What Does "Lossless" Mean in Audio?
A lossless audio format compresses audio without discarding any data. When decompressed, the result is bit-for-bit identical to the original — unlike MP3, AAC, or OGG which discard audio information to reduce size.
Lossless formats are essential for professional archiving, audio editing and mastering, audiophile playback, and future re-encoding without cumulative quality loss.
WAV — The Uncompressed Classic
WAV (Waveform Audio File Format) — developed by Microsoft and IBM in 1991:
- Pure PCM audio, no compression.
- ~10 MB per minute at 44.1 kHz/16-bit stereo.
- Compatible with every audio software.
- Limited metadata (no cover art or lyrics).
Use for: studio recording, DAW interchange, broadcast/film delivery.
AIFF — Apple's WAV
Apple's WAV equivalent: same PCM, same file size. Better metadata support. Native on macOS, Logic Pro, Pro Tools.
FLAC — Open-Source Lossless Compression
FLAC (Free Lossless Audio Codec):
- 50–60% size reduction vs. WAV.
- Fully open source and royalty-free.
- Rich metadata: cover art, lyrics, custom tags.
- Supports up to 8 channels (7.1 surround).
- Not natively supported by iOS, iTunes/Apple Music.
Use for: personal music library on PC/Android, high-quality music distribution.
ALAC — Apple's FLAC
ALAC (Apple Lossless Audio Codec) — open-sourced by Apple in 2011:
- 40–60% size reduction vs. WAV.
- Native on Apple: iTunes, Apple Music, iOS, macOS, iPod.
- Uses
.m4aextension (shared container with AAC).
Use for: Apple ecosystem (iPhone, Mac, Apple Music).
Quick Comparison
| Format | Compression | Metadata | Compatibility | Open Source |
|---|---|---|---|---|
| WAV | None | Basic | ✅ Universal | — |
| AIFF | None | Good | ✅ Mac/Pro | — |
| FLAC | 50–60% | Complete | ✅ PC/Android | ✅ |
| ALAC | 40–60% | Complete | ✅ Apple | ✅ |
File Size: 4-minute Song at 44.1 kHz / 16-bit
| Format | Size |
|---|---|
| MP3 320 kbps | ~10 MB |
| FLAC | ~25–30 MB |
| ALAC | ~28–35 MB |
| WAV | ~42 MB |
Convert with FFmpeg
# WAV to FLAC
ffmpeg -i song.wav song.flac
# FLAC to ALAC (M4A container)
ffmpeg -i song.flac -c:a alac song.m4a
# ALAC to FLAC
ffmpeg -i song.m4a -c:a flac song.flac
Which Format to Choose?
- Audio production / DAWs: WAV or AIFF — maximum plugin compatibility.
- Personal archive on PC/Android: FLAC — better compression, rich metadata.
- Apple ecosystem: ALAC — native on all Apple devices.
- Streaming platform delivery: WAV or FLAC (Spotify, Apple Music, Tidal accept both).
Conclusion
All three reproduce exactly the same audio quality — the differences are file size and compatibility. FLAC for PC/Android, ALAC for Apple, WAV for professional production.
Advanced Use Cases
Beyond casual conversion, modern audio formats cover highly specific professional scenarios. Music production: professional studios work with WAV or FLAC during mastering to avoid cumulative loss between passes — lossless format guarantees every modification is bit-perfect relative to the previous state. Streaming platform distribution: Spotify accepts WAV/FLAC at upload but re-encodes to Ogg Vorbis 320 kbps for Premium and AAC 128 kbps for free users; Apple Music uses AAC 256 kbps VBR; Tidal and Qobuz distribute FLAC for audiophiles. Professional podcasting: Apple Podcasts recommends AAC 128 kbps mono for voice (optimal efficiency); Spotify accepts MP3 192 kbps; master files are saved in WAV for future remasters. Audiobooks: Audible uses AAX (DRM variant of AAC) with variable bitrate by quality. Video games: many engines (Unity, Unreal) prefer OGG Vorbis for its royalty-free status and perfect looping support.
Best Practices and Professional Tips
Archival workflow: always keep a master FLAC or WAV of every important audio file. Lossy formats (MP3, AAC, OGG) are derivatives — you can always generate MP3 from FLAC, but never recover quality lost in the reverse direction. Bitrate selection: for music, MP3 320 kbps or AAC 256 kbps are indistinguishable from lossless on casual equipment; for podcast 96-128 kbps mono is enough. Sample rate: 44.1 kHz is the CD standard for music; 48 kHz for video; 96/192 kHz only adds value in professional production with studio monitoring. Metadata and cover art: always use ID3v2.4 with UTF-8 to ensure special characters (accents, ñ, Chinese symbols) display correctly in any player. Embed cover art at 600×600 px JPEG progressive — universally recognized standard format.
Compatibility and Technical Considerations
KaijuConverter processes audio files on dedicated cloud infrastructure with FFmpeg 6.x as the main engine and the best available codec libraries (LAME 3.100 for MP3, libfdk-aac for AAC, FLAC reference encoder, libopus for Opus). Processing is streaming — we don't wait to receive the full file before starting to process, significantly reducing perceived latency. We support files up to 200 MB with sample rates from 8 kHz to 192 kHz, depths of 16/24/32-bit (including float for professional editing), and configurations from mono to surround 7.1 when the destination format allows. Privacy: files are processed in isolated Docker containers, encrypted in transit with TLS 1.3, and automatically deleted with multi-pass overwrite after 2 hours. DRM: protected files (Apple Music DRM, Audible AAX) cannot be converted — DRM blocks access to the original stream. For those cases, you must obtain a legal DRM-free version before conversion.
Related conversions
Audio format pairs that come up most often: