refactor(app): normalize all recorded audio to 16kHz at capture time#50
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refactor(app): normalize all recorded audio to 16kHz at capture time#50
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What: App and mic audio are now resampled to 16kHz when saved instead of preserving the native device sample rate. AudioConstants.targetSampleRate (app) and speechSampleRate (audiotap) provide a single named constant. resampleFile() fast-paths with a file copy when already at 16kHz. Reasoning: - Problem: Mickey Mouse / pitch artifacts when app output device runs at a rate other than 48kHz (e.g. 44100, 96000), or when app and mic tracks had mismatched rates that were silently mixed at the wrong ratio. - Decision: resample to 16kHz at the source — MicCaptureHandler via existing AVAudioConverter, DualSourceRecorder via AudioMixer.resample() before saveWAV(). All WAVs on disk are now always 16kHz; pipeline resampleFile() calls become no-ops.
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Summary
AudioConstants.targetSampleRate(app target) andspeechSampleRate(audiotap package) replace all hardcoded16000literalsresampleFile()fast-paths with a file copy when the source is already at 16kHz (pipeline calls become no-ops)Problem
Mickey Mouse / pitch artifacts occurred when the system output device ran at a rate other than 48kHz (e.g. 44100Hz on some Macs/AirPods setups), or when the app and mic tracks had mismatched sample rates that were silently mixed at the wrong ratio.
Test plan
swift test)swift test --filter E2E)./scripts/run_app.sh)