The AVI or Audio Video Interleave is perhaps the most widely known video container format in the PC industry and is a good specimen for an audio and video format standard of the 20^th century. It is a special instance of the Resource Interchange File Format or RIFF in its file structure that can carry audio and video data in almost any uncompressed form or compression codec such as Intel Real Time (Indeo), MPEG4, RealVideo, Motion JPEG, Cinepak, Full Frame (uncompressed), among others.

A short history

Introduced by Microsoft in November of 1992 for its Video for Windows, the AVI became the de facto standard for audio and video formats for almost a decade. Almost all websites that offer video downloads have them in the AVI container format.

As the name suggests, it contains both audio and video streaming data allowing for synchronous playback of audio and video data – one of the first in the PC industry that has gained near universal acceptance. Like DVD’s VOB container file formats, the AVI can support multiple data streaming of audio and video – a feature rarely used n PC application. There are also AVI files called AVI 2.0 that were developed by the Matrox OpenDML group in 1996 and were eventually supported by Microsoft.

Video codec supported

The AVI container format supports virtually all video codec with the proper filter support like the VFW. However, H.264/AVC can be problematic due to its limited B-frame support.

Dislikes about it

The AVI has significant overhead data that makes its file size unnecessarily large compared to other container formats when using the popular MPEG4 codecs like Xvid and DivX. It also does not support the B-Frames feature of the modern MPEG4 though hacks abound to overcome this, further increasing file size and causing incompatibility issues with some players.

While the AVI container file can also house the highly efficient H.264 codec, it is considered unsuitable due to compression hacks that need to be implemented. In short, AVI format is considered obsolete. But despite these limitations, the format remains popular among internet uses for purposes of file-sharing due to its portability among video editing software. Installing the ffdshow filters in DirectShow and Windows Media players often overcome incompatibility problems.

In mid-2005, DivX, Inc. released its own container file format in the DivX Media Format with the .divx extension. It succeeds the older AVI + DivX combo. However, this is just an enhanced AVI format based on the same RIFF structure and has received little or no support from the file-sharing communities where the DivX codec was once popular. It is interesting to note that the rival derivative Xvid codec has become the more popular codec of choice among file-sharing groups.

There’s a company called DivX, Inc, formerly the DivXNetworks, Inc. that introduced the DivX family of video codecs. Made extremely popular because of its ability to produce high quality video using lossy MPEG4 Part2 compression or MPEG4 ASP, DivX has cemented itself as one of the most popular multimedia codec for the home market.

DivX is known to create a balance between quality and file size with its highly efficient compression abilities. And because of that, it s one of the codecs used for ripping where audio and video are copied from a source to the PC hard disk for archiving and transcoding.

The commercial DivX competes with Microsoft’s Video for Windows in WMV, Apple’s QuickTime in the MOV and RealNetwork’s Real Video in the RMM file formats. An open source version released by Xvid solutions in 2001 is the Xvid file format.

While DivX has long been renowned for its excellent video quality, its free and open source equivalent Xvid today offers comparable quality, also based on MPEG-4 Part 2 (MPEG-4 ASP). In a series of subjective quality tests at Doom9.org, the DivX codec has been successively beaten by Xvid every year since 2003.^[11]

Confusion clarified

DivX are two different things from two different companies. One is DIVX created by Circuit City, a US electronics retail giant that attempted to market a DVD rental system that used special players and discs. And the other is the DivX multimedia codec trademarked and marketed by DivX, Inc. which is actually a reference to the failed Circuit City system.

A short history

DivX roots can be traced back to 1998 as a hacked version of Microsoft’s MPEG4 version 3 which is inferior to the MPEG4 that we know today. It was a French hacker Jerome Rota who, rather than modify his video resume which could not play on the new Windows Media Player at that time, reverse-engineered the MPEG4 format together with a German Hacker Max Morice to come up with an MPEG4 format encapsulated in AVI instead of the ASF it originally had. It only took them a week. Between 1998 and 2002, the DVD hacking community had independent hackers enhance the format that later came to have the Divx with a smiley emoticon J attached as version 3.0.

