Several unique terms and phrases describe the features of software we review on this site, some easier to grasp than others. This list briefly defines terms relevant to Audio Converter Software.

Features Set

Audio Tags

This is the information regarding the artist, title and album associated with the song track. Most audio converters allow users to edit or transfer audio tags to converted songs.

Batch Conversions

Useful when there are a lot of files to convert, a batch conversion option simply allows users to create a list of files for the program to convert automatically.

Command Line

Command Line functionality is mostly useful for professionals because it allows users to integrate the program into larger sound editing systems.

Sample Rate/Frequency

This setting determines the number of times per second that the program samples the audio signal from the original audio file.

Channels

This setting allows users to change the way the song plays on different stereos and speaker configurations.

Bitrate

This setting determines the quality of the song, allowing users to increase the audio information in a file in exchange for making it larger. The higher the bitrate the better the quality.

Normalize

Normalizing increases or decreases the amplitude of the audio file. This allows users to improve the signal level without distorting the file.

Removes DRM protection (iTunes, Rhapsody, etc.)

Music bought online usually has Digital Rights Management (DRM) protection. Only some programs are able to remove the DRM code during conversion. In order to make music purchased online compatible with all MP3 players, the DRM protection must be removed.

Input

MP3

This format is by far the most common in digital music. Nearly every digital music player and computer can play this format. The extension stands for MPEG, audio layer 3. There are several standard ways to compress audio signals and MP3 uses the third layer.

The MP3 format was first developed in the late 1980s and early 90s and became the ISO/IEC standard in 1991. In 1994, the first public encoder was released for the MPEG-3 format and the developers chose the .mp3 file extension. The format became popular throughout 1995 and has continued to gain popularity up to the present.

The MP3 format uses audio coding and compression to remove all the extraneous information from an audio signal that the human ear can’t hear anyway. This allows the audio files to be much smaller but still have good quality. The small file size made them especially popular for use on the internet and in download content. The popularity of MP3s expanded from there and the format is still a staple of digital music.

WAV

The WAV format, or Waveform audio format, is one of the most ubiquitous in the digital music industry. It was developed by IBM and Microsoft and is the standard audio format on the Windows operating system. Another abbreviation that commonly accompanies WAV is PCM. This stands for pulse-code modulation. The WAV format is becoming less popular for internet audio and music downloads because it does not usually use compressed audio and, therefore, the file sizes are usually larger than MP3 or AAC.

Many professionals still use WAV because it is a lossless codec that has excellent audio quality. And WAV is still in common use elsewhere because it is compatible with almost any media player and it is simple. It is often used in audio file conversions because it is guaranteed to be compatible.

WMA

The WMA format, short for Windows Media Audio format, was developed by Microsoft. Though it was originally used for the Windows operating system, Microsoft released it for third-party use and the WMA format has become very common in MP3 download services.

Microsoft originally claimed that WMA offers the same quality as MP3 at half the bit rate. But many people are skeptical of this and some independent testing has brought serious doubt to the claim. Nevertheless, WMA is still a good format that allows for customization and audio tag metadata. The format functions like MP3 in that it is a lossy codec, meaning it leaves out audio signals that can’t be heard by the average human. WMA also has a few design improvements over the MP3 format that have made it popular.

There are three other formats related to WMA. They are WMA Pro, WMA Lossless, and WMA Voice. Inexplicably, these formats are not mutually compatible with WMA. But the standard WMA format is the most common, especially in music downloads. When used for MP3 download services, the WMA format will include DRM protection, called PlaysForSure, that prevents duplication. Unfortunately, it also makes the file incompatible with MP3 players that cannot handle protected WMA.

AAC

Developed by the same organization that created the MP3 format, AAC files, or Advanced Audio Coding files, are an improvement over the quality and compression of MP3 files, but not enough of an improvement to overcome MP3’s popularity. The AAC format was introduced in 1997 and works similar to MP3 because it only contains audio information that the human ear can hear. But AAC audio has more sample frequencies, more channels, more efficient coding and several other improvements over MP3.

The most popular company to use AAC files is Apple, which uses it for iPod audio devices and the Apple iTunes Music Store. Apple has created a DRM protected version of the AAC format, which is sold at the iTunes Music Store. The AAC format is extremely common only because of the success of the iPod and iTunes Music Store. There are few other companies or websites that use it exclusively.

AIFF

The file extension for AIFF music files stands for Audio Interchange File Format. It is used as the standard sound format on Macintosh computers and is actually quite similar to the WAV format used by Windows. AIFF files can carry the extensions .aif or .iff depending on the application. These files are usually quite large because they do not support file compression.

OGG

The OGG file extension commonly refers to the Ogg Vorbis format, although there are several subversions. OGG first appeared on the digital music scene in 2003. It is an open-source format that is designed to be an efficient compression codec.

OGG is often used in distribution of free multimedia because the format itself is open-source. But many audio enthusiasts have begun to adopt it and several popular video games have incorporated the OGG format into game audio. As it has become more popular many MP3 players and media player programs have begun supporting the format as well.

OGG is usually a lossy codec, meaning that it removes some audio information that is out of the normal human hearing range. Though the OGG format has good quality, many people don’t like to use it for digital music libraries because the format does not support metadata, such as the artist, album, track name and other information that other formats include with the file.

FLAC

The Free Lossless Audio codec, or FLAC, is public domain. It is compressed like MP3 files, but it does not remove parts of that audio signal during compression, maintaining the quality of the recording. Usually, commercial software doesn’t support open-source formats very well, but surprisingly many media players support the FLAC audio format. It is difficult to find music in FLAC format from major music download sites, but many people who prefer it have converted music to FLAC formats. There are customizable bitrates, sample rates and channels in the FLAC format as well.

M4A

M4A, M4B and M4P file extensions are all related to the MPEG-4 format (or MP4), and are basically audio versions of the MP4 codec. The reason that these file extensions are so common is that they have been adopted by Apple for use in the iTunes Music Store. M4A files are very similar to MP4 files, and the M4B format is only different from M4A because it can be “bookmarked,” allowing an MP3 player to return exactly to the last listening point. M4B is popular for audiobooks and podcasts for this very reason.

M4P is Apple’s version of the M4A format that includes DRM protection. This is the format used for protected music purchased from the iTunes Music Store.

These three extensions of the MP4 format can be embedded with information from AAC, MP2 and MP3 formats, making them versatile. Most media players that support the MP4 format will be able to play M4A and M4B. Playback of M4P will depend on whether the media player can support the DRM protected versions of songs.

DRM Protected

DRM stands for Digital Rights Management and is a term that can mean several different things. The most basic explanation is that DRM protects creative works from being duplicated. Manufacturers and producers in the music industry rely heavily on DRM to protect their revenue stream, while consumers detest DRM because it causes problems.

The main problem for consumers isn’t the fact that they want to illegally duplicate MP3 downloads. In fact, most consumers hate DRM because it makes songs incompatible with some MP3 players. Most of the major producers have created their own DRM codes, none of which are compatible with all MP3 players. Add to that the fact that various MP3 download services also use completely different DRM protection and the prospect of listening to MP3s can actually be a very frustrating experience.

Since the record companies haven’t provided a solution to the compatibility problem, many consumers have turned to programs and services that remove DRM restrictions from files or convert them to formats that will work with their MP3 players.

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