BIN File Documentation

Summary

A Binary Disc Image (BIN/CUE) is a raw, sector-by-sector copy of a CD or DVD, paired with a small .cue text file that describes the track layout. The .bin holds the disc’s raw bytes; its MIME type is application/octet-stream. Because a raw image stores full 2352-byte sectors including error-correction and CD-audio, PlayStation 1 and Sega Saturn game dumps are usually BIN/CUE rather than a plain ISO. You almost always work with the .cue, which points to the .bin.

Technical details

Feature	Value
Full name	CD/DVD Disc Image (BIN/CUE)
File extension	`.bin` (paired with `.cue`)
MIME type	`application/octet-stream`
Format type	Raw sector-by-sector CD/DVD image, described by a companion CUE sheet
Developer	Popularized by CDRWIN (Golden Hawk), mid-1990s
Introduced	Mid-1990s
Sector standard	ECMA-130 (CD-ROM sector structure)
Open standard	Partial — sectors follow ECMA-130; CUE is a de facto format
Raw sector size	2352 bytes (Mode 1/2352, audio)
Magic number (hex)	`00 FF FF FF FF FF FF FF FF FF FF 00` (CD sync, data-track sectors only)
Byte order	Raw disc bytes; filesystem inside uses its own order
Filesystem	None of its own — ISO 9660 / UDF lives inside the sectors
Companion file	`.cue` sheet: track list, MODE, INDEX points
Holds audio tracks	Yes — the reason mixed-mode discs use BIN/CUE over ISO
Typical use	PS1, Sega Saturn, PC-Engine CD, Video CD, audio CD dumps
Related extensions	`.cue`, `.iso`, `.img`, `.mdf`, `.nrg`, `.ccd`
Specification URL	`ecma-international.org/publications-and-standards/standards/ecma-130/`

File signature (magic bytes)

00 FF FF FF FF FF FF FF FF FF FF 00

Offset 0, 12 bytes — the CD sync pattern that begins each 2352-byte sector of a Mode 1 or Mode 2 data track (defined by ECMA-130). This is not a whole-file signature but a per-sector marker, so a data-track BIN reliably starts with it. Audio-only tracks have no sync header, so a pure-audio .bin has no fixed signature at all — identification then relies on the companion .cue sheet. Identify an unknown .bin with the file command, TrID, or a hex editor.

What is a BIN disc image?

In the disc-image sense, a .bin file is a raw, sector-by-sector copy of a CD or DVD. It is one half of a BIN/CUE pair: the .bin holds the disc’s raw bytes, and a small companion .cue text file describes how those bytes are divided into tracks. The pairing was popularised by CDRWIN (Golden Hawk Technology) in the mid-1990s and became the common way to preserve discs that a plain ISO cannot represent. The word “binary” is generic, and the same extension is reused by device firmware, game-ROM dumps and arbitrary program data; this page covers the disc-image meaning.

The key difference from an ISO is fidelity. An ISO stores only the 2048-byte user-data portion of each data sector. A raw BIN stores the entire 2352-byte sector, including the sync pattern, header and error-correction bytes, and it can also store CD-audio tracks. That is why console discs that mix a data track with Red Book audio tracks, such as PlayStation 1, Sega Saturn and PC-Engine CD titles, are distributed as BIN/CUE rather than ISO.

The 2352-byte raw sector

A raw CD image stores each sector in full. Under ECMA-130, a Mode 1 data sector is 2352 bytes laid out as a 12-byte sync pattern, a 4-byte header, 2048 bytes of user data, and 288 bytes of error detection and correction.

Mode 1 data sector (2352 bytes total)
 0    Sync       12 bytes  00 FF FF FF FF FF FF FF FF FF FF 00
 12   Header      4 bytes  minute, second, frame (BCD) + mode byte
 16   User data 2048 bytes  the actual ISO 9660 / UDF payload
 2064 EDC          4 bytes  error-detection code (CRC-32)
 2068 Intermediate 8 bytes  reserved/zero (Mode 1)
 2076 ECC        276 bytes  Reed-Solomon error correction (P + Q)

The 12-byte sync pattern 00 FF FF FF FF FF FF FF FF FF FF 00 begins every data sector and is how a reader locks onto sector boundaries; it is also the reason a data-track BIN reliably starts with those bytes. An audio sector, by contrast, is 2352 bytes of raw 16-bit stereo PCM with no sync, header or ECC, so an audio-only BIN has no fixed signature at all. Because BIN keeps the ECC bytes, it preserves the disc closely enough to reproduce even subtle mastering, which matters for accurate emulation.

The CUE sheet: tracks, MODE and INDEX points

A raw BIN has no table of contents of its own, so the .cue sheet supplies it. The CUE is a short text file that names the data file, then lists each track with its MODE and its INDEX points, expressed in MM:SS:FF (minutes, seconds and frames, where 75 frames make one second).

FILE "game.bin" BINARY
  TRACK 01 MODE2/2352
    INDEX 01 00:00:00
  TRACK 02 AUDIO
    INDEX 00 03:12:15
    INDEX 01 03:14:00

Here MODE2/2352 marks a raw data track and AUDIO marks a Red Book audio track; INDEX 01 is a track’s start, while INDEX 00 marks the pre-gap that precedes it. A player or emulator reads the CUE first, learns the track boundaries, and then seeks into the BIN at the right byte offsets. This is why you open the .cue, not the .bin: opening the BIN alone discards the track and audio layout the CUE encodes.

Why a BIN has no filesystem header

A BIN image contains no header identifying itself as a disc image. It is simply the disc’s raw bytes in order, and the real filesystem, usually ISO 9660 or UDF, lives inside the user-data portion of the sectors. A tool that mounts a BIN strips the sync, header and ECC from each 2352-byte sector to expose the 2048-byte payload, then reads the ISO 9660 volume descriptor that begins at logical sector 16. This layering is what makes converting BIN to ISO possible for data tracks: the conversion discards the raw sector framing and keeps only the user data.

BIN versus ISO, and when conversion loses data

Converting a data-only BIN/CUE to ISO is lossless for the file content, because the user data is identical; the ISO simply drops the raw framing. The limit is audio: an ISO has no way to store CD-audio tracks, so converting a mixed-mode game disc to ISO silently loses its music and sound tracks. For that reason mixed-mode and audio discs should stay as BIN/CUE, while pure data discs can be flattened to ISO for tools that expect it. Renaming a .bin to .iso is not a conversion: the raw 2352-byte sectors remain, and most tools will reject or misread the file.

Recovering a missing CUE sheet

Because the CUE is plain text, a lost one can often be rebuilt. For a single-track data image the sheet is three lines: a FILE line, a TRACK 01 line with the right MODE (commonly MODE1/2352 for PC data or MODE2/2352 for console discs), and INDEX 01 00:00:00. Tools such as IsoBuster or PowerISO can also open a lone .bin, guess the layout and regenerate a CUE. Multi-track discs with audio are harder to reconstruct by hand, because the exact INDEX offsets of each audio track are not recorded anywhere in the BIN itself.

Frequently asked questions

Should I open the .bin or the .cue?

Open the .cue. It records the track layout, each track’s MODE and its INDEX points, and it names the .bin that holds the data. Opening the BIN directly gives a tool no track or audio information, so a multi-track or mixed-mode disc can load incorrectly.

Why is BIN/CUE used instead of ISO for game discs?

Because those discs mix a data track with CD-audio tracks, and an ISO can only hold the data. A raw BIN stores full 2352-byte sectors and audio tracks faithfully, so PlayStation 1, Sega Saturn and PC-Engine CD dumps are kept as BIN/CUE to preserve their music.

References

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