100hz Motionflow TVs - Does it work with 60hz signals?

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Infrasound

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# 42551 6-Oct-2009 18:59

I'm sure we've all seen 100hz TVs and the nice smooth motion they produce.

We also know that they achieve their smoothness by a "frame interpolation" effect known as Motionflow (and other names) rather than by actually accepting a 100hz source.

What I want to know is this: can the "frame interpolation" effect that the internal 100hz refresh rate allows still work on a 60hz signal?

I'm not asking if the TV can accept a 60hz signal - I know they can, I'm asking if the Motionflow "frame interpolation" aspect still works on a 100hz TV with a 60hz source.

From what I've read, the source needs to be an even multiple of the refresh rate, which 60hz to 100hz is not. I ask this question as I intend to hook up a PC monitor at 60hz to a 100hz LCD TV and still want to see the nice smooth Motionflow "frame interpolation" effect.

If indeed it can't interpolate with 60hz, then I could try setting my videocard to output 50hz and see if it works that way.

Side note: why the hell don't they just sell the American 120hz TVs in New Zealand with variable settings to give us the choice?

sbiddle

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# 261809 6-Oct-2009 19:04

If you are buying a new TV and presumably using HDMI for the input then there is no reason to a run the TV at 60Hz unless you're not getting 1:1 pixel mapping at 50Hz. NZ is a 50Hz country and if you're presumably hooking your PC up to the TV to play video then 50hz is the optimal setting.

As for the whole 100Hz it's the first thing I turn off on any LCD TV. I'm still totally unconvinced by it.

LennonNZ

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# 261820 6-Oct-2009 19:37

Yes, turn OFF MotionFlow (or whatever they call it on other TVs). IMHO things look very strange with it turned on ....

fahrenheit

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# 262139 7-Oct-2009 16:38

Side note: why the hell don't they just sell the American 120hz TVs in New Zealand with variable settings to give us the choice?

100Hz is used for 50Hz sources and 120Hz for 60Hz sources. The TV will adapt to whatever it is fed.

Why it isn't mentioned is purely down to marketing.
If they (the manufacturers) were to mention 100Hz and 120Hz in the same breath, then they'd be inundated with consumers saying "But I want to switch to 120, its 20 better!!!!!!!".

Its confusing enough for the average consumer to comprehend, so they figure they simply don't need to mention '120Hz'. Lets face it, most NZ buyers will never feed their TVs a 60Hz source. Why even mention it?

The question of - should you even care for this interpolation has already been answered. No, you shouldn't. Its an abomination and an afront to good taste. Anyone endorsing it is either blissfully ignorant or is trying to sell it to you.

ZollyMonsta

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# 262160 7-Oct-2009 17:04

My later model series 7 has 200hz motion flow... LOL, it's like 100hz but on turbo. It in itself introduces strange effects (and quite often makes me feel ill!) so I turn it off.

mikerussellnz

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# 262195 7-Oct-2009 18:05

You need to match the source frames per second with the refresh rate. playing video files that are 30 FPS or 24fps (movie) in 50hz results in jumping once a second on panning shots for me. Changing to 60hz fixes it. From what I have read, using 60hz produces smoother motion with videos as it uses the 2:3 pulldown whereas with 50hz, there is no defined pulldown, in NZ the sound is slowed down to match the 50hz refresh rate rather than using a pulldown.

120hz should result in smoother motion as 24fps is a multiple of 120 so frames can be displayed an equal number of times.

fahrenheit

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# 262197 7-Oct-2009 18:13

^ Motion interpolation and 24p/pulldown are entirely different topics.

richms

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# 262199 7-Oct-2009 18:17

sound is sped up in 50Hz countries so that the 24FPS becomes 25. Plus it means room for another couple of ad's which is even better for the stations.

Only reason to match to powerline freq is recording since you get flicker with the lighting at other rates. For playback you are better off matching the source, which if it a majority of tv shows off bittorrent like me then is best in 60Hz so you get a 3:2 pulldown on movies and the video sourced stuff will play at its native frame rate. If you watch local stuff then 50Hz.

Richard rich.ms

Infrasound

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# 262245 7-Oct-2009 21:08

fahrenheit:
Side note: why the hell don't they just sell the American 120hz TVs in New Zealand with variable settings to give us the choice?

