Audio Package - Known Issues

🟠 Major Issues

AUD-001: Go Mixer uses unsafe pointer casting

File: go/pkg/audio/pcm/mixer.go:226

Description:
The mixer uses unsafe.Slice and unsafe.Pointer to cast between []byte and []int16:

i16 := unsafe.Slice((*int16)(unsafe.Pointer(&p[0])), len(p)/2)

Risk:

• Platform-dependent endianness (assumes little-endian)
• Potential undefined behavior if buffer alignment is wrong

Impact: May produce incorrect audio on big-endian systems.

Suggestion: Add explicit little-endian encoding/decoding or document platform requirements.

AUD-002: Rust opusrt missing OGG Reader/Writer

Description:
Go opusrt has OggReader and OggWriter for reading/writing Opus in OGG containers. Rust implementation is missing these.

Impact: Cannot read/write Opus files in OGG format in Rust.

Status: ⚠️ Partial implementation.

AUD-003: Rust missing portaudio module

Description:
Go has audio/portaudio for audio device I/O. Rust has no equivalent.

Impact: Cannot capture/play audio from hardware devices in Rust.

Status: ❌ Not implemented.

🟡 Minor Issues

AUD-004: Go Format panics on invalid value

File: go/pkg/audio/pcm/pcm.go:36-38

Description:
Format.SampleRate(), Channels(), Depth() all panic on invalid format:

func (f Format) SampleRate() int {
    switch f {
    // ...
    }
    panic("pcm: invalid audio type")
}

Impact: Runtime panic instead of error return.

Suggestion: Return (int, error) or use MustXxx naming convention for panicking versions.

AUD-005: Go SilenceChunk uses fixed global buffer

File: go/pkg/audio/pcm/pcm.go:177

Description:
Uses a shared fixed-size zero buffer and loops for long durations.

Impact: None functionally; avoids repeated allocations.

Status: Not a bug. Keep as implementation note only.

AUD-006: Go Opus encoder max frame size hardcoded

File: go/pkg/audio/codec/opus/encoder.go:95

Description:
Encode function allocates fixed 4000 byte buffer:

buf := make([]byte, 4000)

Impact: Allocation on every encode call.

Suggestion: Use buffer pool or allow caller to provide buffer.

AUD-007: Rust Format re-export from resampler is confusing

File: rust/audio/src/pcm/format.rs:7

Description:
pcm::Format is actually re-exported from resampler::Format:

#![allow(unused)]
fn main() {
pub use crate::resampler::format::Format;
}

Impact: Confusing import paths, circular dependency appearance.

Suggestion: Define Format once at top level and import in both modules.

AUD-008: Go mixer notifyWrite spawns goroutine every call

File: go/pkg/audio/pcm/mixer.go:391-405

Description:
notifyWrite() spawns a new goroutine each time:

func (mx *Mixer) notifyWrite() {
    go func() {
        // ...
    }()
}

Impact: Goroutine overhead for every write notification.

Suggestion: Use single dedicated notification goroutine or avoid goroutine.

🔵 Enhancements

AUD-009: No stereo format support in predefined formats

Description:
Only mono formats are predefined (L16Mono16K, etc.). No stereo formats.

Suggestion: Add L16Stereo16K, L16Stereo24K, L16Stereo48K.

AUD-010: No 8-bit or 24-bit PCM support

Description:
Only 16-bit PCM is supported. Some audio sources use 8-bit (low quality) or 24-bit (high quality).

Suggestion: Add format variants for different bit depths.

AUD-011: Resampler quality not configurable

File: go/pkg/audio/resampler/soxr.go:52

Description:
Quality is hardcoded to SOXR_HQ:

qSpec := C.soxr_quality_spec(C.SOXR_HQ, 0)

Impact: Cannot trade quality for performance when needed.

Suggestion: Add quality parameter to New().

AUD-012: No WAV file support

Description:
No utilities for reading/writing WAV files, only raw PCM.

Suggestion: Add WAV header parsing/writing for file I/O.

⚪ Notes

AUD-013: CGO/FFI dependency complexity

Description:
Both Go and Rust rely heavily on CGO/FFI for native codec libraries. This adds:

• Build complexity (pkg-config, Bazel rules)
• Platform-specific issues
• Memory management concerns

Status: Necessary for performance, but increases maintenance burden.

AUD-014: Mixer uses float32 internally

Description:
Mixer converts int16 PCM to float32 for mixing, then back to int16:

// int16 → float32
s := float32(trackI16[i])
// ... mix ...
// float32 → int16
i16[i] = int16(t * 32767)

Impact: Slight precision loss during mixing, but standard practice.

Summary

Overall: Functional audio processing with significant native library integration. Main gaps are Rust parity (opusrt OGG, portaudio) and some unsafe code patterns.