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PAL or NTSC matter in digital tv?


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#1 Shidan Saberi

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Posted 03 July 2011 - 03:59 AM

Hi,

Does PAL or NTSC make any difference for broadcasting with modern digital tv?

Thanks

Edited by Shidan Saberi, 03 July 2011 - 04:00 AM.

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#2 Stephen Williams

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Posted 03 July 2011 - 04:44 AM

Hi,

Does PAL or NTSC make any difference for broadcasting with modern digital tv?

Thanks


Yes is does, as the fps is different. I think you need to give more information so we can answer your real question.
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#3 Shidan Saberi

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Posted 03 July 2011 - 05:32 AM

Yes is does, as the fps is different. I think you need to give more information so we can answer your real question.


I was just discussing with someone that australian tv uses PAL which is 25fps. But my friend suggested that doesnt matter what fps your footage is with digital tv, because PAL NTSC all work in all regions now.

So i guess my question is can Australian tv broadcast NTSC as well with the introduction on digital tv? Also, can it broadcast footages with higher frames rates? Like 60fps or even higher?

Edited by Shidan Saberi, 03 July 2011 - 05:36 AM.

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#4 Freya Black

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Posted 03 July 2011 - 08:03 AM

I was just discussing with someone that australian tv uses PAL which is 25fps. But my friend suggested that doesnt matter what fps your footage is with digital tv, because PAL NTSC all work in all regions now.

So i guess my question is can Australian tv broadcast NTSC as well with the introduction on digital tv? Also, can it broadcast footages with higher frames rates? Like 60fps or even higher?


Your friend is wrong.
People in the US need special equipment to play PAL DVD's because NTSC can't cope with the extra resolution etc. People in PAL land can play NTSC and PAL DVD's but only if the discs are "Region 0" or the player is region free.

As to Australian digital TV, it would depend on what the set top box or TV decoder was capable of. I imagine it's more than possible that peoples set top boxes would be unable to decode an NTSC digital signal. They may well just assume that the signal will be PAL 50i and get confused at other frame rates or resolutions. NTSC would be considered non standard in any case. A broadcaster would be far more likely to just convert any NTSC material to PAL and avoid any potential issues in the chain.

love

Freya
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#5 Brian Drysdale

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Posted 03 July 2011 - 08:23 AM

I was just discussing with someone that australian tv uses PAL which is 25fps. But my friend suggested that doesnt matter what fps your footage is with digital tv, because PAL NTSC all work in all regions now.

So i guess my question is can Australian tv broadcast NTSC as well with the introduction on digital tv? Also, can it broadcast footages with higher frames rates? Like 60fps or even higher?


It can't because the whole standard definition broadcast system including receivers are set up for PAL and haven't been changed. You may be able to play region 1 DVDs in PAL countries (if your player is chipped), but that's not the same as broadcasting NTSC.

HD isn't PAL or NTSC, but PAL countries still use the same 25 fps frame rates, they don't broadcast the NTSC frame rates. Their next step up is 50 fps rather than 60 fps.
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#6 Shidan Saberi

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Posted 03 July 2011 - 09:03 AM

It can't because the whole standard definition broadcast system including receivers are set up for PAL and haven't been changed. You may be able to play region 1 DVDs in PAL countries (if your player is chipped), but that's not the same as broadcasting NTSC.

HD isn't PAL or NTSC, but PAL countries still use the same 25 fps frame rates, they don't broadcast the NTSC frame rates. Their next step up is 50 fps rather than 60 fps.


Just so i understand correctly PAL and NTSC apply to analogue television, and also apply to digital television. Or PAL and NTSC are only restricted to analogue television and are outdated and make no difference with digital HD and SD television. So Australian digital channels can now broadcast all formats whether rendered in PAL, NTSC or SECAM?
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#7 Stephen Williams

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Posted 03 July 2011 - 09:12 AM

Just so i understand correctly PAL and NTSC apply to analogue television, and also apply to digital television. Or PAL and NTSC are only restricted to analogue television and are outdated and make no difference with digital HD and SD television. So Australian digital channels can now broadcast all formats whether rendered in PAL, NTSC or SECAM?


NO SD Tevevision can be PAL, NTSC & Secam.

HD is neither Pal no NTSC

No it's always been answered.
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#8 Shidan Saberi

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Posted 03 July 2011 - 09:18 AM

NO SD Tevevision can be PAL, NTSC & Secam.

HD is neither Pal no NTSC

No it's always been answered.


ok cool, and by HD=digital and SD=analogue?
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#9 Brian Drysdale

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Posted 03 July 2011 - 10:47 AM

ok cool, and by HD=digital and SD=analogue?


No, you can use digital on both formats. SD has been mostly been shot in digital for about ten years, although it continues to be transmitted using analogue along side digital transmission. HD = high definition, SD = standard definition.
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#10 David Mullen ASC

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Posted 03 July 2011 - 11:15 AM

PAL and NTSC may be analog terms, but since many of their specs carried over into digital transmission in terms of frame dimension and frame rates, etc. the compatibility issues haven't gone away.

