gapless-lossy-codec

Proof of concept lossy audio codec written in Rust that preserves gapless playback.

Development Status

Please note that this is currently a somewhat buggy implementation. It does achieve gapless playback and lossy compression, but at the cost of mangling the amplitude as much as 25% in a few outlier samples. Why this happens is still under investigation.

Command-Line Usage (Encoding)

Basic usage

glc <file1.wav> [file2.wav] [file3.flac] ...

Supported Formats

• WAV files (.wav)
• FLAC files (.flac)

Behavior

1. Each input file is encoded to a .glc file with the same base name
2. Example: song.wav → song.glc
3. Multiple files can be processed in one command
4. If any file fails, the program continues with remaining files but exits with code 1

Examples

Encode a single file

glc audio.wav
# Creates audio.glc

Encode multiple files

glc song1.wav song2.wav song3.flac
# Creates song1.glc, song2.glc, song3.glc

Error handling

glc missing.wav  # Error: File not found
glc song.mp3     # Error: Unsupported file type

Output

For each successfully encoded file, the program displays:

• Input filename
• Sample rate, channel count, and sample count
• Output filename, size, and compression ratio

Example output:

Loading: "test.wav"
Encoding: 44100 Hz, 2 channels, 88200 samples
Saved: "test.glc" (7014 bytes, 4.0% of original)

Command-Line Usage (Decoding)

Decode a file and save output (FLAC by default)

glc -d file.glc

Creates file.flac with default compression level 5

Decode with specific FLAC compression level (0-8)

glc -d --flac-level 8 file.glc

Decode to WAV format instead

glc -d --wav file.glc

Decode a file and play it back using a pure Rust implementation (requires playback or ui feature to be enabled):

glc -p file.glc

Decode a file and play it back using ffplay (may not work currently):

glc -p file.glc --ffplay

Features Overview

No features are enabled by default for a minimal command-line build. You can enable specific features as needed.

Build with default settings (command-line only)

cargo build --release

Produces a minimal binary with encoding/decoding capabilities only.

Build with GUI support

cargo build --release --features ui

Includes GUI support. May require system libraries for GUI (glib-2.0) and audio playback (alsa on Linux).

Build with playback support (no GUI)

cargo build --release --features playback

Enables audio playback through the command line using rodio.

FLAC Support

FLAC encoding and decoding is now implemented in pure Rust, requiring no external libraries. The encoder supports compression levels 0-8, with level 5 as the default. This implementation follows RFC 9639 and produces standard-compliant FLAC files.