In 2000, Rota was hired by Jorda Greenhall to form a company called DivXNetworks (later renamed to DivX, Inc.) based in the French Riviera. The association resulted in the OpenDivX codec a year later. Its source code was open to anyone and could be downloaded from the projectmayo.com website. The following year, the two left for San Diego and developed the OpenDivX software to become DivX version 4.0. Other developers took the Encore2 software to enhance the open source OpenDivX to arrive at the rival Xvid format.maintained by Xvid Solutions, Inc.

The DivX Company continued to enhance the DivX software that in 2002 has taken on the fifth version. By 2004, the features of the DivX format are as complete as we know it today. In May 2007, the Windows Vista version DivX 6.6 for the PC and the Mac was released.

The advantages and benefits of using DivX

DivX found itself at the heart of video piracy in the late 90s as its format became widely popular for ripping copyrighted DVD materials for bootleg replication and distribution. A number of generic DVD players as well as branded ones are claiming to play DivX materials

What’s so appealing about the format is that it’s free. Same with the software players you can use to play it with. It belongs to the open source community together with Xvid offering competitive if not better quality.

Gaining a much wider use on the internet these days, the FLV or Flash Video file format is the format of choice in major internet sites like YouTube, Yahoo and Google Video. Previously known as the Macromedia Flash Player file, Flash Video can be played on the Adobe Flash Player as a format proprietary to the maker. It can be viewed on most operating platform, notably Windows and Mac, using the downloadable Adobe Flash player or a plug-in application for the browser. Third party multimedia players can also play them with the ffdshow filter support installed with the application.

Video support

The Flash player from Adobe is a multimedia and application player that plays FLV files from SWF files created by the associated Adobe Flash authoring tools as well as third party tools. As a browser add-on or plug-in, flash video players can be embedded in webpages to be viewed in browsers with the plug-in. This is what happens with the YouTube site.

The Flash Video files contain video bit streams which are slightly off from the H.263 video standard called as Sorensen Spark . Flash Player 8 and newer revisions support the playback of On2 TrueMotion VP6 video bit streams that can provide better visual quality than Sorenson Spark, especially at lower video bitrates. However, it is computationally more elaborate and may not run as well on certain older PCs. Recent trial versions of Flash Player 9 include support for H.264 video standard (also known as MPEG4 Part 10 or AVC) which while more computationally demanding provides significantly better quality/bitrate performance.

The FLV file format supports two versions of a so called ’screenshare’ codec designed for Screencasts. Both formats are bitmap based and can be lossy by reducing color depths lower than 8 bits for compression using zlib. The second version is only playable in Flash Player 8 and newer.

Audio in FLV files is often done in the mp3 format. However, FLV files recorded from the PC microphone use the proprietary Nellymoser codec. The most recent beta versions of Flash Player 9 support a number of profiles under AAC.

Most multimedia players based on the FFmpeg libraries can play back the FLV video format. Any player which plays back QuickTime formats also can but after installation of the required FLV software component. Below are some other media players that do:

• VLC multimedia player
• Mplayer (with FFmpeg)
• Xine (with FFmpeg)
• RealPlayer
• Any player which can use the ffdshow (based on FFmpeg) DirectShow codecs:
  • Media Player Classic
  • Windows Media Player
  • Windows Media Center (requires some registry hack)

Flash plans

Just recently, Adobe announced Update 3 of the Flash Player (currently in beta) that now will support the MPEG4 Part 10 standard, audio compressed using AAC (MPEG-4 Part 3), the MP4, M4V, M4A, 3GP and MOV multimedia container formats (MPEG-4 Part 14), 3GPP specification (MPEG-4 Part 17) which is a standardized subtitle format and parsing support for the ID3 equivalent of iTunes stored n the metadata. Adobe also will be gradually phasing out the proprietary FLV format to the standard MP4 format owing to functional limits within the FLV structure when streaming H.264.

Advantage of using FLV

More of a letdown than an advantage, Flash video files are embedded in SWF files when authoring from an associated Adobe software tool. The FLV needs to be decoded from the SWF file for playback to happen in the associated FLV player. Editing the video requires having the original SWF file or having it rebuilt.

