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Inventive Software
10th October 2007, 17:37
I read something somewhere that escapes me, that PAL films are actually sped up. In that case, is it worth slowing the 25 FPS down to 24 FPS?

bourtzovlakas
10th October 2007, 17:47
Only a 4% speed-up....
Hardly noticeable....

zambelli
11th October 2007, 11:18
It's barely noticeable in the video, but lots of people notice it in the audio if the pitch has been shifted up. Musicals and movies with well known soundtracks are the ones that always get noticed because a 4% pitch shift is like a tone or semi-tone shift in scale.

Manao
11th October 2007, 11:33
I do hope however that audio conversions are properly made : the audio can be sped up while the pitch remains the same.

dragongodz
11th October 2007, 14:56
I read something somewhere that escapes me, that PAL films are actually sped up.

some are and some are not.

Manao
11th October 2007, 15:01
All PAL films coming from the cinema are sped up, since cinema == 24fps. So even film coming from PAL countries are sped up when shown in PAL countries...

Brother John
11th October 2007, 15:24
I do hope however that audio conversions are properly made : the audio can be sped up while the pitch remains the same.
Judging from the DVDs where I’ve also heard (or own) the soundtrack: Proper audio speedup *without* changing the pitch does not happen.

jethro
11th October 2007, 16:14
I'd say PAL movie speedup is a *feature* not something to be corrected. PAL movies run say 100 minutes instead of 104 - you save like entire 4 minutes for other things AND you get through the boring scenes faster :).

FlimsyFeet
12th October 2007, 12:00
Judging from the DVDs where Iíve also heard (or own) the soundtrack: Proper audio speedup *without* changing the pitch does not happen.It does happen, but only on rare occasions such as when the director requests it.

A normal speedup is just really resampling, and there are quite simple algoritms that give high quality results.

Speedup and preserving the pitch is a much more complicated process and can result in audible digital artefacts. I think it was the PAL DVD release of the first Lord of the Rings film that caused audiophile people to complain about bad pitch correction.

dragongodz
12th October 2007, 12:10
All PAL films coming from the cinema are sped up, since cinema == 24fps.

if you are saying they have the same amount of frames but the play rate is just increased, so shorter runtime, which is what was asked about, then you are wrong.

example, all the ghibli movies released by Madman(Aus only) before about may 2005 were not sped up but had blended frames to make up the speed.
i just confirmed this with a guy who was one of the encoders for Madman.

if you look at the releases in other PAL countries, such as the UK, and see they also have the same runtime as the NTSC releases its a reasonable bet they are not sped up either.

MfA
12th October 2007, 14:48
I'm guessing the UK was/is one of the forerunners in using motion compensated conversion though, because of Snell and Willcox and BBC R&D evangelizing it.

Manao
12th October 2007, 15:04
Anime != cinema, even when they are as good as ghibli's. And adding blends is indeed a way to do the conversion, but it's definitely not the good way.

burfadel
12th October 2007, 15:08
Thats a tradeoff between Pal & NTSC :D . PAL you get the 4 percent speedup, but you also have a natively have a 20 percent higher resolution (720x576 for PAL as compared to 720x480 for NTSC).

Inventive Software
12th October 2007, 15:44
So there's plus points to PAL against NTSC after all! :D

I know you can't necessarily see whether it's sped up, but would it be worth checking the PAL release durations vs NTSC durations?

dragongodz
12th October 2007, 15:58
Anime != cinema, even when they are as good as ghibli's.

sorry but you are wrong. ghibli films are made for the cinema, end of story. besides i just used them as an example because i have a source that i could confirm how they were done. it should not be assumed that other films are never done the same. for another example Madman has other divisions/labels such as Eastern Eye which they release asian live movies through so no doubt some of them have been done the same aswell. or how about some of the smaller/budget dvd production houses ? you can not guarentee they never do the same aswell.

And adding blends is indeed a way to do the conversion, but it's definitely not the good way.

i think we are getting away from what the actual question asked was. so let me restate it in a different way and answer it again.

is it worth slowing the 25 FPS down to 24 FPS?

now this question is based on this first piece of information

I read something somewhere that escapes me, that PAL films are actually sped up.

now if that was true of all movies then it would be possible to say yes slowing it down is an option. however it isnt true, as i have said, for all films so to just assume slowing it down is a good option is working from bad information.

