The short answer
Deliver a stereo WAV or FLAC at the resolution you mixed in: 16-bit or 24-bit, 44.1 kHz or higher, never an MP3. Keep true peaks at -1 dBTP or lower and let store normalisation handle loudness. Dolby Atmos is a separate ADM file from a real spatial mix, worth it only when mix and budget are real.
Formats: WAV or FLAC, nothing lossy
Stores accept two source formats: WAV and FLAC. Both are lossless; FLAC is a compressed container for the same audio and unpacks to an identical file. Your distributor converts what you deliver into every format each store streams, so what you send is the ceiling of quality.
That is why an MP3, AAC or M4A should never be the source. A lossy file encoded again loses more, and many stores reject it outright. If an old master survives only as an MP3, say so and ask your distributor how to handle it rather than renaming the file.
Sample rate and bit depth
Deliver at the resolution the track was mixed and mastered in. 44.1 kHz at 16-bit is the CD standard and remains fully acceptable; 24-bit at 44.1, 48, 88.2 or 96 kHz is preferred by most stores and feeds the lossless and high-resolution tiers. Most stores accept up to 192 kHz and 24-bit.
Two mistakes are common. Upsampling a 44.1 kHz, 16-bit master to 96 kHz, 24-bit adds no quality and may be flagged; deliver the native file. Reducing 24-bit to 16-bit without dither adds faint distortion; apply dither once at the final export, or deliver the 24-bit file.
- Stereo; no multichannel in the standard file
- 16-bit or 24-bit; 24-bit preferred when the mix was made in it
- 44.1 kHz minimum; keep the native rate, do not upsample
- No clipping: sample peaks below 0 dBFS
Loudness: mastering for normalisation
Every major store normalises playback: it turns quiet songs up and loud songs down so a listener does not reach for the volume between tracks. The reference levels differ by service but sit roughly between -14 and -16 LUFS integrated. A master pushed far louder is simply turned down, and what remains is the distortion the limiting caused.
The practical targets are modest. Keep true peaks at -1 dBTP or lower, nearer -2 dBTP for a loud master, because the lossy encoding stores apply can push peaks above the original. Aim for an integrated loudness that suits the genre rather than a number: an acoustic ballad can sit well below -14 LUFS and sound better for it. Check in mono too. Trim silence at the start, keep the ending short, and keep an album consistent in level.
What Dolby Atmos actually is
Dolby Atmos is a spatial format: instead of a left and a right channel, the mix is a bed of channels plus sound objects placed in three-dimensional space, which each device renders for its own speakers or headphones. It is delivered as an ADM BWF file, a WAV container carrying that object metadata, at 48 kHz and 24-bit, with loudness around -18 LUFS and true peaks at -1 dBTP. The stereo master is still delivered separately.
Apple Music, Amazon Music and Tidal stream it, and Apple Music has said it gives extra weight in its royalty calculation to tracks available in Spatial Audio. Not every distributor delivers Atmos, so ask before you commission a mix; an automatic upmix of a stereo file is usually rejected.
When Atmos is worth it
An Atmos mix needs an engineer with the Dolby tools, ideally in a calibrated room, and costs more per track than a stereo mix. It is worth that cost when the stereo production is finished and strong, when the arrangement has real space to use, such as orchestral, live, ambient or richly layered electronic music, and when the release has a budget and a plan for the playlists that feature spatial tracks.
It is not worth it for a quick single, a demo-quality production or a catalogue moved in bulk. Start with one track you trust, judge it on headphones and a spatial speaker, then decide about an album.
A delivery checklist
Before you upload, open the file and confirm each line below; audio is the one thing your distributor cannot fix for you. At Mazufa Records it is checked on receipt and delivered as supplied, on the same terms for every release: no upload fee, no subscription, no per-release fee; the revenue share is set out in your written agreement.
- WAV or FLAC, stereo, native sample rate, 16-bit or 24-bit
- True peak -1 dBTP or lower, no clipping, dither once if reduced to 16-bit
- Silence trimmed; track order and lengths match the metadata
- Atmos: ADM BWF, 48 kHz, 24-bit, a genuine spatial mix, stereo master alongside
Questions people ask
Is 24-bit, 96 kHz better than 16-bit, 44.1 kHz on the stores?
Only if the music was recorded and mixed at that resolution. Delivering the native file is what matters; upsampling adds nothing, and converting down without dither does harm. Both are accepted everywhere.
What loudness should I master to for streaming?
There is no single number. Services normalise to roughly -14 to -16 LUFS, so far louder masters are turned down. Keep true peaks at -1 dBTP or lower and let the genre decide the integrated level.
Can I make an Atmos version from my stereo master?
Not with an automatic upmix; stores usually reject those. A real Atmos mix starts from the stems or the session and is built by an engineer with the Dolby tools. With only a stereo master, release in stereo.