Format
MPEG 1/2 Audio Layer 3
Summary
- Name
- MPEG 1/2 Audio Layer 3
- Identifiers
-
- MIME: audio/mpeg
- PUID: fmt/134
- Apple Uniform Type Identifier: public.mp3
- Format type
- Audio
- Description
- MP3 is a digital audio format, formally known as MPEG-1 Audio Layer III or MPEG-2 Audio Layer III. A third variant, known as MPEG 2.5, which supports lower bit rates implemented by the LAME MP3 encoder among others, but is not a recognised standard.
- File extensions
-
mp3 - Source
- Digital Preservation Department / The National Archives
Relationships
- Has lower priority than
-
- Acrobat PDF 1.0 - Portable Document Format 1.0
- Acrobat PDF 1.1 - Portable Document Format 1.1
- Acrobat PDF 1.2 - Portable Document Format 1.2
- Acrobat PDF 1.3 - Portable Document Format 1.3
- Acrobat PDF 1.4 - Portable Document Format 1.4
- Acrobat PDF 1.5 - Portable Document Format 1.5
- PCX 5
- Acrobat PDF 1.6 - Portable Document Format 1.6
- Macromedia Flash 1
- Macromedia Flash 2
- Macromedia Flash 3
- Macromedia Flash 4
- Macromedia Flash 5
- Macromedia Flash 6
- Macromedia Flash 7
- Macromedia FLV 1
- AutoCAD Drawing 2007-2008
- Acrobat PDF 1.7 - Portable Document Format 1.7
- Tagged Image File Format
- Audio Interchange File Format
- Matroska 1-4
- Nullsoft Streaming Video
- NCH Dictation Audio File
- STOS Memory Bank
- multiArtist File
- MAKIchan Graphics File
- Beam Software SIFF File
- Spectrum 512 Compressed | Spectrum 512 Smooshed
- Spectrum 512 Uncompressed | Spectrum 512 Uncompressed Enhanced
- XL-Paint
- Persuasion Mac Document 2.1
- Pablo Paint Raster Image
- Canon SIF File
- Audio Data Transport Stream
- GoDot 4Bit Graphics Format
- SWiSH Movie File
- GST Art File 1
- VBM (VDC BitMap) File
Internal signatures
MPEG-1 Audio Layer 3 with ID3v2 Tag
- Note
- Regularly-spaced frame headers should always be discoverable near EOF. An ID3v1 tag of up to 355 bytes may be present at EOF.
Byte sequences
- Min Frag Length
- Absolute from EOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{47-1795}- Endianness
- Little-endian
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
494433- Endianness
- Little-endian
MPEG-2 Audio Layer 3 with ID3v2 Tag
- Note
- Regularly-spaced frame headers should always be discoverable near EOF. An ID3v1 tag of up to 355 bytes may be present at EOF.
Byte sequences
- Min Frag Length
- Absolute from EOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{47-1795}- Endianness
- Little-endian
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
494433- Endianness
- Little-endian
MPEG-1 Audio Layer 3 with ID3v2 Tag (protected)
- Note
- Regularly-spaced frame headers should always be discoverable near EOF. Header has CRC bit off to indicate protected. An ID3v1 tag of up to 355 bytes may be present at EOF.
Byte sequences
- Min Frag Length
- Absolute from EOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{47-1795}- Endianness
- Little-endian
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
494433- Endianness
- Little-endian
MPEG-2 Audio Layer 3 with ID3v2 Tag (protected)
- Note
- Regularly-spaced frame headers should always be discoverable near EOF. Header has CRC bit off to indicate protected. An ID3v1 tag of up to 355 bytes may be present at EOF.
Byte sequences
- Min Frag Length
- Absolute from EOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{47-1795}- Endianness
- Little-endian
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- None
- Byte Sequence
494433- Endianness
- Little-endian
MPEG-1 Audio Layer 3 without ID3v2 Tag
- Note
- Regularly-spaced frame headers should always be discoverable starting at BOF.
Byte sequences
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- 1795
- Byte Sequence
FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]{46-1439}FFFB[10:EB]- Endianness
- Little-endian
MPEG-2 Audio Layer 3 without ID3v2 Tag
- Note
- Regularly-spaced frame headers should always be discoverable starting at BOF.
Byte sequences
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- 1795
- Byte Sequence
FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]{46-1439}FFF3[10:EB]- Endianness
- Little-endian
MPEG-1 Audio Layer 3 without ID3v2 Tag (protected)
- Note
- Regularly-spaced frame headers should always be discoverable starting at BOF with each header having CRC bit set off to indicate file is protected.
Byte sequences
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- 1795
- Byte Sequence
FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]{46-1439}FFFA[10:EB]- Endianness
- Little-endian
MPEG-2 Audio Layer 3 without ID3v2 Tag (protected)
- Note
- Regularly-spaced frame headers should always be discoverable starting at BOF with each header having CRC bit set off to indicate file is protected.
Byte sequences
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- 1795
- Byte Sequence
FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]{46-1439}FFF2[10:EB]- Endianness
- Little-endian
MP3 2.5
- Note
- Regularly-spaced frame headers should always be discoverable starting at BOF. MPEG 2.5 is an extended variant of MP3 that provides wider support of lower bit-rates than standard MP3. It is implemented by LAME encoder among others, however is not an officially recognised standard.
Byte sequences
- Min Frag Length
- Absolute from BOF
- Offset
- 0
- Max offset
- 1795
- Byte Sequence
FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]{46-1439}FFE3[10:EB]- Endianness
- None
Changelog
-
Updated in V96
- Release date
- 21 January 2020
MPEG 1/2 Audio Layer 3: Added brief description and MP3 2.5 variant signature. Submitted by Church of Jesus Christ of Latter-day Saints.
-
Updated in V94
- Release date
- 17 September 2018
MPEG 1/2 Audio Layer 3: Increased number of sync bytes each signature variant is seeking to address increase in false-positives for unrelated formats being reported since changes introduced in v93 PRONOM update. Previously a set of null bytes was being sought near the end of an MP3 file to compensate for an old (since fixed) DROID bug with fragmented signatures, however these null bytes in the identification signature were themselves causing false-negatives.
-
Updated in V93
- Release date
- 30 November 2017
MPEG 1/2 Audio Layer 3: Adjusted signature to allow range at the BOF for files without ID3v2, adjusted EOF section for files with ID3v2 due to submission by University of Mississippi.
-
Added in V36
- Release date
- 1 June 2010
MPEG 1/2 Audio Layer 3: Signature updated as part of DROID 5.0 research to improve efficiency
-
Added in V34
- Release date
- 2 April 2010
MPEG 1/2 Audio Layer 3: Signature developed through DROID 5.0 research