fmv is the movie capture format of EmulatorResources/Famtasia, a NES emulator.
FMV file format description
FMV file consists of a 144-byte header and the frame data.
Header format:
000 4-byte signature: 46 4D 56 1A "FMV\x1A"
004 1-byte flags:
bit 7: 0=reset-based, 1=savestate-based
other bits: unknown, set to 0
005 1-byte flags:
bit 5: is a FDS recording
bit 6: uses controller 2
bit 7: uses controller 1
other bits: unknown, set to 0
006 4-byte little-endian unsigned int: unknown, set to 00000000
00A 4-byte little-endian unsigned int: rerecord count minus 1
00E 2-byte little-endian unsigned int: unknown, set to 0000
010 64-byte zero-terminated emulator identifier string
050 64-byte zero-terminated movie title string
090 frame data begins here
Each frame consists of 1 or more bytes.
Controller 1 takes 1 byte,
controller 2 takes 1 byte,
and the FDS data takes 1 byte.
If all three exist, the frame is 3 bytes.
For example, if the movie is a regular NES game with only controller 1 data, a frame is 1 byte.
The file has no terminator byte or frame count.
The number of frames is the <filesize minus 144>
divided by <number of bytes per frame>.
The rerecord count stored in the file is the number of times a savestate
was loaded. If a savestate was never loaded, the number is 0.
Famtasia however displays "1" in such case.
It always adds 1 to the number found in the file.
The file format has no means of identifying NTSC/PAL. It is always assumed that the game is NTSC - that is, 60 fps.
The bit values in hex for the buttons are as follows.
01 Right 02 Left 04 Up 08 Down 10 B 20 A 40 Select 80 Start
See also: EmulatorResources, frequently asked questions