VAG at 17:21, 15 April 2012

2012-04-15T17:21:10Z

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* Extension: ubb , sometimes hnm
* Company: [[CRYO Interactive Entertainment]]
* Samples: '''ADD ME'''

UBB2 is another generation of FMV format developed by Cryo. It is an improved version of [[HNM4]] format. While general container format remains the same, video encoding is slightly improved.

== File Format ==
Remains the same as was used in [[HNM4]]. Following parts has changed:
* File signature is "UBB2" now.
* Video chunk has "IV" TwoCC.

== Video Compression ==
The video frame is encoded in a series of horizontal colums of variable width and height. However, columns height (and some of their coding properties) may only change at the beginning of new line.

<br>Encoded stream consist of column copy mode bytes:
bits:
7 - swap rows/columns
6 - vertical reverse
5 - horizontal reverse
4..0 - column width index (table lookup, see below)

Each of such code generally means ''"copy a width-by-height column from some other place to the current, using flags provided."''
<br>Flags behavior can be illustrated as follows (assuming 2x3 block and the source points to 'M' pixel):
Source Normal Horizontal Vertical Swap

ABCDE MN ML MN MR
FGHIJ RS RQ HI NS
KLMNO -> WX WV CD OT
PQRST
UVWXY

Multiple flags can be used together.

Encoded column width depends on column's height:
2: 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,20,22,24,26,28,30,32,34,36,38,40,44,48,52,56
3: 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,22,24,26,28,30,32,34,36,38,40,42,44
4: 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,28,30,32,34,36,38

Source column offset may be an "absolute" offset - byte distance from the current column, or relative X:Y offset.
* For absolute offset read next 2-byte value (unsigned, little-endian) and add base oofset.
* For relative offset read next byte, extract X and Y deltas from it and add base deltas.

Certain combination used for special purposes. Those are:
* 0x20 - skip: read next byte (width) and copy width+1 column from previous frame
* 0x60 - solo: draw 1-pixel wide column using next bytes of input
* 0xA0 - draw: read next byte (width) and draw width+2 column using next bytes of input (top-down, left-right)
* 0xE0 - mode: examine next byte.
** if byte is zero, then read two bytes (width, color) and fill width+1 column with color.
** if byte is non-zero, change the decoding properties as follows:
+------+--------+--------+--------+----------+---------+--------+
| byte | height | source | offset | Y.X bits | X-base | Y-base |
+------+--------+--------+--------+----------+---------+--------+
| 1 | end of decoding |
+------+--------+--------+--------+----------+---------+--------+
| 2 | 2 | prev | -32768 | N/A | N/A | N/A |
| 3 | 3 | prev | -32768 | N/A | N/A | N/A |
| 4 | 4 | prev | -32768 | N/A | N/A | N/A |
| 5 | 2 | prev | N/A | 4.4 | -8 | -8 |
| 6 | 3 | prev | N/A | 4.4 | -8 | -8 |
| 7 | 4 | prev | N/A | 4.4 | -8 | -8 |
+------+--------+--------+--------+----------+---------+--------+
| 8 | 2 | prev | N/A | 4.4 | -2 | -8 |
| 9 | 2 | prev | N/A | 4.4 | -14 | -8 |
| 10 | 2 | prev | N/A | 4.4 | -8 | -2 |
| 11 | 2 | prev | N/A | 4.4 | -8 | -14 |
| 12 | 2 | prev | N/A | 4.4 | -2 | -2 |
| 13 | 2 | prev | N/A | 4.4 | -14 | -2 |
| 14 | 2 | prev | N/A | 4.4 | -2 | -14 |
| 15 | 2 | prev | N/A | 4.4 | -14 | -14 |
+------+--------+--------+--------+----------+---------+--------+
| 16 | 3 | prev | N/A | 4.4 | -2 | -8 |
| 17 | 3 | prev | N/A | 4.4 | -14 | -8 |
| 18 | 3 | prev | N/A | 4.4 | -8 | -2 |
| 19 | 3 | prev | N/A | 4.4 | -8 | -14 |
| 20 | 3 | prev | N/A | 4.4 | -2 | -2 |
| 21 | 3 | prev | N/A | 4.4 | -14 | -2 |
| 22 | 3 | prev | N/A | 4.4 | -2 | -14 |
| 23 | 3 | prev | N/A | 4.4 | -14 | -14 |
+------+--------+--------+--------+----------+---------+--------+
| 24 | 4 | prev | N/A | 4.4 | -2 | -8 |
| 25 | 4 | prev | N/A | 4.4 | -14 | -8 |
| 26 | 4 | prev | N/A | 4.4 | -8 | -2 |
| 27 | 4 | prev | N/A | 4.4 | -8 | -14 |
| 28 | 4 | prev | N/A | 4.4 | -2 | -2 |
| 29 | 4 | prev | N/A | 4.4 | -14 | -2 |
| 30 | 4 | prev | N/A | 4.4 | -2 | -14 |
| 31 | 4 | prev | N/A | 4.4 | -14 | -14 |
+------+--------+--------+--------+----------+---------+--------+
| 32 | 2 | curr | -65536 | N/A | N/A | N/A |
| 33 | 2 | curr | N/A | 3.5 | -16 | -8 |
| 34 | 2 | curr | N/A | 4.4 | -8 | -16 |
| 35 | 2 | curr | N/A | 4.4 | -24 | -16 |
| 36 | 2 | curr | N/A | 4.4 | +8 | -16 |
| 37 | 2 | curr | N/A | 5.3 | -4 | -32 |
| 38 | 2 | curr | N/A | 5.3 | -12 | -32 |
| 39 | 2 | curr | N/A | 5.3 | +4 | -32 |
+------+--------+--------+--------+----------+---------+--------+
| 40 | 3 | curr | -65536 | N/A | N/A | N/A |
| 41 | 3 | curr | N/A | 3.5 | -16 | -8 |
| 42 | 3 | curr | N/A | 4.4 | -8 | -16 |
| 43 | 3 | curr | N/A | 4.4 | -24 | -16 |
| 44 | 3 | curr | N/A | 4.4 | +8 | -16 |
| 45 | 3 | curr | N/A | 5.3 | -4 | -32 |
| 46 | 3 | curr | N/A | 5.3 | -12 | -32 |
| 47 | 3 | curr | N/A | 5.3 | +4 | -32 |
+------+--------+--------+--------+----------+---------+--------+
* prev means source is the previous frame, curr - current
* Y.X means "Y" value in upper Y bits of byte, "X" in lower X bits.

== Trivia ==
Apparently this format has another less-used name - HNM5.

[[Category:Game Formats]]
== Games Using UBB ==

* [http://www.mobygames.com/game/megarace-2 Megarace II]
* lots of others

[[Category:Game Formats]]
[[Category:Video Codecs]]
[[Category:Formats missing in FFmpeg]]

UBB - Revision history

VAG at 17:21, 15 April 2012