MPO

Overview

MPO = Multi-Picture Object

Document describing the file format used in mpo files: http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-007_E.pdf

Nintendo uses a common format for its 3D pictures. MPO is basically two JPG files concatenated in one file. The two JPG files has an EXIF data structure in their headers (This was developed by CIPA).

EXIF is a standard that specifies the formats for images, sound, and ancillary tags used by digital cameras (including smartphones), scanners and other systems handling image and sound files recorded by digital cameras.[1]

Nintendo's EXIF Data Structure

ID	DESCRIPTION	VALUE
0x010F	Manufacturer	Nintendo
0x0110	Camera	Nintendo 3DS
0x011A	XResolution	72:1
0x011B	YResolution	72:1
0x0128	ResolutionUnit	2
0x0131	Software	00204
0x0132	DateTime	YYYY:MM:DD HH:mm:SS
0x0213	YCbCrPositioning	2
0x9000	ExifVersion	0220
0x9003	DateTimeOriginal	YYYY:MM:DD HH:mm:SS
0x9004	DateTimeDigitized	YYYY:MM:DD HH:mm:SS
0x9101	ComponentsConfiguration	[0x01,0x02,0x03,0x00]
0x927C	MakerNote	[DATA - 174 bytes] (yet to be understood)
0xA000	FlashPixVersion	0100
0xA001	ColorSpace	1
0xA002	PixelXDimension	640
0xA003	PixelYDimension	480
0x5041	InteroperabilityIndex	R98
0x5042	ExifInteroperabilityVersion	0100
0x1000	InteroperabilityVersion	JPEG Exif Ver 2.2
0x501B	ThumbnailData	[DATA - 3000+ bytes]
0x5023	ThumbnailCompression	6
0x502D	ThumbnailXResolution	72:1
0x502E	ThumbnailYResolution	72:1
0x5030	ThumbnailTransferFunction	2
0x0201	JPEGInterchangeFormat	682
0x0202	JPEGInterchangeFormatLength	3000+
0x5091	ChrominanceTable	[DATA - 128 bytes]
0x5090	LuminanceTable	[DATA - 128 bytes]

Nintendo's EXIF MakerNote Tag

This still need to be figured out:

The MakerNote is made with Tiff Exif information (Big Endian)

first 2 bytes are the IFD Count (IFD is a 12 byte tag), Regulary there are 2 IFDs.

IFD structure

Tag	Type	Count/Value	Value/Offset
2 bytes	2 bytes	4 bytes	4 bytes

Nintendo's IFDs

Tag	Desc	Type	Count/Value	Value/Offset
0x1100	Unknown	7-Undefined	Count	Count=1 ? Value : Offset
0x1101	Nintendo 64byte Note	7-Undefined	Count	Offset

After the IFDs comes a 4 byte Zero ( {0,0,0,0} ).

And then the Data the IFDs point at (if at all)

Nintendo's 64Byte Note

Offset	Description	Type	Default Value
0	Magic	Byte[4]	{'3','D','S','1'}
38	Unknown	Unknown	Unknown
40	3D Parallax*	NegInt?	?

• The 3D Parallax value is the distance that the right image needed to move in order to get focus.

My formula to get that value isn't so good but here it is:

x = (lsb - 0xC0) << 8 + msb;

Parallax = - round( 2 ^ (x/128 + 2) )

If someone makes sense of this, please explain or maybe correct..