FlyMovieFormat (.fmf) file specification

This file type defines 8-bit grayscale image sequences where each image is associated with a timestamp. There are currently two versions implemented, versions 1 and 3. (Version 2 was briefly used internally and is now best forgotten.) For documentation about the purpose of the format and the reference Python implementation, see motmot.FlyMovieFormat.FlyMovieFormat.

File structure

• header (either version 1 or version 3)
• arbitrary number of timestamp and frame pairs (“frame chunks”)

.fmf header version 1

Only supports MONO8 format.

Typecode	Name	Description
I	version	Version number (1)
II	framesize	Number of rows and columns in each frame
Q	chunksize	Bytes per “chunk” (timestamp + frame)
Q	n_frames	Number of frames (0=unknown, read file to find out)

.fmf header version 3

Typecode	Name	Description
I	version	Version number (3)
I	lenformat	Length of the subsequent format string
*B	format	string containing format, e.g. ‘MONO8’ or ‘YUV422’
I	bpp	Bits per pixel, e.g. 8
II	framesize	Number of rows and columns in each frame
Q	chunksize	Bytes per “chunk” (timestamp + frame)
Q	n_frames	Number of frames (0=unknown, read file to find out)

.fmf frame chunks

Typecode	Name	Description
d	timestamp	Timestamp (seconds in current epoch)
*B	frame	Image data, rows*columns bytes, row major ordering

Typecodes used above

All numbers are little-endian (Intel standard).

Typecode	description	bytes	C type
B	uint8	1	unsigned char
I	uint32	4	unsigned int
Q	uint64	8	unsigned long long (__int64 on Windows)
d	double64	8	double
*B	data		an unsigned char buffer of arbitrary length