Difference Between AAC and M4A (With Table)

Advanced Audio Coding is a codec mechanism that is intended to replace MP3 because it provides an improved audio output. Whereas M4A is an extension format that is used to store the files that use this kind of coding system.

AAC vs M4A

The main difference between AAC and M4A is that latter is a file extension format, while the former is a system that encodes and compresses audio files. An Audio that is encoded using Advanced Audio Coding (AAC) can have extensions like AAC, AP4, and M4A.

One of the most efficient audio compression techniques available at the moment is present in the Advanced Audio Coding (AAC). AAC is standardized by the ISO MPEG. The specialty of AAC is that it can provide audio of high quality even at lower bit rates. AAC uses bits rates that are lower than the previous MPEG coding format.

M4A is a file extension that is used with the MPEG-4 audio files. Apple’s iTunes Store often uses this format in its song downloads. A large number of M4A files are usually encoded with the lossy AAC codec. This is done usually to reduce the size of the file. But instead, some may use the Apple Lossless Audio codec to retain the original audio.

Comparison Table Between AAC and M4A

Parameters of ComparisonsAACM4A
MeaningAAC is a codec system to compress files.M4A is a file extension to store audio files
Audio qualityAAC is a lossy codec.M4A files may contain a lossy compression or a lossless compression.
File TypeEncoding formatFile extension
Supported Audio formatsAAC supports MPEG-2 and MPEG-4M4A supports MPEG-4 ONLY
UseIt is a compression codec that may lose quality but reduce the audio file size.M4A is a file container that is compatible with the AAC codec and the ALAC codec.

What is AAC?

AAC (Advanced Audio Coding) is a digital codec standard that helps in compressing the audio formats. It is based on lossy audio compression. It is considered to be the successor of the MP3 file format. MP3 faced issues in implementing new processes to compress the audio files.

AAC can generate better audio output than MP3 at the same bit rate. Hence, we can say that AAC is an advanced version of the MP3 format. Companies like Nokia, Dolby, AT&T, and Sony declared AAC as an international standard by MPEG in April 1997.

This format was later adopted by various organizations namely YouTube, Apple iTunes and various other platforms. AAC file format can provide the user with more flexibility to design codec than MP3. MPEG-2 Part 7 and MPEG-4 Part 3 are the file formats that are supported by the The AAC.

AAC helps in developing enhanced effectiveness of the compression. To enhance the compression, it uses the prediction coefficients of MDCT-time, parametric stereo, perceptual noise substitution, spectral band replication (SBR).

What is M4A?

M4A is a file extension format that can store the compressed audio file in the MPEG-4 format. This file format became popular when Apple Inc started using it in iTunes and iPod for songs. Apple used either the Advanced audio coding (AAC) or the Apple Lossless (ALAC) codec for the M4A files.

M4A files are unprotected files. Files that are protected generally use the MP4 file extension. The audio quality used in the M4A can be reverted to the original audio quality before the file was compressed.

Another feature of M4A is that the audio files do not have Digital Rights Management. This helps creators to edit or transfer the files more freely. M4A is a format that is widely used by Apple in its devices but it has poor compatibility with other devices. This is the reason why audio playback in the M4A format is inconvenient when compared to the MP3 format.

It is easy to distribute the M4A audio files on the internet without worrying about protecting them. For people using apple products, M4A is the most recommended but people who use android might prefer MP3 over M4A.

Portable media players are usually called MP4 Players, but they do not play M4A Audio Format. They are MP3 players that have the capability to play AMV video but that is not necessarily MPEG-4 format files.

Main Differences Between AAC and M4A

  1. AAC is a codec system whereas M4A is a file extension.
  2. The audio quality for AAC files is lossy whereas the M4A files may support the lossy audio files but they can also support the files which have lossless quality.
  3. AAC files require a lesser amount of space. M4A files which are can contain small files but the lossless audio files may require a lot of space.
  4. AAC supports MPEG-2 as well as the MPEG-4 format, but the M4A only supports MPEG-4.
  5. AAC is used to compress the audio files on the other hand M4A is a file extension that is used to store the audio files.


The main differentiation is that the AAC and the M4A are different formats that are related to the audio files. AAC is a compression codec that compresses the audio files and M4A is a file extension that can store such audio file compressions.

On an operational basis and quality basis, AAC is more compatible with all the products but the lossy audio is a major issue. M4A is less compatible with all the devices except for Apple products and platforms like VLC, but M4A has the features to offer original and lossless audio.

However, both, AAC and M4A, are audio formats and we can convert both of them into the MP3 format. Both AAC and M4A have their positives as the former helps to occupy less amount of space and the latter helps in storing lossless audio.

One thing to note is the type of files that it supports. AAC supports the MPEG-2 and MPEG-4 formats. M4A  can only support the MPEG-4 formatted files. Both AAC and M4A have their positives as well as negatives.


  1. https://ieeexplore.ieee.org/abstract/document/625587/