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2024-09-18T10:42:46Z

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* Company: TopWare
* Extension: avx

This is a rather weird multi-layered format that starts with a constant amount of audio and has block structure that may contain one or more FLX animations with different parameters.

Overall file header:
16-bit number of FLX animations in the file
8-bit number - always 4?
8-bit number - audio depth (8 for raw PCM or 16 for IMA ADPCM compressed audio)
N bytes - audio data (0x27100 bytes for 8-bit audio and 0x1AEC0 for 16-bit audio)

Then block data follows using the following block header format: 32-bit block size and some other 32-bit number.

FLX animations start with the following header:
4 bytes - "FLX\0"
2 bytes - number of frames
2 bytes - width
2 bytes - height
2 bytes - frames per second
8 bytes - unknown

FLX frames start with 16-bit frame type and 32-bit size (which includes the header). Known frame types are:
* 0 - intra frame plus audio
* 1 - inter frame plus audio
* 2 - inter frame with an additional RLE compression plus audio
* 4 - palette

Palette type can be determined from its size: 768+6 bytes mean 24-bit RGB palette while 512+6 bytes mean RGB565 palette.

In case of 16-bit audio it is compressed using IMA ADPCM with the default predictors and state not being reset during the decoding. Audio data is stored in interleaved 32-bit little-endian word per channel and it should be decoded from low nibble first.

Video data consists of <code>(skip, copy)</code> byte pairs followed by pixel data to copy (colour value 0 also means skip). Inter frames start with 32-bit offset in the frame at which decoding should begin. Frame type 2 additionally starts with 32-bit size of unpacked data. Its RLE scheme is very simple: if byte value is not <code>0xFF</code> then copy it verbatim, otherwise read run value and its repeat length.

[[Category:Game Formats]]

Jack Orlando AVX - Revision history

Kostya: fill description