What is an M4A file?
The M4A file format, an abbreviation for MPEG 4 Audio, is a versatile audio container known for its high-quality, lossy compression via the Advanced Audio Coding (AAC) codec. Identified by the .m4a file extension, it is the standard for un-protected audio content and can store a diverse range of media, including songs, podcasts, and audiobooks. Technologically, M4A is recognized as a more advanced successor to the MP3 format. A key differentiator is its dedicated design for audio, whereas the MP3 format was originally conceived as a mere audio layer within MPEG 1 or MPEG 2 video files.
M4A format is encrypted by FairPlay Digital Rights Management as were sold via the iTunes Store use the .m4p extension. The Apple iPhones use MPEG-4 audio for their ringtones but those audio files use the .m4r extension.
Key Characteristics of M4A Files
| Characteristic | Description |
|---|---|
| High Efficiency | Delivers superior audio quality at lower bitrates than MP3, resulting in smaller file sizes without perceptible loss in quality. |
| Multi-Codec Support | Uniquely supports both high-efficiency lossy (AAC) and completely lossless (ALAC) audio within the same file extension. |
| Apple Ecosystem Native | It is the default audio format for Apple’s iTunes, iOS, and macOS, ensuring seamless integration across iPhones, iPads, and Macs. |
| Broad Compatibility | While native to Apple, M4A files are now widely supported by most modern media players, including VLC, Windows Media Player (on supported codecs), and Android devices. |
| ich Feature Set | Supports advanced features like chapter markers, high-resolution embedded art, and comprehensive metadata, making it suitable for both music and podcasts. |
M4A vs MP3
Both M4A and MP3 are audio-only file formats.
M4A: Better than MP3 in terms of quality and sizes when encoded at the same bit rate. The .m4a file extension is so common because they have been used by Apple for use in the iTunes Music Store. The M4A is an audio file which is compressed using MPEG-4 technology; an algorithm for lossy compression. It is basically associated with “MPEG-4 Audio Layer”, files with .m4a extension are the audio layer of MPEG-4 movies. It is intended to overtake MP3 and become the new standard in audio compression. It is very near to MP3 in many ways but introduced to have a better quality in a same or even smaller file size. The M4A format was first introduced by Apple. The format type is also realized as the Apple lossless Encoder (ALE).
Therefore, currently the M4A couldn’t get the MP3’s mainstream success because the audio format is not generally playable yet. It is somehow limited only to MacOS, iPod, and other Apple products.
Mp3: The most famous digital audio format. It was also one of first compression formats on the scene and became very popular among music lovers. Its mainstream success is so fast that the file type is capable of being played universally and with almost anything, hardware or software. In a general sense, the M4A will produce better sound quality, but many would argue that, whether it’s true or not, the sound difference is not distinguishable, and it would be a waste of time trying to convert MP3 files into M4A files. Eventually, the conversion will just make you lose the original sound quality.
M4A file format specification
The M4A files consist of consecutive chunks. Each chunk has 8 byte header and sub-divided as:
- 4-byte chunk size (big-endian, high byte first)
- 4-byte chunk type - one of pre-defined signatures: “ftyp”, “mdat”, “moov”, “pnot”, “udta”, “uuid”, “moof”, “free”, “skip”, “jP2 “, “wide”, “load”, “ctab”, “imap”, “matt”, “kmat”, “clip”, “crgn”, “sync”, “chap”, “tmcd”, “scpt”, “ssrc”, “PICT”.
First chunk will be of type “ftype” and has a sub-type at offset 8. The M4A defined by sub-type which must be “M4A_”, for M4B sub-type must be “M4B_” and for M4P sub-type must be “M4P_”.
Iterating chunks, until chunk of unknown type is detected, It will compose M4A (MPEG-4 Audio) file.
FAQ
Q1: Is M4A better quality than MP3?
A: Yes, an M4A file using the AAC codec typically provides better audio quality than an MP3 at the same file size or bitrate.
Q2: Can I play M4A files on Windows?
A: Yes, Windows Media Player can play most M4A files, and universal players like VLC and iTunes support them without any issues.
Q3: What is the difference between M4A and MP4?
A: An M4A file contains only audio, while an MP4 file is a general container that can hold both audio and video streams.
Q4: Are M4A files lossless?
A: They can be. M4A files using the AAC codec are lossy, but those using the Apple Lossless (ALAC) codec are lossless.
Q5: Does converting MP3 to M4A improve quality?
A: No, converting a lossy MP3 to a lossy M4A will not recover lost audio data and may even result in a slight generational loss in quality.
