Nintendo Nitro graphics formats · Tongari Boushi Archive

Every Nitro resource lives inside a RESO TOC entry with the corresponding reversed-ASCII type_tag. Magic identifiers on disk are little-endian 4-byte words; the reversed form spells the intuitive name (e.g. RGCN on disk → NCGR read forward).

NCGR (RGCN) — tile graphics

Type tag rgcn. 4,337 instances.

Offset	Size	Type	Field
`0x00`	4	`char[4]`	magic = `"RGCN"`
`0x04`	2	`u16`	byte_order_mark (0xFEFF)
`0x06`	2	`u16`	version
`0x08`	4	`u32`	file_size
`0x0C`	2	`u16`	header_size (0x10)
`0x0E`	2	`u16`	section_count
`0x10`	4	`char[4]`	section magic = `"RAHC"` (CHAR)
`0x14`	4	`u32`	section_size
`0x18`	2	`u16`	tiles_h or `0xFFFF`
`0x1A`	2	`u16`	tiles_w or `0xFFFF`
`0x1C`	4	`u32`	bpp_code (3 = 4bpp / 16-color, 4 = 8bpp / 256-color)
`0x20`	4	`u32`	mapping_type (1D / 2D OBJ mapping)
`0x24`	4	`u32`	linear_flag (0 = 8×8 tiled, 1 = linear NCBR)
`0x28`	4	`u32`	tile_data_size
`0x2C`	4	`u32`	tile_data_offset (typically `0x18`, relative to `RAHC` start + 0x18)
`0x30`	—	`u8[]`	tile pixels

Tile order in 4bpp tiled mode: 8×8 tiles stored row-major, 4 bits per pixel (two pixels per byte, lo-nibble first). Tile-bank index appears in the NSCR/NCER reference (10-bit field).

0xFFFF dimensions mean "deferred" — for OBJ sprites the canvas comes from a paired NCER; for BG screens it comes from a paired NSCR (typically 256×192 = 32×24 tiles).

NCLR (RLCN) — palette

Type tag rlcn. 2,600 instances.

Offset	Size	Type	Field
`0x00`	4	`char[4]`	magic = `"RLCN"`
`0x10`	4	`char[4]`	section magic = `"TTLP"` (PLTT)
`0x14`	4	`u32`	section_size
`0x18`	4	`u32`	bpp_code (3 = 16-color, 4 = 256-color)
`0x1C`	4	`u32`	unknown
`0x20`	4	`u32`	palette_data_size
`0x24`	4	`u32`	palette_data_offset (typically `0x10`, relative)
`0x28`	—	`u16[]`	BGR555 colors

Color word layout (16-bit LE): 0BBBBB GGGGG RRRRR — 5 bits per channel, top bit ignored on hardware. Slot 0 is conventionally transparent in OBJ palettes.

When section_count ≥ 2, a "PMCP" section follows at 0x10 + ttlp_size. It maps each 16-color bank to a VRAM bank index — when absent, banks are assumed sequential 0..N-1.

NCER (RECN) — cells / OAM

Type tag recn. 1,553 instances.

Offset	Size	Type	Field
`0x00`	4	`char[4]`	magic = `"RECN"`
`0x10`	4	`char[4]`	section magic = `"KBEC"` (CEBK)
`0x14`	4	`u32`	section_size
`0x18`	2	`u16`	cell_count
`0x1A`	2	`u16`	cell_attr (0 = 8-B entries, 1 = 16-B entries with bbox)
`0x1C`	4	`u32`	cell_data_offset (relative to `KBEC`+8)
`0x20`	4	`u32`	mapping_type

Cell entry (8 or 16 bytes):

Offset	Size	Type	Field
`+0x00`	2	`u16`	obj_count
`+0x02`	2	`u16`	attrs
`+0x04`	4	`u32`	obj_offset (relative to OAM block)
`+0x08`	2	`s16`	xmax (only if cell_attr=1)
`+0x0A`	2	`s16`	ymax
`+0x0C`	2	`s16`	xmin
`+0x0E`	2	`s16`	ymin

