FSSD to VOC Converter

FSSD is a raw audio format that originated in the classic Macintosh ecosystem, where Farallon Computing's MacRecorder hardware (1988) stored digitized sound as unsigned 8-bit PCM in resource fork entries tagged with the 'FSSD' type code. In modern audio processing tools such as SoX, FSSD is treated as an alias for the u8 (unsigned 8-bit) raw format — headerless files containing a flat stream of single-byte amplitude samples, where each value from 0 to 255 represents an audio level with 128 as the center point. Because there is no header, playback parameters like sample rate and channel count must be provided externally. The original MacRecorder typically captured at rates up to 22 kHz in mono, though any sample rate is valid when interpreting the raw data. FSSD and its compressed companion format HCOM (which adds Huffman compression to the same underlying data) were the standard audio formats for early Mac multimedia: HyperCard stacks, educational CD-ROMs, and system alert sounds of the late 1980s and early 1990s relied heavily on this encoding. One advantage of the raw FSSD format is trivial parseability — with no container overhead, the audio data begins at byte zero and can be read by any tool capable of processing unsigned 8-bit PCM. The format's historical significance also makes it practically relevant for digital archivists: converting FSSD recordings to modern containers like WAV preserves the original audio content losslessly, since the raw samples only need a header prepended, not any form of transcoding.

VOC (Creative Voice) is a digital audio container developed by Creative Technology and introduced alongside the original Sound Blaster card in 1989. It served as the native audio format for the Sound Blaster family during the DOS era, when Creative's hardware dominated PC audio. VOC files are block-based: each file consists of typed data blocks that can carry 8-bit unsigned PCM, 4-bit and 2.6-bit Creative ADPCM, 16-bit signed PCM, as well as A-law and mu-law encoded audio. This block structure also supports silence intervals, repeat loops, and marker points, giving game developers fine-grained control over sound playback. A notable advantage was hardware-level decoding — Sound Blaster cards could play VOC data directly via DMA transfer, freeing the CPU for other tasks in an era when processor cycles were precious. The format saw extensive use in DOS games from id Software, Sierra, and LucasArts. With the rise of Windows and the WAV format, VOC gradually fell out of mainstream use, yet it remains important for retro gaming preservation and for anyone working with vintage PC audio archives.