Measure a track's integrated loudness (LUFS), true peak (dBTP), loudness range (LRA) and gating threshold. Call before/after mastering to verify levels against a target (hip-hop ~-9 to -10 LUFS, streaming -14, ceiling -1 dBTP).

Run a full professional mastering chain (corrective EQ -> glue compression -> 3-band multiband compression -> saturation -> harmonic exciter -> stereo stage -> driven limiter) with 2-pass loudnorm to hit an exact loudness/true-peak target. Outputs a 320kbps MP3. The 'spatial' option sets the stereo image: 'immersive' keeps the bass mono for a solid low end while widening the highs and adding subtle air for a bigger, more premium feel; 'subtle' adds light width; 'none' leaves the image as-is.

Mix a vocal over an instrumental with sidechain ducking (the beat dips under the vocal so words cut through), plus presence EQ + light reverb on the voice and the beat pulled underneath. Outputs a 24-bit WAV pre-master that you then feed to master_audio.

Encode a track to a Dolby codec: 'eac3' = Dolby Digital Plus (E-AC-3), 'ac3' = Dolby Digital. IMPORTANT: these are channel-based Dolby codecs (the 'Dolby' badge), NOT object-based Dolby Atmos, and for a stereo music single give no sonic benefit over a good stereo master. True Atmos requires Dolby's Renderer (e.g. Logic Pro) and the separate stems. Default stereo at 48kHz; set channels=6 for a basic 5.1 upmix.