Tuesday, September 19, 2006

Data and MP3 Compression: Why Do We Compress?

We hear the term "compression" all the time when it comes to MP3 and MP4 players these days. Where did it come from and why do we care?

In the last article (Data and MP3 Compression: Understanding "Digital"), I explained what a "digital" signal is. Remember, data can be stored as raw, or "analog" signals (like cassette tapes, VHS, or records) or they may be digitized (converted into a series of 1's and 0's) which we can later convert back into its raw format. Digitizing signals allows us to store information in an errorless format. So why don't we digitize everything? The answer is simple: It takes a lot of 1's and 0's to represent the shortest songs, videos or movies. A standard 5 minute song can take over 70MB (which is 70 mega-bytes; each byte is made up of 8 bits or 1's and 0's). That is 560 million 1's and 0's! That is a lot! Not only do you have to store all of that information, but we need to process it and convert it back to its analog signal in a short amount of time.

Luckily, fast processing has been around for some time now and formats such as CDs have taken advantage of this. But CDs are limited in space: about 700MB (which will hold about 10 songs). The space issue definitely became a problem. That is when compression techniques were first introduced. How compression works is that we take the 70MB signal (as we described above) and by using either a mathematical algorithm or map, we can organize the bits in such a way that less bits are required to store the same amount of information (My next articles will cover the details about this a bit more).

For example, with MP3 coding, we can reduce a 70MB song down to below 5MBs! (That is a 92% reduction in size!). Now understand this, though: Compression theory itself has been around much longer than MP3s have been sold. Why? It gets back to the technology question posed above. We have now reduced the storage size of the song, but in order to decompress the signal requires a lot more signal processing in the same amount of time.

I remember about 7 years ago having to buy a big internal computer hardware card to fit inside my computer to watch DVD's from my new DVD-ROM. Why? DVD data is coded in an MPEG-2 format (similiar to MP4). At that time, computer processors were not fast enough to process the decoding. Now computers are fast enough to process the data with software.

Just in the past few years have the two technologies now collided. MP3 and MP4 players are now a reality for a variety of reasons:

1) Advanced compression techniques have made file sizes even smaller than ever.

2) Storage hardware has increased into the 100s of GB range in a very small package.

3) Processors are small enough, fast enough and cheap enough to fit into the palm of your hand.

So where does technology go from here? MP4 (or video compression) is building momentum. Still, it is in its infancy and it is still lacking in the necessary storage and processing requirements it needs to produce the sharpest and clearest video quality that we are now coming to expect.

- Matthew Bredel

Visit http://www.MP4nMore.com for iPod and portable media reviews and resources!

Wednesday, September 13, 2006

Apple iTunes Introduces Movies, but Is It Worth IT?

So Apple announced today that it will begin to expand its video selection on iTunes to movies. Up to this point, Video iPods have been primarily been given access to only music videos and TV shows. By adding movies, this is another big step in the MP4 revolution. But are we really there yet?

I have two inherent problems with this:

1) Would you really want to watch a 2 and half hour movie on a three inch screen?

2) Videos take up space and at this rate, a full movie is going to take a majority of your iPod drive space no matter how you look at it. 30GB is a lot for music, but for video, it is not too much.

Now I get it's practical uses, though. I have watched a thirty minute TV show while on a flight and it was pretty cool. But am I willing to first spend the time to download it, pay for it, fill up my iPod and spend 2 more plus hours watching it on this tiny screen in moderate resolution? Not yet. (That is what I have a portable DVD player for).

This is the direction of the future, no doubt. Thank goodness I got Lasik surgery a few years ago, because things keep getting smaller and smaller and my eye strain is getting worse. But who am I to complain! If you like watching stuff on your Video iPod, this is nothing but good news to you. Maybe I am just getting old and cranky. Who knows!

I think I'll download a episode of Lost and see how that goes...but I'm not ready to pull the trigger on Lord of the Rings!

Check out the iTunes website for their new movie offers! Click Here!

Wednesday, September 06, 2006

Data and MP3 Compression: Understanding "Digital"

One of the biggest mysteries to many is what data compression is all about and why it matters to me. But before this, you must first understand what digital data is.

The MP3 and MP4 generation was generated mostly due to advances in data compression. Let us first take a step back and focus on digital music. There are two types of data in the world: Analog and Digital data. Analog data is real time data, and it is essentially how we perceive the world. As you listen to any music, you are listening to an analog signal. Everything we see and hear is analog. So what is the significance of digital? Digital is a way of storing and transferring this data. Think of a twelve inch ruler. With this ruler, you can measure any distance between between 0 and 12 inches. Depending on how good you are at reading the ruler, you can probably measure to a resolution of 1/16 of an inch. Even though there is measurable distance between these 1/16 inch marks, the distance is rather insignificant to you. At this point, you can record the distance two ways:

1) You can mark the ruler with a pencil and store it in its true "analog" value
2) You can round the value to the nearest 1/16th and record it. This could be referred to as a "digital" value.

