In the first of this series of articles, we introduced the free video hosting services provided by companies such as YouTube and Metacafe. We also stressed that when presenting screencasts, these services were far from appropriate.

In this, and following articles, we will discuss some of the reasons why this is the case, beginning with the final resolution of the video.

With sweeping developments in modern day technology, and in particular within the computing industry, the availability of higher and higher specification graphics machine has dramatically increased. The ability to run two graphics cards in one machine, using either NVidia's SLI chipset, or ATI's Crossfire, has lead to the ability to display even higher resolutions.

While development in computer monitors hasn't quite kept up with that of the graphics industry, it has in no way become stagnant, and displays capable of much higher resolutions are now becoming the standard.

To put this into context, at present the most common display resolution for browsing the internet is 1024 x 768 (1024 pixels wide, 768 pixels high), with 58% of internet users option for this resolution. At the end of 2002, just 4 years ago, a resolution was 800 x 600 was used by 49% of all internet users (just 38% used 1024 x 768), and a resolution of 640 x 480 was not unheard of. Nowadays, you will struggle to find a monitor that will display a resolution less than 800 x 600.

So what effect does this have on Screencasting, and particular YouTube?

If your the lowest resolution that your monitor is able to display is 800 x 600, then if you happen to doing a fullscreen presentation, then your final video have dimensions of 800 pixels wide, by 600 pixels high.

In the case of the free video hosting companies such as YouTube and Metacafe, this is where the problem with hosting screencasts lies, as they only allow much smaller videos. If larger videos are uploaded, they are automatically resized to the allowed dimensions before they are added to the database.

Consider the example of YouTube, which allows videos up to a maximum resolution of 320 pixels wide, by 240 pixels high. In the following calculations, we will assume we are trying to upload a standard 800 x 600 pixel screencast to YouTube.

First, let us consider the screencast at the original dimensions of 800 x 600:

800 x 600 = 480,000

At its original resolution, each frame of the video consists of 480,000 pixels.

Now let's consider trying to upload this video to YouTube:

YouTube allows videos up to a maximum dimension of 320 x 240 pixels

320 x 240 = 76,800

Once the video has been uploaded to YouTube, each frame of the video consists of only 76,800 pixels.

So by shrinking the video, what have we lost?

If you make a direct comparison between the number of pixels that are used per frame, compared to the number of pixel used per frame once the video has been uploaded to YouTube:

(480,000 - 76,800) / 480,000 = 84%

So, by uploading the video to YouTube we lose a staggering 84% of the data from the original screencast. It is no wonder that the videos are difficult to make out, once they have been uploaded.

The following two images show two examples of the effect of uploading a screencast to YouTube:

The first shows an images taken from the screencast at its original dimension of 800 x 600 pixels (the image has been cropped slightly to fit on the page)

The second example, shows the same image once it has been resized to 320 x 240 pixels, and uploaded to YouTube:

As you can clearly see, resizing the screencast has a major impact of its quality and clarity, and as a result, means that the free hosting services such as YouTube and Metacafe are totally inadequate for uploading screencasts.

Related Screencasts

·  Screencasts, YouTube and Metacafe - The Problems Exposed Part 3 - Aspect Ratio ·  Screencasts, YouTube and Metacafe - The Problems Exposed Part 1