Convert MOD to AAC — Free Online Converter

The MOD format is a cornerstone of computer music history, created for the Commodore Amiga's Ultimate Soundtracker in 1987. It pioneered the concept of tracker music: rather than recording a continuous audio performance, MOD files embed short instrument samples (typically 8-bit at around 8 kHz) and arrange them through pattern-based sequencing data. Each pattern contains rows of note events across 4 channels (extended to 8+ by ProTracker), with per-note effect commands controlling pitch slides, vibrato, volume envelopes, and sample manipulation. The entire system was a marvel of efficiency — a 3-minute song might occupy just 200 KB by reusing the same drum loop sample hundreds of times at different pitches.

AAC (Advanced Audio Coding) represents the opposite end of the audio spectrum: a modern perceptual codec that encodes continuous audio waveforms with psychoacoustic compression. Converting MOD to AAC means rendering the tracker's symbolic music notation into an actual audio stream through software synthesis, then applying AAC's sophisticated compression model. This transformation is essential for anyone who wants demoscene or retro game music to play on iPhones, iPads, web browsers, or any platform that supports the dominant streaming codec of the modern era.

The demoscene community produced tens of thousands of MOD compositions between 1987 and the late 1990s, representing a unique musical tradition that influenced electronic music for decades. However, playing these files requires a tracker-compatible rendering engine that most modern software and devices lack. Converting to AAC makes this cultural archive accessible through any standard music player, streaming service upload pipeline, or web audio API — without requiring listeners to understand what a tracker is.

Content creators producing retro gaming videos, chiptune compilations, or demoscene documentaries need MOD music in a standard audio format for their editing workflows. AAC is the preferred format for Apple ecosystem tools (Logic Pro, Final Cut Pro, GarageBand) and provides better compression efficiency than MP3 at equivalent quality, making it ideal for podcast episodes, YouTube uploads, and streaming platforms that accept AAC submissions.

The MOD-to-AAC pipeline begins with FFmpeg's module decoder (libopenmpt or libmodplug), which parses the MOD file's header to identify the 15 or 31 instrument sample definitions (each containing sample length, finetune value, default volume, loop start, and loop length), the song arrangement table mapping pattern sequence positions, and the pattern data encoding note/instrument/effect triplets for each channel per row. The renderer synthesizes audio by fetching sample data at pitch-adjusted playback rates according to Amiga period values, applying per-tick effect processing (speed/BPM changes, portamentos, arpeggios, volume slides), and mixing all channels to a stereo PCM output. This PCM stream feeds into the AAC-LC encoder (libfdk_aac or native FFmpeg encoder), which applies MDCT transforms, psychoacoustic masking, temporal noise shaping, and Huffman coding to produce the final AAC bitstream in an ADTS or M4A container.