HD broadcast, though digital, also has different specs for 50 Hz countries compared to 60 Hz countries, so the same compatibility problems carry over into HD.
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#11 Freya Black

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Posted 03 July 2011 - 02:28 PM

Just so i understand correctly PAL and NTSC apply to analogue television, and also apply to digital television. Or PAL and NTSC are only restricted to analogue television and are outdated and make no difference with digital HD and SD television. So Australian digital channels can now broadcast all formats whether rendered in PAL, NTSC or SECAM?


Secam at its basic level was always very similar to PAL and as a result doesn't really exist in the digital world. Places that used secam generally migrate to PAL digital. There are no secam DVD discs for example! Secam is a bit meaningless in the digital world as it is the same resolution and frame rate as PAL normally. So secam IS an analogue thing.

Digital broadcast can be both HD and SD. Here in the UK standard definition digital terrestrial broadcasts have been around for a little over 10 years, whereas HD DTT broadcasts are a very recent thing here.

What you will find is that basically, digital tv channels will broadcast in 1 format only. So for instance, if it is a high definition channel, it will broadcast 720p or 1080i only. It won't broadcast 720p one moment, 1080i another and PAL at another instant. If it is a 720p channel, all formats will need to be converted to 720p for broadcast. If it is a 1080i channel, then all formats will need to be converted to that format for broadcast. TV channels don't switch around resolutions. In fact that kind of thing is known to upset set-top boxes here in the UK.

Hope that makes things clearer.

love

Freya
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#12 Shidan Saberi

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Posted 04 July 2011 - 10:30 AM

Secam at its basic level was always very similar to PAL and as a result doesn't really exist in the digital world. Places that used secam generally migrate to PAL digital. There are no secam DVD discs for example! Secam is a bit meaningless in the digital world as it is the same resolution and frame rate as PAL normally. So secam IS an analogue thing.

Digital broadcast can be both HD and SD. Here in the UK standard definition digital terrestrial broadcasts have been around for a little over 10 years, whereas HD DTT broadcasts are a very recent thing here.

What you will find is that basically, digital tv channels will broadcast in 1 format only. So for instance, if it is a high definition channel, it will broadcast 720p or 1080i only. It won't broadcast 720p one moment, 1080i another and PAL at another instant. If it is a 720p channel, all formats will need to be converted to 720p for broadcast. If it is a 1080i channel, then all formats will need to be converted to that format for broadcast. TV channels don't switch around resolutions. In fact that kind of thing is known to upset set-top boxes here in the UK.

Hope that makes things clearer.

love

Freya


Thanks for your replies everyone. It makes sense now:)
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#13 John Sprung

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Posted 05 July 2011 - 02:01 PM

NTSC (National Television System Committee): Analog SD, 525 total lines, 483 active lines, 29.97 frames/sec, 59.94 fields/sec. Used in the U.S. from 1953 to 2009, still in use in other 60 Hz. countries.

PAL (Phase Alternation by Line): Analog SD, 625 total lines, 576 active lines, 25.00 frames/sec, 50.00 fields/sec. Used in most 50 Hz. countries from 1965 onward.

SECAM (French acronym, something like electronic color system with memory) Much like PAL, except for how color was encoded. No professional equipment ever existed for SECAM production or post, it was strictly a broadcast format, converted on the air from playback of PAL tapes. Used in France and most of the former communist countries.

ATSC (Advanced Television Systems Committee): All Digital, both High Definition and Standard Definition, both interlaced and progressive. There's a table of 18 different combinations of pixel grids and frame rates (36 if you count the .00's and .9something's). Most commonly used are 1080i/29.97 and 720p/59.94. Designed as a successor to NTSC.

DVB-T, DVB-S, DVB-C (Digital Video Broadcast, with variants for Terrestrial, Satellite, and Cable) The digital HD/SD successor system to the European PAL and SECAM systems.




-- J.S.
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#14 Oli Williams

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Posted 11 November 2011 - 02:14 AM

The reason for the different encoding systems is because of different frequencies that power was being delivered at - for example power in the UK is delivered at 50 Hz - US 60 Hz. That's why TV's in the UK are 50 Hz and multiples there of - TV's in the US are 60 Hz and multiples there of. There is a conversion process from say 30 fps (29.97) to 25fps but it can be tricky and will change the speed in which it's presented and also the pitch of the sound. I doubt a general audience will consciously pick up on it but I do think it will in the sub-conscious.
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#15 Brian Drysdale

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Posted 11 November 2011 - 07:07 AM

The reason for the different encoding systems is because of different frequencies that power was being delivered at - for example power in the UK is delivered at 50 Hz - US 60 Hz. That's why TV's in the UK are 50 Hz and multiples there of - TV's in the US are 60 Hz and multiples there of. There is a conversion process from say 30 fps (29.97) to 25fps but it can be tricky and will change the speed in which it's presented and also the pitch of the sound. I doubt a general audience will consciously pick up on it but I do think it will in the sub-conscious.


