feat(lambda-rs): Implement a SoundBuffer with support for decoding wav and ogg files.

[vmarcella]

Summary

Related Issues

• Resolves [Feature] Sound file loading (WAV, OGG) #111

Changes

Add Symphonia wrapper in lambda-rs-platform for WAV and OGG Vorbis decoding

• Add granular feature flags for audio decoding (audio-decode-wav, audio-decode-vorbis, audio-sound-buffer)
• Add comprehensive error types (AudioError) with decode-specific variants
• Add test audio fixtures (WAV: mono/stereo, 16/24/32-bit; OGG: Vorbis stereo)
• Add sound_buffer_load example demonstrating the loading API
• Add play_slash_sound example demonstrating playback integration
• Add lambda_audio tool for testing audio loading and playback
• Update docs/features.md with new audio feature documentation
• Add docs/specs/audio-file-loading.md specification

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• Feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (updates to docs, specs, tutorials, or comments)
• Refactor (code change that neither fixes a bug nor adds a feature)
• Performance (change that improves performance)
• Test (adding or updating tests)
• Build/CI (changes to build process or CI configuration)

Affected Crates

• lambda-rs
• lambda-rs-platform
• lambda-rs-args
• lambda-rs-logging
• Other: tools/lambda_audio

Checklist

• Code follows the repository style guidelines (cargo +nightly fmt --all)
• Code passes clippy (cargo clippy --workspace --all-targets -- -D warnings)
• Tests pass (cargo test --workspace)
• New code includes appropriate documentation
• Public API changes are documented
• Breaking changes are noted in this PR description

Testing

Commands run:

cargo build --workspace
cargo test --workspace
cargo build -p lambda-rs --no-default-features --features audio-sound-buffer
cargo run --example sound_buffer_load -- <path-to-audio-file>
cargo run --example play_slash_sound
cargo run -p lambda-audio -- --file <path> --format <wav|ogg>

Manual verification steps (if applicable):

1. Verified WAV loading with various bit depths (16-bit, 24-bit, 32-bit float)
2. Verified WAV loading with mono and stereo configurations
3. Verified OGG Vorbis loading with stereo audio
4. Verified error handling for unsupported/invalid files
5. Verified playback integration with play_slash_sound example
6. Verified lambda_audio tool can load and play audio files

Screenshots/Recordings

Platform Testing

• macOS
• Windows
• Linux

Additional Notes

Feature Flag Structure

The new audio features follow the existing feature flag patterns:

lambda-rs:

• audio-sound-buffer-wav - WAV file loading
• audio-sound-buffer-vorbis - OGG Vorbis loading
• audio-sound-buffer - Umbrella for all sound buffer features
• audio - Updated umbrella including output device and sound buffer

lambda-rs-platform:

• audio-decode-wav - Symphonia WAV decoder
• audio-decode-vorbis - Symphonia Vorbis decoder

Supported Formats

WAV:

• Sample formats: 16-bit PCM, 24-bit PCM, 32-bit float
• Channel configurations: Mono, Stereo
• Sample rates: Any standard rate (44100, 48000, etc.)

OGG Vorbis:

• Channel configurations: Mono, Stereo
• Sample rates: Any standard rate

API Design

The SoundBuffer type provides:

• samples() - Access to interleaved f32 PCM data
• sample_rate() - Audio sample rate
• channels() - Number of audio channels
• duration_seconds() - Computed duration
• frame_count() - Number of audio frames

All decoding errors are mapped to AudioError variants without exposing Symphonia internals.

[github-actions]

✅ Coverage Report

📊 View Full HTML Report (download artifact)

Overall Coverage

Metric	Value
Total Line Coverage	38.82%
Lines Covered	4084 / 10519

Changed Files in This PR

File	Coverage	Lines
crates/lambda-rs-platform/src/audio/cpal/device.rs	61.12%	448/733
crates/lambda-rs-platform/src/audio/cpal/mod.rs	N/A	(no coverage data)
crates/lambda-rs-platform/src/audio/mod.rs	N/A	(no coverage data)
crates/lambda-rs-platform/src/audio/symphonia/mod.rs	66.87%	224/335
crates/lambda-rs-platform/src/cpal/mod.rs	N/A	(no coverage data)
crates/lambda-rs-platform/src/lib.rs	N/A	(no coverage data)
crates/lambda-rs/examples/play_slash_sound.rs	N/A	(no coverage data)
crates/lambda-rs/examples/sound_buffer_load.rs	N/A	(no coverage data)
crates/lambda-rs/src/audio/buffer.rs	68.22%	88/129
crates/lambda-rs/src/audio/devices/mod.rs	N/A	(no coverage data)
crates/lambda-rs/src/audio/devices/output.rs	32.64%	47/144
crates/lambda-rs/src/audio/error.rs	0.00%	0/31
crates/lambda-rs/src/audio/mod.rs	N/A	(no coverage data)
crates/lambda-rs/src/lib.rs	N/A	(no coverage data)
tools/lambda_audio/src/main.rs	0.00%	0/191

PR Files Coverage: 51.63% (807/1563 lines)

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_{Last updated: 2026-02-03 22:47:34 UTC · Commit: a4d7064}