Digital is a collection of zeros and ones that represent a number. Because there are two values, the system is base 2. Our normal system is a base 10 system. For example:

The number 1456 is really:

6x(1) + 5x(10) + 4x(100) + 1x(1000) = 1456

Where the number in parentheses are 10^x power.

Let's try a base 2 number of 100110:

0x(1) + 1x(2) + 1x(4) + 0x(8) + 0x(16) + 1x(32) = 38 (decimal)

Where the number in parentheses are 2^x power.

In this base-2 example, the number is referred to as "6-bits". A typical "byte" is normally "8-bits". So instead of storing the number 38, computers would store the number 100110.

So why would you want to do that? There are 6 digitals in base-2 versus two digitals in base-10. The answer is simple! Ones and zeros are much easier to store (It is like a light switch, either ON or OFF). Further, in a base-2 system, there are only 2 possible solutions. In a base-10 solution, there are 10 solutions per digit. The more solutions you have, the more chance to make errors.

Now let's revisit the the analog signal. In this type of data, there are an infinite number of solutions. Mind you, the error won't be great, but you ARE guaranteed some error every time. Every time you recall a analog signal, the results will be varied to some degree.

Think about your cell phone. About 5 years ago, all cell phones were analog. When you entered areas of poor reception, you received static, distortion and noise. Now, most cells phones are digital. As long as a portion of the ones and zeros are transmitted, you will receive a perfect signal every time. (If you transmit the number 1.2 or 1.5 or 0.8, it will always be read a one! i.e., the signal is immune to noise!) If you cannot even read these simple ones and zeros, you drop off completely. The clarity of the signal is perfect and repeatable, as long as the data is present.

Music works in the same manner. Old-school records and cassette tapes are analog signals. These media will product static and noise and will degrade over time. CDs are digital signals. As long as the compact is readable, the CD player will provide you with the exact sound as it was recorded. The CD itself might degrade over time, but the data will always be stored in its original form.

Since the inception of digitally stored music, the quality of music has remained high and to the same standard as it is today. Compact discs still offer the highest form of music available. The problem with compact discs is that the amount of bits required to store a song is high. That leads us to the modern use of data compression and MP3. (And another article for another day!)

- Matthew Bredel

Visit http://www.MP4nMore.com for iPod and portable media reviews and resources!

Thursday, August 24, 2006

MP4nMore is Complete!

After two weeks, I have finally got my website, MP4nMore.com up and running! This website is meant to compliment this blog with reviews, resources and tips to all that is portable media. Right now, I am focuses on a few major aspects of portable media, primarily the places to get or buy content (such as MP3's and MP4's) that you play on your player. The website is separated out into three areas:

1) Unlimited MP3 or MP4 Download Programs - I go into what they are (basically, peer-to-peer file-sharing) and question why anyone would actually pay for this service. For one, you can get if for free if you want. And two, this still not legal. Click here to read the full report.

2) Music Share Programs - If you are looking for a legal and easy way to download content, music share programs are really what you should be doing. Right now, there are a handful of very good programs. They do require subscriptions, but for $15/month (a price of a CD), you can have access to limitless amounts of music...and it is legal. Click here to see the reviews of the programs.

3) Anti-Virus and Anti-Spam Software - Since I am not going to convince many people that file-sharing can be illegal, I at least would prefer they spend their $30 on something useful like computer protection. File-sharing is notoriously brutal when in comes to infecting your machine. All anti-virus programs don't work the same, either. Click here to find out which programs work the best.

So I am very excited about the website and I have aimed to fill it will a lot of quality information and insight. People advertise a lot of things concerning MP3's and MP4's these days, but I have spent a lot of time determining what is real and what is a scam. Please check out my new website and provide comments to what you think!

- Matt


Monday, July 31, 2006

My MP4 and More Blog

Hello! My name is Matt and this is my first entry on my experiences, trials and evaluations of everything related to MP4 and video portable media devices. In college, I studied electrical engineering and one of the sets of classes that I took was data compression. In those days (which was about 7 years ago), MP4 was nothing more than theory. Now that I see it being used in some of the hottest and newest items on the market, my interest in the data compression technique as well as the cool products that use it inspires me to become an expert in the field. Luckily, with blogs, I don't need to learn this in a day or week, but over time, I will continue to gather knowledge and share them in my blog. Comments and questions are always welcome!