OSM Map On Garmin/TDB File Format
A reverse-engineering of Garmin's TDB file format
Here are only some differences and additions to the document "Garmin TDB File Format. Rev 1.0, 7/2/2005" by John Mechalas.
The source document you can easily find by yourself.
v.4.07 File Overview
Block structure
| Byte offset | Length (bytes) | Description |
|---|---|---|
| 0x00 | 1 | Block ID |
| 0x01 | 2 | Block length = BL |
| 0x03 | BL | Block data |
Header block
Block ID = 0x50
| Relative offset | Length (bytes) | Description |
|---|---|---|
| 0x00 | 2 | Product ID |
| 0x02 | 2 | Family ID |
| 0x04 | 2 | TDB version * 100 |
| 0x06 | LS | Map series name (0x00 terminated) |
| 0x06+LS | 2 | Product version * 100 |
| 0x08+LS | LF | Map family name (0x00 terminated) |
Other data following Map family name relates to routing levels,whether a map is locked,can be printed,viewed or contains dem,routing or elevation.Preview Map offsets are also declared. For more information see TDB Editor http://www.pinns.co.uk/osm/tdbeditor.html.
Copyright block
Block ID = 0x44
| Relative offset | Length (bytes) | Description |
|---|---|---|
| 0x00 | Varies | Array of copyright segments |
Copyright segment
| Relative offset | Length (bytes) | Description |
|---|---|---|
| 0x00 | 1 | Copyright code (0x00 = sources, used to create this map; 0x06 = copyright information from the map manufacturer) |
| 0x01 | 1 | Where code (0x01 = show this copyright info in MapSource; 0x02 = print this copyright info on maps, printed with MapSource; 0x03 = both show and print) |
| 0x02 | 2 | Extra properties |
| 0x04 | CS | Copyright string (0x00 terminated) |
Overview map block
Block ID = 0x42
| Relative offset | Length (bytes) | Description |
|---|---|---|
| 0x00 | 4 | Map number |
| 0x04 | 4 | Parent map number = 0x00000000 |
| 0x08 | 4 | North limit |
| 0x0C | 4 | East limit |
| 0x10 | 4 | South limit |
| 0x14 | 4 | West limit |
| 0x18 | LS | Description string (0x00 terminated) |
Map limits are in TDB units. 1 TDB unit = 360/2^32 degrees.
Detail map block
Block ID = 0x4C
| Relative offset | Length (bytes) | Description |
|---|---|---|
| 0x00 | 4 | Map number |
| 0x04 | 4 | Parent map number |
| 0x08 | 4 | North limit |
| 0x0C | 4 | East limit |
| 0x10 | 4 | South limit |
| 0x14 | 4 | West limit |
| 0x18 | LS | Description string (0x00 terminated) |
| 0x18+LS | 2 | Unknown (always 0x0004 or 0x0005?)(new edit:relates to number of subfiles + 1) |
| 0x1A+LS | 2 | Number of subfiles in IMG-file = N |
| 0x1C+LS | 4 * N | Array of subfiles sizes |
| 0x1C+LS+4*N | 7 | byte:0 has copyright text,byte 1: has 0x53 text : byte 2:if 1 then bytes 3_7: an unknown total (density) |
| 0x23+LS+4*N | varies (typicaly = 13) * N | Array of subfiles names (each 0x00 terminated) |
| 2 | Unknown (always 0x0000?) |
Map limits are in TDB units. 1 TDB unit = 360/2^32 degrees.
Checksum block
Block ID = 0x54
This is always the last block in TDB file
CRC32 checksum is calculated for the entire TDB-file except checksum block
| Relative offset | Length (bytes) | Description |
|---|---|---|
| 0x02 | 1 | 1-st byte of CRC32 |
| 0x09 | 1 | 2-nd byte of CRC32 |
| 0x0C | 1 | 3-rd byte of CRC32 |
| 0x11 | 1 | 4-th byte of CRC32 |
All other data in this block seems to be random. Typical block lenght = 20 bytes.