[Webkit-unassigned] [Bug 73545] [GStreamer] FFTFrame implementation

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=73545





--- Comment #15 from Sebastian Dröge <slomo at circular-chaos.org>  2012-01-18 04:32:25 PST ---
(From update of attachment 122727)
View in context: https://bugs.webkit.org/attachment.cgi?id=122727&action=review

> Source/WebCore/platform/audio/gstreamer/FFTFrameGStreamer.cpp:29
> +unsigned unpackedFFTDataSize(unsigned fftSize)

Shouldn't this be static or something to prevent it from being exported?

> Source/WebCore/platform/audio/gstreamer/FFTFrameGStreamer.cpp:48
> +    ASSERT(1UL << m_log2FFTSize == m_FFTSize);

GstFFT can handle FFT sizes that are multiples of only 2, 3, 5 fast (e.g. 30 too) but can also handle every other size (but might be slow)

> Source/WebCore/platform/audio/gstreamer/FFTFrameGStreamer.cpp:52
> +    int fftLength = gst_fft_next_fast_length(m_FFTSize);

This doesn't make sense, you're forcing it to a power of two anyway ;) Either remove that assertion or this here.

> Source/WebCore/platform/audio/gstreamer/FFTFrameGStreamer.cpp:154
> +    for (unsigned i = 0; i < halfSize; i++) {

Hm, aren't you dropping one value here? It's n/2 + 1, not n/2.

> Source/WebCore/platform/audio/gstreamer/FFTFrameGStreamer.cpp:175
> +    const float scaleFactor = 1.0 / (2 * m_FFTSize);

You only have to divide by m_FFTSize IIRC. Or divide by 1/sqrt(m_FFTSize) after both transformations.

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