Supported audio formats
BitDek plays the files you have, the way you have them. No transcoding, no conversion, no compromise.
Supported formats
Section titled “Supported formats”| Format | Extension | Compression | Quality | Notes |
|---|---|---|---|---|
| FLAC | .flac | Lossless | CD to Hi-Res | Full multi-genre support |
| ALAC | .m4a | Lossless | CD to Hi-Res | Apple Lossless Audio Codec |
| AAC | .m4a, .aac | Lossy | Very good | Common iTunes format |
| MP3 | .mp3 | Lossy | Good | Universal compatibility |
| WAV | .wav | Uncompressed | CD to Hi-Res | Limited metadata support |
| AIFF | .aiff, .aif | Uncompressed | CD to Hi-Res | Apple’s uncompressed format |
Lossless vs. lossy
Section titled “Lossless vs. lossy”Lossless formats (FLAC, ALAC, WAV, AIFF) preserve every bit of the original audio. Lossless playback preserves the audio exactly as it was encoded. File sizes are larger, typically 20-40 MB per track for CD-quality audio.
Lossy formats (MP3, AAC) reduce file size by discarding audio information deemed less perceptible. At high bitrates (256-320 kbps), the difference is subtle for most listeners. File sizes are smaller, typically 5-10 MB per track.
BitDek plays both equally well. Your ears and your storage space determine the right choice for your collection.
Metadata capabilities by format
Section titled “Metadata capabilities by format”Not all formats handle metadata equally. This matters if you care about genre organization or classical music fields.
FLAC uses Vorbis comments, a flexible tagging system with no fixed field limits.
Strengths:
- Multiple genres per track, as repeated GENRE tags or one delimited string
- Multiple artists per track
- Full classical music field support (Work, Movement Name, etc.)
- Large embedded artwork
- Custom fields for any purpose
How BitDek reads FLAC: Native parsing of Vorbis comments without relying on iOS system libraries. This ensures full multi-genre support.
MP3 uses ID3 tags, the original digital music metadata standard.
Strengths:
- Universal compatibility
- Mature tooling for editing
- Embedded artwork support
- Classical music fields (ID3v2.4)
Limitations:
- Multiple genres survive only as a delimited string. Taggers writing ID3v2.4’s null-separated lists lose everything after the first genre
- No repeated-tag support the way Vorbis comments have
How BitDek reads MP3: Through iOS AVFoundation, which handles ID3v2.3 and ID3v2.4 reliably. See Multi-genre tagging for the one tagger setting worth changing.
M4A (AAC and ALAC)
Section titled “M4A (AAC and ALAC)”M4A files use Apple’s iTunes metadata format.
Strengths:
- iTunes compilation flag support
- Good classical music field support
- Embedded artwork
- Efficient storage for lossy audio
Limitations:
- Multiple genres survive only as a delimited string in the one genre atom
- Some specialized fields require iTunes-specific atoms
How BitDek reads M4A: Through iOS AVFoundation, which handles Apple’s native format well.
WAV and AIFF
Section titled “WAV and AIFF”Uncompressed formats designed for production work.
Strengths:
- Full resolution audio quality
- Zero processing overhead
Limitations:
- Minimal metadata support
- Large file sizes
- Artwork often missing
- Files ending in
.aifrather than.aiffimport from source folders and WiFi Transfer, but not from the share extension
Recommendation: For listening collections, FLAC provides identical audio quality with better metadata and smaller files. Reserve WAV/AIFF for production masters where you need uncompressed audio for editing.
Format comparison table
Section titled “Format comparison table”| Feature | FLAC | ALAC | AAC | MP3 | WAV | AIFF |
|---|---|---|---|---|---|---|
| Audio quality | Lossless | Lossless | Very good | Good | Lossless | Lossless |
| File size | Medium | Medium | Small | Small | Large | Large |
| Multi-genre | Repeated tags or delimited | Delimited only | Delimited only | Delimited only | No | No |
| Embedded artwork | Yes | Yes | Yes | Yes | Limited | Limited |
| Classical fields | Full | Full | Good | Good | Limited | Limited |
| Compilation flag | Yes | Yes | Yes | Yes | No | No |
Choosing a format
Section titled “Choosing a format”For audio quality purists: FLAC or ALAC. Both are lossless. FLAC has better metadata support. ALAC integrates better with Apple devices and iTunes.
For maximum compatibility: MP3 at 320 kbps. Plays everywhere, sounds good enough for most situations, smallest files.
For Apple ecosystem users: AAC at 256 kbps. Apple’s preferred lossy format, excellent quality, good metadata.
For genre-heavy collectors: FLAC. Every format can carry multiple genres in BitDek, but FLAC is the only one where they can live as separate tags, so nothing depends on a separator your tagger might drop.
Converting your collection
Section titled “Converting your collection”If you want to convert existing files to a different format, several tools can help:
- XLD (Mac) - Excellent for lossless conversions, preserves metadata
- dBpoweramp (Windows/Mac) - Comprehensive format conversion
- fre:ac (Cross-platform) - Free, open-source converter
When converting from lossless to lossless (WAV to FLAC, for example), audio quality is preserved perfectly. Converting from lossy to lossless (MP3 to FLAC) does not improve quality and wastes storage space.
Technical details
Section titled “Technical details”FLAC parsing
Section titled “FLAC parsing”BitDek uses a native FLAC parser that reads only the metadata blocks at the start of each file. For a 500 MB FLAC file, only the first ~1 MB is read during import. This makes large-file imports fast and efficient.
Vorbis comment parsing handles both standard field names (ARTIST, ALBUM, TITLE) and common variations (ALBUMARTIST vs ALBUM ARTIST).
AVFoundation PROCESSING
Section titled “AVFoundation PROCESSING”For non-FLAC formats, BitDek uses iOS AVFoundation’s AVAsset API to extract metadata. This ensures compatibility with Apple’s native handling of MP3, M4A, AAC, WAV, and AIFF files.
AVFoundation reads metadata efficiently but has one notable limitation. A text frame holding several values as a null-separated list, which ID3v2.4 permits, comes back truncated at the first value. Genres written that way lose everything after the first. Genres written as one delimited string are read in full and split by BitDek.
Audio playback
Section titled “Audio playback”BitDek uses AVAudioEngine for playback, providing:
- Hardware-accelerated decoding
- Gapless track transitions
- Real-time audio analysis for visualizations
- System audio session integration
The playback engine handles all supported formats identically. Once decoded, audio quality depends only on the source file.
Further reading
Section titled “Further reading”- How BitDek reads your tags - Field-by-field extraction details
- Multi-genre tagging - Making the most of FLAC’s multi-genre support
- Recommended tagging tools - Software for managing your collection