Daggerfall:BSA file formats

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This is a description of the format of the various .BSA files found in the ARENA2 directory of Elder Scrolls: Daggerfall by Bethesda. The information here is not complete or 100% percent accurate, although the basic formats appears to be well understood.

1 Contributors
2 General BSA Files
3 Files using the BSA format
4 Appendices

[edit] Contributors

Significant contributors to these formats include:

Michael (subproperty@hotmail.com)
- Dungeon Pre/Postrecords
- Location types
- BLOCKS.BSA RDB format

[edit] General BSA Files

There are five BSA files in Daggerfall's ARENA2 directory (ARCH3D, MAPS, MONSTER, MIDI, and BLOCKS). Although they contain different data, their overall structure is the same. This format has been derived from all these five files. The following description appears to be complete.

[edit] General File Layout

BSA Header
...BSA Records...
BSA Directory

[edit] BSA Header

This is the first 4 bytes found at the start of a BSA file and gives information about the BSA directory at the end of the file.

        [Bytes 0-1] short DirectoryCount;
                Gives the number of entries in the directory at the end of the 
                file.
        [Bytes 2-3] short DirectoryType; 
                Gives the type of directory at the end of the BSA file (See
                BSA Directory below).
                        0x0100 = Directory has records of 18 bytes in size
                                 consisting of a 14 byte filename and a long
                                 record length.
                        0x0200 = Directory has records of 8 bytes in size
                                 consisting of long ID and a long record size.

[edit] BSA Records

This data will depend on the actual BSA file. The basic contents for the five known BSA files are as follows:

ARCH3D: 3D Object Information
BLOCKS: Dungeon/town block information
MAPS: Location information (towns, dungeon, houses, temples, etc...)
MONSTER: Monster data (no images)
MIDI: HMI formatted music

[edit] BSA Directory

The directory contains the information needed to access the various data records in the BSA file. The contents of each record depends on the BSA file. In general, the directory gives an identification number/string and a record length for each record. There are two known types of directories identified by the DirectoryType bytes in the BSA header (0x0100 and 0x0200).

[edit] BSA 0x0100 Directory (Name)

The 0x0100 type directory consists of records 18 bytes in size and give a record size and 13 byte name for each BSA record.

   
        [Bytes 0-13] char FileName[14];
                The filename which identifies this data section.  Filenames
                are in the usual DOS 8.3 format.
        [Bytes 14-17] long DataSize;
                The size of the data in bytes.  The first record starts at 
                offset 4 in the file, ignoring the 4 bytes of the BSA Header.
                The subsequent section offsets can be calculated from this.

[edit] BSA 0x0200 Directory (Number)

The 0x0200 type directory consists of records 8 bytes in size and give a record size and long identifier for each BSA record.

        [Bytes 0-3] long RecordID;
                A long number which assumbly identifies the record somehow.
        [Bytes 4-7] long DataSize;
                The size of the data in bytes.  The first entry starts at 
                offset 4 in the file, ignoring the 4 bytes of the BSA Header.
                The subsequent section offsets can be calculated from this.

[edit] Files using the BSA format

[edit] MAPS.BSA

Main article: Daggerfall:MAPS.BSA

See also:

Daggerfall:Region Numbers

[edit] ARCH3D.BSA

Main article: Daggerfall:ARCH3D.BSA

[edit] BLOCKS.BSA

Main article: Daggerfall:BLOCKS.BSA

See also:

Appendix C (to be added)

[edit] MIDI.BSA

Contains MIDI data stored in the proprietary HMI format in a type 0x0100 directory.

[edit] MONSTER.BSA

Contains ASCR####.ANC and ENEMY###.CFG files in a type 0x0100 directory.

[edit] DAGGER.SND

Contains raw audio data (8-bit unsigned, mono, ~11025 samples per second) in a type 0x0200 directory.

[edit] MAPSAVE.SAV

Contains MAPSAVE.0## files for each region in a type 0x0100 directory.

[edit] Appendices

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Category: Daggerfall Hacking