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2025-03-14T16:00:50Z

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This is an animation format used by Ascorn (later Ascaron) in some of its games like [https://www.mobygames.com/game/3816/gloriana/ Elisabeth I (aka Gloriana)] or [https://www.mobygames.com/game/40963/das-hexagon-kartell/ Das Hexagon Kartell]. Unlike many other formats it decodes YUV picture with 5 or 6 bits per component.

File is organised into a series of chunks, each with 4-byte type and size. First chunk should be <code>AN15</code>, last one should be <code>ENDE</code>

=== Header chunk ===
4 bytes - "AN15"
4 bytes - size (usually 64)
4 bytes - zero
4 bytes - header size again
4 bytes - "V0.9"
4 bytes - number of video frames
4 bytes - number of audio frames
4 bytes - unknown, usually zero
4 bytes - offset to video frame index
4 bytes - offset to audio frame index
12 bytes - always zero?
3 bytes - unknown
4 bytes - unknown
1 byte - unknown
4 bytes - frames per one hundredth of second (e.g. 1250 for 12.5 fps)
4 bytes - unknown

=== Audio chunk ===
4 bytes - "SAMP"
4 bytes - size
4 bytes - CRC
4 bytes - header size (usually 15, starting from CRC field)
3 bytes - sample rate
1 byte - number of channels
1 byte - bits per sample
2 bytes - usually zero

Audio data is unpacked PCM

=== Palette chunk ===
4 bytes - "PALT"
4 bytes - size
4 bytes - usually zero
4 bytes - unknown
768 bytes - VGA palette
rest - LUT

This chunk provides look-up table for mapping YUV data into indexed colours.

=== Picture chunk ===
4 bytes - "BILD"
4 bytes - size
4 bytes - usually zero
4 bytes - header size
2 bytes - width
2 bytes - height
2 bytes - compression mode
4 bytes - luma size
4 bytes - first chroma component size
4 bytes - second chroma component size
8 bytes - unknown
if header size > 34 {
11 bytes - unknown
1 byte - bits per luma sample (0 or 5 - 5 bits, 6 - 6 bits)
}

There are several compression methods known:
* 2 - raw YUV data packed in bits (5 or 6 bits for luma, signed 8 bits for chroma), luma plane first, chroma planes afterwards
* 3 - differences to the previous YUV frame
* 4 - same as method 3 but data is motion compensated with MV data sent before the change data (each 8x8 luma block having MV source consisting of 9-bit vertical offset and 10-bit horizontal offset)
* 16 - RGB compression

Method 3 codes data almost in the same way as method 2 except that zero component value means skip with the next 8- or 16-bit value (top bit set means 16-bit value, 8 bits otherwise) being the number of values to leave unchanged.

Method 16 is LZ77-like compression performed on RGB24 data. Flags are grouped in bytes and sent before the rest of the data. Flag 1 means raw RGB triplet, flag 0 means reading 16-bit offset plus 8-bit length (plus three) and copying that number of pixels from that offsets.

Image data is stored in wrapped 128000-pixel buffer which fits two images, so the previous image may be referenced while decoding the current one.

=== Index chunks ===
4 bytes - "SPTR" (audio) / "BPTR" (video)
4 bytes - usually 4
4 bytes - usually 12
4 bytes - number of entries
N*4 bytes - offsets to the audio/video frame chunks

[[Category:Game Formats]]

Ascorn animation - Revision history

Kostya: fill information