OAM entry (6 bytes per OBJ):

Word	Bits	Field
`attr0` (u16)	0..7	y (signed 8-bit, screen coord)
	8	rotscale
	9	double_size / disable
	10..11	obj_mode (normal/blend/window/bitmap)
	12	mosaic
	13	depth (0 = 4bpp, 1 = 8bpp)
14..15	shape (square / wide / tall / forbidden)
`attr1` (u16)	0..8	x (signed 9-bit)
	9..11	rotscale index / unused
	12..13	hflip, vflip (when rotscale=0)
	14..15	size
`attr2` (u16)	0..9	tile index (10 bits → into NCGR tilebank)
	10..11	priority
	12..15	palette_bank (4 bits — selects NCLR 16-color bank)

(shape, size) → (width_px, height_px) lookup (square 0..3: 8 16 32 64; wide 0..3: 16 32 32 64; tall 0..3: 8 8 16 32). Reference: src/translator/_sprite_decode.OBJ_SIZE_LUT.

Optional extra sections after KBEC: "LBAL" (1,778 instances — cell state labels like "TAB1_off", "TAB1_on") and "TXEU" (1,778 — user extension metadata).

NSCR (RCSN) — BG screen / tilemap

Type tag rcsn. 1,128 instances.

Offset	Size	Type	Field
`0x00`	4	`char[4]`	magic = `"RCSN"`
`0x10`	4	`char[4]`	section magic = `"NRCS"` (SCRN)
`0x14`	4	`u32`	section_size
`0x18`	2	`u16`	width_px (typically 256)
`0x1A`	2	`u16`	height_px (typically 192)
`0x1C`	4	`u32`	bpp_code (often 0 — actual bpp comes from paired NCGR)
`0x20`	4	`u32`	screen_data_size
`0x24`	—	`u16[]`	screen cells, row-major (32×24 = 768 cells for 256×192)

Screen-cell bit layout (16-bit LE, per BG cell):

Bits	Field
0..9	tile_index (10 bits — into NCGR tilebank)
10	hflip
11	vflip
12..15	palette_bank (4 bits — only used for 4bpp tilesets)

NANR (RNAN) — animation

Type tag rnan. 225 instances.

Offset	Size	Type	Field
`0x00`	4	`char[4]`	magic = `"RNAN"`
`0x10`	4	`char[4]`	section magic = `"KNBA"` (ABNK)
`+0x08`	2	`u16`	bank_count
`+0x0A`	2	`u16`	frame_count_total

Per-bank entry: frame_count, loop mode, frame data offset. Per-frame entry: cell_idx, flag, dx, dy, duration. Animation playback is not yet decoded by the project tooling (each cell renders as a static frame).

Section-magic census

Section magic	Resource	Occurrences
`RAHC`	NCGR CHAR data	4,338
`TTLP`	NCLR PLTT colors	2,600
`PMCP`	NCLR palette-bank map	2,600
`LBAL`	NCER cell labels	1,778
`TXEU`	NCER user extension	1,778
`KBEC`	NCER cell block	1,553
`NRCS`	NSCR screen data	1,128
`KNBA`	NANR animation bank	225

Cross-format references

A composed image requires resolving references across formats:

NSCR cell.tile_index (10 bits) → tile in NCGR tilebank
NSCR cell.palette_bank (4 bits) → bank in NCLR (×16 colors)
NCER OBJ.attr2.tile (10 bits) → tile in NCGR (OBJ mapping aware)
NCER OBJ.attr2.palette_bank (4 bits) → bank in NCLR
NCGR ↔ NCLR pairing rules: see palette resolution

Source

src/translator/_sprite_decode.py — parse_ncgr, parse_nclr, parse_ncer, parse_nscr, compose_*
src/translator/_sprite_encode.py — NCGR re-encoder (template-based)
notes/asset_extraction_methodology.md — full pipeline writeup