Name: 1-bit
Author: Ars

Why 1-bit?

DSD stores audio as a single bit per sample at 2.8, 5.6, or 11.2 MHz — the DAC reconstructs the waveform from density. iOS has no first-party way to play DSD. Most apps transcode it to 48 kHz PCM and move on. 1-bit doesn't.

What's new in 1.5

Play to a Chord 2Go (and other DLNA renderers) Cast to a DLNA / UPnP renderer on your network — the Chord 2Go is the headline target. The app sends the renderer the track's metadata and a link to the file on your own bridge; the renderer fetches the audio directly over your LAN. Bit-exact, nothing routed through a server I operate.

Playlist backup to your bridge Optional, off by default. Back up the playlists you build so they survive a reinstall or re-pair. They go only to the bridge you run — never to me or a third party. Per-bridge toggle in Settings.

Listening history to your bridge Optional, off by default. The app reports what you played — track, duration, format, output device — to your own bridge, viewable on its admin console. No account, no identity. Per-bridge toggle in Settings.

On-device diagnostics A small daily performance summary (CPU/energy, memory, playback runtime) from Apple's MetricKit, surfaced in the in-app diagnostics screen. It never leaves your device.

Same audio path No transcoding. No resampling. No hidden processing. The app — and the bridge — move bytes; the DAC (or DLNA renderer) does the rest.

What it does

Plays from three sources — an SMB share, a 1-bit bridge you run yourself, or files on the iPhone itself
Scans into a proper library — albums, artists, playlists, artwork
DSD (DSF) bit-exact to a USB DAC via DoP — DSD64, DSD128, DSD256
PCM (FLAC, ALAC, WAV, AIFF, MP3, AAC) at the file's native sample rate
Gapless between tracks when the format matches
Now Playing, Lock Screen, AirPods, and Apple Watch remote controls
CarPlay: browse, Now Playing, search, and tap-to-play on a CarPlay head unit (new in 1.4)
DLNA / UPnP renderers: play to a Chord 2Go or other DLNA renderer on your network, served bit-exact from your bridge (new in 1.5)

How DSD playback is handled

Bit-exact, end to end

DSF files are read off your network or local storage, wrapped in DoP (DSD-over-PCM) frames, and handed straight to the USB audio endpoint. There is no system mixer in the path, no resampling, no dithering, no hidden processing. If your DAC reports DoP lock, you are hearing the original 1-bit stream.

DSD playback uses a full file pre-cache by default, so the DoP marker stream cannot stutter mid-song under network jitter. An opt-in "Stream large DSD files" Settings toggle trades that for faster starts on a reliable link. PCM goes direct: the hardware sample rate is renegotiated to match the file — 44.1, 88.2, 96, 176.4, 192 kHz, whatever is on disk.

The render thread is lock-free: no syscalls during the audio callback, atomic publication of state across threads, and per-DAC PLL settling tuned for the trickier hardware (Chord FPGAs need longer than most). DoP marker phase is preserved across track boundaries so gapless DSD doesn't flicker between songs.

Going through a 1-bit bridge? TLS fingerprint pinning means only the bridge you paired with — captured on first contact — can serve audio to your phone. No public CA, no MITM window, no transcoding on the wire.

Three sources, one library

SMB share Point the app at your NAS or Mac File Sharing, scan, listen. Credentials live in the iOS Keychain.

1-bit bridge ↗ Free, open-source companion server. Faster than SMB, reachable over Tailscale or WireGuard, side-steps the Samba edge cases.

On-device library Drop files into the app's Documents folder via Files or Finder over USB. No server needed.

Requirements

iOS 26.1 or later, iPhone or iPad
At least one of: an SMB share (Synology, QNAP, TrueNAS, macOS File Sharing, Samba), a 1-bit bridge on Mac / Windows / Linux / Raspberry Pi, or files in the app's Documents folder
For DSD: a USB DAC with DoP support (USB-C or a Lightning-to-USB camera adapter). PCM plays through any output, including Bluetooth and the built-in speaker.

Privacy at a glance

No account, no sign-up, no analytics, no ads, no tracking.
SMB credentials and bridge bearer tokens stay in the iOS Keychain on your device.
Zero personal data collected — inherently complies with the GDPR, the Swiss FADP, and the CCPA.
Full privacy policy →

1-bit