NRG (file format)
Encyclopedia
A .nrg file is a proprietary CD
image file format used by Nero Burning ROM
, a utility suite made by Nero AG
, to create and burn ISO 9660
CD images.
Other than Nero Burning ROM, a variety of software titles can use these image files. For example, Power ISO, Alcohol 120%, or Daemon Tools
can mount
NRG files onto virtual drive
s for reading.
Contrary to popular belief, .nrg files are not ISO image
s with .nrg extension and a header attached. For technical details on the nrg format, see below.
The data contents of NRG files can be extracted directly without creating an ISO image using freeware
file archiver
s such as IZArc
.
The nrg file format uses a variation of the Interchange File Format
(IFF) and stores data in a chain of "chunks". All integer values are stored unsigned
in big endian byte order. Version 1 nrg format stores values as 32bit integers. Nero Burning ROM v5.5 introduced a new nrg file format, version 2, with support for 64bit integers.
chunks. To get the offset of the first chunk one must read the nrg footer from the last 8 or 12 bytes of the file.
Cue sheet information. Not yet documented
DAOI chunks store disc at once sessions specific information in two parts. The first part contains data that is specific for the session only. The second part repeats track specific information (grey) once for each track. Parse the SINF chunks to get the number of tracks for a specific session.
CDTX chunks contain raw CD-text
data.
ETNF chunks are used to store track information for track at once sessions. The data is repeated once for each track. Parse the SINF chunks to get the number of tracks for a specific session.
Session information chunks should be used to quickly scan the image for session and track count. SINF chunks are always listed in sequential order corresponding to the sessions order. To get more details information about a specific session one must parse the corresponding DAOI or ETNF chunk.
This chunk and its use is unknown.
End of chain chunk is signals that there are no more chunks to be read.
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
image file format used by Nero Burning ROM
Nero Burning ROM
Nero Multimedia Suite is a popular software suite for Microsoft Windows by Nero AG . Version 10 of this product was released in April 2010.- Included products :The following applications are included in Nero 11 :Disc authoring...
, a utility suite made by Nero AG
Nero AG
Nero is a global computer software company headquartered in Karlsbad, Germany. It is perhaps most well-known for its burning software, Nero Burning ROM.-History:The company was founded as Ahead Software GmbH in 1995 by Richard Lesser....
, to create and burn ISO 9660
ISO 9660
ISO 9660, also referred to as CDFS by some hardware and software providers, is a file system standard published by the International Organization for Standardization for optical disc media....
CD images.
Other than Nero Burning ROM, a variety of software titles can use these image files. For example, Power ISO, Alcohol 120%, or Daemon Tools
Daemon Tools
Daemon Tools is a disk image emulator and optical disc authoring program for Microsoft Windows. Daemon Tools was originally a furtherance in the development of another program, Generic SafeDisc emulator, and incorporated all of its features. The program claims to be able to defeat most copy...
can mount
Mount (computing)
Mounting takes place before a computer can use any kind of storage device . The user or their operating system must make it accessible through the computer's file system. A user can access only files on mounted media.- Mount point :A mount point is a physical location in the partition used as a...
NRG files onto virtual drive
Virtual drive
A virtual drive in computing is a device that to the operating system appears to be an ordinary physical disk drive, with disc images substituted for disc reading hardware through the use of software called a disk emulator...
s for reading.
Contrary to popular belief, .nrg files are not ISO image
ISO image
An ISO image is an archive file of an optical disc, composed of the data contents of every written sector of an optical disc, including the optical disc file system...
s with .nrg extension and a header attached. For technical details on the nrg format, see below.
Converting nrg files
There are several tools available to convert a.nrg data file into an ISO 9660 CD image.- Free but not Open Source tools include:
- Open Source command line tools include:
- nrg2iso — cross-platform. hardcoded to read all nrg files as disc at once (DAO) type causing it to fail on track at once (TAO) type images.
- iat — cross-platform. Tool for detecting the structure of many types of CD/DVD image and convert image CD/DVD to ISO9660
- fusenrg — for Unix-likeUnix-likeA Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
systems. Hardcoded to read all nrg files as disc at once (DAO) - nrg4iso — (project abandoned by author - last updated Oct 2007) for Unix-like systems (including Mac OS X). Can convert both DAO and TAO images into ISO 9660 CD images.
