What Is The Simplest Audio Format?

Digital audio formats are significantly more advanced than their analog predecessors. However, some digital audio formats are less complex than others. So, which is the simplest audio format?

LPCM is the simplest audio format. Audio in the LPCM format is uncompressed and sometimes stored as raw data in headerless files. LPCM data is most commonly converted into container formats like WAV and AIFF. For this reason, WAV and AIFF are considered among the least complex audio formats.

Audio formats range in complexity depending on their design and technical applications. The following information aims to enlighten anyone wondering which audio format is the simplest.

Uncompressed Audio Is The Simplest Format

The simplest type of audio format is one that stores uncompressed sound data. Uncompressed file formats store audio data that is unaltered by compression encoding. The resulting uncompressed files are pure and unaltered copies of the original sound waves.

There are several types of uncompressed formats, the most common of which are:

  • LPCM,
  • AIFF,
  • WAV.

LPCM (linear pulse-code modulation) is the primary uncompressed audio coding format. The format is standard on compact discs.

Audio data in the LPCM format is sometimes stored in a raw form, meaning the information is not compressed or held in a container. Raw LPCM is the most basic and pristine version of the format and precludes the storage of accompanying metadata.

In most cases, however, LPCM data is converted into the WAV (Waveform Audio File Format) or AIFF (Audio Interchange File Format) container formats. For this reason, people often refer to WAV and AIFF as uncompressed audio formats. These formats are as simple as LPCM but they can include header information.

The simplicity of uncompressed file formats contrasts starkly with lossy and lossless compressed formats. These formats hold audio data that underwent complex coding manipulations. For instance, compression formats involve sophisticated psychoacoustic modeling and input data approximation.

A Closer Look At Uncompressed Formats

It is worth examining the design and function of uncompressed audio formats to gauge their relative complexity.

LPCM

LPCM is a specific form of PCM (pulse-code modulation) and replicates sampled analog audio data.

Though the terms are often used interchangeably, LPCM is not identical to PCM. LPCM performs linear quantization on input audio signals. With PCM, quantization is determined by the amplitude of each sample taken from the input audio.

Aside from the characteristics of the source audio, there are only two variables that influence the quality of audio in the LPCM format, namely bit depth and sampling rate.

The fidelity and resolution of LPCM data depend on how many samples are processed per second from an audio signal (sampling rate), together with the number of bits contained in every sample (bit depth).

As noted above, data in the LPCM format can be stored as pure or raw audio information. In this form,  data is uncompressed, so the files contain the complete bit stream from the input audio. Files with raw LPCM only include audio data and exclude header metadata (such as bit depth or sampling rate).

Another characteristic of raw, uncompressed LPCM data is that it is not held in a container file.
Raw LPCM audio files are identifiable by the .raw, .pcm, or .sam file name extensions.

In most cases, LPCM data gets converted into container formats like WAV and AIFF. These containers add header information to the LPCM data but retain the overall simplicity of this uncompressed audio format.

WAV

The WAV container format (file extension .wav) is most commonly used to store LPCM (though it also supports compressed audio). WAV is also the primary container for uncompressed audio on Windows OS. Consequently, many people classify WAV as a simple, uncompressed format.

Using the WAV container format to store LPCM data does not alter the input information, which remains in a simple, uncompressed state. WAV has a degree of additional complexity, however, because it uses the RIFF (Resource Interchange File Format) technique to store data in chunks with tags.  

WAV is also slightly more complex than raw LPCM because this container format enables users to store LPCM audio data alongside its corresponding metadata (such as track information and album art).

The primary benefit of storing LPCM audio in the WAV container format is increased compatibility. Having LPCM on WAV expands the range of software and media players that will play LPCM data.

AIFF

Uncompressed LPCM audio data is also routinely stored in the AIFF container format (file extension .aiff, .aif, or .aifc). Apple Inc. created AIFF for macOS. AIFF is closely related to WAV and uses the IFF (Interchange File Format) format, which is functionally equivalent to RIFF.

AIFF only stores uncompressed audio data. There is another version of the format called AIFF-C (or AIFC) that holds compressed audio. 

AIFF is marginally more complex than raw LPCM because the format relies on the IFF method of compartmentalizing and tagging audio data. The AIFF format also has the potential to store LPCM data with its corresponding metadata.

Despite these additional nuances, AIFF is one of the simplest formats because it is a container that stores uncompressed LPCM audio data.

The Simplicity Of Uncompressed VS Compressed Formats

Uncompressed audio formats like LPCM and its WAV and AIFF containers are technically less complex than those using compression encoding. Compression formats reduce the file size of audio data with highly-sophisticated algorithms that approximate the original audio data.

Note that it is possible to convert uncompressed LPCM audio to a compressed format. The configuration of the data on the new file will, however, be more complex than the uncompressed original.

Lossy Compression Formats

In lossy compression, a portion of the input audio data gets discarded (or lost) when creating a new, smaller file.

During lossy compression, encoders perform complex psychoacoustic modeling to identify and remove information that is not audibly perceptible to the average listener. The process generally achieves a 75% to 95% reduction in file size.

MP3 is the most widely-used lossy compression format. The format contains audio data encoded with a combination of MDCT (modified discrete cosine transform) and FFT (fast Fourier transform) algorithms.ย 

AAC is a later version of MP3 and uses a pure MDCT algorithm to compress audio data to achieve while maintaining a higher-quality sound. This lossy compression format is more technologically complex than MP3 because it has multiple additional capabilities (including more sampling rates and higher coding efficiency).

Lossless Compression Formats

Lossless formats like FLAC and ALAC hold compressed audio data encoded without losing a single bit of essential and aurally-perceptible information. Consequently, lossless compression creates files with identical data to the original audio information.

The most recognizable lossless formats are FLAC and ALAC. These encoders (or codecs) are more complex than lossy formats, partly because they model input data and map it to a new bit sequence. 

Consider, for instance, how FLAC encodes audio. Firstly, the FLAC encoding algorithm separates the data into blocks. Secondly, the algorithm determines an optimal arithmetic approximation of each block (using linear predictive coding or a polynomial).

In the third step, a description of the approximation gets written with the minimal possible number of bits. Finally, FLAC deploys Rice coding to encode the residual, which is the discrepancy between the approximation and the source audio. 

From this brief explanation of the complexities of lossless compression, one can easily appreciate the comparative simplicity of uncompressed audio formats like raw LPCM, WAV, and AIFF.

Conclusion

The simplest audio format is LPCM. Audio data in the LPCM format is uncompressed and can either be stored in a raw state (usually with the .raw file extension) or within a container format such as WAV or AIFF.

References

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