Minecraft uses LevelDB but doesn't use its standard Snappy compression, instead adding compression types 2 and 4 for zlib deflate—which they term ZlibCompressor in their modified LevelDB code—and flate deflate (ZlibCompressorRaw).
LevelDB keys (and data) are byte arrays, but hex strings are more human-friendly, so we use those to represent the keys.
Most of the game data is tied to chunks (16x16x256-block-sized bits of the world), so most keys consist of an X and Z chunk coordinate, then optionally a dimension coordinate (for Nether, End, etc.), then a tag that identifies the type of data, and then for block data a Y subchunk index. See below for more details.
Some game data is not tied to chunks, and those keys are simple text descriptions. Here are some hex string keys for known simple keys:
| Simple Name | Hex Key | Format | Contents |
|---|---|---|---|
| ~local_player | 7e6c6f63616c5f706c61796572 | nbt | Local player data including inventory |
| AutonomousEntities | 4175746f6e6f6d6f7573456e746974696573 | ||
| BiomeData | 42696f6d6544617461 | ||
| Overworld | 4f766572776f726c64 | ||
| mVillages | 6d56696c6c61676573 | ||
| portals | 706f7274616c73 | ||
| player_ | 706c617965725f | nbt | Keys beginning with this represent multiplayer players |
X, Y, Z is the typical coordinate order, but when dealing with the data we find X, Z, Y is the order of greatest-to-least significance, which is why this explanation tends to express X, Z, Y ordering.
All division below is of course integer division. The remainder/modulus will be used to find the byte offset within the subchunk data. X, Z, and dimension are 32-bit signed integers in little endian byte order. In the examples below, I've bolded the chunk Z coordinate for clarity.
Each chunk is 16x16x256 (X,Z,Y), and the subchunk block data keys are 16 high. So for x, z, y coordinates of 413, 54, 105:
- chunk X = 413 / 16 = 25 or 0x19 signed 32-bit integer in little endian byte order ([0x19,0, 0, 0] == 19000000)
- chunk Z = 54 / 16 = 3 ([0x3, 0, 0, 0] == 03000000)
So all keys beginning with 1900000003000000 are about this coordinate's chunk. (In the overworld; other dimensions add a 32-bit dimension ID, so the same coordinates in the Nether I think have keys that start with 1900000003000000FFFFFFFF and 190000000300000001000000 for the End.)
The tags and subchunk indexes are 8-bit values. (Unsigned? Not sure it matters as there are no negative Y chunk coordinates and no tags <0 or > 127.)
47 ([0x2F]) is the subchunk prefix tag, so all keys beginning with 19000000030000002f are the Y subchunks for this coordinate.
- subchunk Y = 105 / 16 = 6 ([0x06])
So, the subchunk key for X=413, Z=54, Y=105 is 19000000030000002f06
ref: https://minecraft.gamepedia.com/Bedrock_Edition_level_format
% is modulo division, the remainder of integer division. Note that subchunks may not exist if they are empty.
(X % 16) * 256 + (Z % 16) * 16 + (Y % 16) + 1- 1-byte Block ID that determines if the block is e.g. air, water, sand, dirt, tree, lava, etc.- The following three are odd in that each byte holds data for two blocks, in the high and low nybbles.
(X % 16) * 128 + (Z % 16) * 8 + (Y % 16) / 2 + 4096 + 1- Block data e.g. rotation(X % 16) * 128 + (Z % 16) * 8 + (Y % 16) / 2 + 6144 + 1- Sky light(X % 16) * 128 + (Z % 16) * 8 + (Y % 16) / 2 + 8192 + 1- Block light