It tends to be a full standards conversion with 29.97fps, but shooting 23.98fps (which is common for dramas) means can be played back at 25 fps within the PAL (or countries) TV transmission chain. They may or may not correct for the pitch change in that particular case.
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#16 Phil Rhodes

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Posted 11 November 2011 - 10:57 AM

SECAM


Séquentiel couleur à mémoire (ka-ching!) is quite clever. NTSC pictures can lose both luminance and colour stability if they are subject to interference; things turn odd colours if the signal isn't strong. PAL can lose colour stability, but not luminance; PAL pictures in marginal reception typically fade to black and white with patches of chroma noise . SECAM is theoretically stable in both luminance and chroma because it sends the R-Y and B-Y signals sequentially, on alternate lines, using a delay line to store the colour information for the next line (and as such is more or less a 4:2:0 analogue implementation).


SECAM is cute.


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#17 Freya Black

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Posted 11 November 2011 - 08:11 PM

Séquentiel couleur à mémoire (ka-ching!) is quite clever. NTSC pictures can lose both luminance and colour stability if they are subject to interference; things turn odd colours if the signal isn't strong. PAL can lose colour stability, but not luminance; PAL pictures in marginal reception typically fade to black and white with patches of chroma noise . SECAM is theoretically stable in both luminance and chroma because it sends the R-Y and B-Y signals sequentially, on alternate lines, using a delay line to store the colour information for the next line (and as such is more or less a 4:2:0 analogue implementation).


SECAM is cute.



Night of the living thread!

I used to think it was Sequentially Encoded Colour Aided Memory, but your version sounds more likely to me, I suspect what I've heard is just an English translation like "Never twice the same colour".

I'm curious tho, you seem to know a lot more about SECAM than I do, or at least yours is the first explanation to make sense to me, but I'm wondering if you know anything about the 810 line version of secam?
I know it never really got off the ground as they decided 625 lines was plenty and people wouldn't be able to discern the extra resolution but I've often wondered about it but it seems to be something thats kept kind of hush hush!

Do you know any details?

love

Freya
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#18 Phil Rhodes

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Posted 12 November 2011 - 05:43 AM

I'm afraid I know very little more than is in the wikipedia article. SECAM sends the red colour difference signal for one line, which is displayed immediately with the previously-stored blue colour difference signal and stored in a delay line for one scanline. The next line uses the blue colour difference signal as transmitted with the previously-stored red, and stores the blue, etc. It does make the receiver quite a bit more complicated, but it avoids artifacts caused by the inevitable imperfection of separating two slightly different AM signals. Basically, it solves one of the problems of NTSC (which is sort of the most basic workable approach) that PAL doesn't solve.

This stuff alone doesn't make SECAM a pain in the neck; the real difference is that it frequency-modulates the colour information, which makes for additional trickiness but better robustness. The upshot of it is that if you have two (synchronised) PAL or NTSC signals you can, theoretically, make a vision mixer for them by simply feeding them into a resistor divider. You can't do this with SECAM, because the FM modulation on the colour subcarrier will be turned into gibberish by it; you'd have to decode it to RGB, mix the three, then reencode it back to SECAM again. Of course in reality this is never a problem because nobody actually does studio work on SECAM signals, it's always component at that stage, so it's a problem of theoretical interest only.

P
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#19 Freya Black

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Posted 12 November 2011 - 06:46 AM

I've not looked at the wiki article in a long time but your explanation makes more sense than anything I've read before. I'm guessing the real problem with Secam is that it probably made tv sets more expensive, but thats just a problem of scale really.

Back in the days when information was stored on the remains of dead trees and people were excited by prestel, I used to read a few books where they would mention the 810 line version of secam. I was always really curious about it, but over the years it seems like it's become some kind of dirty secret nobody likes to talk about anymore. I know there were test transmissions and that eventually the whole idea was dropped before it became a commercial proposition (I think?) but I don't know more than that. There might have been bandwidth issues too, like maybe it used the space of two of the older 405 line channels but I might be inventing that based on the numbers?

I suspect this will become one of those bits of information that will become lost to time soon.

love

Freya

Edited by Freya Black, 12 November 2011 - 06:47 AM.

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#20 Dirk DeJonghe

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Posted 12 November 2011 - 07:06 AM

When I was a little kid, we used to watch B&W television at my grandfather's place. Cable distribution didn't exist yet and he used an antenna with different aerials to get the national broadcast (625 lines) and he could also tune in to French television (819 lines). In that case he went to the receiver and activated a 'secret' switch at the back of the receiver. Anyway he was the only one in the household who held the secret and he kept it for himself.

About twenty years later, color television had arrived and I was doing a lot of tv-film postproduction for the french networks. I delivered all my programs on Beta SP and later Beta Digi, all PAL. The entire production chain was PAL, except for the transmitted signal. The only time I had to provide SECAM tapes was for VHS viewing copies.

I still fail to understand why we have to deliver digital tapes (HDCAM-SR) of finished programs on drop-frame (23.98) when sending to the US today.
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