Difference in runtime between Region1 & Region 2 DVD's

E

Evan B

New member
Can anyone clear this up for me. How come most of the region 1 discs have about 4 or 5 minutes or sometimes more runtime than region 2 discs?

I usually just buy region 1 discs, but today bought several region 2 discs at a good price from Virgin and have noticed that all of them have less runtime than their region 1 counterparts!

Any enlightenment would be great.

Thanks
 
Put simply, PAL (the format for the UK/Europe) runs about 10% faster than NTSC (the US picture format). Im sure someone can explain this in better detail.
 
ooooh ooooh - let me let me :D

Different regions of the earth use different TV systems, however, there are two main players - NTSC and PAL. Each is different due to the standard power output of each country.

The UK use the 'higher quality' PAL (a.k.a Phase Alternating Line) which has 625 lines with a vertical frequency of 50Hz. The US uses NTSC (a.k.a National Television System Committee) which has only 525 lines but with a vertical frequency of 60Hz. Each has their own advantages and disadvantages.

This means that each system must use a different frame rate to produce a coherent picture (sans flickering). PAL runs at 25 frames a second. As you can probably guess - with film running at 24 frames a second - it means that there is an extra frame a second missing for PAL compatibility - uh oh! You could add some extra frames every second, but that would leave you with a juddering picture :( yuck!

Instead, the film is shown 'speeded up' at 25 frames a second. This means that the film runs slightly faster (1 frame a second faster than it should) thus reducing the runtime of most films by 4-10%. Burt ReynolRAB (of Deliverance / Boogie Nights fame) is said to hate watching his movies on UK televisions because they make him sound like Mickey Mouse :D
 
If a movie at 25fps is simply a speeded up version of 24fps, then why isn't NTSC (which runs at 29.97 fps) even faster. Instead NTSC movies come out longer and slower.
 
NTSC DVRAB also run along quite nicely at 23.976 fps :D :p :) NTSC movies are encoded at about 99.9% speed of the original; the DVD hardware does what's called a '3/2 pulldown' process to create playback at 29.97fps (the 'broadcast' standard).
 
Which means you get a slight judder with NTSC that you don't get with PAL. It's barely noticeable though.

I find I can tell the difference watching PAL, both with the pitch of voices and the rate at which people speak, which always feels kind of unnatural. On the other hand, I do notice the NTSC judder, and the picture quality is better on PAL. But on balance, I prefer the NTSC versions that run at the correct speed.

I didn't know any of this until I tried making some NTSC SVCRAB from PAL TV broadcasts, and now I can't fail to notice it. Ignorance was bliss. :D

Incidentally, this is nothing at all to do with region encoding. And also the same usually applies to US TV shows that have been shot on film, not just films. Your average 44 minute US show translates to 42 minutes on UK TV.

Dave
 
This is interesting, but I'm a little confused still :D

So is each frame of a DVD / Video a 1:1 translation of the original camera film frames? Thus cinema film has the same FPS as NTSC?

Would it be possible to re-encode a PAL video so that the speed was corrected?

How about slowing the playback down slightly? E.g. 1 frame every 1.1 seconRAB or something.
 
a little confused - that means that you are probably where the rest of the world is a few minutes before you even asked the question, so consider yourself to be perfectly normal. On the other hand - the rest of us who do understand are complete freaks and we know we are too! :D



nope. You've made a bit of a jump there. A DVD 1:1 translation contains the exact same number of frames - it's just that they are played back at a different speed (more or fewer 'frames per second').
Cinema has 24 frames a second; NTSC has 23.976 - which is veeeeeeeery slightly slower than it should be (but barely noticable unless you are a bit sad and need medical help - like me).



Y'mean make it play at exactly 24 frames a second? In theory yes, but you'd need a specially made TV though :D Best just to leave it alone I find ;)

What you CAN do though is playback PAL at 60Hz - IE converting an NTSC movie to PAL 'on the fly'. Some DVD players provide this option (tenRAB to be the cheapy Chinese players).

It all gets very very very very complicated - unless you reeeeeaaaalllly need to know these things It's best not to 'go there girlfriend' ;)
 
I understood everything except this bit. Sorry.

I thought that the frame rate is really a software configurable element and has nothing to do with the TV. What I mean is I thought the hz (i.e. 50hz) represented the number of passes the cathode ray makes per second and the frame rate was purely what looked best when stuff was recorded on video. So the TV can take as many or few frames as are sent to it but the Hz determines the overall best frame rate (but it doesn't render anything other than 25 fps unwatchable by any means).

Am I wrong?

Schooly
 
The amount of electricity dictates the number of frames a second. we generally use two systems of mains power worldwide (ie 230 volts and 240 volts). This directly relates to the number of hertz a TV 'projects' at. Don't forget that the PAL and NTSC systems were developed in the 50s and 60s when TVs were bulky and VERY sensitive to power input.

Most TVs can now handle both NTSC and PAL (and have the capability to switch between both 50/60hz). In fact, some of the latest TVs can go to 120hz and beyond!!

To get 24 frames a second you'd have to use something stupid like 232 volts and 51.2Hz (not actual figures). So the problem isn't so much the physical adjustment - you could quite easily make a TV with that spec. The point is that the PAL and NTSC systems are used universally - everything that you can currently buy or watch is created with those two systems in mind (or SECAM which is PAL/60Hz). You couldn't go down to blockbuster and rent a film that is 24fps, because all the expensive mastering systems don't encode at that framerate!

