Checks an audio file before it goes to a distributor: format, sample rate and bit depth against Apple's delivery requirements, bits that only pad the file, clipping, true peak, DC offset, silence at the start and the end, and title, artist, ISRC and cover from the tags. The file is read in the browser and not uploaded.
Choose the release file
WAV, RF64, AIFF, FLAC, MP3, M4A, Ogg Vorbis and Opus. WAV and AIFF are read sample by sample; the other formats go through the browser's decoder.
| Check | Value | Finding |
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| Field | Value | Stored in |
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Apple Music takes audio at 44.1, 48, 88.2, 96, 176.4 or 192 kHz with 16 or 24 bits and asks for the master in the highest resolution available. A lossy file does not meet that: the encoder has already discarded parts of the signal, and the service encodes once more.
Bits in use: for every sample the lowest bits are checked. If they are zero throughout the file, the extra depth carries nothing, as with a 16-bit master saved as 24 bits. Apple Digital Masters explicitly rules out this padding. In floating-point files the check asks whether every value lies on the 16-bit or the 24-bit grid.
Full scale is the highest integer value, and three or more such samples in a row count as a clipped passage. The true peak follows ITU-R BS.1770 with the 48-coefficient filter at four times oversampling. It finds peaks between the samples that a conversion or an encoder turns into real ones.
Silence here means below −60 dBFS. The limits of one second at the start, five seconds at the end, −40 dBFS for the first and the last sample and −60 dBFS for the DC offset are rules of this check, not requirements of a service. They mark what is worth a listen before the upload.
Tags are read from ID3v2 and ID3v1, from Vorbis comments in FLAC, Ogg and Opus, from RIFF INFO and ID3 chunks in WAV and AIFF, and from the MP4 metadata. For the ISRC the field matters: TSRC in ID3, ISRC in Vorbis comments. ffmpeg writes other fields for -metadata ISRC=…, as the article on release metadata measured.
Apple recommends 3000 × 3000 pixels or more, requires at least 1400 × 1400 and a square image, as JPEG or PNG. The check uses the embedded image; the cover uploaded to the distributor is a separate file.
Sources: Apple Music Provider Support: Digital packaging for music · Apple Digital Masters · ITU-R BS.1770 · AES TD1008 · ISRC Handbook · ID3v2.4 frames · Vorbis comment · RIFF Tags (ExifTool)
The requirements quoted are Apple's; other distributors publish their own. Formats other than WAV and AIFF depend on the browser's decoder, which in some browsers cannot read ALAC or compressed AIFC. Loudness is measured by the LUFS meter.