TM2X
- FOURCCs: TM2A, TM2X
- Company: On2 (formerly Duck)
- Sample: http://samples.mplayerhq.hu/V-codecs/TM2a.avi
- Sample: http://samples.mplayerhq.hu/V-codecs/TM2x.avi
Duck TrueMotion 2X is believed to be related to Duck TrueMotion 2.
Frame structure
Each frame consists of chunks with the following structure:
0-2 always 0xA0 0x00 0x01 3 chunk identifier 4-7 chunk size (big-endian) 8-... chunk payload
Analyzed frames have chunks in the following order:
0x06
(usually takes more than a half of coded frame)0x15
- small, variable size0x09
- 3 bytes long, seems to be some initialisation data0x02
- two chunks of variable size0x0B
- there are always 16 of them with size=4. Maybe for some Huffman tables?0x0A
- variable size
In order to ease reverse-engineering Duck seemed to used pseudo-encryption on data. Pseudo-encryption means XORing some chunks with parts of LFSR which may be updated before some chunks. Register data is stored as big-endian number and looks like first 4 bytes of 0x06
chunk are used to initialize it (it also seems to be that chunk size minus four bytes).
LSFR update algorithm:
calculate sum by modulo 2 of bits 31, 21, 3 and inverted bit 0 shift register contents left by one bit and store new sum in LSB repeat 4 times
0xA0000102
There should be up to two chunks.
First byte gives the chunk number (0 or 1).
Second byte tells how many 16-bit words of actual dat this chunk has (up to 128).
The rest of chunk is 16-bit words.
0xA0000103
First byte - ID?
Seems to be similar to 0xA000010B
0xA0000106
First 32-bit word is used to initialise LSFR key.
0xA0000109
Byte 0 - ? Byte 1 - ? Byte 2 - ?
0xA000010B
First byte - chunk ID.
0xA000010E
Also seems to be related to 0xA000010B
First byte - chunk ID.
0xA0000112
This represents some 2D array.
First byte is number of elements per line. Second byte seems to be padding. Following 16-bit word is number of lines.
The rest of chunk is 16-bit words forming some 2D array.
0xA0000119
Another extended form of 0xA000010B
?