libflac-rs 0.143.1

Bit-exact pure-Rust port of libFLAC 1.4.3: a complete FLAC encoder and decoder (incl. Ogg FLAC) byte-identical to the C reference.
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  • Source code size: 232.39 kB This is the summed size of all the files inside the crates.io package for this release.
  • Documentation size: 1.36 MB This is the summed size of all files generated by rustdoc for all configured targets
  • Ø build duration
  • this release: 2s Average build duration of successful builds.
  • all releases: 2s Average build duration of successful builds in releases after 2024-10-23.
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  • danifunker

libflac-rs

A pure-Rust, bit-exact port of libFLAC 1.4.3 — a complete FLAC encoder and decoder whose output is byte-identical to the C reference. Unlike a "produces valid FLAC" library, the goal is to recreate the exact bytes libFLAC/MAME produce, so tools like chd-rs can reproduce and verify CHD files losslessly. (flacenc, the existing pure-Rust encoder, is not byte-identical to libFLAC — which is precisely why this exists.)

Status — complete and byte-exact

Every byte was verified against the real libFLAC (and libogg for Ogg), compiled from source as a differential oracle. That oracle is no longer vendored — the repo is 100% pure Rust — but the process to re-establish and re-run it is documented in ORACLE.md:

  • ✅ Encoder, byte-identical to libFLAC: compression levels 0–8, bit depths 8/12/16/20/24/32, mono / stereo (mid-side) / multichannel, the audio MD5, and every metadata block (STREAMINFO, VORBIS_COMMENT, PADDING, APPLICATION, SEEKTABLE, PICTURE, CUESHEET).
  • ✅ Decoder: lossless and MD5-verified, with seek() and variable-block-size support.
  • ✅ Ogg FLAC (encode + decode), byte-identical to libFLAC + libogg.
  • ✅ Pure Rust, #![forbid(unsafe_code)], zero runtime dependencies.

Usage

use libflac_rs::{Encoder, EncoderConfig};

// 2-channel, 16-bit, 44.1 kHz, compression level 8 (libFLAC's defaults).
let enc = Encoder::new(EncoderConfig::new(2, 16, 44_100));
let pcm: Vec<i32> = vec![0; 4096 * 2]; // interleaved: L R L R …

let flac: Vec<u8> = enc.encode(&pcm);      // a complete .flac file
let frames: Vec<u8> = enc.encode_frames(&pcm); // raw frames (what MAME/CHD embeds)
let ogg: Vec<u8> = enc.encode_ogg(&pcm, 0);    // an Ogg FLAC stream

let decoded = libflac_rs::decode(&flac).unwrap();
assert_eq!(decoded.interleaved, pcm);
assert!(decoded.md5_ok);

For the exact configuration MAME's CHD codec uses (level 8, 2ch/16-bit/44.1 kHz, MD5 off), construct with EncoderConfig::chd(block_size) and call encode_frames.

Pure Rust, zero dependencies

The crate is #![forbid(unsafe_code)], edition 2024, with no dependencies at all — not even a build script. There is no C in the repository.

cargo test   # pure-Rust unit + lossless round-trip tests (any platform)

Byte-exactness against the C reference is re-checked on demand by restoring the differential oracle (vendored libFLAC + libogg, built under glibc/gcc — the libm parity target MAME/chdman use). See ORACLE.md for the exact process.

License

BSD-3-Clause, retaining the Xiph.Org copyrights on the ported libFLAC and libogg sources. See LICENSE.