Why it matters
A perfect master delivered in the wrong format, with wrong metadata or badly trimmed silences, causes delays, rejections by distributors, or defects at release. Delivery is part of mastering.
Main formats
| Destination | Typical format | Notes |
|---|---|---|
| Streaming / digital distributors | WAV or FLAC, 24 bit, 44.1 or 48 kHz | some distributors also accept 16 bit/44.1; check the specs |
| Apple Digital Masters (formerly “Mastered for iTunes”) | 24 bit, ideally high resolution | master designed for Apple's AAC encoding; requires the path indicated by the distributor |
| CD | DDP (Disc Description Protocol) at 16 bit/44.1 kHz | image file for the plant; includes tracks, gaps, ISRC, CD-Text |
| Vinyl | WAV 24 bit 44.1–96 kHz, one file per side or per track | separate master, less limited (see the dedicated lesson) |
| Video / sync / TV | WAV 24 bit 48 kHz | loudness per spec (e.g. EBU R128 −23 LUFS) |
| Promo, previews | MP3 320 kbps or AAC 256 kbps | never as a source for release |
| Club / DJ | WAV or AIFF 16/24 bit 44.1 kHz | formats supported by all players |
| Immersive audio | ADM BWF for Dolby Atmos | dedicated mix, not a converted stereo master |
The CD standard (Red Book)
16 bit, 44.1 kHz, stereo; maximum 99 tracks; standard length around 74–80 minutes; an initial gap (pre-gap) of 2 seconds before the first track; gaps between tracks chosen in mastering (even 0 for linked tracks). DDP avoids the errors of home-burned CD-Rs.
Metadata
- ISRC (International Standard Recording Code): a 12-character code that identifies each recording (country, registrant, year, number). It is assigned by the label or distributor (in Italy there are national agencies and many digital distributors provide it for free). Each different version (radio edit, instrumental, remix) has its own ISRC.
- UPC/EAN: product code (album, EP, single).
- CD-Text: titles and artist readable by players.
- Credits: writers, producers, engineers, musicians (entered in the distributor).
- BWF/iXML metadata can be embedded in the WAV file, but distributors mainly use the data entered in their system.
Versions to deliver
Main master; clean (without explicit language); instrumental; a cappella; TV mix (without lead vocal, for live TV performances); radio edit; extended mix for DJs; any stems for sync, remixes, live.
Preparing the files
- Clear name: “01_Artist_Title_Master_24-44.wav”.
- Silences: clean start (a few ms of silence or none, without cutting the transient), end with the complete tail and a fade to digital silence.
- True peak below the required limit (−1 dBTP for streaming is the most common recommendation; Spotify recommends −2 if the master is louder than −14 LUFS).
- No clicks at the start and end (a fade of a few ms).
- Final check: listen again to the exported files, not the session.
- Delivery document: track list, durations, ISRC, LUFS/true peak, notes.
Example
Pop single in A minor for an independent label: delivery as 24-bit/44.1 kHz WAV (master, instrumental, clean, TV mix), each with its own ISRC; master at −9 LUFS integrated, true peak −1.2 dBTP; MP3 320 for promotion; stems (drums, bass, music, vocals, FX) for the remix. Zip folder with a text file summarizing the data.
Common mistakes
- Delivering an MP3 as the master.
- Dither applied twice or 16-bit export when 24 was requested.
- End of the track cut off abruptly.
- ISRCs reused across different versions.
Exercise
Prepare the complete delivery of one of your singles as if for a label: all the files, the names, the metadata, and an accompanying PDF document.
Links
“Dithering, Bit Depth, and Conversion”, “Mastering for Streaming”, “Mastering for Vinyl”, “Mastering for Clubs”, “Goals of Mastering”.