Lexicon

AAudio

Android's modern low-latency audio API, often relied upon by audiophile-Android players as the route to bit-perfect output. The Engine does not use it. AAudio's “exclusive mode” promises bit-perfect delivery, but enforcement varies by OEM, firmware, and route — and even where genuine, the platform exposes no surface that proves it to the listener at runtime. The Engine bypasses AAudio entirely on the USB path, carrying its own native transport directly to the USB host controller, where the path is witnessed end to end.

Alt setting

A USB Audio Class term, short for alternate setting: a declared operating mode the device exposes to the USB host, specifying bit depth, sample rate, subslot size, and transport. A DAC may expose several alt settings — different bit depths at different rates — and the Engine chooses among them per fidelity policy: Wide picks the widest the device offers, Source Matching picks the exact match, Bit Perfect picks the exact match or declines.

Ambient Field

The Engine's set of optional dynamic backdrops behind the Player screen, drawn from the current track's album art or rendered procedurally as Vox-authored material. Each Ambient Field is a register — a slab, a panel, a mask. The category has sixteen modes; the listener picks one in Settings, and the Engine composes it live.

AudioFlinger

Android's system-level audio mixer, the layer that historically reroutes, resamples, or downmixes audio bound for the speaker, jack, or USB out. The Engine bypasses AudioFlinger entirely on the USB path — the decoded stream is committed directly to the USB host controller, so the platform mixer has no opportunity to alter the bytes.

Auguries

The dynamic listening surfaces the Engine composes from the listener's own patterns of return: what they reach for in a given hour, what they have not played in months, what shares a hand or a shelf with what they just played. The Auguries are local, computed on device, never dispatched outward. Eight kinds exist; the Engine surfaces them in the Library's Smart section, without being asked.

Bit Perfect

The strictest of the three fidelity policies. Under Bit Perfect, the Engine sends integer PCM to the USB wire exactly as it left the decoder — no float conversion, no DSP, no headroom adjustment, no resampling. If the connected DAC exposes no alt setting that matches the source format natively, Bit Perfect declines to play the track rather than alter it. The Sealed Witness's verdict is surfaced on the Pipeline Card under this policy.

Codex Machina

The Engine's in-app doctrinal canon: twenty-nine entries (0 through XXVIII) covering the reasoning behind every refusal, every transform, every architectural decision the Engine has made. The Codex is read inside the app, where the listener has already chosen to be a listener; it is the Engine's account of itself to its own audience.

Contained Heresy

The Engine's term for an alteration of the signal that would normally be forbidden, permitted only because it has been declared, bounded, and made revocable by doctrine. The Engine recognizes one Contained Heresy: Digital Volume Control under Bit Perfect, where listener-applied attenuation is admitted as a post-reservoir gain stage that preserves the integer bypass path. Bit Perfect refuses every other alteration; Contained Heresy is the lone, named exception. Bluetooth — which inherently transcodes — is presently under consideration by the Forge as a candidate Heresy for the Engine to admit, contained and declared.

Descriptor (USB)

The block of data a USB audio device publishes to the host on connection, declaring its alt settings, bit depths, sample rates, transport modes, and capabilities. The Engine treats the descriptor as ground truth: marketing copy, datasheets, and reviews may lie, but the descriptor is what the device itself says it can carry. Every routing decision the Engine makes is descriptor-witnessed.

DoP

DSD over PCM. A transport convention by which DSD audio is carried inside PCM-shaped USB frames: two DSD bytes packed into the lower 16 bits of a 24-bit container, with an alternating marker pattern in the upper 8 bits. The DAC strips the marker, recognizes the payload as DSD, and plays it natively. DoP is what most USB DACs that “support DSD” actually do; the Engine treats DoP as transport-legal under Source Matching and Wide, but refuses it under Bit Perfect, which permits only declared-native DSD.

DSD

Direct Stream Digital. A one-bit-per-sample audio format running at extreme sample rates (DSD64 at 2.8224 MHz, DSD128 at 5.6448, DSD256 at 11.2896, and higher orders such as DSD512 at 22.5792), the native encoding of SACD and a significant share of modern audiophile releases. The Engine carries DSD natively where the DAC declares native support, via DoP where the descriptor permits it, and by decimation to PCM where neither path exists — with the transformation always declared.

Engine

Vox Machina, the player itself. The word names the whole — decoder, pipeline, DSP, USB transport, library, UI — as a single instrument. The Forge speaks of the Engine; the listener uses it.

Fidelity Badge

The Engine's running declaration of what is actually happening to the current stream — not which policy is set, but what the live pipeline is doing to the bytes. The Badge resolves to one of three tiers — BIT PERFECT, LOSSLESS PROCESSING, or DSP ACTIVE — with an optional ATT suffix where the volume control is engaged. Under Bit Perfect policy with no DSP and no attenuation, the Badge reads BIT PERFECT; engage the volume control and the policy remains Bit Perfect, but the Badge becomes LOSSLESS PROCESSING · ATT — and the Sealed Witness, observing the same path, issues an ALTERED verdict for the same reason: the bytes leaving the Engine are not the bytes that left the decoder. The Badge declares what is happening, not what was intended.

Forge

The Vox Machina workshop: the keeper, the work, the discipline, and the standing rites. The Forge speaks; the Engine carries. The word is used in the same sense one names a smithy — a place where work is done, with a hand and an anvil behind it.

