CAA vs. MP3: what is the best audio file format?

Offline music is making a comeback, and if you’re about to break free from streaming platforms and store your music locally (or if you’re just looking to use your soundbar’s USB port to listen to a few tunes), you might be confused about the different audio formats available and which one is best. At first glance, the best audio files are those with a higher bit depth and sample rate (16-bit/44.1 kilohertz and above). Lossless formats like FLAC (Free Lossless Audio Codec) and uncompressed audio such as WAV (Waveform Audio File Format) preserve all audio information, meaning they simply sound better than compressed files. So is this a done deal?

Not really. WAV and FLAC may be high fidelity, but they are also heavy in file size. As an example, let’s take any song that is three minutes long. A WAV file will weigh between 30 and 50 megabytes (MB), while an MP3 compressed at 320 kilobits per second (kbps) will only take up 7 MB. So compressed or lossy formats like MP3 or AAC (Advanced Audio Coding) may be more practical if you prefer a barely perceptible drop in audio quality but much more hard drive space.

But which of them is the best? Well, when you dip your toes into the conundrum of AAC versus MP3, AAC has a significant advantage. As a more efficient (and newer) format, it sounds better than MP3, even at a lower bit rate. However, MP3 is no slouch either if you don’t like compression and keep it at around 320 kbps, which is a standard quality you’ll get in download stores.

MP3, or MPEG Audio Layer III, originated in a bygone era when storage space was not as widely available as it is today and download speeds moved at a snail’s pace. So the best solution for moving files across the internet and between devices is to destroy the original audio and sacrifice parts of it in the name of reducing storage requirements. By implementing lossy compression, MP3s eliminate parts of the audio that are less likely to be noticed by listeners in an effort to reduce file size. For example, a 128 kbps MP3 eliminates all frequencies above 16 kHz while also removing duplicate information from the left and right channels. A similar process also applies to some low-frequency information.

This is an exaggerated example, so to speak. With MP3, the damage is still there, but sound quality ultimately depends on bitrate. For example, the loss of audio fidelity at 128 kbps is much more noticeable than at 320 kbps. In fact, many users online claim that MP3 produces sound quality comparable to uncompressed audio at bit rates above 320 kbps, with the differences barely noticeable on high-end systems. Although MP3 remains popular due to its wide compatibility, it has fallen somewhat out of favor as higher lossy formats have appeared.

The field of audio compression does not stop at MP3. Apple designed AAC for efficiency, and it’s safe to say they succeeded. Supporting up to 48 channels (MP3 is limited to 5.1: five normal channels and one low frequency channel), the new improved algorithm achieves maximum audio quality even at lower bit rates. Granted, if you compare them at high bitrates, you might not hear much of a difference. But the more you compress the audio (128 kbps and below), AAC versus MP3 practically turns into a match of a world heavyweight champion versus a semi-professional boxer.

To illustrate the demise of MP3, let’s just consider that none of the major streaming platforms use it. Apple Music relies exclusively on AAC at a bitrate of 256 kbps. Likewise, the Spotify mobile and desktop apps have moved to Ogg Vorbis (up to 320 kbps for premium accounts), while Spotify’s premium web player still runs AAC at 256 kbps.

That said, if you’re building a home library, there’s nothing wrong with opting for MP3 compressed to 320 kbps. Audio is a fickle entity, where the majority of people have difficulty differentiating between lossless audio and high-resolution audio, and even between lossless audio and files compressed at 320 kbps. In short, if you have the storage space, target FLAC or WAV. Otherwise, AAC and MP3 are strong competitors if you don’t push them below the 320 kbps bracket.