FLV files have become popular because of the YouTube phenomenon belatedly copied by Google and Yahoo websites. Other than that, there’s really not much sense using FLV format or other formats that have already made their mark in the home PC entertainment industry. That should be pretty much obvious as YouTube is expected to convert their format into QuickTime formats soon enough to accommodate the huge demand for online video expected to be generated with Apple’s promise for YouTube access on its iPhone.

Everyone who is acquainted with running Windows will be familiar with the Windows Media Video or WMV video file format. Simply put, the WMV is a video format that uses lossy compression algorithm proprietary to the Windows operating platform. It is developed by Microsoft as a competitor to the RealVideo multimedia platform.

As a codec, the WMV is encapsulated or contained in the ASF (Advanced System Format) file container format. The file with extension .wmv is precisely an ASF file that contains a proprietary Microsoft video codec for Windows. Interestingly enough, WMV can also be contained in the AVI file container format.

A short history

The very first version of the format, WMV7 was released in 1999 based on the MPEG4 Part2 as implemented by Microsoft. It was among the first video codec that supported constant and variable video bitrates. Since then, newer versions have been developed to keep up with competition culminating in the WMV9 specification released.in 2003. It has adopted much of the specification of professional video formats with support for frame interpolation, interlaced video and non-square pixels.

In 2006, the SMPTE group adopted it as its standard SMPTE 421M or VC1 that became one of the mandatory video formats for the emerging high resolution HD DVD and Blu-Ray formats for Home Theater entertainment. It supports both 720p and 1080p video resolutions and multichannel audio.

One of its features that made movie studios accept it is its support for the Digital Rights Management or DRM . It does provide encryption protection that studios are adamant about when releasing titles from their catalogues as well as new ones. But while WMV video codec itself does not contain DRM, the ASF container file that encapsulates the WMV video stream does. Windows Media DRM is standard in Windows PCs using the new Windows Vista.

The Benefits of using WMV

The WMV codec is the most recognizable video codec format. Its competitors, apart from RM of RealVideo, include MPEG4 AVC, DivX and Xvid. The MPEG4 AVC is the other high resolution format developed for HD DVD and Blu-Ray.

Understandably, WMV is the mandatory video format for Portable Media Center devices that run special versions of the Windows operating system. They include the Microsoft Zune that competes with the Apple iPod, the Xbox 360 gaming console and mobile phones using the Windows Mobile platform. Needless to say, it is the default video format for the Windows Media Player that comes bundled with the Windows operating system.

Video player software that can play WMV files includes PowerDVD, Mplayer, VLC MediaPlayer and the Media Player Classic. Interestingly enough, RealPlayer against which the WMV file was meant to compete also plays WMV files.

Video quality of the WMV9 is claimed to be superior to MPEG4 and about three times better than MPEG2, the codec used for the home video standard DVD. That’s what Microsoft claims. But independent tests have not confirmed this.

Dislikes about WMV

The newer WMV9 and WMV HD which uses the WMV codec have received unwanted criticisms from the press and mostly from users. It has more to do with the issue of DRM which has never really grown on users. Restoring licenses for DRM protected WMV files in other PC is problematic and these same files can’t even be played when downloaded on Zune devices. The standard Windows Media DRM systems apparently are not supported in Zune.

To those who often use the QuickTime video player software, whether in a Mac or Windows PC, the file extension .MOV should be quite familiar. It’s a file format extension developed by Apple as its multimedia format of choice for its QuickTime environment. QuickTime is widely used in iTunes and is the default file format for the QuickTime player application as well as the emerging Safari platform for mobile devices. The format is quite popular in many websites for audio or video streaming. Thanks to the QuickTime multimedia player software that many have downloaded from the net as a freeware, the format has achieved universal reach and acceptance in Windows multimedia applications.

QuickTime’s MOV file is not a codec (code/decode) format like MPEG4 but is a container video file format. As the term suggests, a MOV file can contain a number of both video codec file formats like H-263,H-264/AVC, WMV, and MPEG4, to mention the more often used video codecs, and audio codecs like Vorbis, MP3, FLAC, WMA, AC3, DTS and AMR, to mention some. Unlike other popular container file formats like AVI, 3GP, the MOV container format supports the most number of video and audio codecs through its internal codec and sound manager core engines that the others don’t have.

