MPO
Overview
MPO = Multi-Picture Object
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: We will address the MakerNote byte array as 'mnote' (i.e. mnote[0] is the first byte)
There is a dynamic byte array at first which its size is at mnote[9]. After the dynamic array starting at mnote[6 + mnote[9]] an 88 bytes array starts.
| Offset from 6+mnote[9] | Description | Type | Default Value |
|---|---|---|---|
| 0 | Comment | String[24] null terminated | 0 for a 3D picture / <some_text> if taken from AR game |
| 24 | Magic | Byte[4] | {'3','D','S','1'} |
| 28 | Tags | Unknown | Unknown |
What is known that on mnote[mnote[9]+72] & mnote[mnote[9]+73] lays the parallax value. The 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: b0 = mnote[mnote[9]+72] b1 = mnote[mnote[9]+73]
x = (b1 - 0xC0) << 8 + b0;
Parallax = - round( 2 ^ (x/128 + 2) )
If someone makes sense of this, please explain or maybe correct..