optical.h File Reference

On-disk structures describing optical disc tracks (Track list block). More...

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Data Structures
struct	TracksHeader
	Header for an optical tracks block listing track entries. More...
struct	TrackEntry
	Single optical disc track descriptor (sequence, type, LBAs, session, ISRC, flags). More...

Typedefs
typedef struct TracksHeader	TracksHeader
typedef struct TrackEntry	TrackEntry

Detailed Description

On-disk structures describing optical disc tracks (Track list block).

An optical tracks block (identifier == BlockType::TracksBlock) stores a list of TrackEntry records describing the logical layout of tracks and sessions for CD/DVD/BD and similar media.

Layout: TracksHeader (fixed) TrackEntry[ entries ] (array, packed)

CRC semantics:

• TracksHeader::crc64 is a CRC64-ECMA over the contiguous TrackEntry array ONLY (header excluded).
• For legacy images (imageMajorVersion <= AARUF_VERSION_V1) a byte swap is applied when verifying.

Field semantics (TrackEntry):

• sequence: Logical track number (1..99 typical for CD). Values outside that range may encode extras.
• type: Value from TrackType (Audio, Data, Mode variants, etc.).
• start / end: Inclusive Logical Block Address (LBA) bounds for the track. end >= start.
• pregap: Number of sectors of pre-gap preceding the track's first user-accessible sector (can be 0 or negative if representing lead-in semantics; negative interpretation is implementation-defined).
• session: Session number starting at 1 for multi-session discs (1 for single session).
• isrc: 13-byte ISRC (raw code, no terminating null). If fewer significant characters, remaining bytes are 0.
• flags: Bitmask of track/control flags. Unless otherwise specified, recommended mapping (mirrors CD subchannel Q control bits) is: bit0 Pre-emphasis, bit1 Copy permitted, bit2 Data track, bit3 Four-channel audio, bits4-7 reserved. Actual semantics may be extended by the format specification.

Invariants / validation recommendations:

• identifier == BlockType::TracksBlock
• entries * sizeof(TrackEntry) bytes are present after the header in the block image.
• 1 <= sequence <= 99 for standard CD tracks (non-conforming values allowed but should be documented).
• start <= end; pregap >= 0 (if negative pregaps unsupported in implementation).
• ISRC bytes either all zero (no ISRC) or printable ASCII (A-Z 0-9 -) per ISO 3901 (without hyphen formatting).

Definition in file optical.h.

Typedef Documentation

TrackEntry

typedef struct TrackEntry TrackEntry

TracksHeader

typedef struct TracksHeader TracksHeader