A short history of the format

In was in December of 1991 when Apple released the first commercial QuickTime platform and its associated MOV file format for the Mac system 6 operating system. MAC users were enthralled to see the famous 1984 apple TV ad played on the MAC workstation – the first for any desktop computer. (It’s interesting to note that Windows would not be releasing its video for Windows platform until a year later, in November 1992.)

Succeeding versions improved on the MOV files and about the same time that Video for Windows was launched in 1992, it contained the Cinepak vector quantizing video codec called Compact Video for its version 1.5 that swiftly endeared itself among Mac users for being the first video on the desktop to run 30 frames per second at a resolution of 320 x 240. Thereafter, Apple released QuickTime version 1.6 for Windows in the last quarter of 1993 to give Windows PC users a better alternative to the Windows native video application.

These days, QuickTime is now on its 7^th version with 7.1.06 supporting Windows XP and 7.2 destined as the first version for the Windows Vista. The version 7 family now has the Core Audio and the core Video that allows high resolution H.264/AVC and Mpeg4 video codec to be played

Audio and Video support

The MOV file container format can contain the following audio, video and graphics files and codecs.

Audio

• Apple Lossless
• AIFF or Audio Interchange File Format
• CDDA or 16-bit CD audio
• MIDI
• MP3 or MPEG-1 Layer 3 Audio
• MPEG-4 AAC Audio (.m4a, .m4b, .m4p)
• QCELP or Qualcomm PureVoice
• AU Audio from SUN
• ULAW and ALAW Audio
• WAV or Waveform Audio

Video

• 3GPP & 3GPP2 file formats
• AVI file format
• BMP or Bitmap codec and file format
• DV file (DV NTSC/PAL and DVC Pro NTSC/PAL codecs)
• Flash & FlashPix files
• Animated GIF files
• H.261, H.263 and H.264 codecs
• JPEG, Photo JPEG, and JPEG-2000 codecs and file formats
• MPEG-1, MPEG-2, and MPEG-4/AVC codecs and file formats
• QTZ or Quartz Composer Composition for Mac OS X only
• Other video codecs: Apple Video, Cinepak, Component Video, Graphics, and Planar RGB
• Other still image formats: PNG, TIFF, and TGA

Benefits of MOV file container

The MOV file under QuickTime lends itself better to editing the video file than its competing media containers from Windows. In 1998, ISO (International Standards Organization) approved the MOV file format to form the basis of the MPEG-4 Part 14 (.mp4) file container standard so that by 2000, MPEG-4 Part 14 has became an industry standard, first appearing in 2002 with QuickTime version 6. As such, the MPEG-4 container can capture and edit, unlike in earlier MPEG iterations.

MP4 is the default file container format for MPEG4, and both MOV and MP4 containers can use the Mpeg4 video codec as they are interchangeable in the QuickTime environment. But it should be noted that MP4 has better international hardware support among DVD players, mobile devices and game consoles such as the Sony PSP. On the Software side, most video platforms like Video for Windows and Direct Show do contain better codec support like parsers for the MP4 format than for MOV.

On the otherhand, when using the QuickTime platform, MOV files can now support multichannel audio while MP4 files can only be played in stereo.

QuickTime is integral to the MAC operating platform and is optional in the Windows platform. But increasingly more Windows applications are using QuickTime when displaying audio and video information. Many PC encyclopedic software applications use QuickTime and its default MOV file support when playing multimedia files.

During the earlier days of development in video and audio compression, it was the MPEG, or the Motion Picture Experts Group which was in charge with coming up with standards to keep up with the video requirements as they came out. Standards such as MPEG-1 and MPEG-2 were developed. However, there were some instances where these standards had to be tweaked to accommodate variations to the mediums they supported.

An example of this sort of variation is the VOB file format. If you look at some files contained in a DVD movie, chances are you would see a few with the extension .vob. The term VOB is actually short for ‘Video OBject’, and if you compare it to the MPEG-2 standard, you will see that their encoding schemes are quite similar. In fact, if you take a VOB video file and change its extension to .mpeg or simply .mpg, you would still be able to run it.

