| Digital audio and video formats - why so many?|
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Why are there so many different audio and video formats?
This is a general, easy to understand explanation intended for beginners and does not claim to be a complete and detailed overview of the topics discussed. It is only an introduction to help the novice grasp basic concepts and hopefully investigate the information further.
Internet, computers and video
Today, people are more and more using the internet to share information, find information, communicate and learn. Video has become a big part of this information pool. Video has to be created on some kind of device and eventually uploaded to the internet in order to share. Camcorders have been typically used to record video but other devices are also used. Each video device records in a specific format used on that device. For example, the Mini-DV format (DV) is specific to camcorders popular around 2003 to 2009 which used small magnetic video tape cassettes to record video and audio.
AVCHD is another camcorder format which is newer than DV. AVCHD (Advanced Video Coding High Definition) is a format for the recording and playback of high definition video. Developed jointly by Sony and Panasonic, the format was announced in 2006 primarily for use in high definition consumer camcorders. AVCHD is a file-based format and does not use magnetic tape like Mini-DV. Instead, video can be recorded onto DVD discs, hard disk drives, non-removable solid-state memory and removable flash memory such as Secure Digital and Memory Stick cards. Sony and Panasonic released the first AVCHD camcorders in autumn of 2006, followed by Canon and JVC.
Sony High-Definition video camcorder HDR-CX12 uses Memory Cards to store video and audio in AVCHD format
Today, web sites like YouTube.com store video in files for viewing in your web browser and the files are computer files, not camcorder recordings which may be on video tape, disk or memory cards. YouTube.com uses several video formats such as FLV or MPG but not just any format. Therefore you may need to convert to a format compatible with the web site. But why are there so many video formats?
People and computers store and use information in very different ways. You may use symbols like asterisk, letters like CAT and numbers like 1, 2, 4, 8 in your daily life to convey information. Computers on the other hand, use a simpler tablet to represent information. So simple in fact that it only consists of two symbols, one and zero. This is because computers are electrical devices. Take away their power source and they do not function. Computers store and use information in a digital form known as binary. Binary is just two numbers or digits, one and zero. Each digit is a bit and eight bits is a byte. Megabytes (Mb) and Gigabytes (Gb) are sometimes needed to represent a lot of information.
Computers use electronic circuits to process electrical currents. Information is stored and processed as a string of currents, on or off, current or no current, one or zero. What is amazing about computers is how these two simple binary numbers can be used to electrically represent information and how fast and accurate this information can be processed.
Making digital information useful
Since computers use information or data in a digital form, there has to be a way to make this data mean something to people. A string of data in a computer or other digital device may look like this: 110010101011, hardly meaningful to people. To interpret this data, a software program or application or app is used to translate the bits to something people can use. The applications are coded to be executed on a particular computer and to perform a particular task or group of tasks. The application is written or coded by people in what is called a source language, something people can work with, until being put into a form a computer can work with. These programs instruct the computer what to do and how to manipulate data. You may know these, as one example, a Player like Windows Media Player. This program or application plays music or video, translates bits into audio or images that people can hear and see.
One of the reasons there are so many formats for audio and video is profit driven. If I create a computer program to interpret digital data in such a way that the quality of the audio or video is much better than ever before, I may want to protect my creation and make money selling it to customers. If somebody else comes along with a better way of doing it, maybe they want to make money also with their program. Ever heard of Microsoft and Apple? Two competing companies with different applications basically to accomplish the same thing. However, doing it in slightly different ways and therefore different styles and using different formats. Microsoft wants you to do things their way, use their software and make them money while Apple wants you to do things their way, use their software and make them money. Multiply this times all the competition and you begin to understand why we have so many different formats.
Audio and video require a lot of data to be stored (recorded) in order to be able to play back for people to enjoy. Typical 3 or 4 min. songs may need Megabytes while full length video may need Gigabytes or more. Years ago somebody got the bright idea to compress data to save storage space. Another reason for so many different audio and video formats is how the data is compressed. There are many ways to compress and manipulate data. Is this a good idea? That depends on many factors. Music on a CD (compact disc) is stored in a digital format and is not compressed. A CD can hold how many songs... 10, 20, maybe 30 short songs. How many can an iPod player hold.... thousands. Why, because the iPod uses different storage than a CD, but also because the data is compressed, typically in a MP3 format or Apple Corp. proprietary format. Physical limitations dictate capacity. Compression is a way to get more bang for the buck, hopefully without loss of quality.
