CPU Usage in iOS

[jon2718]

We are testing RNNoise on in iOS on an iPhone X. We are seeing significant CPU usage out of the box of approximately 20%. The function that seems to be quite expensive is feature_calculation. Is this expected? Do you have any data on CPU efficiency on mobile devices or techniques that we could investigate to reduce CPU usage.

[contribu]

just idea

• replace fft with https://developer.apple.com/documentation/accelerate/vdsp/fast_fourier_transforms
• calculate cross correlation using fft (O(n^2) -> O(nlogn))
• use simd https://github.com/p12tic/libsimdpp

[TerenzeY]

@jon2718 interesting, altho how are you running this on iOS?

[Ornolfr]

@jon2718 How did you go about the hardcoded FRAME_SIZE? It is working great when the audio buffer size matches the FRAME_SIZE but otherwise the audio gets distorted and I don't see any possibility for ring buffer due to AUAudioUnit specifics.