An NRG file is a proprietary optical disc image file format originally created by Nero AG for the

Nero Burning ROM Nero Burning ROM, commonly called Nero, is an optical disc authoring program from Nero AG. The software is part of the Nero Multimedia Suite but is also available as a stand-alone product. It is used for burning and copying optical media such ...

utilit

It is used to store Disk image, disc images. Other than Nero Burning ROM, however, a variety of software titles can use these image files. For example,

Alcohol 120% Alcohol 120% is a disk image emulator and disc burning software for Microsoft Windows developed by Alcohol Soft. An edition named Alcohol 52% is also offered which lacks the burning engine. The software can create image files from a source CD/ ...

, or

Daemon Tools DAEMON Tools is a virtual drive and optical disc authoring program for Microsoft Windows and Mac OS. Overview DAEMON tools was originally a successor of ''Generic SafeDisc emulator'' and incorporated all of its features. The program claim ...

can mount NRG files onto virtual drives for reading. Contrary to popular belief, NRG files are not

ISO image An optical disc image (or ISO image, from the ISO 9660 file system used with CD-ROM media) is a disk image that contains everything that would be written to an optical disc, disk sector by disc sector, including the optical disc file system. IS ...

s with a .nrg extension and a header attached. They can store audio tracks for Audio CDs, which ISO images cannot. Nero's NRG format is one of the few formats besides BIN/CUE,

's MDF/MDS and

CloneCD CloneCD is proprietary optical disc authoring software for ripping music and data CDs and DVDs, capable of making exact, 1:1 copies even of copy protected discs, bypassing several types of digital rights management (DRM). CloneCD can rip dis ...

's CCD/IMG/SUB disc image formats to support

Mixed Mode CD A mixed mode CD is a compact disc which contains both data and audio in one session. Typically the first track is a data track while the rest are audio tracks. The most common use for mixed mode CDs is to add CD-quality audio to video games on a ...

s which contain audio CD tracks as well as data tracks.

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 (IFF) is a generic digital container file format originally introduced by Electronic Arts (in cooperation with Commodore) in 1985 to facilitate transfer of data between software produced by different companies. IFF file ...

(IFF) and stores data in a chain of "chunks". All integer values are stored unsigned in big endian

byte order '' Jonathan_Swift.html" ;"title="Gulliver's Travels'' by Jonathan Swift">Gulliver's Travels'' by Jonathan Swift, the novel from which the term was coined In computing, endianness is the order in which bytes within a word (data type), word of d ...

. Version 1 NRG format stores values as 32-bit integers. Nero Burning ROM v5.5 introduced a new NRG file format, version 2, with support for 64-bit 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

IFF In logic and related fields such as mathematics and philosophy, "if and only if" (often shortened as "iff") is paraphrased by the biconditional, a logical connective between statements. The biconditional is true in two cases, where either both ...

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.

Chunks

(CUES) Cue Sheet

Available in all versions of NRG file format. The CUEX chunk is the concatenation of fixed-size blocks, each one representing a cue point. The index0 points are present even when they are identical to the index1 ones. The index0 points in audio tracks are incorrect if Nero has been asked to record all the sub-channel data (in that case the sector size is 2448 bytes). No index other than 0 or 1 has been encountered, although the chunk format allows for such cue points to be recorded; thus the number of cue blocks seems to be always 2*(#track + 1): two indices for each track, an index0 for the lead-in and an index1 for the lead-out.

(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.

(CDTX) CD-text

Available in version 2 NRG file format. The CDTX chunk is the concatenation of raw

CD-text CD-Text is an extension of the Red Book Compact Disc specifications standard for audio CDs. It allows storage of additional information (e.g. album name, song name, and artist name) on a standards-compliant audio CD. The specification for CD-T ...

packs of 18 bytes each.

(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.

(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.

(MTYP) Media Type?

Available in all versions of NRG file format. ''This chunk and its use is unknown''. A value of 1 (big endian) was found in images of several CD (audio or data; CD-ROM or CD-R).

(DINF) Disc Information?

Found in TAO images in version 2 of NRG file format. Found in DAO images in version of NRG file format only if Nero was asked not to close the disc. ''This chunk and its use is unknown''.

(TOCT) TOC T?

Found in TAO images in version 2 of NRG file format. ''This chunk and its use is unknown''.

(RELO)

Found in TAO images in version 2 of NRG file format. ''This chunk and its use is unknown''.

(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. {{DEFAULTSORT:Nrg (File Format) Archive formats Disk images