Converters to for UK electrical appliances in USA
#76
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Re: Converters to for UK electrical appliances in USA
#77
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Re: Converters to for UK electrical appliances in USA
#78
Re: Converters to for UK electrical appliances in USA
So to play material recorded in one system on the player of the other system, you have to convert between these two frame rates.
To play an NTSC signal (30 frames/sec) on a PAL TV (designed for 25 frames/sec), you can simply drop every 6th frame and thus, convert 30 frames/sec to 25 frames/sec (over-simplification, but good enough). But to play a PAL signal on an NTSC TV, you have to increase the number of frames, and that requires some kind of 'frame buffer' ("hold that last frame you just got and repeat it") which adds cost and complexity - it's generally easier to discard information than it is to introduce information. These days, though - most NTSC TVs can handle it.
Note that professional converters (what studios would use to prepare UK material for the US market, etc) take a much more sophisticated approach, analyzing adjacent frames, looking for changes, etc.
That required a lot of cobwebs to be cleared from info I haven't thought about since 2003 but I believe it's correct!
#79
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Re: Converters to for UK electrical appliances in USA
To play an NTSC signal (30 frames/sec) on a PAL TV (designed for 25 frames/sec), you can simply drop every 6th frame and thus, convert 30 frames/sec to 25 frames/sec (over-simplification, but good enough). But to play a PAL signal on an NTSC TV, you have to increase the number of frames, and that requires some kind of 'frame buffer' ("hold that last frame you just got and repeat it") which adds cost and complexity - it's generally easier to discard information than it is to introduce information.
Ian
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Re: Converters to for UK electrical appliances in USA
Yep, quality. Makes a lot of sense, I don't doubt that that's correct.
#81
Re: Converters to for UK electrical appliances in USA
Sounds like it makes good sense to me too thanks!
#82
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Re: Converters to for UK electrical appliances in USA
That's the clearest explanation I've heard. Cheers.
#83
Re: Converters to for UK electrical appliances in USA
This web page has a good deal of techno-babble detail on the whole process, with some good diagrams (diagrams REALLY help with this topic) at this sub-section.
Another piece of technical trivia that my notes jogged my memory on is that all movies, regardless of country of origin (at least, movies shot on celluloid - some new movies are done without film these days), are shot at 24 frames/sec, which is neither PAL nor NTSC compatible. So going from a movie to TV is a challenge that has to be faced by both PAL and NTSC folks. When converting a movie to DVD, you don't want to convert from 24 frames/sec to 30 frames/sec 'on' the DVD, because space is at a premium and you want to optimize the storage usage. So what the MPEG-2 spec (the 'way' movies are encoded on DVD) allows for is a 'flag' that says "repeat every 'n'th field during playback" to convert 24 frames to 30 frames (or 25 frames). This is called 'pulldown'. If you've ever watched a movie and noticed that motion is not 'smooth', it's probably caused by this. A movie on DVD is stored differently from a 'TV show' on DVD (recorded originally on video equipment). This page has a few nice diagrams to explain it.
I got started on this back in 2002 when my family sent me a copy of "the office" on PAL DVD and I could not play it on my equipment here (this was before cheap 'region free' players, and cheap pal/ntsc tv's). Back then, the conversion process would run 24 hours non-stop on my PC for a high quality conversion.
Another piece of technical trivia that my notes jogged my memory on is that all movies, regardless of country of origin (at least, movies shot on celluloid - some new movies are done without film these days), are shot at 24 frames/sec, which is neither PAL nor NTSC compatible. So going from a movie to TV is a challenge that has to be faced by both PAL and NTSC folks. When converting a movie to DVD, you don't want to convert from 24 frames/sec to 30 frames/sec 'on' the DVD, because space is at a premium and you want to optimize the storage usage. So what the MPEG-2 spec (the 'way' movies are encoded on DVD) allows for is a 'flag' that says "repeat every 'n'th field during playback" to convert 24 frames to 30 frames (or 25 frames). This is called 'pulldown'. If you've ever watched a movie and noticed that motion is not 'smooth', it's probably caused by this. A movie on DVD is stored differently from a 'TV show' on DVD (recorded originally on video equipment). This page has a few nice diagrams to explain it.
I got started on this back in 2002 when my family sent me a copy of "the office" on PAL DVD and I could not play it on my equipment here (this was before cheap 'region free' players, and cheap pal/ntsc tv's). Back then, the conversion process would run 24 hours non-stop on my PC for a high quality conversion.