It's 404, yo!
SP-404 sample pack converter
It's 404, yo! batch-converts a whole sample pack into the format the Roland SP-404 MkII imports from an SD card: 16-bit linear PCM WAV at 48 kHz, or 44.1 kHz if you choose. It keeps your folder structure, copies files that already import cleanly untouched, and says in plain words what it changes in the rest, such as “32-bit float → 16-bit”, “96 kHz resampled” or “FLAC → WAV”. It is for SP-404 MkII owners whose downloaded packs come up as “Unsupported File”. It runs offline with no account, and your samples never leave your Mac.
For developers
How the app behaves, why it targets the format it does, how to build it, and how it is put together.
What it does
Drop a folder (or files) → see exactly what will change, in plain language → click
Make SP-404 Ready → get a converted copy that imports cleanly.
- Analyzes every file and tells you why it would fail (
32-bit float → 16-bit,
96 kHz resampled, FLAC → WAV).
- Converts to the documented safe target: 16-bit linear PCM WAV, 48 kHz (or 44.1),
channels preserved, exotic metadata chunks stripped.
- Copies already-compatible files unchanged, no needless re-encoding.
- Preserves your folder structure in the output.
- Warns about edge cases (over 16 min / ~185 MB, or under 100 ms).
- Optionally sanitizes file names for SD-card import (off by default), keeping structure.
Everything runs offline, on-device. No network, no account, no data leaves your Mac.
The target format (why these choices)
The SP-404 MkII processes audio internally at 16-bit linear PCM / 48 kHz and conforms all
imports to it. Direct SD-card import accepts only 16-bit linear WAV/AIFF/MP3; anything else
risks “Unsupported File.” See docs/build-spec.md for the full,
source-cited specification.
| Aspect | Rule |
|---|
| Codec | Linear PCM WAV |
| Bit depth | Force 16-bit (handles 32-bit float, 24-bit, …) |
| Sample rate | 48 kHz (default) or 44.1 kHz; resample anything else |
| Channels | Preserve mono/stereo |
| Metadata | Dropped via a clean WAV re-write |
Requirements
- macOS 13 (Ventura) or newer
- Xcode 16+ and XcodeGen to build from source
Build from source
The Xcode project is generated from project.yml (it is not committed).
brew install xcodegen # one-time
make generate # writes Its404Yo.xcodeproj
make open # open in Xcode
# or, headless:
make build
make test
See the Makefile for the underlying commands.
Architecture
A small SwiftUI app over a Core Audio conversion engine. See
docs/ARCHITECTURE.md.
- UI: SwiftUI, styled with the IAMJARL design tokens Swift package.
- Engine:
ExtAudioFile (AudioToolbox), decode → 16-bit PCM → WAV, with sample-rate conversion.
- No backend, no third-party runtime dependencies beyond the design tokens.
- Website: its404yo.iamjarl.com is built from
site/ and deployed with GitHub Pages.
Support
Email [email protected], or use Help › Send Feedback… in the
app, which fills in your app and macOS version. The maker also reads the
Elektronauts thread.
GitHub issues are welcome too. More on the support page.
Roadmap
Live on the Mac App Store. Open work is tracked in
GitHub Issues, highlights:
- Splitting files over the 16 min / 185 MB limit (#6)
- Optional level normalization (#18)
- In-app text size (#9)
- Exploring additional device profiles (#15)
Credits
Roland and SP-404 are trademarks of their respective owners. This is an independent tool and is
not affiliated with or endorsed by Roland.
License
MIT. It's 404, yo! is made by Jarl at IAMJARL.
