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Topic: How To Keep Pitch After Ntsc <-> Pal (Read 7425 times) previous topic - next topic
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How To Keep Pitch After Ntsc <-> Pal

i often have to convert NTSC Movies to PAL. but after editing the audio the voices are different. a little bit "higher". i heard about besweet which can keep the pitch after framerate-conversion 23,976 -> 25  but it seems to it can't handle 29,970 -> 25 or 29,970 -> 23,976 without changing the pitch. any suggestions ? thx in advance

How To Keep Pitch After Ntsc <-> Pal

Reply #1 –
Might want to check out Doom9.net too. It claims that it's "The definitive DVD backup resource," but unlike r3mix.net, it's true. (Ooh, couldn't resist the r3mix jab).

No seriously, go to Doom9. I hang out there and so do some other HA members.
Everything I've learned about space, I've learned from psytrance.

How To Keep Pitch After Ntsc <-> Pal

Reply #3 –
Quote
it seems to it can't handle 29,970 -> 25 or 29,970 -> 23,976 without changing the pitch.

You should never speed down 29,970 -> 25 or 29,970 -> 23,976 because the whole video will run in slow motion.
Depending on the source nature (interlaced (and how), pulldowned), the NTSC->PAL conversion should reconstruct 23.976 or 25 frames from 29.97, without changing the playing time. If the result is 25 fps (interlaced source), the audio doesn't need to be edited, and if the result is 23.976 (3:2 pulldown source), you just have to apply the 23,976 -> 25 speedup.

How To Keep Pitch After Ntsc <-> Pal

Reply #4 –
OK, the problem is very easy to solve. You just need to change the framerate of the video. The problem is that you have to remux your file to keep the video in sync with the audio in the file.

As some of you may know, I'm working on a replacement container for AVI called matroska. And it will be possible to do that losslessly and without any reencoding. Even mix a 25fps-based audio track with a 23.96fps-based audio track together... But it's not implemented yet...

How To Keep Pitch After Ntsc <-> Pal

Reply #5 –
a question from a complete video noob: whats better ntsc or pal ? i heard that pal has better colors and ntsc is faster. here (pal country) is sometimes some best-of-talkshow-shit on tv and they also show american talkshows and the picture quality of those american tv shows (i guess ntsc) is incredibly bad. it's really an offence to my eyes. how come it looks so bad since the tv i can watch here (digital sat) is almost dvd quality. is it because of transcoding from ntsc to pal or has the ntsc standard really such a bad quality ? and by the way: whats the advantage that it is faster ? i mean, pal is fast enough. looks fine to me.

How To Keep Pitch After Ntsc <-> Pal

Reply #6 –
PAL :-)

NTSC = Never Twice the Same Color :-)
Sven Bent - Denmark

How To Keep Pitch After Ntsc <-> Pal

Reply #7 –
Yeah, and the Americans dub PAL = Picture Always Lousy ;)

If you experience both systems in their native countries, they both look pretty darned good.

There are a number of problems with converting NTSC to PAL (and probably the other way too), and in some cheaper systems the colours can get messed up, though that's less of a problem these days, and we Europeans generally recognise that Americans don't all have green or magenta faces anymore like they seemed to in the 80s. Resampling 515 lines to 625 isn't a problem to do on the fly with modern computers.

The biggest difficulty is in adjusting the frame rate and field rate, so motion effects can be bad. The US, with 60 Hz AC mains power, has 60 fields per second (roughly), while Europe has 50 Hz and 50 fields per second.

Because each field contains half the picture (the odd lines or the even lines), a complete frame comes through at 30 fps (NTSC) or 25 fps (PAL).

The interlacing of more frequently updated fields, reduces the apparent flicker and obtains most of the perceived fluidity of 50 or 60 frames per second in half the bandwidth. Both NTSC and PAL use 6 MHz bandwidth per channel - one gets more frames per second in exchange for lower resolution (fewer lines). PAL has also allowed Teletext to be transmitted in the few unused lines above the visible picture for decades, so people had access to near-instant news, sport stories, TV listings, captioning and share prices on demand long before the internet or digital interactive TV became publically available.

