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1 #include "StdAfx.h"
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2
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3 #include "VisUtils.h"
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4
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5 namespace VisUtils {
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6 void PrepareFFTChunk(audio_chunk const & source, audio_chunk & out, double centerOffset) {
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7 const t_uint32 channels = source.get_channel_count();
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8 const t_uint32 sampleRate = source.get_sample_rate();
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9 FB2K_DYNAMIC_ASSERT( sampleRate > 0 );
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10 out.set_channels(channels, source.get_channel_config());
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11 out.set_sample_rate(sampleRate);
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12 const t_size inSize = source.get_sample_count();
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13 const t_size fftSize = MatchFFTSize(inSize);
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14 out.set_sample_count(fftSize);
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15 out.set_data_size(fftSize * channels);
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16 if (fftSize >= inSize) { //rare case with *REALLY* small input
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17 pfc::memcpy_t( out.get_data(), source.get_data(), inSize * channels );
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18 pfc::memset_null_t( out.get_data() + inSize * channels, (fftSize - inSize) * channels );
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19 } else { //inSize > fftSize, we're using a subset of source chunk for the job, pick a subset around centerOffset.
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20 const double baseOffset = pfc::max_t<double>(0, centerOffset - 0.5 * (double)fftSize / (double)sampleRate);
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21 const t_size baseSample = pfc::min_t<t_size>( (t_size) audio_math::time_to_samples(baseOffset, sampleRate), inSize - fftSize);
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22 pfc::memcpy_t( out.get_data(), source.get_data() + baseSample * channels, fftSize * channels);
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23 }
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24 }
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25
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26 bool IsValidFFTSize(t_size p_size) {
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27 return p_size >= 2 && (p_size & (p_size - 1)) == 0;
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28 }
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29
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30 t_size MatchFFTSize(t_size samples) {
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31 if (samples <= 2) return 2;
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32 t_size mask = 1;
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33 while(!IsValidFFTSize(samples)) {
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34 samples &= ~mask; mask <<= 1;
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35 }
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36 return samples;
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37 }
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38 };
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