Quality: YUY2 vs. HuffYUV 2.1.1 vs. Matrox MJPeg

[Michel Carleer]

Doc,
I fully agree with you, we have only scratched the top of the technical iceberg and up to now we did not even talk about human perception and interpretation of what the eye "sees".
As for my remark concerning the quality of PAL versus NTSC, it is kind of a joke because of the above. Moreover, when I travel to America, I almost always watch TV in a hotel room, where the signal is distributed amongst so many sets and through so badly laid cables that I am sure I should not compare it to what I get home with a decent cable provider. Anyway, we should define "quality" first.
I am astonished when you say that you see the flicker more at the theater, because there is a huge difference in how the picture is presented. As you know, on TV, the picture is made by phosphors emitting light following excitation by a rapidly scanning electron beam. If you look at the on/off ratio at anyone pixel, you conclude that a TV screen is in fact totally black most of the time and if you see a picture, it is only because of the retinal decay time following a photoexcitation. At the theater, on the contrary, the picture is presented on screen most of the time, the screen going black only for a very short time while the film advances by one frame. Your visual recovery must be pretty fast indeed.

Joachim,
I wonder if the difference you mention in the colour looking natural or artificial might come from the fact that the colours used as the two reference axes of the graph representing all colours are different: NTSC uses Cb and Cr, whereas PAL uses U and V. Don't ask me to what exact colours these correspond. What I also found out (but this is once again from my hotel TV viewing experience) is that americans seem to like more saturated colours than we europeans do.
Oh, and once again, flickering has no meaning with LCD or plasma screens.
Michka

[paulw]

I thought your tax return was going towards a DVD burner??

[Dr Mordrid]

It is going for a DVD burner, at least partially. We're expecting to get back over $5000 from the Feds alone this year. The State return should net another $700 or so.

More than enough

And yes, I do see the flicker more in a theater. This is very unfortunate for me since I love going to movies. If I had my way I'd go 2-3 nights a week, but after a long enough movie I start getting a headache from the flicker. Very annoying.

As for my visual recovery, yes it is very fast. I also have the ability to read a newspaper in a darkroom using just the filtered safelight (Wratten 6B).

The opthalmologist I see actually does do research and has tested me about every year since age 35. So far no detectable deterioration in acuity, recovery, night vision or color perception since then and I'm 52.

Now, if I could bottle & sell those genes....

My oldest son (23) seems to have the same characteristics and we're waiting to see if Erik, soon to be 3, has them as well. My daughter, 22, is blind as a bat (nearsighted). So much for the females getting the right genes

Dr. Mordrid


[This message has been edited by Dr Mordrid (edited 18 January 2001).]

[paulw]

To get a refund like that you must have big shares in the IRS :-)

[Dr Mordrid]

Nope. I just plan my yearly finances very well. In fact this next year we'll probably reduce the wifes witholdings to bring it down a bit. I'd rather invest it during the year than let them have the free loan.

Dr. Mordrid

[Michel Carleer]

Do you know that here in Belgium if you pay your taxes in advance (not waiting for the final bill, but paying your taxes regularly during the year), you get the interest of it? And quite a good rate I must say (something like 12% on what you pay before the end of first quarter, 9% before the end of second quarter, ...).
But then, we probably pay ten times more taxes than you do, so...
Michka

[wkulecz]

Doc what about Presbyopia? At age 50 I'm still 20/20 - 20/10 depending on the viewing distance of the test. But when the viewing distance 3 feet its 20/60 or worse! Damn I hate needing reading glasses!

I also percive the flicker in movie theaters. Its mostly a wide screen effect -- flicker perception is much higher in the peripheral than in the fovea. Never noticed flicker in my limited viewing of PAL television, must be the longer persistance phosphors used or double scan sets combined with much less peripheral vision on the small screen. I can see NTSC flicker by turning my head a bit to the side and looking at the screen with mostly peripheral vision. I always thought the headaches I get from viewing films was becuase the movies my wife drags me to stink, but I guess it could be the flicker :-)

I just got the Time-Warner digital cable six months ago. Its much better than anything I can get with an antenna, but I still noticed how the PAL from the satallite looked better while in Budapest.

[Dr Mordrid]

Presbyopia is pretty much normal once you're past 40, but it seems mine is either delayed or absent. It's caused by a loss of flexibility in the lens of the eye and therefore the ability to focus on close objects.

It's also fairly normal to have more sensitivity to flicker or motion in the peripheral vision. That provided our ancestors with better warnings against incoming predators (or husbands)

Dr. Mordrid




[This message has been edited by Dr Mordrid (edited 18 January 2001).]

[wkulecz]

The stiffening of the lens as the cause of presbyopia is the conventional view. However a new proceedure based on Dr Robert Schachar theory is now undergoing clinical trials in Houston and a few other places. Developed after tests on cadaver eyes found young and old lens had similar stiffness, his theory is the muscles stretch over time leading to reduced deflection of the lens. The surgery implants little plastic pieces under the muscle to "take up the slack" and restore the accomadation range to about what it was at age 25. He'll get a Noble Prize if this really works!

Unlike Lasik, it doesn't touch the refractive elements of the eye and is reversable by removing the implants.

--wally.

[KRSESQ]

Doctor:

Your comment on theatrical motion picture flicker was particularly interesting.

To my knowledge, theatrical projectors use a multi-blade shutter system which "refreshes" each frame presented three times before the next frame is displayed.

This equates to a "flicker" rate of 72 fps. However, it doesn't change the fact that each frame of film remains onscreen for 1/24th of a second.

It sounds as if you are in fact sensitive to the motion refresh rate, which is indeed lower than either NTSC or PAL. In NTSC conversion this is compensated for somewhat by the synchronising process of telecine.

FWIW

Kevin

[Michel Carleer]

Kevin,
Do you know the reason to "refresh" the picture three times before switching to the next one?
Michka

[Dr Mordrid]

If indeed presbyopia can be fixed by shimming the muscles then he will indeed be a popular guy My wife would freak since she is very nearsighted.

Dr. Mordrid

[Michel Carleer]

I am hopeless. Strongly nearsighted, suffering astigmatism. And, being 55, now presbyopia as the topping on the cake. I don't tell you the shape of the surfaces of my glasses. And the subsequent price, of course
Michka

[KRSESQ]

Michel:

The basic reason is to relieve the eyestrain viewers would experience with a raw 24 fps flicker rate. Most of us find a monitor refresh rate of 60 uncomfortable to one degree or another, and 72 fps refresh rate is the minimum generally recommended for viewing comfort.

Kevin

[Hulk]

Hey Doc,

Would it be too much to ask for you to also include the PICVideo codec at quality settings 18, 19, and 20 to your comparision page?

I am curious to see how it compares to the Matrox hardware compression.