MP3 Encoding and File Format

This section describes MP3 encoding and file format for audio recording.

What is MP3? MP3 is a short name for MPEG-1 Audio Layer 3, which is a very popular encoding format for audio recording. MP3 was invented by a team of European engineers at Philips, CCETT, IRT and Fraunhofer Society in 1991.

MP3 supports several bit rates: 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256 and 320 kbit/s. But 128 kbit/s is most commonly used since it typically offers very good audio quality in a relatively small space. By contrast, uncompressed audio as stored on an audio CD (Compact Disc Digital Audio or CD-DA) has a bit rate of 1,411.2 kbit/s (16 bits/sample * 44100 samples/second * 2 channels / 1000 bits/kilobit).

A MP3 file name has the file extension of .mp3.

A MP3 file contains many MP3 frames with a MP3 header and a MP3 data in each frame:

MP3 Header | MP3 Frame
MP3 Data   |
MP3 Header | MP3 Frame
MP3 Data   |
MP3 Header | MP3 Frame
MP3 Data   |
...

A MP3 header has the following structure:

Bits    Meaning            Value          Note

1-12    Sync word          111111111111   
13      Version            1              1 = MPEG-1
14-15   Layer              01             01 = Layer 3
16      Error protection   1              1 = No
17-20   Bit rate           1000           1000 = 128 kbps
21-22   Frequency          00             00 = 44100 Hz
23      Pad bit            0              0 = Frame is no padded
24      Priv. bit          0              Unkown
25-26   Mode               01             Joint stereo
27-28   Mode extension     00             00 = Intensity and MS off
29      Copyright          0              0 = Not copyrighted
30      Original           0              0 = Not original
31-32   Emphasis           00             00 = None

The original MP3 file format does not allow any places to store information about the MP3 file. So a new standard called ID3v1 was developed in 1996. ID3v1 adds a 128-byte tag space to the end of a MP3 file. The tag space starts with the string TAG, and contains information about the MP3 file like, title, artist, album, comment, etc.

In 1998, ID3v2 was created to add tags at the start of MP3 files. ID3V2 tags uses frames to store pieces of metadata.

Table of Contents

 About This Book

 Audio CD (Compact Disc Digital Audio or CD-DA) Format

 Audio CD (Compact Disc Digital Audio or CD-DA) Players

 Audio CD (Compact Disc Digital Audio or CD-DA) Rip Music

 WAV Audio File Format

MP3, MPEG-1 Audio Layer 3, Encoding Format

MP3 Encoding and File Format

 Editing MP3 ID3 Tags

 Converting MP3 to WAV

 Burning MP3 Music to Audio CD

 Windows Sound Recorder

 ISO 9660 Standard for Data CD

 Recording Data on CD

 VCD (Video CD) Standard

 DVD (Digital Video Disc) Standard Format

 TOC (Table Of Contents) on CDs

 IsoBuster - A Nice CD GUI Tool

 MPlayer - The Movie Player

 vStrip - Rip and Manipulate DVD VOB Files

 mpgtx - Manipulating MPEG Files

 CD/DVD - File Name Extension and Format Types

 References

 PDF Printing Version