The VOB file format is mostly used in DVDs. Unlike VCDs which contain just the video, you will probably notice that DVD Video manufacturers add a decorative opening menu for viewers to go through prior to playing the actual movie. Also you will probably see another feature for those who are hard of hearing or the subtitle option. The menu, subtitles, and other additional features integrated into the DVD are all contained in the .VOB file.

These .vob files are usually grouped, depending on the features of the DVD. These groups are called ‘titles’ and oftentimes the feature presentation is located under one of these titles, further truncated per ‘chapter’. The structure of files with .vob extensions is standard. When you explore a DVD, you will always find one file with the VOB video format which is named ‘Video_TS.vob’. This file contains the first pieces of information that the viewer will see when playing the DVD. Menus and opening trailers are usually contained in this particular .vob file.

Furthermore, you will notice other .vob files containing title and section information. These names adhere to standards, so it would be easy for the system and the user to understand. For example, the file VTS_02_1.vob can be interpreted as a file part of the Video Title Set, allocated to Title 2, Section 1 in particular. Additionally, the last section in say, title 2, would be named VTS_02_n.vob.

In a DVD, a VOB file is usually accompanied with supplementary files. Files with the .ifo extension have information regarding the specific attributes and options of the content of a VOB file. This sort of information comprises of but is not limited to subtitles, aspect ratio, and languages. These IFO files have backups, which are also files with the aptly designated file extension .bup. These files are responsible for the intricate presentations which are shown every time a DVD is played.

With the growing capabilities of computers, many people have resorted to watching DVD videos in computers instead of a hardware player hooked up to a TV. This is made possible due to the compatibility of the VOB video files in the DVDs. During the earlier days, people took advantage of watching DVDs by going through the trick of changing a VOB video file’s extension mentioned earlier.

Nowadays, it is standard that the media player software is able to play DVD Video or VOB files in particular. If a consumer happens to be using one of the many Windows operating system versions, its built-in Media Player should have no problem in opening DVDs and their VOB files, just as long as the DVD-ROM is calibrated with the disc’s region. If a person is using a Mac, it is just as easy to watch DVD videos on Apple DVD Player software.

The versatility of the VOB file format makes it easy to convert into other video file formats. There are many video converters available on the internet, capable of truly converting a file with the .vob extension to a legitimate MPEG or MPG file, going beyond the simple changing of its extension.

These video converters are able to compress the huge-sized, high-quality VOB files into simpler and smaller videos compatible for viewing on mobile devices. This means a person can purchase a DVD Video and convert a good portion of VOB files to be copied and stored on a palmtop device which is capable of playing videos. The fact that VOB files can be played by virtually every conventional video player and converter opens many opportunities for anyone wants seamless video options.

MPEG is virtually associated with video files on a computer; however, the acronym actually stands for the Mobile Picture Experts Group. This group comprises of researchers from the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Their first collaboration was in May 1988, and since then they have been meeting every four years, usually in a week at a time.

Members of MPEG have been responsible for continuously developing the standards for digital audio and video (AV) compression and during each meeting a certain compression format is announced and standardized. Since 1988 there have been many ancillary standards developed by MPEG.

MPEG-1 is one of these formats. It comprises of AV encoding and data compression standards set by the MPEG. This format (which came out during the early parts of the 90’s) was developed specifically because the MPEG saw the potentials of compressing video clips to fit in an average CD-ROM. The compression which was involved in the MPEG-1 format decreased the quality of the original video clip to resolutions close to that of a VHS tape.

The fact that MPEG-1 was developed this early has made it the most compatible file format which was developed by MPEG. However, MPEG-1 was limited in the sense that it only supported pictures displayed through progressive scanning, which is only one of many methods used to display motion pictures.

This limitation of MPEG-1 ushered the development of a newer file format, MPEG-2. Besides being able to accommodate other methods used in the transmission of moving images, MPEG developed this format to be used for movies which were digitally transmitted to be shown over cable and satellite television systems. The AV compression involved in MPEG-2 would define how the video clips distributed on more advanced forms of data storage should be formatted.

