Help me to understand HD (in small browser window)...

T

Tim_

Member
Hi guys.

My end result videos are always for internet streaming (mostly self-hosted, sometimes youtube).

So here is maybe dumb (not for me!) question:

If my end result will be in small 640 pixel wide window in embedded to browser flash player, what is ideal format for that (HD or DV)?

Ok, I see the difference, but WHY THE DIFFERENCE IN SHARPNESS ACTUALLY EXIST if we compare DV video (720 x 576) and HD (1920 x 1080) in the small 640 x 400 browser player??

Please, help me to understand HD ...

Are HD pixels vs real monitor (browser) pixels are somehow defferent animals?

I mean if you go full screen or HD TV the difference is obvious... But how to understand switching from 360p to 720p and so on if we talking about small minimized youtube window?

Thank you very much
 
If your final result measures 640x480 in real display pixels, then you won't gain anything by producing an HD 1920x1080 file. Pixels is pixels -- there is nothing special about HD pixels, they are the 'same' as computer monitor pixels. In fact, you can confuse yourself into producing video that won't look good, if you format your text and titles for instance in HD, then display it in an effective SD window -- you might find your titles unreadable.

Cheers,
GB
 
well, one reason would be if you shot two videos, identical in shot and everything, side by side with an HD camera and an SD camera, and then displayed them in the same web window of 640 wide. strictly technically speaking they should be indiscernible. HOWEVER: since a SD lens is designed to resolve SD resolution(actual resolve, not pixels), and an HD camera designed to resolve an HD resolution, there can be a noticeable difference in clarity aka sharpness of the two videos, but honestly in a small window it will not likely be a night and day difference. the main reason to use an hd video for web is that pesky little full screen button.

another explanation is that downrezzing/shrinking a high resolution file will almost always make a video appear sharper, i cant think of a great technical explaination at the moment, but practically speaking just think of like this: when you play a file on your computer which is low resolution, it looks fine until you make the video window bigger, then it looks like crap, because it's making up pixels that aren't there. then the opposite is when you play a high res file, when you shrink it, it can only look the same if not better, because you're throwing away pixels/combining them. and when viewing the same video in two different sizes, of course the smaller size will seem sharper because you can't see as much detail, unless perhaps you get your nose to the screen and squint. just like viewing a road sign from near and far.

long rainy day. brain only half working, so possibly only half sensible explanations.
 
The technical explanation for this lies within how digital sampling works. When an analog (or simply, real life) signal is captured to a digital format, it must be sampled at a given resolution. In audio, we see this as 44.1k, 48k, etc, which, you may notice, is more than double a human's estimated hearing range of 20k (though that number is generous). This has to do with a little something called the Nyquist-Shannon Theorem, which basically states that in order to accurate represent a signal, it must be captured at twice it's original frequency. The same rules apply to video of course, which is why you often see cameras whose sensor pixel-density exceeds their output resolution.

In simpler terms, you can capture your video at its destination size (ie, SD), or you can oversample, and capture in HD, but display in SD. The resizing of HD to SD material will result in a superior image due to availability of more detail in the source image, which then becomes averaged into the SD picture. Additionally, you have a few other benefits, such as noise becoming reduced when you downscale, which may result in a perceptually cleaner image than an SD-shot version.
 
Hey guys, THANX A LOT!

Here's a few interesting ongoing stuff...

So right now I shoot on GH2 (HD) and then downscale my material to SD.

I "shoot" my girlfriend (heh) and have got two versions of the same small video, HD and downgraded SD.

SO HERE WAS MY EXPERIMENT:

I call my GF and ask her what version she preffers better (not saying to her about all this HD / SD thingy)...

Suprisengly, not only she voted for SD, she also said that SD version seems with richer colors to her.

I use 15 inch Macbook Pro 2010 and showing versions using Streamclip in fullscreen mode.

I know, I know, it seems rediculous to us. And what she says about richer colors cannot be true.

But I guess we don't have to be so overwhelmed by constantly changing high-tech stuff and always thinks about who is our audience.

I'm in no way an expert on this (that's why I'm asking all this questions), but there is a lesson here at least for me (and I strongly encourage you to try the same experiment capturing your non-techy-savy relatives, friends and GFs on your super new 190000 million x 1080000 thousands glidecams with 10 K lenses and then ask them if they eyes could tell the difference...)

I mean my girlfriend is not dumb - she's into amateur photography but as long as SHE'S INTERESTING ABOUT WHAT'S ON THE SCREEN (her) - the last thing that she can spot is HD SD difference.

Many of us are so overwhelmed by DSLR hype that soon people will shoot more "1000Mb/s hack test" more that actual creative stuff / tell stories / influence others with our videos...

It seems like all this DSLR revolution makes it so relatively cheap to so many to shoot super-quality stuff, but in reality I see the opposite. Another kid just shooting "10 K lens undoxing" 10 min long at his home, proud and happy.

Once again thanx for clearing this up for me. I'm almost fall for this "you absolutely need to upgrade your computer "hardcore" and everything else to catch with HD hype"...

Please don't get this the wrong way. Most guys here are very bright and cool. Lots to learn from them...
 
Last edited:
You must log in or register to reply here.
Back
Top