With high definition video you need even more data to be stored (recorded) and saving storage space becomes more critical and so more formats come into play with different methods to compress data. This creates confusion and frustration for many but progress is not easy sometimes. High definition is progress most would agree.
What is data compression? If you had to write out PERSONAL COMPUTER 300 times, how would you do it? Would you write out both words 300 times? Suppose you compress it to just PC. Could you now do it faster and save time and space? All you need to know is that PC is really Personal Computer. This is how data can be compressed.
If you take a photo with a digital camera and the image contains blue sky, the camera can store blue over and over again, picture element by picture element (pixel), megapixels of blue, basically all the same. Rather than storing all this same data over and over, a picture format such as JPG, the format for digital still images, compresses the information so that blue is stored once along with the number of pixels of blue to be retrieved later upon readout such as printing the image. DVD works the same only uses MPEG-2 to compress video information. If a scene is the same frame after frame, why store every full frame? Compression stores one frame along with the number of frames with the same data.
Computer files and file extensions
Computers store data in files just like people have since filing cabinets appeared. One file for car insurance, another file for taxes and another file for your phone bills. Computers need to organize data so applications along with the operating system can function correctly. Computer files usually have an extension, myimage.jpg for example. Anything after the period is the extension. The extension tells you and any application program what to expect, how this data is stored. .JPG says still image while .MP3 says compressed music is in this file.
Even though people get confused with all the different file types, there is some method in this madness. When Microsoft first standardized audio files on Windows PCs, the .WAV file extension appeared and was used for years. The problem was these audio files used up more storage space on your disk drive than you wanted, particularly if the audio was a long song. To solve this issue, data compression in the form of the .MP3 format often replaced the .WAV file. Same song but less storage space. If encoded and decoded (codec) correctly, people can hardly notice a difference in quality even though less data is stored.
Likewise video files have gone from the .AVI format (audio video interleave) to the Flash video .FLV format often used on YouTube.com videos or in the case of Windows PCs, the .WMV (Windows Media Video) format used by the Windows Movie Maker application. Microsoft also uses the .WMA (Windows Media Audio) format for audio files. You can convert from one format to another sometimes, using applications you buy online or download for free from the internet. So .AVI files can be converted to .MPG video files for example.
You can record or capture almost any video you want from the internet, such as YouTube.com videos and save them on your PC. There are hundreds of applications but be careful with all these formats. Some recorders only record in one or two formats and your playback application needs to be compatible with the format you recorded the video in such as .FLV or other video formats on the web.
Capturing video from other sources such as camcorders, or older VHS tapes can also be done. Then the file can be burned or copied to a DVD for example. A lot depends on the software application you use to capture and record the information.
FLV - Flash Video is a container file format used to deliver video (and audio) over the Internet. The audio and video data within FLV files are encoded in the same way as they are within SWF files. Adobe Flash Player by Adobe Systems and other 3rd party applications can play these files. FLV was originally developed by Macromedia.
The format has quickly established itself as the format of choice for embedded video on the web. Notable users of the Flash Video format include YouTube, Hulu, Google Video, Yahoo! Video, metacafe, Reuters.com, and many other news providers.
MPEG - Popular video format standardized by the Moving Picture Experts Group (MPEG); compressed using MPEG-1 or MPEG-2 compression; often used for creating movies that are distributed over the Internet.
MPEG movies are typically saved with the .MPG file extension.
MPEG-2 - The widely used format of digital television signals that are broadcast by terrestrial (over-the-air), cable, and direct broadcast satellite TV systems. It also specifies the format of movies and other programs that are distributed on DVD and similar discs. As such, TV stations, TV receivers, DVD players, and other equipment are often designed to this standard. MPEG-2 was the second of several standards developed by the Moving Pictures Expert Group (MPEG) and is an international standard (ISO/IEC 13818).
While MPEG-2 is the core of most digital television and DVD formats, it does not completely specify them. MPEG-2 is the data compression standard only and does not specify the signal transmissions standards.
MP3 - MPEG-1 or MPEG-2 Audio Layer 3 more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard of digital audio compression for the transfer and playback of music on digital audio players.
MP3 is an audio-specific format that was designed by the Moving Picture Experts Group as part of its MPEG-1 standard and later extended in MPEG-2 standard.
WMV - Windows Media Video (WMV) is a video compression format for several proprietary codecs developed by Microsoft. The original video format was designed for Internet streaming applications, as a competitor to RealVideo. WMV 9 has gained adoption for physical-delivery formats such as Blu-ray Disc.
H.264/MPEG-4 AVC - a standard for video compression, currently one of the most commonly used formats for the recording, compression, and distribution of high definition video.