Mug Funky
13th October 2007, 09:30
there's lots of grey areas here...

for audio:

pitch shifting sometimes happens, sometimes doesn't. personally i'm not a big believer in it - pitch shifting algorithms vary in quality, and even the best ones aren't perfect, whereas simple resampling is a lot safer, artefact-wise. also, i'm of the opinion that someone with perfect pitch will also probably have a pretty good sense of the faster tempo, which obviously you can't correct for without remixing and re-editing the movie special for PAL.

one thing worth noting is a HDCAM/SR deck typically has the option to output sped-up PAL with pitch shifting (and the option to link individual channels together in the process, which avoids a lot of the timestretch problems in surround tracks). so newer films that have had digital intermediates done (or anything where a HD-DVD/BD version exists) will likely get a better conversion.

for video:

just because something's shot on film, doesn't mean it's at 24fps. take short films, commercials, low budget cinema, some features, music videos, series, etc. basically, in PAL land it's a lot easier to deal with things like sound sync if you shoot at 25fps.

then you've got the increasing trend of shooting on video, or HD. unless you're using VariCam at an odd rate, or an NTSC camera, you'll be shooting at 25fps.

an example is Kenny, the second most popular australian film of last year (after happy feet... hard to beat that one really). it was shot in DV PAL and output to film. so the cinema version was actually slower than the original, and the DVD is more faithful to what was actually shot.

Morte66
13th October 2007, 17:29
I read something somewhere that escapes me, that PAL films are actually sped up. In that case, is it worth slowing the 25 FPS down to 24 FPS?

It bothers some people more than others (I speed correct about 1000 PAL DVD rips a year). Try it and compare. If you immediately feel that one is right and one is wrong, it's worth doing.

The relevant bit of my typical script....
video=DGDecode_mpeg2source("D:\MeGUI\314 2am - 3am\314 2am -3am.d2v",info=3)
audio=nicac3source("D:\MeGUI\314 2am - 3am\314 2am - 3am Track 1 English DELAY -24ms.ac3",2)
audiodub(video,EnsureVBRMP3Sync(audio))
delayaudio(-0.024)
assumefps(24,1,true)
SSRC(48000,false)
#deinterlace
#levels
#deblock
#crop
#denoise
#sharpen
#deband
.... then feed that to your audio and video encoders

Incast
13th October 2007, 18:01
Thats a tradeoff between Pal & NTSC . PAL you get the 4 percent speedup, but you also have a natively have a 20 percent higher resolution (720x576 for PAL as compared to 720x480 for NTSC).

The coming years will be interesting because with HD the difference now simply lies in the frame rate, the resolutions are the same.

I believe it would make far more sense to go with the 25/50 system ultimately for the entire planet. With this you never have to mess around with pulldown and the vast majority of viewers cannot detect the audio pitch change where conversion is necessary.

If this will ever happen though remains unclear. The US as the world's largest market -with Hollywood within it- has little incentive to change. With the rise of internet TV the position of the 'NTSC' system is probably being strengthened too given that virtually all PC TFTs are at 60Hz.

Morte66
13th October 2007, 18:04
The coming years will be interesting because with HD the difference now simply lies in the frame rate, the resolutions are the same.

The Blu-Ray and HD DVD movies are all 23.976 (sometimes with reversible telecine on top), there is no PAL or NTSC concept. HD displays don't follow the same rules as PAL and NTSC TVs.

Incast
13th October 2007, 18:10
The Blu-Ray and HD DVD movies are all 23.976 (sometimes with reversible telecine on top), there is no PAL or NTSC concept. HD displays don't follow the same rules as PAL and NTSC TVs.

Well that will apply to Hollywood releases, but not necessarily releases from the PAL regions nor to HDTV.

Shinigami-Sama
15th October 2007, 03:13
Well that will apply to Hollywood releases, but not necessarily releases from the PAL regions nor to HDTV.

then they have to get with the times?

Inventive Software
15th October 2007, 14:59
Not necessarily... some PAL shows are still shot in 25 FPS, because it's only intended for a PAL TV audience. Examples include "Have I Got News For You", "QI", "After You've Gone", and most day-time TV shows, like (the scourge of daytime) "The Jeremy Kyle Show", "This Morning", "Countdown" etc.... the list goes on! Having them switch to 24 FPS would probably be a step backwards for them. Most of those shows never make it to another medium other than TV broadcasts, and they probably never will.