by: Matthew Bredel

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!)

About The Author

Matthew Bredel is a 31 year old online entrepreneur and engineer currently living in San Diego, CA.

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

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By Gabriel J. Adams

Digital media has revolutionized the world of media – digital media is highly portable, easily sent or transferred. Sometimes, though, the many different file formats can leave one somewhat confused. In this article, we’ll go over a few of the most common file formats.

Wave format – *.wav
The Microsoft wave format is a lossless, usually un-compressed audio format. Advantages of the wav format include is cross platform compatibility and ease of editing in various programs. The main disadvantage is a wave files large size.

MP3 format – *.mp3
The MP3 format is the most widely used audio format on the internet. An MP3 file has very good quality in relation to its file size. When creating an MP3 file, you can choose what quality level to save the file as. The MP3 format is cross-platform, and compatible with nearly all media applications.

MPEG – varies, often *.mpg
The MPEG is not a single file format, but rather a “video and audio encoding standard”. There are quite a few different MPEG standards, MPEG-1 and MPEG-4 being the most commonly used for the average consumer.

Windows Media Video – *.wmv
The Windows Media Video format is a common media format for internet usage. It is easily created using Windows Movie Maker (which comes free on any windows computer.) Windows Media Videos can be created using a wide variation of quality settings.

Windows Media Audio – *.wma or *.asf
The Windows Media Audio format is the second most popular media format, second only to Mp3. It is very similar to MP3, except that it supports DRM (Digital rights management).

Quicktime Movie – usually *.mov
The Quicktime Media formats all have a serious disadvantage, in that very few programs support them. You must have Quicktime player to play them, and only a very few programs can edit them. They are far less flexible than many other formats.

By Gijo George

Software testing assumes a very important role in Software life cycle. Without proper testing software is incomplete. Testing should adhere to some general standards. To help a software tester, a test plan is prepared. This test plan broadly describes the approach towards testing particular software, the tools that can be used and scripts to help the tester to perform his work in an orderly fashion. Another document that is generated for testing is the test plan is test case. A test case contains various inputs and expected results.

A good testing team not only helps eliminating serious errors but also contributes lot of additional features to the software. A tester first look for the common errors which can normally appear in any software. Then he move forwards for data validation errors. Finally he goes for functional testing. Software tester should have some functional knowledge before he begins functional testing. For this, he can sit with functional experts in order to better understand the functional aspects the tested software is intended to accomplish. A software tester also looks for logical errors during the functional testing phase.

Code review is also a part of testing. Code review has to be done by another programmer or a tester who have some knowledge about coding. Code review involves ensuring proper comments in place before a block of code begins. The comments should be clear and easily understood. Apart from this, code review involves looking for proper arrangement of coding. Using white space properly, minimizing the number of character in one line of code etc. also has to be taken care. A proper code review ensures that the software is easily maintainable in future.

Releasing software without proper testing is like sailing in a ship without enough resources. It will be abandoned immediately.

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