MP3, short for MPEG Layer 3, is designed by Moving Pictures Experts Group. It is the most common lossy and compressed digital audio format around, with the bit rates ranging from 8 kbit/s up to 320 kbit/s, and the sampling rates ranging from 16 kHz to a maximum of 48 kHz.
Normally, MP3 is widely used to store music files with smaller file size, which means songs ended with .mp3 file extension take up less space than the same songs using lossless format, like FLAC, ALAC. This is why MP3 music files can be universally played with an array of music players like Windows Media Player, VCL, Apple devices, Android smartphones & tablets, and even vehicle as well as lots of other devices. See also: How to convert MP4 to MP3 audio for Mac
How MP3 File Works
MP3 files use the compression technique to strip out of a lot of sounds in a song so as to reduce the file size down and save storage space. As a result, the sound quality of MP3 files is not identical to the originals' CD-quality audio but this will not impact the listening experience for average people (some audiophiles may prefer the lossless audio files).
Technically, bitrate is used to encode audio files and measure audio quality. The higher the bitrate an MP3 file encoded, the better audio quality it has — 128 kps, 192 kbps and 256 kbps are the most common bitrates that MP3 songs are used.
How to Convent File to and from an MP3 Audio File
Since MP3 is a lossy format, it's only wise to convert it to a lossy audio. For example, you can convert MP3 to M4R for iPhone ringtone or to AAC, which is also a compressed audio format but has slightly better sound quality than MP3.
What is MP4?
Definition - What does MP4 mean?
MP4 is a file format created by the Moving Picture Experts Group (MPEG) as a multimedia container format designed to store audiovisual data. The MP4 is largely replacing earlier multimedia file formats, and creating some changes in the way that vendors sell audiovisual files to the public.
The MP4 is based on a QuickTime file format, and has various file name extensions that can help provide clues to what kind of content is contained in the file. This has led to some confusion on the part of users over just what an MP4 is and how a particular MP4 is set up.
Experts point out that some MP4 files are encrypted with what’s called Fairplay Digital Rights Management,
which is a technology used by Apple to protect some of the content that it sells on the iTunes platform.
A quick history of the MP4 and Fairplay technology reveals that while Apple did use Fairplay encryption on songs,
the company currently sells songs without Fairplay encryption in the United States. However, some other kinds of audio files may be encrypted. Common extensions include .mp4, which is commonly used for audiovisual files,
.m4a, which is often used for non-protected content, and m4p, which can indicate that the file is protected by Fairplay encryption. The use of Fairplay encryption has led to a number of freeware offerings aimed at decrypting Fairplay.
However, the greater issue is whether audiovisual file vendors will continue to maintain a hybrid strategy of encrypting some files while not encrypting others.