FMF File Format
Fuse can save movies with sound in a specific file format (FMF - Fuse Movie File). This recording is very fast, and has a moderate size, but you need to use the fmfconv program in fuse-utils to convert into regular video and/or audio files.
A typical file will have some interspersed blocks:
- File Header
- Screen area
- Sound chunk
- New frame
- End of recording
File Header
| OFFSET | LENGTH | DATA | DESCRIPTION |
|---|---|---|---|
| 0 | 4 | "FMF_" | Magic number |
| 4 | 2 | "V1" | Version |
| 6 | 1 | <e,E> | Endianness (e: little endian, E: big endian) |
| 7 | 1 | <U,Z> | Compression (U: uncompressed, Z: compressed) |
| 8 | 1 | # | Frame rate ( 1:# ) (1:1 is 50 frames/sec) |
| 9 | 1 | <$,R,C,X> | Screen type (standard, HiRes, HiColor, Timex standard) |
| 10 | 1 | <A,B,C,D,E> | Frame timing code (see New Frame block) |
| 11 | 1 | <P,U,A> | Sound encoding (P: 16bit signed PCM, U: u-Law, A: A-Law) |
| 12 | 2 | # | Sound freq in Hz |
| 14 | 1 | <S,M> | Sound channels (S: stereo, M: mono) |
| 15 | 1 | 0x0A | Padding (new line) |
Example:
FMF_V1eZ\001$AU\000\175M
little endian, compressed, standard screen, 48k timing, u-Law mono 32000Hz sound
If compression is enabled, all blocks (except File Header) are compressed by zlib.
After the File Header there should be a slice with full screen area to begin with drawings.
Screen area (slice)
| OFFSET | LENGTH | DATA | DESCRIPTION |
|---|---|---|---|
| 0 | 1 | "$" | Block ID / Data chunk type |
| 1 | 1 | # | X coord (0-39) |
| 2 | 2 | # | Y coord (0-239) |
| 4 | 1 | # | Width (1-40) |
| 5 | 2 | # | Height (1-240) |
| 7 | ? | # | Run-length encoded data |
Run-length encoded data for non-HiRes screen types ($/C/X):
- bitmap
- attributes
Run-length encoded data for HiRes screen type (R):
- bitmap1
- bitmap2
- attributes
Run-length encoding method:
- Two identical bytes plus length (upto 255).
- abcc#defg -> "cc#" means cc string + "# times" c char.
New frame
| OFFSET | LENGTH | DATA | DESCRIPTION |
|---|---|---|---|
| 0 | 1 | "N" | Block ID / Data chunk type |
| 1 | 1 | # | Frame rate ( 1:# ) (1:1 is 50 frames/sec) |
| 2 | 1 | <$,R,C,X> | Screen type (standard, HiRes, HiColor, Timex standard) |
| 3 | 1 | <A,B,C,D,E> | Frame timing code |
Screen type:
- $ - Standard screen,
- R - HiRes,
- C - HiColor,
- X - Standard screen on Timex (double size)
Frame timing code:
- A - ZX Spectrum 16K/48K, Timex TC2048/2068, Scorpion, Spectrum SE (50.080128 Hz)
- B - ZX Spectrum 128K/+2/+2A/+3/+3e/128Ke (50.021152 Hz)
- C - Timex TS2068 (60.114502 Hz)
- D - Pentagon 128K/512K/1024K (50 Hz)
- E - ZX Spectrum 48K NTSC (59.650635 Hz)
In a frame there are zero, one or several screen areas (slices), changed from the previous frame.
Sound chunk
| OFFSET | LENGTH | DATA | DESCRIPTION |
|---|---|---|---|
| 0 | 1 | "S" | Block ID / Data chunk type |
| 1 | 1 | <P,U,A> | Sound encoding (P: 16bit signed PCM, U: u-Law, A: A-Law) |
| 2 | 2 | # | Sound freq in Hz |
| 4 | 1 | <S,M> | Sound channels (S: stereo, M: mono) |
| 5 | 2 | # | Length in frames - 1 (0-65535 means 1-65536 sound frames) |
| 7 | ? | # | Sound frames data (length * frame size) |
Sound frame size:
- A-Law mono: 1 byte.
- A-Law stereo: 2 bytes.
- PCM mono: 2 bytes.
- PCM stereo: 4 bytes.
End of recording
| OFFSET | LENGTH | DATA | DESCRIPTION |
|---|---|---|---|
| 0 | 1 | "X" | Block ID / Data chunk type |
There is no additional data. This block mark the end of the last frame. So we can concatenate several FMF files without problem.