Movies are shot at 24 fps, so they don't easily convert either! (Sometimes they're simply sped up for PAL). At least they have plenty of spatial resolution.

Interpolating between video snapshots in time is difficult to do well - much harder than sample rate conversion in audio, and usually one frame in 6 is simply dropped when converting from NTSC to PAL, causing jumpy motion effects. Going the other way, you need to duplicate a frame now and again to make up 30 frames, and 60 fields.

This frame dropping/duplicating can also cause the effective fluidity of the field rate (50 or 60 Hz) to break down. Mind you, for sporting events in good daylight many producers insist on using fast "shutter speeds" on their cameras, which breaks down the fluidity and analogueness of motion anyway even if you don't convert formats. Sure they get good stills, but the viewers can suffer jerky motion effects when it really ought to blur properly.

I think you'll find differences between the conversion quality of dramas made for export, and possibly converted in a more painstaking manner, compared to talkshows like Jerry Springer, which are shot for NTSC TV then converted in a relatively simple and cheap manner. The jerky rolling credits are often a major giveaway of low quality conversion. The Springer fights scenes probably lose something in the conversion too!

How To Keep Pitch After Ntsc <-> Pal

Reply #8 –
This is a great site:
http://www.ee.surrey.ac.uk/Contrib/WorldTV/

especially the NTSC vs PAL section.


FWIW, Free to air domestic analogue TV in the USA is terrible quality (both picture and content!) compared to that in the UK. That's my biassed opinion.


Seriously, working at their best, PAL has slightly better resolution, but slightly more flicker. If you're used to NTSC, you notice the flicker on PAL (especially when you look away from the screen*). If you're used to PAL, you notice the lower resolution on NTSC (especially when looking at the screen  especially the larger screens typically found in the USA).

Despite what several American TV engineers keep telling me, NTSC does have a colo(u)r disadvantage in the real world. I've seen it. Far too often. They're wrong, or "right" but homogenised.


The US digital HDTV system gives beautiful quality pictures, but comparatively few people are watching. The UK digital SDTV system could give very nice quality pictures (better than NTSC DVDs), but the bitrate is often too low, and blocking artefacts are quite common. Still, 50% of UK houses now have digital TV.

Cheers,
David.

How To Keep Pitch After Ntsc <-> Pal

Reply #9 –
Quote
OK, the problem is very easy to solve. You just need to change the framerate of the video. The problem is that you have to remux your file to keep the video in sync with the audio in the file.

As some of you may know, I'm working on a replacement container for AVI called matroska. And it will be possible to do that losslessly and without any reencoding. Even mix a 25fps-based audio track with a 23.96fps-based audio track together... But it's not implemented yet...

If you change losslessly the frame rate, the playing time will be changed accordingly. The way to keep audio losslessly in sync is then to change the sample rate of the audio.
First it seems difficult for lossy audio, and second it doesn't solve Anaf's problem, because this changes pitch. He want to do this without changing pitch, which requires very advanced audio processing (time stretch). I could not believe this could be done in an acceptable way until I heard the french and english versions of the Lord Of The Rings DVD in PAL, side to side. The music in the French soundtrack is hi-pitched, and stay in sync with the english one (normal pitched) without any audible artifact ! I'll check again with a wav editor to be sure.

Also, for interlaced sources, you shouldn't slow down from 30 to 25 fps, it's too much. You must process the video.

How To Keep Pitch After Ntsc <-> Pal

Reply #10 –
ntsc & Hue Fluctuation - from what i was told this is a transmission problem which was actually fixed in PAL later on.

pal & flickering - this is a real problem whenever you have to make some titles, subtitles or any graphics with relatively sharp edges. 

