.MP3 File Format

MP3 is the ubiquitous audio format that compromises well between audio quality and file size. MP3 is only about 1/10 the size of uncompressed WAV or AIFF files, but keep the same CD-quality sound.

MP3 was developed by the Moving Picture Experts Group as part of its MPEG-1 standard and later extended in MPEG-2 standard. That's why MP3 can stand for MPEG-1 or MPEG-2 Layer III.

The quality of an MP3 file mainly depends on the bit rate used for compressing audio data. The most popular bit rates are 128, 160, 192, and 256 kbps. Since uncompressed audio as stored on an audio-CD has a bit rate of 1,411.2 kbit/s, the compression ratios are approximately 11:1, 9:1, 7:1 and 5:1 respectively. As we have got more Internet bandwidth and larger hard drive sizes, higher bit rates up to 320 kbit/s are widespread. This is also the maximum bitrate that Google Music supports.

MP3 file format are supported by most portable music players, such as the Apple iPod and Microsoft Zune. It's also the standard format to be used by most online music service like Google Music, Amazon Cloud Drive and iTunes Match.

Note: Not to be confused with MPEG-3, which is originally designed to handle HDTV signals at 1080p. But MPEG-3 was soon rolled into MPEG-2 because MPEG-2 would accommodate HDTV at high data rate.