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- Company: Aneiva Interactive, Inc.
- Extension: pac
This is a format used in Cydonia game and not related to PACo.
The file consists of 4-byte magic
Paco, initialisation chunk and one or more data chunks. Chunks starti with single byte for chunk type and 32-bit little-endian chunk size.
Known chunk types:
- 1 - initialisation chunk
- 2 and 3 - video frame
- 4 - new palette data (may be shorter than 768 in theory)
- 5 - audio data
- 20 - silence (32-bit payload tells silence length)
- 21 - something audio-related
- 30-35 - some frame management opcodes
- 50 - unknown
- 60-61 - related to fading?
Initialisation chunk should be 7 bytes long:
16 bits - video width 16 bits - video height 16 bits - number of frames 8 bits - audio present flag
Video is compressed using LZ77-based scheme for both frame types with small differences in codewords and ways to copy previous frame data (one uses lines, another one uses blocks).