(About title makers, i did a test which one looks better some time ago (photoshop and different ways of antialiasing vs discreet smoke vs incriber), where inscriber was a clear winner)
PANIC: CPU 1: Cache Error (unrecoverable - dcache data) Eframe = 0x90000000208cf3b8
NOTICE - cpu 0 didn't dump TLB, may be hung

How To Keep Pitch After Ntsc <-> Pal

Reply #11 –
In my opinion both suck. Interlace is hell... To convert 24fps to 25fps pal, its so easy. Besides the obvious (but dumb) choice of speeding to 25, you can rather simply repeat the last frame each 24 frames. Is that simple. NTSC needs the dreaded Telecine method, people working with DVD ripping should know by now what this could mean if your source is a non progressive movie. PAL has more resolution, lower refresh rate. Colors are supposed to remain more stable, over air it seems a clear advantage. But on perfect conditions (studio, cable) NTSC delivers more colors, only that they are very sensitive (too low bandwidth) and are easy to distort if enough care is not taken. The horizontal resolution is basically infinite (depends on bandwidth), but usually each line won't have much more than 330 discernible dots over air broadcast (these analog lines will always stretch to the screen size whetever it has 10 or 1000 dots on them). The number of vertical lines is always fixed, and refreshed in par/inpar fashion (interlacing). Another thing is that PAL is usually broadcast on what is know as UHF, while NTSC can traditionally use VHF as well. As you know, VHF travels longer distances, but can be blocked more easily than UHF. Think rural vs urban, flat vs mountain, number of repeaters, line of sight, etc.

I simply support anything as long as it is progresive. Even if "480p" were the only choice, it would be a major improvement. Considering the american standard, "720p" (1280x720) is the better tradeoff. I don't understand why they didn't aprove "1080p" (1920x1080) as well as "1080i" (but i am of the opinion that "i" should be dropped).
She is waiting in the air

How To Keep Pitch After Ntsc <-> Pal

Reply #13 –
smok3,

PAL is designed to avoid the Hue problems of NTSC. That's why we have PAL, and not NTSC - we waited well over a decade for colour (compared to the USA), and chose a better system. But both are find under perfect conditions. (btw Brazil uses PAL with 60Hz broadcasts).

The flickering of sharp edged graphics is common to both 50Hz and 60-Hz systems, and clearly visible on both, due to the interlace (I agree with Artemis3 - even 480p is surprisingly good). The solution (if we must have interlacing) is not to put sharp horrizontal edges in the frame - all good modern video graphics generators carefully filter the signal in the vertical direction to ensure this - old ones didn't, and very cheap ones don't. This isn't the flicking I was refering to.

The screen flicker (rather than interlace) in 50Hz countries is noticable if you look away from the set. But it's the same with tube lights in 50Hz countries, so we're quite used to it. 60Hz is certainly better in this respect.


Pio2001,

They apparently do have a "box" that pitch shifts, allowing 24fps material to be replayed at 25fps, whilst restoring the corrent pitch (not speed). My ears tell me that this process is about 1000 times better than the one in Cool Edit Pro!


Artemis3,

As you say, the horrizontal resolution isn't really infinite - it's bounded by the signal bandwidth, and the fact that the top of the luminance signal is overlaid by the colour signal. Where the two interfere you get strange effects which comb filters in some modern TV try (and often fail!) to remove.

The US system has the colour centered around 3.58MHz above the luminance, the UK system has the colour centered around 4.43MHz above the luminance. This means we get less interference between the luminance and colour signals.

The US system has a 4.5MHz total video bandwidth, the UK system has a 6MHz total video bandwidth. This means that we get higher resolution in the horrizontal (as well as vertical) direction.


For all these differences, it's worth remembering that both systems are almost identical in most ways:

Conceptually, if you want to run the 60Hz NTSC system at 50Hz, then, to keep the signal bandwidths (or the amount of information per second) similar, you need to have more lines per frame. So we have! It's almost a coincidence that this gives us more spatial resolution - it's just a result of having less temporal resolution.

Then, if you want to solve the Hue instability of NTSC, you need a way of canceling it out - so PAL flips the phase of one colour signal every other TV line, so errors cancel out.

