Tutorial 2: Video Compression

One concept I found particularly interesting was the idea of inter-frame compression. The idea behind this type of compression is that you don't want to transmit pixels that aren't changing from frame to frame because that would be a waste of bandwidth. I realize though that those are a lot of words/ideas some of you may not be familiar with so let's take it from the top.

Pixels

Every image is made up of several tiny colored dots that will form that image to what you and I see. The more pixels the image has, the more realistic it will look. 

Take for example the two images above. The one on the right has a much higher pixel density meaning it has more pixels per inch. Obviously the quality on the image on the right is far superior.

Motion Pictures

I bring up the idea of motion pictures because I mentioned the process of frame to frame compression. That's all motion pictures really are. They are separate frames of one image per frame that, when compiled together at extremely fast speeds, look as though there is motion. 

Inter-Frame Compression

This brings me to the idea of Inter-Frame Compression. The first thing to know is that a key frame will be identified. This is the first frame in the series that acts as the base point for comparison. It is the initial frame. In the image below, the first image all the way to the left is the key frame. The I Frames are the next frames in the series of images.

So let's say this is a small sample of frames in a video that you want to compress. You could compress each of these images individually but this is an unnecessary use of bandwidth. This does not take advantage of the capabilities of video compression. You'll notice that, from frame to frame, some of the images do not change. These pixels then will not be transmitted when compressing the video. Think of a lecture that you've seen where the teacher is hardly moving around the classroom. So many of the pixels are identical from frame to frame, so why waste space transmitting those identical pixels. There is just a command that will copy that part of the identical pixels. For example, in the image I created above, The second image is identical, so instead of the second frame being transmitted, it will simply be copied. Moving on to the third frame, once again the identical pixels will be copied, and the new pixels that make up the red line will be transmitted.

Drawback

1) Data Corruption - If the first frame is corrupted then the corruption will carry on until a new key frame is established. 

Acknowledgments: http://www.gadgetell.com/tech/author/Gregadeaux/      © 2011 Gadgetell LLC. See our Privacy Policy.

Second Image produced and copyrighted by Leandro Gutierrez 2011

Excel Project

       I found this Excel project to be extremely helpful. Excel will undoubtedly be an important asset when we enter the business environment. In fact, it has proved to be extremely helpful even now with school projects and various internships I have participated in. This particular project didn't necessarily demand a wealth of knowledge concerning Excel and its attributes, but it covered many of the basic tools and shortcuts that virtually everyone needs when completing tasks in Excel. The project started off simple enough, requiring me to rename certain worksheets and center some information. Quickly however it required us to utilize some of the other functions in Excel, such as the "Help" function. Of course, we could have just as easily googled how to "Freeze Panes" but that would have been just as helpful, requiring that we put to use our searching skills previously learned in this course.
       What I liked about this project is that it did require us to put into practice everything that we've learned. Last week we watched several tutorial videos on how to properly and efficiently use Excel, but it's one thing to learn, and another thing to practice. For example, it's quite helpful to have a visual of someone utilizing absolute and relative cell addressing, but it takes it to an entirely different level when you are asked to create formulas that can involve both times of addressing, like this project demanded. It really helps you understand the concepts behind the formulas. This project asked that we do MAX functions and IF logical tests. The concepts seemed easy enough when I was listening to them being explained in the comfort of my room, but the knowledge really stuck when I had to make these formulas on my own.
       At my last internship over the summer, I used Excel almost on a daily basis. Any knowledge or skills I had came from my middle and high school memories of learning the system. I was no master by any means, and I certainly didn't think I could ever make a pivot table, let alone really even know what one was. This project really helped me understand how to properly use one. I actually felt it was necessary to go back and watch both Pivot Table videos over again which really helped solidify everything I had learned.

Tutorial 1: Memory and Storage

       Hardware is a generally new subject to me. I am a Marketing major will very little background in computer knowledge. When it comes down to it, computer knowledge is like another language to me; it's foreign in almost every way. This was initially the reason I took the class, as a challenge and an opportunity to delve into unfamiliar territory. But even with my elementary knowledge, I still found many of the topics in this module to be interesting, in particular, memory and storage. Although somewhat complicated to the computer newbie, I figured the best way for a newbie to learn is to hear it from a newbie.

    

       The first topic I found particularly interesting was cache. To understand cache though, there needs to be a basic memory of Random Access Memory, or RAM. RAM is basically where all the work gets done. It is the general memory in your computer and is used to perform the necessary tasks when the computer is on. While RAM is substantially faster than it used to be, your computer has much more potential for speed, and that's where cache comes in. Cache is a block of a small quantity of high speed memory located in the RAM. As shown in the picture, imagine RAM as a large circle of memory. Inside that circle is another small circle called the cache, only this circle is much quicker and more efficient. You make several requests as you use your computer, and if you make certain requests several times then the data will be stored in the cache memory. The next time you go to make that same request, your command will be sufficed much quicker because your CPU will request the data from the cache. An easy way to think about it is to relate it to when you fold clothes in your drawer. Naturally you will put the clothes you wear most often at the top of the pile. For example you would put your favorite shirt at the top of the pile especially if you knew you were going to wear it soon. Taking out that shirt to wear takes very little time because it's easily accessible. If you wanted to wear a different shirt, let's say the one at the bottom of the pile, you could still retrieve it pretty easily, but it would obviously take more time to search through the pile.

       When watching the lectures I found fragmentation to be particularly interesting as well. When you save files on your computer they are not necessarily stored on a disk in one continuous piece because throughout the lifetime of your computer you are constantly saving new files and deleting old ones. Fragmentation occurs because your computer wants to be as efficient as possible. It's almost like a game of Tetris. Consider the following situation, and I'll make the numbers as easy as possible for simplicity's sake:

 

1) You have a rectangle dish that's 40 inches long

2) You put 5 in of red jello in the rectangle

3) You then put 10 in of green jello in the rectangle

4) Then you put 7 in of blue jello

5) You then take out the red jello and the blue jello

6) Now you want to put in 8 in of yellow jello, but to be more efficient on space you want to start putting it in from the beginning of the dish. So you put in 5 in to the right of the green jello and the remaining 3 in to the left of the green jello

Now the yellow jello is fragmented, and imagine if this process continued for several years. It would become extremely messy and complicated and you can imagine how your storage would slow down because your computer would have to work that much harder to be able to locate these fragmented files.