The Benefits of 120Hz

[jjkilleen]

I've been seeing ads for 120 Hz refresh rate TVs, and wondering if this is just marketing hype. I understand that there are some people who see flickering on 60 Hz TVs ,and who would welcome these. Also, I imagine this may be advantageous for gamers. But for everyone else, why would there be any point in the TV refreshing twice as fast as the source signal?

[Richard]

from an internal discussion...

neither 30 nor 60 go into 24 evenly
24 does not go into 30 evenly, but is exactly half of 60
neither 30 nor 60 go into 48 evenly
24 does not go into 60 evenly, but is twice 30
neither 30 nor 60 go into 72 evenly
neither 30 nor 60 go into 96 evenly
All rates go into 120 evenly


So a device with anything BUT 120 will have to add/drop frames to match at at least one source frame rate mentioned (24, 30, 60)

That is my point.

Oh wow... I get it... that is cool but...

You say that means no processing or conversion; not true.

So using the Sony 120hz 1920x1080 display as an example you can't get a straight shot through the system with anything because it has to be converted to 120hz which does not match the source. You have to use processing and while it is true that should be quite simplistic and error free there is no guarantee it is being done properly. Sony likely will but that is a big catch 22 if 120hz becomes the new marketing tool. Think of the first Samsung Blu-ray providing 1080p24 output but the process was 1080p24 disc source converted to 1080i60 converted back to 1080p24; yes it had errors. So let's say the Sony does it right. That leaves only 1080p 24/30/60 as your straight shot. 1080i will require deinterlacing and either motion adaptive processing or 24 frame detection (similar to 2/3 pull down to detect the cadence or it will put the wrong fields together -difference is no dropped frames and therefore no film jutter or audio timing issues). Everything else requires at least pixel conversion along with deinterlacing and either motion adaptive processing or 24 frame detection. The catch here is SD DVD because most movies come with 480p flags on the disc so you can use a dumb scaler and get excellent results. Sure, you could feed the Sony 480i component but then you are at the mercy of even more aggressive processing which in most cases is riddled with errors - just something about 480i and manufacturer scaling designs. I have always put a big question mark on this topic of what is the best SD DVD method due to those progressive flags which insure accurate 2/3 pulldown with NO processing. In many ways the external scaler has died or is clearly dying... I only use them these days to correct display errors rather than source scaling errors.

The only real benefit for consumers is that by using one scan rate that is one less area to screw up for the manufacturer; the ISF charges per input /scan rate due to such errors. None the less the internal scaler remains in play so feasibly there still could exist separate problems based on input/scan rate.

Professional PC gamers, yes there are pros and leagues and money, on the other hand may have found their 120hz holy grail!!! That is the desired frame rate for those folks and their native output. They claim in competition it can make or break the win! Alexander knows more about this... The way I play would not qualify for such competition due to being too close and missing things so the same could be said for pro gamers with a large display unless they adjust their veiwing distance. I have seen Alexander play on that level a few times and he prefers a very short viewing distance and narrow viewing angle so he can see everything without moving his eyes. His need is the exact opposite of what we preach.

[Shane]

You say that means no processing or conversion

Did I? :wink:

From what I've seen of 120Hz, and from the specs I've read ... this is not just smoke and mirrors. If implemented intelligently (as you pointed out), it will provide a better HD experience, especially with film content (ie 24fps).

- Shane