However, both systems use interlacing; both systems use a supressed colour sub-carrier driven from a colour burst at the start of each TV picture line, both systems put the colour information over the top of the luminance band, both systems use horrizontal and vertical synchronisation and blanking, both broadcast systems use negtive luminance modulation (brighter picture = lower voltage) etc etc.


There's an interesting idea I've read: In the 21st century, the UK has lower broadcast standards - our digital TV and radio bitrates are about as low as they can be, and profit comes before technical quality. If this attitude had won in the 1960s, then we would have had 405-line 50Hz NTSC colour with a ~3.5MHz video bandwidth - the worst of all possible systems!

Cheers,
David.

How To Keep Pitch After Ntsc <-> Pal

Reply #14 –
Quote
our digital TV and radio bitrates are about as low as they can be

about as low?  Oh, they'll get lower and lower as time goes on.... you know it!

How To Keep Pitch After Ntsc <-> Pal

Reply #15 –
Quote
Quote
our digital TV and radio bitrates are about as low as they can be

about as low?  Oh, they'll get lower and lower as time goes on.... you know it!

True - I'm really looking forward to hearing stereo music at 48kHz sampling rate, but only 112kbps via mp2!

My comments on the regulation of audio quality on UK DAB digital radio include the quote from the UK Radio "authority" where they suggest that they will allow 112kbps or below in the future.


As for video - if BBC2 gets any lower during newsnight (or BBC1 gets any lower during Top of the Pops) they might as well replace the titles with a static slide show!

Cheers,
David.

How To Keep Pitch After Ntsc <-> Pal

Reply #16 –
Quote
Besides the obvious (but dumb) choice of speeding to 25, you can rather simply repeat the last frame each 24 frames.
there are 2 methods http://www.zerocut.com/tech/pal/pal.html (actually each method depends on available resources and both just cant be made in every production house), also from what i remember the method B is kinda more complex (from the editors point at least).

On the other hand film and 24 fps is not really always the point, lots of 'for the pal' movies are shot at 25 fps originaly. (link leads to the 'prepairing for editing' example, but it is likely quite the same for final production)

pio2001, about ur doom9 question: not sure exactly how thx colorbars are constructed, but in pal world there are 2 types of color bars, called 75% and 100% one, if that is of any help. (in any case it is not about the 'inherent loss when transcoding from YUV to RGB ')

examples:
100% http://users.volja.net/smoker/pub/pal_colo...ars/pal_100.png
75% http://users.volja.net/smoker/pub/pal_colo...bars/pal_75.png
PANIC: CPU 1: Cache Error (unrecoverable - dcache data) Eframe = 0x90000000208cf3b8
NOTICE - cpu 0 didn't dump TLB, may be hung

How To Keep Pitch After Ntsc <-> Pal

Reply #17 –
Both NTSC and PAL are horrible, ridiculously outdated, and technically inferior to modern technologies.

The single worst crime of them all, interlacing, applies to both formats. Computer monitor manufacturers realized the importance of progressive scan a long time ago, in case you were wondering why monitors have a sharper image than TV sets. TV really needs to get progressive, or at least double the interlaced vertical resolution. We europeans have heard rumours about something called 'HDTV' but I reckon they will stay as rumours for at least the next fifty years.

When looking at the formats from current HDTV/DVD perspective, NTSC wins hands down since most modern non-HDTV sets can already do progressive NTSC (480p). Progressive PAL (576p) is stalled ad infinitum because of some stupid copyright issues, I hear. Currently no non-HDTV set I know of supports it, despite that most PAL DVD's are in progressive scan format.

And to give TV engineers few additional brownie points, these technologies are not interchangeable because of the different frame rate. So I can't watch progressive PAL DVD's in 480p NTSC mode, which would be a lot better than interlaced PAL.

I really wish converting between image formats would be as easy as speeding up audio from 23.97 to 25 fps

Edit:

I meant non-HDTV when I said TV..