One of the approaches in video compression for this standard involves the elimination of the repeated display of a pixel deemed as constant in a given period of time. In other words, if a stationary background such as a sky is displayed in numerous frames at a time, then display information of the constant sky is captured on the first frame and simply replicated instead of being rebroadcast as frames progress. The whole process usually ends up with little to no effect on the quality of the moving image.

MPEG thought that a different standard should be developed to handle High-definition Television (HDTV). For this matter, the standard MPEG-3 was developed. It was discovered later on that tweaking the MPEG-2 standard worked just as good to accommodate the signals of HDTV, so the MPEG-3 standard was abandoned. By the way, this standard should not be confused with the famous MP3 audio file format, which is short for MPEG-1 Audio Layer 3.

With the quick progress of technology, there have been more and more powerful decoding hardware available in the consumer market. Demands for video from other sources have also been defined, and for this matter the MPEG came up with the MPEG-4 standard. This standard was developed for the purpose of compressing digital AV Data, and therefore it is critical in the transmission of media through the internet. Examples include streaming video, and videophone conversations. Besides integrating MPEG-1 and MPEG-2 features, this standard also incorporates other functions for more advanced display techniques, including 3D rendering. Since illegal downloading has been a concern for many producing companies, there have been many approaches to ensuring that modern video files grant exclusive access to people who have say, purchased a movie. One of these approaches is called Digital Rights management, and it has also been incorporated with the MPEG-4 Standard.

As of today, MPEG-4 is still a work in progress based on the many more demands for video now than ever, and the whole standard has its own standards under it. MPEG-4 Part 2 is one of these video compression standards. MPEG-4 Part 2 has as much as 21 grouped features to accommodate all applications from the simple video camera to the high-quality DVD.

MPEG has also joined with the International Telecommunication Union’s Standardization Sector (ITU-T) to develop the MPEG-4 Part 10 standard. MPEG-4 Part 10 is being developed for the purpose of maintaining good video quality and design simplicity while lowering bit rates substantially. This is being developed not only to accommodate the video demands of the present times but the upcoming devices and upgrades in the future. Both MPEG and ITU-T have finished the drafts for the initial standard to be rolled out last May 2003. These entities have been working hard ever since to finalize all details regarding this lucrative standard.

It is just fortunate that groups like MPEG exist to ensure that the proper standards are developed for the speedy and highest quality displays and transmissions of video clips. The members of this esteemed group are definitely recognized for their accomplishments which started nearly two decades ago.

The MP3 is known to be one of the most popular audio file formats known to most people around the civilized world today. However, many people may not realize it, but they also may be using audio files with the AMR file format for a good number of times too. If you find yourself buying a cell phone model which came out at least 2 years ago, chances are it will probably have a voice recorder integrated with it. When you copy these recordings onto your computer, you will find out that these files have .amr file extension.

AMR stands for Adaptive Multi-Rate, and it is named for the philosophy behind it. There are unique data constraints which are defined by the compression scheme which makes audio files. These constraints are integral to the principle that as interference from the audio source increases, codec rates are lowered to allow more effective application of error correction. It is for this matter that AMR audio file players and encoders have a good range of data rates for the overall scheme to adjust to.

AMR is used primarily in speech coding, and it also incorporates data compression to ensure that more .amr files can be saved in a single device. When an AMR file is played, one will not necessarily notice a considerable variance in audio quality. Of course, this is considering if the original source is of good quality, and there are no significant noise interferences in the background. It is also possible to record music to be saved in AMR file, however the chances of the audio quality being top quality are slim.

The AMR file format is best known for applications and other features integrated in modern cellular phones. These programs range from simple audio player/recorders to programs linked to VoIP (Voice over Internet Protocol) technology.

There have been other file formats used by cell phones prior to the introduction of AMR, such as the EFR or Enhanced Full-Rate codec. AMR’s flexibility to adjust its bit rate depending on the quality of the audio source makes it stand out among these other alternatives. Additionally, the features involved in the AMR format make the resultant file intricate in all considerable aspects.

First, there is VAD, or Voice Activity Detection. This AMR feature simply differentiates instances of speech from instances of silence coming from an audio source. There are times where the AMR file format utilizes VAD to improve the quality of the speech recording. Depending on the properties set on a particular cell phone or program, AMR can use VAD to stop recording during dead air to save space and to shave time off the length of the file.

