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2025-06-17T10:12:32Z

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* Company: ICOM Simulations Inc.
* Extension: imv

This is a format used in the original version of [https://www.mobygames.com/group/10092/sherlock-holmes-consulting-detective-series/ Sherlock Holmes: Consulting Detective] series. The files consists of blocks forming logical groups with video for one scene.

Blocks start with 32-bit size, 32-bit previous block size (useful for seeking backwards), and 16-bit block type. Known block types are:
* 0x01 - global header (first 6 bytes meaning is unknown then there are 2-byte width, height and fps)
* 0x02 - logical group (scene) start, it contains total group size in multiple of CD sectors
* 0x04 - audio plus delta frame. First 4-byte value is block number, followed by 2-byte audio data size, followed by audio and video data
* 0x08 - audio plus raw frame (with the same header)
* 0x20 - audio plus raw frame plus palette update. First 4-byte value is block number, followed by 2-byte audio data size and video data size, followed by audio and video data, ending with palette update. Palette update starts with 2-byte values for start colour index and number of colours followed by partial VGA palette
* 0x40 - palette update

Delta frames are coded as a mix of update mask bytes followed by pixel values. E.g. <code>0x7A 0x01 0x02 0x03 0x04 0x05</code> means skipping one pixel, setting next four pixels to <code>0x01 0x02 0x03 0x04</code>, skipping one pixel, setting next pixel to <code>0x05</code> and skipping last pixel. Mask value <code>0x05</code> is used as an escape value: if it is followed by <code>0x02</code> then 16-bit number of 8-pixel groups to skip follows, otherwise just ignore that following byte.

[[Category:Game Formats]]

ICOM video - Revision history

Kostya: fill description