BTI (File Format)
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BTI is a image file format and similar to TEX0, TPL and BREFT file formats. The difference is only the file header.
Appearance in MKW
BTI files are used rarely in Mario Kart Wii. They can be found in some tracks (SZS files) with 3 different file names:
File Format
The file format is very simple. It starts with a file header followed by the image data. All data is big endian.
File Header
The following table shows the file header. It is 0x20 (32) bytes long. There is no magic to identify these kinds of files, so tools may do some plausibility checks to identify them.
| Offset | Size | Description |
|---|---|---|
| 0x00 | 1 | Image format. |
| 0x01 | 1 | Enable alpha (0x00 means alpha is disabled, anything higher means alpha is enabled). |
| 0x02 | 2 | Width of image in pixels. |
| 0x04 | 2 | Height of image in pixels. |
| 0x06 | 1 | wrap_s[1] (0x01 for posteffect.bti, 0x00 for others). Probably Repeat, Clamp or Mirror wraps for U Projection Maps. |
| 0x07 | 1 | wrap_t[2] (0x01 for posteffect.bti, 0x00 for others). Probably Repeat, Clamp or Mirror wraps for V Projection Maps. |
| 0x08 | 2 | Palette Format (palette formats not used in MKWii). |
| 0x0a | 2 | Number of palette entries. |
| 0x0c | 4 | Offset of palette data relative to file header. |
| 0x10 | 4 | Unknown. Always 0 in MKWii. |
| 0x14 | 1 | Magnification filter type (0x00 means nearest, 0x01 means linear). |
| 0x15 | 1 | Minification filter type. |
| 0x16 | 2 | Unknown. Always 0 in MKWii. |
| 0x18 | 1 | Number of images (= number_of_mipmaps + 1). |
| 0x19 | 1 | Unknown. Always 0 in MKWii. |
| 0x1a | 2 | Unknown. Always 0 in MKWii. |
| 0x1c | 4 | Offset of image data relative to file header |
| 0x20 | end of file header | |
Image and palette data
The image and palette data starts at the given data offset in the file header. The data depends on the image and palette formats format. The image format values are listed below.
| ID | Name | Bits per pixel | Block width | Block height | Block size | Type |
|---|---|---|---|---|---|---|
| 0x00 | I4 | 4 | 8 | 8 | 32 bytes | Gray |
| 0x01 | I8 | 8 | 8 | 4 | 32 bytes | Gray |
| 0x02 | IA4 | 8 | 8 | 4 | 32 bytes | Gray + Alpha |
| 0x03 | IA8 | 16 | 4 | 4 | 32 bytes | Gray + Alpha |
| 0x04 | RGB565 | 16 | 4 | 4 | 32 bytes | Color |
| 0x05 | RGB5A3 | 16 | 4 | 4 | 32 bytes | Color + Alpha |
| 0x06 | RGBA32 (RGBA8) | 32 | 4 | 4 | 64 bytes | Color + Alpha |
| 0x08 | C4 (CI4) | 4 | 8 | 8 | 32 bytes | Palette (IA8, RGB565, RGB5A3) |
| 0x09 | C8 (CI8) | 8 | 8 | 4 | 32 bytes | Palette (IA8, RGB565, RGB5A3) |
| 0x0A | C14X2 (CI14x2) | 16 | 4 | 4 | 32 bytes | Palette (IA8, RGB565, RGB5A3) |
| 0x0E | CMPR | 4 | 8 | 8 | 32 bytes | Color + optional Alpha (compressed) |
Tools
- SZS Modifier and CTools Pack support BTI images.
- Wiimms SZS Tools can convert BREFT, BTI, TEX0, TPL and PNG images in any directions. It may also convert the image and palette formats.