There’s also CNG, short for Comfort Noise Generation. As the name implies, this feature introduces background static in a very low and tolerable level. Why would adding static while recording a good thing? It minimizes a considerable number of bad effects derived from absolute silence. For one, it keeps the codec rates in a decent level, in preparation for the possibility of disruption from sudden increases in volume. It also gives the person on both sides of the line the assurance that the phone connection is still active, keeping either one of them from hanging up during instances of dead air.

Discontinuous Transmission (DTX) is a feature used particularly in mobile devices with AMR audio file format capabilities. This feature saves power by controlling the device’s transmitter switch to make sure that the battery and amplifiers are not used during those instances of dead air during wireless conversations. It would mute a mobile phone when there is no voice input being made.

These three features of AMR are used together for the main purpose of reducing the usage of precious bandwidth during periods of silence.

Finally, there’s ACELP, which is short for Algebraic Code Excited Linear Prediction. AMR makes use of this sub-algorithm in integral parts of encoding, specifically during times when codec rates are adjusted to ensure continuous recording despite audio interference. As the name implies, it is a set of computation which determine the next best codec rate for the AMR encoder to adjust, where the audio source shows an abrupt change in volume or interference.

What does all of this mean? It simply implies that files of AMR format may be underestimated in terms of audio quality, but its features still make it the premier file format when it comes to recording conversations and other forms of speech from a cell phone. Almost all recordings which come from mobile devices may be converted to audio file formats of better quality, but they have to go through the basic process of AMR formatting first.

When it comes to audio files, the WAV file format used to stand out during its time. This particular audio file type has been a standard ever since Windows 95 came out. With a vast number of operating systems coming out since then, WAV has become one of the most recognized audio file formats. Almost all of the conventional programs we have today are able to support WAV.

Files with the WAV file format are known as one of the simplest out of the many formats when it comes to storing audio tracks. It is considered a direct transcription of sound to data, with mere formatting being the only pre-processing required. Unlike compressed formats such as MPEG, a WAV file consists of only three parts, three “chunks” of information. The purposes of these chunks are very basic: There’s the RIFF chunk which basically tells the computer that it is dealing with a WAV file. There’s the FORMAT chunk which contains sample rate data, besides other information pertinent to the details of the audio track. Finally, there’s the DATA chunk, which is where the actual audio sample is contained. The WAV file format is not necessarily complicated, which is why files with .wav extensions are bigger than usual.

Many people have also known audio files with the .wav extension for their large size. This is due to the high audio quality capabilities of the file. It is for this reason that it is used for audio CDs. Sound tracks are recorded and saved in the .wav file format, and then these files will be manipulated and encoded in Pulse-code Modulation (PCM) into precise locations or sectors in a conventional blank CD. A common music track of the WAV file format which is around 4 minutes long can take around 50MB of space, and a normal CD can store up to 600-700MB of data. This is why many audio CDs have an average of 13-15 tracks.

Files with the .wav extension have become less and less popular as internet file sharing was recognized and utilized by more and more people. Files which are bigger naturally take longer to upload or download, which is bad for people who frequent the internet looking for music. In this field, other file formats which take less memory to store and less time to transfer are definitely more popular. Files with the MP3, AAC, and WMA extensions are good examples of these formats.

Many people have also been known to encode their audio CDs with WAV quality tracks to MP3 files to add to their own libraries. Methods such as compression reduce the quality of Audio CD tracks converted to MP3 files. When these MP3 files are “burned”, or converted back into Audio CD tracks, many people do not notice or ignore the effects of quality reduction. This is an example of how a majority of enthusiasts are usually satisfied with what they hear and download the first time, as long as the tracks they have take less memory space to store.

If there are so many other formats which take less space and less time to acquire, then why is the .wav file still being given attention? WAV files are suitable for systems which prioritize sound quality over disk space. Software developers who are looking to make sound an integral promoter of their products usually make use of high-quality audio in the form of .wav files. For example, programmers in the field of gaming usually use WAV files for sound effects. Multimedia designers also prefer using audio files with the .wav extension for creating their own video and sound clips. Radio broadcasters who want to eliminate the cost of recording and storing tracks in tapes resort to saving their audio in WAV files. This way, the audio quality of their recordings is preserved.