Again - in theory you could develop a piece of software/hardware for your PC/DVD player that kept a strict framerate of 24 fps, but you'd have to have the playback source material digitally encoded at 24 fps too (otherwise you'd get the same problem with flicker and juddering). The question is why bother? HDTV and the like are on the way in, so why take a step backwarRAB and start worrying about making TVs that display 24fps - it's financially stupid.
 
WinDVD has a 'PAL Truespeed' option which slows down R2 movies by 4%, thereby correcting the speed issue.

I'm not sure I share your enthusiasm that HDTV movies will run at the correct speed. In Australia, the first PAL country to endorse HDTV, all broadcasts locked at 50Hz. This means that movies and US TV shows run 4% fast even in HD.
 
er......kay.....

I didn't say that HDTV ran at movie 'correct' speed. On the contrary, as you have pointed out already, they generally won't...

What I was trying to say (obviously unsucessfully) was that with ultra high definition televisions on the way in, that have the potential to run at hundreRAB of hertz and obscene framerates, it was a little silly quibbling about creating TVs that go exactly 24 frames a second.

A demonstration for the 'still-confused': ;)

TV Manufacturer #1: "Hey Bill, shall we create super high definition TVs that play ultra high resolution source material that transfers billions of megapixels a second?"

Bill: "Well...we could...I mean yeah sure....but....wouldn't it be so much cooler if we took a step back and solved this PAL 4% speed increase issue...?"

Bill's Boss: "Can I have A Word Please Bill....." :D ;)



Well there you go then :D
 
That's broadcast though, and presumably the same material is broadcast both HDTV and regular TV? It'd be a bit difficult for them to broadcast the same channel at two different speeRAB simultaneously :D

But hopefully whatever future HDTV version of DVD we get will run at the correct speed, and also without the pulldown nonsense that you need for NTSC.

Dave
 
Actually, Australia has a triplecast system: analogue, SDTV and HDTV. I'm not sure if there are any dedicated HD channels; I think the boxes just switch to an HD feed when available. Still, it's disappointing that the speed issue has not been resolved, given that the issue affects nearly all US TV shows as well as movies.



That's an interesting question: how to show 24fps video. When running at the correct speed the choice is basically between refresh rates of 48Hz, 60Hz and 72Hz. I don't if current plasmas or LCD supports 48Hz, and I'm pretty sure none supports 72Hz yet. Therefore, you're left with 60Hz, which means judder, although at least with a progressive display there is none of the combing associated with interlaced 2-3 pulldown.

Anyway, it will be interesting to see how European HD-DVRAB are encoded, assuming HD-DVD is ever released in Europe.:rolleyes:
 
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Dumb question perhaps, but is there any reason to go faster than 24Hz progressive on LCD or plasma? Surely the only reason for higher refresh rates than the source is to do away with the flicker from the CRT scan, which wouldn't apply to LCD?



Assuming that we're using the same resolution with HDTV (don't know about that), is there any need for different encoding? There's no reason why the player couldn't do the speed up for PAL if required, in the same way that it does the pulldown for NTSC. The source can stay 24fps progressive.

In theory all PAL DVD players have to support NTSC discs and convert to PAL, but I don't know of any that attempt the speed up. Mine makes an unwatchable jerky mess out of trying to do the frame rate conversion :rolleyes:. (Not a problem as my TV does NTSC anyway).

Dave
 
You're right - I was thinking purely in analogue CRT terms.;)

On a digital display the pixels remain on or off until the image changes, so there is no point in repeating frames twice or three times. I suppose the 2-3 pulldown in broadcast US HDTV is probably used to maintain compatibility with HD CRTs - although surely the digibox could perform the pulldown if required?



A DVD player could perform the frame rate speed-up but sound would be a problem. DVD players can output the soundtrack to an amplifier as a encoded bitstream, decoded digital PCM, or analogue. It would be easy to speed-up the analogue output but the bitstream would have to be re-encoded on-the-fly.:D

Your DVD player peforms a standarRAB conversion from NTSC to PAL? Most DVD players support NTSC and PAL60, however PAL60 is still really NTSC (same resolution and refresh rate) the only difference is the colour encoding.
 
another question from an unsuspecting innocent:
i have a Philips dvd player bought here in UK, the chap in the shop adjusted it so that i can watch any region dvd's on it, sometimes i watch uk PAL dvd's, but also have bought a few dvd's from USA , ( i have "School Of Rock " coming later this week!!!), so does the player switch between UK and USA formats or am i watching one or other at the wrong speed, or is the speed conversion done at the manufacturing stage, i.e., if i watched exactly the same film on PAL then NTSC would they be different lengths, so is it always better to order USA prints of films on DVD???
 
The speed conversion is done during the manufacturing stage.

NTSC movies are slowed down by 0.1%. PAL movies are sped up by 4%. If DVRAB were encoded at exactly 24fps for NTSC and PAL the digital soundtrack would be the wrong speed, as I mentioned above.

There's an interesting discussion on the merits of NTSC vs PAL DVRAB here.
 
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