Comparison of common audio formats: which one to use?


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Comparison of common audio formats: which one to use?

WMA

Audio files come in all types and sizes. And although we are all familiar with MP3, how about AAC, FLAC, OGG or WMA? Why are there so many standards? Which ones should you care about and which ones can you ignore?

WMA

It’s actually pretty simple once you understand that all audio formats fall into three main categories. Once you know which category you want, all you have to do is choose the format in that category that best suits your needs.

Uncompressed audio formats
Uncompressed audio is exactly what it sounds like: real sound waves that have been captured and digitized without any additional processing. As a result, uncompressed audio files tend to be the most accurate, but they take up A LOT of disk space, around 34MB per minute for 96kHz 24-bit stereo.

PCM
PCM stands for Pulse-Code Modulation, the digital representation of raw analog audio signals. Analog sounds exist as signals, and to convert a signal into digital bits, the sound must be sampled and recorded at specific intervals (or pulses).

Therefore, this digital audio format has a “sample rate” (how often a sample is taken) and a “bit depth” (how many bits are used to represent each sample). There is no compression. Digital recording is a nearly accurate representation of analog audio.

PCM is the most common audio format used on CDs and DVDs. There is a subtype of PCM called linear pulse code modulation, where samples are taken at linear intervals. LPCM is the most common form of PCM, so at this stage the two terms are almost interchangeable.

Wav
WAV stands for Waveform Audio File Format (also called Audio for Windows at one point, but not anymore). It is a standard developed by Microsoft and IBM in 1991.

Many people assume that all WAV files are uncompressed audio files, but this is not entirely true. WAV is actually a Windows container for audio formats. This means that a WAV file can contain compressed audio, but it is rarely used for this.

Most WAV files contain uncompressed PCM audio. The WAV file is just a wrapper for PCM encoding, which makes it more suitable for use on Windows systems. However, Mac systems can generally open WAV files without any problem.

AIFF
AIFF stands for Audio Interchange File Format. Like Microsoft and IBM developed WAV for Windows, AIFF is a format that Apple developed for Mac systems in 1988.

Like WAV files, AIFF files can contain various types of audio. For example, there is a compressed version called AIFF-C and another version called Apple Loops that use GarageBand and Logic Audio, and they all use the same AIFF extension.

Most AIFF files contain uncompressed PCM audio. The AIFF file is simply a wrapper for PCM encoding, which makes it more suitable for use on Mac systems. However, Windows systems can generally open AIFF files without any problem.

audio file signal format

Lossy compressed audio formats
Lossy compression is a form of compression that loses data during the compression process. In the context of audio, this means that we sacrifice quality and fidelity for file size. The good news is that most of the time you won’t be able to tell the difference.

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However, if the audio is compressed too much or too often, you will start to hear artifacts and other oddities that become more and more noticeable.

See also: Digital Photo Editing? Choose the right monitor and configure it correctly
MP3
MP3 stands for MPEG-1 Audio Layer 3. It was released in 1993 and quickly gained popularity, eventually becoming the world’s most popular audio format for music files. There’s a reason we have “MP3 players” and not “OGG players” …

The main pursuit of MP3 is to remove all audio data that exists outside the audible range of most normal people and reduce the quality of sounds that are not easy to hear, and then compress all other audio data from the as efficiently as possible.

Almost every digital audio capable device in the world can read and play MP3 files, whether we are talking about PC, Mac, Android, iPhone, Smart TV or anything else. When you need versatility, MP3 will never let you down.

Please note that MP3 is not the same as MP4

although their similar names may indicate otherwise.

ACC
AAC stands for Advanced Audio Coding. It was developed in 1997 as the successor to MP3.


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WMA – Everything about WMA (2)

Windows Media Audio Professional: Also known as WMA Pro is a more advanced WMA-based lossy codec. Like traditional WMA it has a 24-bit sample size but uses a maximum sample rate of 96000Hz, instead of 48000 from WMA, and up to 8 channels (thus enabling 7.1 sound) instead of 6 from WMA. It also incorporates DRC (dynamic range compression). In addition, as of version 9 of WMA Pro there is a version of WMA Pro with low bitrate and another with low delay for bidirectional applications.

Despite being superior to WMA and belonging to the giant Microsoft WMA, it has little commercial support. Except for the products of Microsoft Xbox 360 (video game console) and Zune (portable player) and the latest Toshiba and Motorola mobiles, few other systems can play it. This situation is expected to change when WMV HD (Windows Media Video High Definition, a high-resolution video codec) is standardized, as WMV HD incorporates WMA Pro as an audio codec.

Windows Media Audio LossLess: Typically known as WMA LossLess is a lossless codec for audio that is therefore in direct competition with other lossless encoding systems such as FLAC, Monkey’s Audio, or Apple LossLess. To achieve this lossless encoding, a 96Khz sample rate, a 24-bit PCM sample size and a variable bitrate are used depending on the complexity of the section to be encoded. It also provides up to 6 independent channels, so you can get 5.1 surround sound (5 speakers with one audio channel each plus a special channel for lower sounds that are played on a special speaker called a subwoofer). It achieves a compression of 50% on the original audio file (in CD-Audio format), although Microsoft (its creator) states that this compression can be up to 66% (that is, the resulting file would have a size that would be 33% of the original). An interesting feature is that WMA LossLess incorporates Dynamic Range Compression (DRC), which is a technique that aims to control the volume of the audio signal. Specifically, the volume of sounds with high volume (above a threshold) is reduced, and sounds with low volume are left as is. This is done because in noisy environments, if the volume is low, the low volume sounds are inaudible, while if the volume is high, the low volume sounds can be heard but the high volume sounds will be heard with an annoying volume. Thanks to DRC the high volume and low volume sounds can be heard at the same time, since the volume of high volume sounds is reduced but not the volume of low ones, then the general volume can be increased to a point where both are Audible and loud speakers are not annoying. Furthermore, this reduces the dynamic range of the signal.

Windows Media Audio Voice: It is a voice-specific lossy compression format that was born to compete with existing ones such as CELP (Algebraic Code Excited Linear Prediction), Speex (freely distributed), G.711 or G.729. Like all voice codecs, they are designed for very low bitrates and for a bandwidth between 300 and 3400Hz (since the highest spectrum power of the human voice is in that frequency range). This in particular allows a constant bitrate (does NOT allow variable bitrate) of up to 20Kbps, a single mono channel and a sampling rate of up to 22.05Khz. It also solves a problem that most voice codecs have: If the encoded signal contains other types of sounds besides voice (since it is assumed that if a voice codec is used, it is because it is transmitting voice), such as music, encoding is not good, as music will have a broader spectrum than voice. WMA voice solves this lack by detecting which sections contain something other than human voice (music, some kind of effect …) and encodes that section with traditional WMA.

The only version available so far, WMA 9 Voice, is used in Microsoft’s online gaming service Xbox Live, on mobile devices using Windows Mobile and on BBC internet streaming radio.