The image sizes are small because the resolution of the files are low (typically 352*240) and your software defaults to displaying the image at 100%. If your screen in approx 1400 pixels across it follows that the image will be on quarter of the screen.

Now, you can easily alter your software to display full screen but you probably won't like the results. Computer monitors will show every fault and their fast refresh rate (and low persistence) compared to a tv set means that every artifact is seen rather than smeared out.

If you were to pipe these mpegs through to your tv via a suitable graphics card (or, in some cases, create a video cd that would play on your dvd player)you would find a marked improvement in watchability as your tv 'papers over the cracks'.

Given that mpegs and vod are almost always created to a certain bitrate limit ( and don't forget your dvds' themselves are mpegs) then a balance has to be reached between resolution and noise.
By way of example, imagine a picture file to be saved as a 20K jpeg file. We haven't got much space to play with in 20k but remember an mpeg will be 24-30frames/pictures a second! If we make the jpeg small, say 300*200 pixels, the result may be just acceptable; if we make the jpeg large, say 1800*1200 the resulting image will be terrible. The fact is the second image has 36 times as many pixels as the first and so the 20k of allocated space is not going to go very far so the picture will have to be very very highly compressed.
Mpegs don't store data as a series of images but as an odd image and then a series of changes, then another whole image a series of changes etc etc. The jpeg analogy still holds true though - try to make the mpeg really high resolution and you will end up with a mass of little blocks and on-screen mush. At 352*240 it may look small but we are still at the kind of resolution you'd expect from a VHS tape.
You will note that even your dvds resolution is substantially lower than your monitor - and even if you are on a fast connection I doubt you can dload at dvd bitrates!!!

Sir noel.

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Sir Noel covers this pretty well, but the short answer is that yes, it has to do with bitrates and bandwidth. The internet, at it's highest consumer speeds would not be able to keep up with the bitrate that DVD's use to display their audio-video information. DVD's store between 4 and 8 gigabytes audio/video information on the disc. This equates to a very very high number of Kb per second that need to be transfered from the disc to the software DVD player in order to continuously display the image. Since the source information for Video on Demand is actually residing on a server at Gamelink (for example), the information that the player on your computer needs in order to create a continuous movie has to be transfered in real time over the internet. There are many factors that dictate how fast that information can travel. Therefore only a small fraction of the bitrate of a DVD is used to send a VOD. The idea is to optimize as much as possible how good the image is while still being able to consistently deliver the needed information over the unpredictable internet in real time.

There are also financial considerations with regard to number of servers and bandwidth of the internet connection at the host.

Straight MPGs that you would download of the internet are largely in the MPG1 format, which is generally smaller bitrates than the MPG2 format that DVD's use. When you download an MPG, all the information needed to play the file is transfered to your computer before you play it. However, the same problem still applies. Trying to download gigabytes of information is a tall tall order on todays internet. It's much better to compress the hell out of it and reach a compromise between video quality and file size.

It is for this reason that I do not do VOD. :) I'll rent my DVDs thank you very much. It's cheaper, more predictable, and looks a heck of a lot better. Many people don't have the option of renting porn though... so VOD is their only option.

Hope that helps.

Mike L.

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Sir Noel, I have expanded it to full, or fuller screen, and in your terminology, got on-screen mush, which is totally unacceptable.

Any additional comments on the 'cam' views?

As I said, I watched a few mpegs, but don't bother anymore. I much prefer the DVD quality that I get.

DenverDon

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Sir Noel

PS the faq is at dvddemystified.com

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