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.streamdb File Extension

.streamdb stands for stream database. The .streamdb files contain the majority of game data in DOOM Eternal. 

As a general rule, any struct with _t appended to the end is an actual struct used by the game engine. Any other struct names have been created by the wiki author for organization/convenience purposes.

Signature

DOOM Eternal ".streamdb" files can be identified by the first 8 bytes of the file header, which is always: 0x50A5C2292EF3C761.

Internally, the game engine references a 2nd type of stream database, which would be identified by a slightly different file signature: 0x4FA5C2292EF3C761- however, this signature has not been observed in any files used in DOOM Eternal.

File Structure

The .streamdb file consists of 3 parts. An INDEX section, which is a list of all the files contained within, followed by a PREFETCH section, and finally the DATA section, which contains data referenced by the index.

struct STREAM_DB_FILE
{
	INDEX index;
    PREFETCH prefetch;
    DATA data;
};

The INDEX contains a list of hashed IDs rather than plaintext names. All files contained within the .streamdb are stored in a headerless format, and are usually compressed via Oodle Kraken or Oodle Leviathan compression technology.

Files embedded in the .streamdb are impossible to identify by looking at the .streamdb alone. Instead, they are referenced via data contained in .resources files.

Index Section

The .streamdb INDEX structure is of varying length. It consists of a 32-byte header, followed by a variable number of 16-byte entries. The overall structure is described as follows:

struct INDEX
{
	streamDatabaseHeader_t header;					// File signature + metadata
	streamDatabaseEntry2_t streamdbEntries[];		// One 16-byte entry for each header.numEntries
};

The streamDatabaseHeader_t struct is a 32-byte sequence:

struct streamDatabaseHeader_t
{		
	uint64 magic;							// 50 A5 C2 29 2E F3 C7 61
	uint32 headerLength;	
	uint32 pad0;							// null padding
	uint32 pad1;							// null padding
	uint32 pad2;							// null padding
	uint32 numEntries;						// Total entries, not including prefetch IDs
	uint32 flags;							// Always 3
};

The streamDatabaseEntry2_t struct is a 16-byte sequence. It will be repeated n times, where n = streamDatabaseHeader_t.numEntries. Therefore, the total length of the INDEX section can be calculated as length = 32 + (16 * streamDatabaseHeader_t.numEntries) 

struct streamDatabaseEntry2_t
{		
	uint64 identity;						// Shuffled version of .resources ID
	uint32 offset16; 						// Multiply by 16 for data offset within .streamdb
	uint32 length;							// Size of the file in .streamdb (usually compressed)
};

After the last entry, the INDEX section ends and the PREFETCH section begins.

Prefetch Section

The .streamdb PREFETCH structure is of varying length. It consists of a 16-byte header, followed (optionally) by either one or two 16-byte prefetchBlocks, and a number of 8-byte prefetchIDs.

The overall PREFETCH structure is described as follows:

struct PREFETCH 
{
    streamDatabasePrefetchHeader_t prefetchHeader;	// Prefetch section header
    streamDatabasePrefetchBlock_t prefetchBlock[];	// (Optional) Between 0-2 prefetch "blocks"
	uint64 prefetchID[];							// (Optional) 0 or more prefetch file IDs.
};

The streamDatabasePrefetchHeader_t struct is a 16-byte sequence. It is always present in the .streamdb file, even if this .streamdb does not contain any prefetch entries.

struct streamDatabasePrefetchHeader_t
{
	uint32 numPrefetchBlocks;
	uint32 totalLength;						// Total length of prefetch header, blocks, entries
};

If streamDatabasePrefetchHeader_t.numPrefetchBlocks = 0, then the PREFETCH section ends here. Otherwise, it is followed by the number of streamDatabasePrefetchBlock_t structs specified (which is always an integer between 0 and 2). 

struct streamDatabasePrefetchBlock_t
{
	uint64 name;							// Hash of "AI" or "FirstPerson"
	uint32 firstItemIndex;					// Offset relative to end of prefetch blocks
	uint32 numItems;						// Num prefetch entries in this block
};

The  "name" is a hash of either the word AI or FirstPerson. A value of 5891933081285280768 is a hash of the word AI, and a value of 6801151928053439575 is a hash of the word FirstPerson.

Finally, the PREFETCH section ends with an array of uint64 prefetchIDs[] - each of these IDs will match a  streamDatabaseEntry2_t.identity from the INDEX section above. The number of prefetchID is the specified by streamDatabasePrefetchBlock_t.numItems. 

Data Section

The DATA section begins at the offset given in streamDatabaseHeader_t.headerLength. This section is simply a series of compressed files. The starting offset and the length (in bytes) of each file is given by a streamDatabaseEntry2_t in INDEX section.

There is often some null padding at the end of each compressed file. This is because the starting offset must be evenly divisible by 16 (because streamDatabaseEntry2_t.offset16 is multiplied by 16 for the file offset - presumably to allow these offsets to be stored as uint32 rather than uint64). 

The compressed files commonly begin with the bytes 8C 06 or CC 06 which identifies Oodle Kraken compression. 

010 Editor Template

A 010 Editor template for use with Doom Eternal's .streamdb files can be found here: https://github.com/brongo/eternal-010-templates/blob/main/templates/DoomEternalStreamDB.bt

 

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