Gilded Census

The Engine's library scan rite. The Census is the deep cataloguing pass that reads every file's metadata, identifies its envelope and format, and assembles the searchable reliquary the Player draws from. The first Census of a large library takes time; subsequent passes reconcile changes only.

Gilded Lineage

The Engine's doctrine on how a track's identity — title, artist, album, date — is witnessed and preserved. Identity is read once, from the file itself, in a single deterministic cascade; where a tag is absent, the Engine declares lawful silence rather than fabricating a value; where the listener has supplied identity by their own hand, the Engine does not overwrite it. The Lineage is what makes a song the song, across rescans and across DAC swaps.

Integer Bypass

The Engine's name for its central fidelity guarantee: integer PCM remains integer PCM from decoder output to USB submission, never crossing into the float domain unless a DSP rite explicitly requires it. Integer Bypass is what makes Bit Perfect physically possible; the moment a sample crosses into float and back, bit-perfection is forfeit and the Engine declares it.

Iron Furnace

The Engine's resampler — a polyphase windowed-sinc filter with sixty-four phases and eight thousand one hundred ninety-two taps in total, running in ARM NEON double precision, with four selectable kernel modes (Mathematical, Minimum Phase, Apodizing, Brickwall). The Iron Furnace engages only when the destination alt setting cannot accept the source rate natively, and the transformation is always declared in the Fidelity Badge.

Outward Cadence

The Engine's optional scrobbling feature: the dispatch of the listener's play record to Last.fm or ListenBrainz, two open listening-history services. The Outward Cadence is silent by default and must be activated by the listener's hand with their own credentials; it is the only outward network channel the Engine exposes.

Pipeline Card

The Engine's live diagnostic surface, accessible from the Player. The Card declares every step the current track is traversing: envelope, decoder, pipeline domain, packing, DAC alt setting, final route, and — under Bit Perfect — the Sealed Witness verdict. The Card is the Engine's open ledger; nothing the Engine does is hidden from the listener.

Reliquary

The Engine's name for its local library catalogue — the assembled record of every track the Engine has read, with its identity, format, envelope, and provenance. The reliquary is the Player's source: every track surfaced anywhere in the UI is drawn from it. It is local, computed on device, never dispatched outward.

Sanctum (Anamnesium)

Spoken of by acolytes, in low whispers, as a chamber within the Engine where the Engine listens back. A hall that remembers — what the listener returned to in winter, what shared a hand or a shelf with what they just played, what was once held close and let slip. The Forge does not confirm what the acolytes describe. The Engine, when asked, opens a door.

Sealed Witness

The Engine's integrity check. The Witness computes a CRC32 over the decoded stream at the decoder boundary and compares it, after declared lawful transforms, against the CRC of the stream just before USB submission. Verdicts: VERIFIED (the path was bit-perfect end to end), ALTERED (a declared lawful transform such as Digital Volume Control altered the stream), MISMATCH (the path was not bit-perfect when bit-perfect was expected), UNVERIFIABLE. The verdict is surfaced on the Pipeline Card under Bit Perfect.

Source Matching

The middle of the three fidelity policies. Under Source Matching, the Engine chooses the DAC alt setting that matches the source format exactly — same bit depth, same sample rate, same transport — and routes the stream through it without padding or resampling. Where no exact match exists, Source Matching falls back to the nearest workable alt and declares the divergence. DSD is routed natively, via DoP, or by decimation to PCM, in that order of preference.

Sovereign Decimator

The Engine's name for its DSD-to-PCM decimation path, taken when a DAC accepts neither native DSD nor DoP and the listener has chosen Source Matching or Wide. The Decimator converts the one-bit DSD bitstream to multi-bit PCM at a rate the DAC can accept, with the transformation declared; the Fidelity Badge reads DSP ACTIVE, since decimation is a lossy filter that discards energy above the new Nyquist. Under Bit Perfect, no decimation occurs — DSD plays natively, or it does not play.

Subslot

The byte width of a single audio sample inside a USB Audio frame, as declared by the device descriptor. A 32-bit alt setting may have a subslot size of 4 (full 32-bit container) or 3 (24-bit data packed in a narrower container with the upper byte cleared) — and which is which matters for how the Engine packs the wire. The Wide policy ranks alt settings partly by minimum-subslot preference, so that what is transmitted is as close to the data's actual width as the alt allows.

URB

USB Request Block. The unit of data Android submits to the USB host controller for transmission to the connected device, and the level at which the Engine's visibility ends. The Sealed Witness's transport CRC is captured one step above — post-gain, immediately before USB submission — so what is verified is exactly what is about to leave the Engine.

Vinyl Field

The Engine's visual rite for the Player when album art is absent: an abstract obsidian field carrying five orbital broken-arc bands. Three material registers are available — Auramite at full lustre, Auramite subdued, and Graphite — each casting the bands in its own light. The Field is optional where the reliquary holds an image for a track, and obligatory where it does not — the Engine renders the Vinyl Field rather than leave the Player empty. Decorative only; it does not affect playback.

Wide

The most permissive of the three fidelity policies. Under Wide, the Engine surveys every alt setting the DAC exposes and chooses the widest the device offers — highest bit depth first, with subslot efficiency as a tiebreaker — zero-padding source samples MSB-justified into the larger container as needed. Wide trades minimal data alteration for maximum transport headroom; it engages the Iron Furnace only when the chosen alt cannot accept the source rate natively.