How To Keep Pitch After Ntsc <-> Pal

Reply #18 –
OK, I think I got the pb wrong. No need for something lossless as there is some time-stretching needed (a native audio+video @ 23,976 converted into a native audio+video @ 25).

How To Keep Pitch After Ntsc <-> Pal

Reply #19 –
Quote
The single worst crime of them all, interlacing, applies to both formats. Computer monitor manufacturers realized the importance of progressive scan a long time ago, in case you were wondering why monitors have a sharper image than TV sets. TV really needs to get progressive, or at least double the interlaced vertical resolution.

With analogue broadcasts, 576 50i is exaclty half the bandwidth of 576 50p. Or, to put it another way, there would be room for exactly half the number of TV stations within the broadcast spectrum if everything went progressive.

In the digital world, if anything, progressive images require a lower bitrate to look reasonable (on progressive capable displays) than interlaced pictures.

The actual comparisons are here:

http://www.svt.se/svtinfo/inenglish/dev/sv...dexga_final.pdf
http://www.ebu.ch/tech_texts/tech_text_i34....pdf?display=EN
http://www.bbc.co.uk/rd/pubs/whp/whp025.html
http://www.bbc.co.uk/rd/pubs/whp/whp044.html
http://tinyurl.com/bhnn  (page 12)


So, I agree. Digital broadcasting should have been progressive from the start, with all boxes able to re-interlace the signal for existing TV sets. It's comparatively easy to take a progressive source of any resolution, resample it to 576p, and then interlace it to 576i. That's why we should be doing it! It's almost impossible to take 576i, and convert it to anything higher without it looking quite bad. That's why Plasma screens etc are a great way of seeing how bad UK TV can look!

Cheers,
David.

How To Keep Pitch After Ntsc <-> Pal

Reply #20 –
Back to the original question, SoundTouch DSP (Winamp or Foobar2000 plugin) does a fairly good job at speeding up or slowing down audio withouth pitch shift, or shifting pitch without speed change. The SoundTouch website, I think, had a standalone program too. You just need to know the required amount of shift.

How To Keep Pitch After Ntsc <-> Pal

Reply #21 –
Quote
With analogue broadcasts, 576 50i is exaclty half the bandwidth of 576 50p. Or, to put it another way, there would be room for exactly half the number of TV stations within the broadcast spectrum if everything went progressive.

It wouldn't be a big loss, at least not in my country. In Finland we have so few TV channels that probably 99% of the TV network bandwidth is unused. Or actually it's probably around 98%, since concurrent analog/digital TV transmissions began some time ago

And on the other hand, unless they start showing Monty Python again, I couldn't care less in which format the TV broadcasts are. I can watch the news progressive or interlaced, PAL or NTSC, colour or black and white. I would want a PAL 576p TV set mostly for computer and DVD usage. I know that most plasma/high end HDTV's can display something close enough to 576p, but they are ridiculously overpriced and as such unavailable in Finland anyway.

BTW, we made the same error with digital TV, the format is regular PAL 576i. So in other words, the picture is still interlaced, nothing gained. Well, there's a little less noise in the signal. Wow.

I queried the entities which are responsible for digital TV in Finland about the possibility of HDTV transmissions. They replied that they will consider switching to HDTV, or at least to 576p when sufficient amount of people own a HDTV set. But that leads to a bad circular dependency; no one will buy a HDTV before regular HDTV broadcasts begin and the broadcasts won't be started until most people have HDTV's. That's government/consumer relations for you.

How To Keep Pitch After Ntsc <-> Pal

Reply #23 –
Quote
not sure exactly how thx colorbars are constructed, but in pal world there are 2 types of color bars, called 75% and 100% one, if that is of any help.

Yay !
It answers perfectly the three monthes old question
The 8 bits RGB values in the TXH chart are indeed between 188 and 191 (one at 187), while 75% is 191, so this is a good 75 % chart !

Thank you !

[span style='font-size:8pt;line-height:100%']EDIT : added thank you. I wanted to do it yesterday, but my ISP was down.[/span]