100Hz is used for 50Hz sources and 120Hz for 60Hz sources. The TV will adapt to whatever it is fed.

Oh so that's how it is, we actually have 120hz capable TVs and they don't even mention it!

I'll have to verify this somehow before I make my purchase, but you have give me some hope.

Really, to me all this 60hz NTSC and 50hz PAL stuff is rubbish in this digital HD age. I mean, you'd think that with the coming phasing out of the old analog systems this would have been a perfect opportunity to promote a bit of standard unification throughout the world, but yeah, that would just make too much sense right.

richms

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# 262259 7-Oct-2009 21:52

they did with the addition of 24Hz modes and the standardization of resolution rather then having the variance which was a result of the constant horizontal refresh between pal and ntsc timings.

You have to match your cameras sample rate to the refresh of the lighting where you are filming when dealing with video or you get funny things happening, like when you point a cellphone camera at a CRT tv. I would have thought that the BS conversion that things go thru with delivery would become a thing of the past however. There is little reason that they have to send things like CSI miami in 25FPS.

Richard rich.ms

Infrasound

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# 262283 8-Oct-2009 00:03

Regarding 24p playback - first of all, I'll admit my ignorance on this subject.

Is it the case that the TV's sold in New Zealand which claim to support 24p playback actually switch to 24hz mode?

I've read that with 24p content, sometimes it is favourable to evenly convert this content into a 96Hz or 120Hz signal for playback on capable TV's just to make their jobs easier - I also presume that this "even" conversion does not necessarily mean that any Motionflow-esqe frame interpolation jiggery is actually taking place.

But what happens when the Motionflow technique is combined with 24p playback? Does it yield a "better" interpolation effect that what is commonly seen in stores which presumably are feeding their displays with 50hz signals upconverted to 100hz?

Man I just wanna buy one of these damn things and do some testing.

richms

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# 262286 8-Oct-2009 00:21

The ones I have seen allow for it to be turned on and off just as for 50i and 60i stuff going into it.

Richard rich.ms

fahrenheit

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# 262289 8-Oct-2009 00:46

Infrasound: Regarding 24p playback - first of all, I'll admit my ignorance on this subject.

Is it the case that the TV's sold in New Zealand which claim to support 24p playback actually switch to 24hz mode?

I've read that with 24p content, sometimes it is favourable to evenly convert this content into a 96Hz or 120Hz signal for playback on capable TV's just to make their jobs easier - I also presume that this "even" conversion does not necessarily mean that any Motionflow-esqe frame interpolation jiggery is actually taking place.

But what happens when the Motionflow technique is combined with 24p playback? Does it yield a "better" interpolation effect that what is commonly seen in stores which presumably are feeding their displays with 50hz signals upconverted to 100hz?

Man I just wanna buy one of these damn things and do some testing.

24p capable displays come in a range of different refresh rates.
48Hz, 72Hz, 96Hz, 120Hz... these timings all have one thing in common. They are all perfectly divisible by 24.

The display doesn't actually refresh at 24Hz, its always a multiple of it. 120Hz just means that each frame of a 24p source is refreshed five times. 5 x 24 = 120. So whenever you see someone refer to a "24Hz mode", its just a way of encompassing all of the above possible refresh rates that a display could use (depending on the type/manufacturer). I'd argue its safer to say "24p" as '24Hz' is dubious at best.

'Motionflow' (interpolation) when switched on, takes all sources and conforms them to the display's maximum refresh rate. It literally creates new frames by calculating the differences between frames. This process is error-prone and gives very undesireble results.

You have to understand that interpolation is completely seperate to 24p. Turning it off will not stop 24p sources from displaying correctly. You should make zero purchasing decisions based on interpolation. Because if you have any taste, you'll disable it.

Nety

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# 262425 8-Oct-2009 15:41

AFAIK 24Hz has been around for nearly as long as film. It is because of this and because blu rays support the 24 frames that TV's/Projectors are now starting to support it as well. However the kicker is that 24Hz looks horrible on today?s equipment (and has been way to slow for a very long time now). This is why digital recording normally uses a higher frame rate which allows for a much smoother picture.

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