tdarr-plugs/agent_notes/audio_review.md

Audio Standardizer Plugin - Code Review

🔴 Critical Issues

1. Quality preset bitrate display is incorrect (Line 623-624)

response.infoLog += `  Stereo downmix bitrate: ${stereoBitrate}kbps (calculated: 2 × ${inputs.bitrate_per_channel})\\n`;

• Displays inputs.bitrate_per_channel which could be 'auto' or 'original' (not a number)
• Should show actual numerical value used

2. Missing validation for preset quality (Line 261)

const preset = QUALITY_PRESETS[inputs.quality_preset];
if (!preset) {
  return inputs; // Silent failure
}

• Should log warning if preset not found

🟡 Medium Issues

3. Inconsistent emoji usage in logs

• Mix of ☑️ (check) for errors and successes
• Use ❌ for errors, ✅ for success, ℹ️ for info

4. Unused small_size preset has incorrect Opus bitrate

small_size: {
  opus_bitrate_per_channel: '48',  // 48kbps is very low for Opus

• Opus minimum bitrate should be 64kbps for acceptable quality
• 48kbps may produce poor audio

5. Duplicate bitrate calculation in downmix (Lines 319, 590)

const stereoBitrate = calculateBitrate(inputs, 2, null); // Line 319
...
const stereoBitrate = calculateBitrate(inputs, 2, null); // Line 590

• Calculate once and reuse

6. No minimum bitrate threshold

• Unlike video plugin, no floor for calculated bitrates
• Could result in unusable <16kbps audio with certain inputs

7. Opus compression level hardcoded (Line 299)

-compression_level 10

• Could be exposed as input option (0-10 range)
• Higher = slower but better quality

🟢 Potential Improvements

8. Add audio sample rate handling

• No validation or handling of unusual sample rates
• Could add resampling option (48kHz standard for streaming)

9. Add language/title metadata preservation

• Currently only adds "2.0 Downmix" title
• Should preserve original audio titles and language tags

10. Add normalization option

• EBU R128 loudness normalization would be useful
• Common for streaming content

11. Version bump needed

• After fixes, increment from 1.04

12. Add channel layout validation for Opus incompatible layouts

• Currently only logs layout compatibility
• Could warn user before processing

13. Improve auto bitrate calculation

const targetBitrate = 64 * channels; // Line 236

• 64kbps may be overkill for mono/stereo
• Could use: Math.max(32, Math.min(96, 48 * Math.log2(channels + 1)))

14. Add AAC profile selection

• Currently uses default AAC-LC
• Could expose AAC-LC vs AAC-HE vs AAC-HEv2

15. Add 5.1 → 5.1 downmix from 7.1

• Currently only creates 2ch from 6ch/8ch
• Missing 8ch → 6ch downmix option

📋 Redundancies

16. Duplicate COMPATIBLE_CODECS array (Line 171)

• Already defined as constants
• Use CODECS.AAC, CODECS.OPUS, CODECS.LIBOPUS directly everywhere

17. Redundant opus codec check (Lines 530-537)

if (!streamNeedsTranscode) {
  streamNeedsTranscode = true; // Redundant assignment
}

• Can simplify logic

18. Empty lines (415-416)

• Two blank lines in validation function

🔧 Optimizations

19. Use Set for OPUS_INCOMPATIBLE_LAYOUTS

const OPUS_INCOMPATIBLE_LAYOUTS = new Set([...]);

• Faster lookups with .has() vs .includes()

20. Cache regex for star removal

• Currently creates new slice operation each iteration
• Minor but could optimize

21. Reduce try-catch blocks

• Three separate try-catch blocks (Lines 474, 525, 585)
• Could consolidate error handling

🎯 Priority Fixes Table

Priority	Line(s)	Issue	Fix
🔴 High	623-624	Incorrect bitrate display	Show numerical value
🔴 High	261-264	Silent preset failure	Add warning log
🟡 Medium	throughout	Inconsistent emoji	Standardize: ❌ ✅ ℹ️ ⚠️
🟡 Medium	212	Low Opus bitrate	Change 48 → 64 kbps
🟡 Medium	319, 590	Duplicate calculation	Calculate once
🟡 Medium	-	No minimum bitrate	Add 32kbps floor
🟢 Low	-	No sample rate handling	Add resampling option
🟢 Low	-	Missing metadata	Preserve titles/languages
🟢 Low	171	Redundant array	Use constants directly
🟢 Low	299	Hardcoded compression	Expose as option

Summary

Total Issues Found: 20
Critical: 2
Medium: 5
Low/Enhancement: 13

Most pressing fixes:

1. Fix bitrate display in final summary
2. Add minimum bitrate threshold (32kbps)
3. Fix small_size preset Opus bitrate (48 → 64 kbps)
4. Standardize emoji usage
5. Add preset failure warning