FreqTrace

A real-time audio analysis tool for live sound environments. Visualize sounds, track frequencies, and identify resonances and feedback on the fly.

Features

• Real-time Spectrograph — Live frequency spectrum visualization (scrolling waterfall + RTA)
• Frequency Tracker — Monitor and track the loudest frequency, resonances, and feedback candidates
• SPL Meter — Simple sound pressure level metering (A/C/Z weighting, Fast/Slow)
• Signal Generator — Generate test tones (sine) and pink/white noise

Requirements

• macOS 15 (Sequoia) or later
• Any Mac — Apple Silicon or Intel. Releases ship as a universal binary.
• A microphone or audio input device (built-in mic, USB interface, aggregate device, etc.)

Install

1. Download the latest FreqTrace-vX.Y.Z-macos.zip from the Releases page.
2. Double-click the .zip to unpack FreqTrace.app, then drag it into your Applications folder.
3. First launch. The app is signed for development but not notarized by Apple, so macOS Gatekeeper blocks it the first time. To open it anyway:
   • Right-click (or Control-click) FreqTrace.app → Open, then click Open in the dialog. macOS remembers your choice, so later launches are ordinary double-clicks.
   • If no Open button appears, clear the quarantine flag in Terminal and try again:

     xattr -dr com.apple.quarantine /Applications/FreqTrace.app
     

4. Grant microphone access when prompted — FreqTrace needs it to analyze live audio. If you miss the prompt, enable it later under System Settings → Privacy & Security → Microphone.

Heads up: because these builds use an Apple Development certificate and aren't notarized, some Macs may refuse to open the app at all rather than just warn. If the steps above don't work, build from source instead — a notarized, friction-free build is future work.

Running

1. Launch FreqTrace and press Start (or the Space bar) to begin measuring.
2. Choose your input in the Input Device control (bottom-left). The waterfall and RTA fill in as audio arrives.
3. The big Tracked Frequency readout shows the loudest frequency in real time; flagged Anomaly Candidates highlight narrowband tones that are ringing up (feedback / resonance).
4. Freeze pauses the display for a closer look (capture keeps running); Stop halts capture entirely.

Analysis details

For the curious, the numbers behind the readouts:

• FFT window function: Hann (normalized). It's the standard choice for audio spectrographs and RTAs — the same window Smaart uses — balancing frequency resolution against spectral leakage so a loud tone doesn't smear across the display.
• FFT size: selectable (FFT Size control), default 8192 samples. Larger sizes give finer frequency resolution at the cost of time resolution.
• Sample rate: follows your hardware (nominally 48 kHz). At 8192 / 48 kHz that's a raw bin spacing of ~5.9 Hz; the Tracked Frequency readout refines below that with sub-bin (parabolic) interpolation.
• Overlap: consecutive analyses overlap ≥50% (up to 87.5% at the largest window), so the waterfall and RTA update smoothly regardless of FFT size.
• Weighting: A / C / Z, applied to the Tracked Frequency, SPL, and the waterfall/RTA display. The feedback/resonance detector deliberately reads the raw, unweighted spectrum so a low-frequency ring isn't hidden by A-weighting's roll-off.

Build from source

Requires Xcode 16 or later.

git clone https://github.com/vk0eppel/FreqTrace.git
cd FreqTrace
open FreqTrace.xcodeproj    # then press Cmd-R to build and run

Or from the command line:

xcodebuild -project FreqTrace.xcodeproj -scheme FreqTrace -destination 'platform=macOS' build
xcodebuild -project FreqTrace.xcodeproj -scheme FreqTrace -destination 'platform=macOS' test

License

GPLv3