Inline fixes:
- Remove TDRC frame from ID3 writer (ID3v2.3 uses TYER only, not TDRC)
- Add try/finally cleanup in worker to prevent VFS leaks on errors
- Fix Blob creation to use Uint8Array directly (avoid extra bytes)
- Replace loadFFmpeg race guard with promise singleton pattern
- Add -map_metadata -1 to strip source metadata (prevent duplicate ID3)
Error handling improvements:
- Create MP3EncodingError class with code property for reliable detection
- Update api.js to use instanceof check instead of string matching
- Pass AbortSignal to encodeToMp3 for proper cancellation support
- Remove error re-wrapping in mp3-encoder.js (preserve original errors)
Technical details:
- Promise singleton ensures FFmpeg loads once even with concurrent calls
- AbortSignal listener properly cleaned up on success/error/abort
- Virtual FS cleanup in finally block prevents file leaks
- MP3EncodingError.code = 'MP3_ENCODING_FAILED' for robust detection
Implements MP3 320kbps download functionality using ffmpeg.wasm for
industry-standard encoding with libmp3lame.
Features:
- New MP3_320 quality option in download settings UI
- ID3v2.3 metadata writing (title, artist, album, cover art, ISRC, etc.)
- Non-blocking encoding via Web Worker to keep UI responsive
- Proper UTF-16 with BOM text encoding for international characters
- Album artist fallback to track artist (mirrors FLAC/M4A behavior)
- Automatic format detection for downloaded audio
- Year validation to prevent writing NaN to ID3 tags
Implementation:
- mp3-encoder.js: Main encoder module with worker orchestration
- mp3-encoder.worker.js: FFmpeg Web Worker for async encoding
- id3-writer.js: ID3v2.3 tag writer with synchsafe size encoding
- Updates to api.js, metadata.js, utils.js for MP3 support
- Vite config excludes @ffmpeg packages from dep optimization
Technical details:
- Uses @ffmpeg/ffmpeg (libmp3lame 320kbps CBR, 44.1kHz)
- FFmpeg binary lazy-loaded from CDN (~25MB, cached)
- Encoding runs in separate thread (non-blocking UI)
- Proper error handling with distinct encoding vs network errors
- Memory-efficient: transfers ArrayBuffer with zero-copy
Dependencies:
- @ffmpeg/ffmpeg ^0.12.10
- @ffmpeg/util ^0.12.1
- Removed: package-lock.json (project uses bun.lock)
Closes maintainer request to use ffmpeg.wasm instead of lamejs.
