This file format appears to describe a stitch out similar to that used in JEF files.
A source of information about this format can be found on this external page: HUS and VIP File Formats. However, as described in that document, the compression technique used seems to be both proprietary and closed, so encoding and decoding of stitch information may prove to be difficult. It depends on whether or not the compression methods used in the ARJ archive format are closely related to those provided in the library used for HUS files.
The compression/decompression uses a Huffman/LZW style compression on the length and position parts of the codes, so that the most common lengths are further compressed into less bits. In decompression, the first 16 bits are loaded: 16 bits appears to be the longest compressed symbol or code. The first decode uses parameters 19, 5, 3 and fetches 5 bits.
|0||magic number? (0x00c8fc5d for HUS; 0x0190fc5d for VIP)|
|4||(looks like an offset into the file, but can be larger than the file extent)|
|8||number of threads/colours|
|12, 14||maximum coordinates (16-bit, little endian, signed)|
|16 (0x10), 18||minimum coordinates (16-bit, little endian, signed)|
|20 (0x14)||offset to data past colour/thread definitions|
|24 (0x18)||unknown (looking at a file with an odd number of bytes where this field is also an odd number suggests that this could be the start of thread position data)|
|28 (0x1c)||unknown (looks like a length or offset)|
|32-40 (0x20-0x28)||Pattern name or null bytes - VIP format includes extra data at 40 (0x28)|
|40 (0x28)||two zero bytes|
|42 (0x2a)||start of colour/thread definitions (2 bytes each)|
|0||2||Byte||Signature-1 = 0x5d 0xfc or 0x5b 0xaf|
|2||2||Int||Signature-2 = (little endian) 200 HUS or 400 VIP|
|12||2||Int||maximum x coordinates (16-bit, little endian, signed)|
|14||2||Int||maximum y coordinates (16-bit, little endian, signed)|
|16 (0x10)||2||Int||minimum x coordinates (16-bit, little endian, signed)|
|18 (0x12)||2||Int||minimum y coordinates (16-bit, little endian, signed)|
|20 (0x14)||4||Int||file offset to compressed stitch attribute data (move, stitch, thread change)|
|24 (0x18)||4||Int||file offset to compressed stitch x data|
|28 (0x1c)||4||Int||file offset to compressed stitch y data|
|32||4||Int||Unknown = 0|
|36||4||Int||Unknown = 0|
|40 (0x28)||2||Byte||two zero bytes|
|42 (0x2a)||N1||Colour||start of colour/thread definitions (HUS: 2 bytes each, VIP: 4 bytes each)|
The HUS colour table is Colour-Count 16 bit indices. The VIP colour table is a file-offset to next section, then Colour-Count 32 bit encoded RGB values, followed by Colour-count 32 bit Type/Tension numbers. The VIP file then has a 32 bit number which may be a string length count, followed by 16 bit character string giving the name of the design/pattern.