39 lines
1.5 KiB
C++
39 lines
1.5 KiB
C++
#include "stdafx.h"
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#include "VisUtils.h"
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namespace VisUtils {
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void PrepareFFTChunk(audio_chunk const & source, audio_chunk & out, double centerOffset) {
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const t_uint32 channels = source.get_channel_count();
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const t_uint32 sampleRate = source.get_sample_rate();
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FB2K_DYNAMIC_ASSERT( sampleRate > 0 );
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out.set_channels(channels, source.get_channel_config());
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out.set_sample_rate(sampleRate);
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const t_size inSize = source.get_sample_count();
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const t_size fftSize = MatchFFTSize(inSize);
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out.set_sample_count(fftSize);
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out.set_data_size(fftSize * channels);
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if (fftSize >= inSize) { //rare case with *REALLY* small input
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pfc::memcpy_t( out.get_data(), source.get_data(), inSize * channels );
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pfc::memset_null_t( out.get_data() + inSize * channels, (fftSize - inSize) * channels );
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} else { //inSize > fftSize, we're using a subset of source chunk for the job, pick a subset around centerOffset.
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const double baseOffset = pfc::max_t<double>(0, centerOffset - 0.5 * (double)fftSize / (double)sampleRate);
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const t_size baseSample = pfc::min_t<t_size>( (t_size) audio_math::time_to_samples(baseOffset, sampleRate), inSize - fftSize);
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pfc::memcpy_t( out.get_data(), source.get_data() + baseSample * channels, fftSize * channels);
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}
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}
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bool IsValidFFTSize(t_size p_size) {
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return p_size >= 2 && (p_size & (p_size - 1)) == 0;
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}
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t_size MatchFFTSize(t_size samples) {
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if (samples <= 2) return 2;
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t_size mask = 1;
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while(!IsValidFFTSize(samples)) {
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samples &= ~mask; mask <<= 1;
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}
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return samples;
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}
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};
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