) - what else can I say.

Sparktank

16th February 2015, 02:40

A bit off topic, but this is the GD section, and can be applied to literally every thread Katie has started:

With all this strict apprenhension towards proper grammar and syntax, and breaking down every paragraph/sentence, I'm surprised you haven't tried to take up coding to some degree.
With your persistence in paying attention to "internet English", you'd probably better suited towards directing all that angst in programming languages.

You could probably learn the basics of something like C++ or Python well enough to grab older plugins and give them an update, no matter how small.
Or for fun.

If I must admire something, it would be your undying dedication.

That's my only 2 cents, as of late on all things Katie.

Back to you guys.

pandy

16th February 2015, 10:30

:confused:

NTSC is still in use after 70 years - call that this technology is not future proof - FYI first commercial HD TV was Japanese MUSE in half of 80 previous century - this means that NTSC was 40 year old when HD began life, European improved TV MAC (DMAC, D2MAc etc) was possible only due of technology progress and relatively cheap semiconductors (video memories, fast Analog Digital Converters).

And side to this - there is many limitations that shaped SDTV for example 6MHz channel bandwidth (in Europe 7/8MHz) - all video need to be squeezed in this narrow space.

Katie Boundary

18th February 2015, 02:17

I'm surprised you haven't tried to take up coding to some degree.
With your persistence in paying attention to "internet English", you'd probably better suited towards directing all that angst in programming languages.

You could probably learn the basics of something like C++ or Python...

I actually did start learning Python for the purpose of Civ 4 modding, but quickly became distracted by something shiny and forgot to get back into it. Maybe some day...