- eNeRGy — MacOs X, based on nrg4iso, has a graphical user interface
- Shareware tools include:
- PowerISO — converts from nrg to ISO as well as allows for browsing and extracting individual files from a nrg data file.
The data contents of NRG files can be extracted directly without creating an ISO image using freeware
Freeware
Freeware is computer software that is available for use at no cost or for an optional fee, but usually with one or more restricted usage rights. Freeware is in contrast to commercial software, which is typically sold for profit, but might be distributed for a business or commercial purpose in the...
file archiver
File archiver
A file archiver is a computer program that combines a number of files together into one archive file, or a series of archive files, for easier transportation or storage...
s such as IZArc
IZArc
IZArc is a proprietary file archiver for Microsoft Windows developed by Bulgarian programmer Ivan Zahariev. The program is freeware and closed source. In addition to the most commonly used archive formats, like zip, rar, gzip, tar.gz, bzip2, and 7z, IZArc handles a large number of less common formats...
.
File format
The file format specification below is unofficial and as such is lacking some data. There may also be errors.The nrg file format uses a variation of the Interchange File Format
Interchange File Format
Interchange File Format , is a generic container file format originally introduced by the Electronic Arts company in 1985 in order to ease transfer of data between software produced by different companies....
(IFF) and stores data in a chain of "chunks". All integer values are stored unsigned
Signedness
In computing, signedness is a property of data types representing numbers in computer programs. A numeric variable is signed if it can represent both positive and negative numbers, and unsigned if it can only represent non-negative numbers .As signed numbers can represent negative numbers, they...
in big endian byte order. Version 1 nrg format stores values as 32bit integers. Nero Burning ROM v5.5 introduced a new nrg file format, version 2, with support for 64bit integers.
Header
The nrg format does not store its data as a header at the beginning of a file. It is instead attached at the end of the file like a footer. Image information is stored as a serialized chain of IFFInterchange File Format
Interchange File Format , is a generic container file format originally introduced by the Electronic Arts company in 1985 in order to ease transfer of data between software produced by different companies....
chunks. To get the offset of the first chunk one must read the nrg footer from the last 8 or 12 bytes of the file.
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "NERO" |
| 4 | 32bit | Offset of the first chunk data chain |
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "NER5" |
| 8 | 64bit | Offset of the first chunk data chain |
(CUES) Cue Sheet
Available in all versions of nrg file format.Cue sheet information. Not yet documented
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "CUES" |
| 4 | 32bit | Chunk size (bytes) |
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "CUEX" |
| 4 | 32bit | Chunk size (bytes) |
(DAOI) DAO Information
Available in all versions of nrg file format.DAOI chunks store disc at once sessions specific information in two parts. The first part contains data that is specific for the session only. The second part repeats track specific information (grey) once for each track. Parse the SINF chunks to get the number of tracks for a specific session.
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "DAOI" |
| 4 | 32bit | Chunk size (bytes) big endian |
| 4 | 32bit | Chunk size (bytes) little endian |
| 14 | UPC | |
| 4 | 32bit | Toc type |
| 1 | 8bit | First track |
| 1 | 8bit | Last track |
| 12 | ISRC Code | |
| 4 | 32bit | Sector size |
| 4 | 32bit | Mode |
| 4 | 32bit | Index0 (Pre gap) |
| 4 | 32bit | Index1 (Start of track) |
| 4 | 32bit | Index2 (End of track + 1) |
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "DAOX" |
| 4 | 32bit | Chunk size (bytes) big endian |
| 4 | 32bit | Chunk size (bytes) little endian |
| 14 | UPC | |
| 4 | 32bit | Toc type |
| 1 | 8bit | First track |
| 1 | 8bit | Last track |
| 8 | ISRC Code | |
| 4 | 32bit | Sector size |
| 4 | 32bit | Mode |
| 8 | 64bit | Index0 (Pre gap) |
| 8 | 64bit | Index1 (Start of track) |
| 8 | 64bit | Index2 (End of track + 1) |
| 2 | Unknown |
(CDTX) CD-text
Available in version 2 nrg file format.CDTX chunks contain raw CD-text
CD-Text
CD-Text is an extension of the Red Book Compact Disc specifications standard for audio CDs. It allows for storage of additional information on a standards-compliant audio CD...
data.
