Vimeo Quality for Movement Not Good

[Lin Evans]

I created an MP4 export to Vimeo to test the quality of the Flash conversion. The original MP4 used the extremely good mipmapping to absolutely minimize "glitter" or "sparkle" on sharp detail objects. The MP4 which was created by 5.6 was excellent. There was a little jerky movement in pans, zooms, etc., but all-in-all it was excellent. Vimeo's Flash conversion, however, is a totally different and unsatisfactory solution for a PTE show which has pans, zooms or motion and even remotely sharp images. I purposely used a show with very sharp images to test this so your mileage may vary.

Apparently most videos submitted to Vimeo are "very" soft because they apparently use extreme sharpening. What was a very smooth original ended up with excessive glitter, sparkle and edge artifacts such as stairstep aliasing. How bad this will appear depends a great deal on the type monitor you use. If you use an LCD display with a slow refresh rate (fast mouse movement leaves a "trail") then it won't look so bad. On the other hand if you use a high resolution CRT with a fast refresh rate it just won't look right.

My suggestion for those who submit their MP4's to Vimeo is not to use fast motion at all or use gaussian blur, blur AND mipmapping on every image which is remotely sharp. Look for yourself - link below. The original MP4 has almost zero aliasing but the Vimeo conversion is terrible for some monitors. I've looked at it on both very sharp LCD monitors but with a slow refresh rate as well as with my high resolution CRT with a very fast refresh. If the refresh rate is fast it simply will not look good. If the refresh rate is quite slow, the "sparkle" will be much more bearable. Here's the link:

http://vimeo.com/1979714

Best regards,

Lin

[LumenLux]

Thank you Lin for sharing your learning. I had posted a PTE/video on Vimeo about a month ago with the intent to figure a way to find closer to PTE.exe quality on a video site. Some of the pure video on Vimeo looks really fine. But after my first attempt with my PTE to Vimeo, I was ready to either call "Uncle" or "Lin", because my result was less successful than yours. But I also had not yet posted an HD version. I had started to work on it and then decided to wait for Igor's routine.

As for your Southwest Art post in HD on Vimeo -

I guess my LCD monitor qualifies as slow because your Vimeo version really looks quite fine - until I expand it to full-screen view. At full screen, all the motion-triggered trouble appears. On my setup it really deteriorates when full screen. When you speak of monitor refresh rate does that mean the 60 - 75 mhz, etc. or is it the response time listed as 3 ms, or 5ms, etc.?

I have not yet tried Igor's new porting for Vimeo, but I expect it will be a great convenience for us even if Vimeo, at this moment, is not ready to maintain the quality we send. It will be interesting to see if Vimeo or any site will come up with a way to do better or whether it is an inherent limitation of the current status of "flash"?

[Lin Evans]

Hi Robert,

It's the 3ms, 5ms, etc., the term for time between excitations of pixels on a CRT. For example, crt's have phosphor dots or "stripes" depending on the type of individual CRT. There are "triads" of red blue and green phosphor dots or in the case of Sony Triniton technology "stripes" which have a "decay" rate when they are excited by electrons. The more frequently they are energized (excited) by an electron, the less "flicker" from the horizontal sweep frequency is apparent to the eye which greatly eases eye strain. However, this very feature which reduces "flicker" and eyestrain also reveals very quick changes in the states of brightness or contrast such as aliasing produced by rapid changes in size or position of closely positioned detail features such as adjacent horizontal or vertical lines, etc.

In LCD displays the technology is quite different but the end result is that with a slow refresh rate you simply don't see all the "glitter" or "pulsing" because much of it happens faster than the monitor can respond. Typically, LCD monitors are exceedingly sharp and produce stellar images but many (most actually) can't reproduce certain fast movements which can be seen on CRT's. So even though some aliasing flicker is seen with very sharp images, much of it simply lost in between refresh cycles. The end result is that the annoying "glitter" or "flicker" seen on high resolution, fast refresh CRT's just isn't noticed on slower refresh LCD's.

It's this same issue which allows you to see a "trace" when you move a cursor very quickly with the mouse. On CRT's you don't see the trace but on LCD's, often you do. The effective "decay" rate is so slow that where the mouse cursor "was" the image or "ghost" remains for a time after the actual image has moved on.

Perhaps "refresh rate" is less accurate than "decay" time, but the effect nonetheless is that the videos look better on most LCD monitors than on a CRT with fast refresh and quick decay or "persistence" phosphors.

Best regards,

Lin

"As for your Southwest Art post in HD on Vimeo -

I guess my LCD monitor qualifies as slow because your Vimeo version really looks quite fine - until I expand it to full-screen view. At full screen, all the motion-triggered trouble appears. On my setup it really deteriorates when full screen. When you speak of monitor refresh rate does that mean the 60 - 75 mhz, etc. or is it the response time listed as 3 ms, or 5ms, etc.?"

[Ken Cox]

Lin

not too shabby

no edge distortion of picts but some slight jerkiness of pans

you have another winner

ken

[Igor]

Vimeo is continiously working on improvements. We'll write to Vimeo about this problem.

Also it's possible to download original MP4 video file (free registration required).