You have a favorite podcast. Maybe you keep an extensive (and legally-acquired) music library. Sometimes those audio files have an MP3 format noted. Other times, it might be designated MP4. Should you be concerned over audio quality? Is MP3 vs. MP4 a comparison you should worry about making?
First, let's take a quick look at the basics: MP3 stands for MPEG-1 Audio Layer 3. The format was approved in 1991 as a way for audio to be compressed and reduced to a file that was more easily transmitted online. In the simplest definition, MP3s keep their size to a minimum by reducing the information, or sound, that the human ear can’t pick up on. While there were MP1 and MP2 file formats, MP3 improved on the compression and became the standard in audio files that could be shared without sacrificing a noticeable amount of quality in the process—though that is, obviously, highly subjective.
In 2003, the MP4 format was finalized. Short for MPEG-4 Part 14, it’s based on the Apple QuickTime MOV format. While MP3 and MP4 comfortably coexist, there are some significant differences, with the most prominent being MP4’s versatility.
MP3s are generally audio-only files; the format is not able to handle video or imaging. MP4, on the other hand, is a multimedia facilitator. It can handle video, stills, subtitles, or text because it’s a “container” format that stores data rather than just code.
Debating the versatility merits of MP3 vs. MP4 doesn’t really answer the question of which is better for audio purposes or whether you should seek out one type over the other. For audio, the reality is that neither one offers a superior sound experience on format alone. “Lossy” audio, or audio that loses information so it can be reduced in size, is the case for both MP3 and MP4. MP4, however, makes use of codecs that may compress files in different ways. So, while MP4 is not inherently a superior format for sound, it has the capability to offer an upgrade in quality depending on how it’s being used. MP4s typically have the ability to take advantage of Advanced Audio Coding, or AAC, which can encode audio at a higher bitrate (the data used) than MP3s can, and usually sound better even if the bitrate is the same. AAC is what you’ll find in Apple’s iTunes store.
Naturally, a recording is only as good as the source material. If your favorite podcast is taking place in a poorly arranged studio setup, it doesn’t matter what format it’s being offered in. And if you're listening on a pair of cheap earbuds while jogging, you're less likely to hear major differences in audio than if you were using a sensitive pair of headphones.
Still, as with most tech innovations, the standards are always changing; in May 2017, the Fraunhofer Institute for Integrated Circuits—the group that helped to develop the MP3 technology—claimed that the format is essentially dead and announced that its "licensing program for certain MP3 related patents and software of Technicolor and Fraunhofer IIS has been terminated."
You may want to consider converting from one file format to another if your phone or other playback device only supports one type. Otherwise, audiophiles truly concerned about sound quality should probably disregard any MP3 vs. MP4 discussion and opt for FLAC, WAV, or other files that are “lossless.” They’ll take up a lot of storage space due to a lack of compression, but they’ll typically sound better than the rest of the internet’s alphabet soup.
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