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "CDTX" |
| 4 | 32bit | Chunk size (bytes) |
| 18 | CD-text pack |
(ETNF) Extended Track Information
Available in all versions of nrg file format.ETNF chunks are used to store track information for track at once sessions. The data is repeated once for each track. Parse the SINF chunks to get the number of tracks for a specific session.
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "ETNF" |
| 4 | 32bit | Chunk size (bytes) |
| 4 | 32bit | Track offset in image |
| 4 | 32bit | Track length (bytes) |
| 4 | 32bit | Mode |
| 4 | 32bit | Start lba on disc |
| 4 | ? |
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "ETN2" |
| 4 | 32bit | Chunk size (bytes) |
| 8 | 64bit | Track offset in image |
| 8 | 64bit | Track length (bytes) |
| 4 | 32bit | Mode |
| 4 | 32bit | Start lba on disc |
| 4 | ? |
(SINF) Session Information
Available in all versions of nrg file format.Session information chunks should be used to quickly scan the image for session and track count. SINF chunks are always listed in sequential order corresponding to the sessions order. To get more details information about a specific session one must parse the corresponding DAOI or ETNF chunk.
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "SINF" |
| 4 | 32bit | Chunk size (bytes) |
| 4 | 32bit | # tracks in session |
(MTYP) Media Type?
Available in all versions of nrg file format.This chunk and its use is unknown.
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "MTYP" |
| 4 | 32bit | Chunk size (bytes) |
| 4 | ? |
(END!) End of chain
Available in all versions of nrg file format.End of chain chunk is signals that there are no more chunks to be read.
| Size (bytes) | Type | Value / Purpose |
|---|---|---|
| 4 | Chunk ID | "END!" |
| 4 | 32bit | Always zero |
Emulating/editing software supporting NRG
- Alcohol 120%
- CDemuCDemuCDemu is a software suite designed to emulate an optical drive and disc on the Linux operating system.CDEmu consists of:* a kernel module implementing a virtual SCSI host bus adapter,...
- Daemon ToolsDaemon ToolsDaemon Tools is a disk image emulator and optical disc authoring program for Microsoft Windows. Daemon Tools was originally a furtherance in the development of another program, Generic SafeDisc emulator, and incorporated all of its features. The program claims to be able to defeat most copy...
- MagicISOMagicISOMagicISO is a CD/DVD image shareware utility that can extract, edit, create, and burn disc image files. It offers the possibility of converting between ISO and CUE/BIN and their proprietary Universal Image Format disc image format.In addition to being able to edit the contents of the disc images...
- PowerISOPowerISOPowerISO is an application used to create, open, mount / emulate, compress, encrypt, and otherwise manipulate CD / DVD image files. It is most commonly known for its proprietary DAA disc image format. Other supported formats include ISO, BIN, NRG, and CDI. PowerISO is able to modify all supported...
- Roxio ToastRoxio ToastRoxio Toast is an Optical disc authoring and media conversion software application for Mac OS X. Its name is a play on the word burn, a term used for the writing of information onto a disc through the use of a laser....
- UltraISOUltraISOUltraISO is an application for Microsoft Windows for creating, modifying and converting ISO image files used for optical disc authoring.Since the first release of UltraISO on 20 April 2002, its author EZB Systems has maintained and kept the product shareware.UltraISO is currently produced by EZB...
- IsoBusterIsoBuster-External links:*...
External links
- nrg4iso — BSD licensed command line utility. Does not fully support nrg format. Currently abandoned. (POSIXPOSIXPOSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
) - nrg2iso — GPL licensed command line utility. Does not fully support nrg format. (LinuxLinuxLinux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
) - IAT — GPL licensed command line utility without support for CD-AUDIO
- fusenrg — GPL licensed command line utility. Converts NRG to ISO on the fly. Does not fully support nrg format. (LinuxLinuxLinux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
) - nrg2iso — Windows graphical utility. Does not fully support nrg format. (WindowsMicrosoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
) - IMGBURN — Windows Freeware ISO burning software capable of managing the nrg format.
- eNeRGy' — GPL MacOs X utility, based on nrg4iso, has a graphical user interface
- nrgtoiso — Windows Freeware graphical utility. Converts nrg format to iso format.