songsee is a single-binary Go CLI tool that turns audio files into spectral visualization images. It decodes audio natively (WAV, MP3) or via ffmpeg, computes an FFT specrogram, and renders nine visualiation modes (spectrogram, mel, chroma, HPSS, self-similarity, loudness, tempogram, MFCC, spectral flux) as a grid of heatmaps in PNG or JPEG format. The architecture is a monlith: the `cmd/songsee/main.go` entry point parsers flags using Kong, delegates to `internal/audio` for decoding, `internal/dsp` for signal processing (STFT, mel filtering, chroma, median filters, etc.), and `internal/render` for image generation. It produces deterministic output – same input flags yield identical bytes. The codebase is well-structured with comprehensive tests, CI/CD, and a clean separation of concerns. It demonstrates high craftsmanship in DSP optimization (e.g., bit-exact HPSS with median networks, tiling) and safe WAV parsing.
minimp3 is a minimal, high-performance, ISO-conformant MP3 decoder implemented as a single-header C library (minimp3.h). It provides a low-level frame decoding API and a higher-level streaming/seek API (minimp3_ex.h) with callback-based I/O abstraction. The decoder supports SSE and NEON SIMD acceleration, and compiles to a ~30kB binary with zero external dependencies. The repository includes a comprehensive test suite with over 50 test vectors covering standard and edge-case MPEG audio streams, a fuzzing harness, and a full-featured GUI player (using SDL2 and Nuklear) that demonstrates real-world usage. An additional tool (huffopt) generates optimized Huffman tables for Layer III. The library is designed for embedded systems, game engines, and any environment requiring a lightweight MP3 decoder.