The audio in a file with the .wav extension is also relatively easier to edit and manipulate, due to the simplicity of the file format’s structure. The audio track of a WAV file can easily be truncated or edited to add and remove extra effects. There are many third-party WAV editors available in the internet for this purpose.

It is the simplicity of the WAV file which still makes it a desirable file format in a good number of industries. There’s the fact that it is still recognized and supported by a majority of popular audio programs and operating systems which makes it a winner. The audio quality of the tracks a WAV file contains is one advantage it has over other file formats. Additionally, files with the .wav extension have a very basic structure which provides easy access to the actual audio track for quick customization and adjustments.

The WAV file is a good example of how quality is prioritized over quantity. They are literally bigger and better.

Napster and iPod. One was a controversial file sharing program which was integral to early online audio enthusiasm, and the other was a revolutionary gadget instrumental in promoting digital audio appreciation to the public. A majority of the files downloaded from Napster were of the MP3 file format. Most of the files copied into the iPod are also of the MP3 file format.

What is MP3? It is actually a file extension, and it stands for ‘MPEG, Audio Layer 3’. It is an audio encoding format which makes use of an algorithm, or a specific set of instructions, to significantly compress the size required for a high quality digital audio file. This sort of compression involves the removal of certain sections and wavelengths which are beyond a person’s hearing range. The resultant file has a smaller size and its audio quality can be considered identical to the source it was derived from. This combination of convenient storage requirements and nearly indistinguishable audio quality has made it a hit among many audiophiles.

Not many people know that the concept behind what we now know as the MP3 file format were already being developed back in the 1980’s. Professors and engineers from places ranging from Argentina to Germany made significant contributions to the method of creating or converting sound samples to MP3 files. This method became known as the MP3 Algorithm. Back in the early 1990’s the MP3 algorithm was known to be tested on a song by Suzanne Vega, entitled ‘Tom’s Diner.’ This song stood out among other audio samples used to test the effectiveness and efficiency of the MP3 algorithm and was informally named the ‘Mother of MP3s’. The algorithm was eventually finalized, and on July 7, 1994, the first MP3 encoder for the PC was released.

The options for playing music prior to the MP3 were quite limited. People used to resort to cassette tapes and audio CDs. If a person had a computer back then, he or she usually was not so enthusiastic in keeping 40MB of WAV files.

Nearly a year after, MP3 files were known to circulate on the internet. Songs converted to the MP3 format grew more and more popular as software MP3 players was made available to the public via download from the internet. Not many people had broadband internet back then, but those who had a connection to the internet were definitely more excited in acquiring quality music file as small as 4MB in MP3 form, instead of 40mb in WAV form.

An early and still popular example of audio players supporting the MP3 format is Winamp. Other algorithms have been developed to produce similar file formats such as WMA and OGG, but it is the MP3 file format which was in the minds of many who were seeking music at the time. Encoders were developed to derive MP3 files from audio CD tracks, a method more popularly known as ‘ripping’.

Audio players were eventually followed by P2P programs which supported the easier sharing of files over the internet. ‘Ripped’ MP3 files served as the majority of audio tracks exchanged this way due to its small file size. One of the most popular programs of this type was the previously mentioned P2P program Napster. It was Napster which was targeted by lawsuits coming from a good number of record companies who, at the time, experienced a considerable loss of revenue due to this phenomenon of free music sharing.

MP3s have revolutionized the way people obtain music. The number of people who prefer to download music instead of purchasing them in record stores has grown significantly. It is for this reason that portable MP3 players were developed. ‘Walkman’ devices with MP3 storage and playback capabilities have been in the market since as early as 1998. Sales for MP3 players were quite mediocre, prior to the release of the Apple iPod, the portable music gadget which was a surprise hit for a great number of people. Its simple design, reliability, and capabilities have made it a must have even for people who were not necessarily computer enthusiasts.

In the light of these two extremely noteworthy events in the unpredictable world of technology, it would be difficult to tell how the world would be without the MP3. Who would have known that the development of the MP3 would have such an integral effect on the world in the fields of entertainment and economy?