Converting Farandole Composer (.far) to WAV: 16-Channel DOS Tracker Synthesis

In the golden age of PC demoscene trackers between 1993 and 1996, musicians pushed beyond the standard 4-channel limits of the Amiga MOD format. Among the wave of innovative DOS tracking tools was Farandole Composer, created in 1994 by Daniel Potter. Modules composed in Farandole use the .far extension.

Farandole Composer stood out in the tracker underground for its streamlined 16-channel architecture, integrated song comments, per-channel panning assignments, and direct 8-bit linear PCM instrument storage. It provided demoscene composers with an accessible, high-performance tracking workflow on 386 and 486 PCs.

This deep-dive examines the internal binary structure of the Farandole .far file, explains how its 16-channel pattern matrices and sample tables operate, and details how convrtr's FAR to WAV synthesizer renders vintage DOS tracker tracks into clean, CD-quality 16-bit 44.1kHz stereo WAV audio entirely in client-side memory.

The FAR File Header Layout

Every authentic Farandole Composer module begins with a compact 97-byte fixed header:

| Offset | Size (Bytes) | Field Name | Description | | :--- | :--- | :--- | :--- | | 0x00 | 4 bytes | Magic Identifier | Constant signature "FAR\xFE" (0x46 0x41 0x52 0xFE) | | 0x04 | 40 bytes | Song Title | ASCII song title (null-padded or space-padded) | | 0x2C | 1 byte | DOS EOF | Always 0x1A (prevents binary display clutter in DOS) | | 0x2D | 2 bytes (LE) | Header Length | Total byte offset to pattern order data | | 0x2F | 1 byte | Version | Tracker version (typically 0x10 for Farandole 1.0) | | 0x30 | 16 bytes | Channel Map | Channel on/off flags for channels 1 through 16 | | 0x40 | 9 bytes | Reserved | Empty padding bytes | | 0x49 | 2 bytes (LE) | Default Tempo | Initial playback tempo | | 0x4B | 16 bytes | Panning Table | Per-channel stereo panning settings (0 to 15) | | 0x5B | 4 bytes | Coarse Tempo | Playback speed/timing modifiers | | 0x5F | 2 bytes (LE) | Text Message Length | Length of embedded author message in bytes |

The signature "FAR\xFE" identifies the module as a Farandole Composer file.

Embedded Text Messages and Song Notes

Unlike early tracker formats that forced artists to type messages into unused instrument name slots, Farandole Composer incorporated a dedicated author text field.

Immediately following the 97-byte header at offset 0x61, the file stores textLength bytes of ASCII text containing greeting lists, demogroup credits, and musical notes. After this message block, the file transitions directly to the order table.

Order Lists and Pattern Structures

Following the song message, Farandole stores the pattern sequencing structure:

1. Order Table (256 bytes): An array of pattern numbers representing the song's playback order. A value of 255 indicates the end of the song.
2. Song Statistics (3 bytes): Total unique patterns, number of orders played, and song loop point.
3. Pattern Size Table: A 2-byte integer per pattern specifying its packed or unpacked size in bytes.

Each pattern consists of 64 rows across 16 channels. In Farandole Composer, each channel cell is represented by 4 bytes:

[Note Byte, Sample Byte, Volume Byte, Effect Byte]

• Note Byte: 0 indicates no note. Values 1 to 84 represent musical semitones spanning 7 full octaves.
• Sample Byte: The 1-indexed instrument number (1 to 64). 0 indicates no sample trigger.
• Volume Byte: Direct volume setting from 0 to 16 (scaled up to standard 0–64 tracker volume).
• Effect Byte: Encodes pitch bends, volume slides, and vibrato effects.

Sample Descriptors and Waveform Banks

After the pattern tables, Farandole Composer stores 64 sample headers, each occupying 64 bytes:

| Offset | Size (Bytes) | Field Name | Description | | :--- | :--- | :--- | :--- | | +0x00 | 32 bytes | Sample Name | ASCII instrument label | | +0x20 | 4 bytes (LE) | Sample Length | Total PCM length in bytes | | +0x24 | 1 byte | Finetune | Tuning adjustments | | +0x25 | 1 byte | Default Volume | Initial volume level (0 to 64) | | +0x26 | 4 bytes (LE) | Loop Start | Beginning offset of loop window | | +0x2A | 4 bytes (LE) | Loop End | Ending offset of loop window | | +0x2E | 1 byte | Loop Type | 1 if sample loops; 0 for one-shot |

Following the 64 sample headers, the raw 8-bit signed linear PCM waveforms are stored sequentially. Farandole stores sample values as signed 8-bit integers ranging from -128 to +127.

Client-Side Replay Synthesis

To convert a .far file into standard 16-bit stereo WAV audio without a DOS emulator, convrtr's synthesis engine performs real-time multi-channel voice mixing in the browser:

1. Pitch Period Calculation

For any note N from 1 to 84, the target frequency f is calculated using equal temperament relative to middle C (note 49 at 8363 Hz):

f = 8363 * Math.pow(2, (N - 49) / 12)
step = f / sampleRate

2. Linear Interpolation and Loop Wrapping

When stepping through 8-bit PCM waveforms at fractional positions, linear interpolation eliminates high-frequency aliasing distortion:

sample(t) = (1 - frac) * pcm[floor(t)] + frac * pcm[ceil(t)]

If playback reaches loopEnd on a looping sample, the read cursor smoothly resets to loopStart.

3. Stereo Panning Distribution

Each channel's 4-bit panning byte (0 to 15) is converted to fractional stereo gains and scaled with a user-adjustable stereo separation factor:

leftGain  = (1.0 - pan) * stereoSeparation + (1.0 - stereoSeparation) * 0.5;
rightGain = pan * stereoSeparation + (1.0 - stereoSeparation) * 0.5;

All 16 voices are summed, clipped to $[-1.0, 1.0]$, scaled to signed 16-bit integers (-32768 to +32767), and packaged into a canonical 44-byte RIFF/WAVE container.

Preservation and Playback

Because modern operating systems lack native Farandole players, valuable demoscene compositions and vintage PC game soundtracks risk becoming unplayable. Converting .far modules to uncompressed 16-bit 44.1kHz stereo WAV ensures that vintage tracker music can be played on modern smartphones, imported into digital audio workstations (DAWs), and permanently preserved for future generations.