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fftw3 傅里叶变换求频率

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JIe Jie 2024-02-26 09:10:10 +08:00
parent e6ce8e1781
commit f7700bb398
1 changed files with 21 additions and 0 deletions
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21
src/audioDecoder.cc
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@ -1,10 +1,12 @@
#include "audioDecoder.h" #include "audioDecoder.h"
#include <iostream>
#include <SDL2/SDL_audio.h> #include <SDL2/SDL_audio.h>
#include <SDL2/SDL_stdinc.h> #include <SDL2/SDL_stdinc.h>
extern "C" { extern "C" {
#include "libswresample/swresample.h" #include "libswresample/swresample.h"
#include "fftw3.h"
} }
int RequestAudioFrame(AudioParam& param, uint8_t* audioBuffer, int bufSize) int RequestAudioFrame(AudioParam& param, uint8_t* audioBuffer, int bufSize)
@ -37,6 +39,25 @@ int RequestAudioFrame(AudioParam& param, uint8_t* audioBuffer, int bufSize)
if (frame->ch_layout.nb_channels > 0) { if (frame->ch_layout.nb_channels > 0) {
av_channel_layout_default(&frame->ch_layout, frame->ch_layout.nb_channels); av_channel_layout_default(&frame->ch_layout, frame->ch_layout.nb_channels);
} }
int nbSamples = frame->nb_samples;
uint8_t* audioData = frame->data[0];
fftw_complex* fftwInput = static_cast<fftw_complex*>(fftw_malloc(sizeof(fftw_complex) * frame->nb_samples));
fftw_complex* fftwOutput = static_cast<fftw_complex*>(fftw_malloc(sizeof(fftw_complex) * frame->nb_samples));
for (int i = 0; i < nbSamples; i++)
{
fftwInput[i][0] = audioData[i];
fftwInput[i][1] = .0f;
}
fftw_plan fftwPlan = fftw_plan_dft_1d(nbSamples, fftwInput, fftwOutput, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(fftwPlan);
for (int i = 0; i < nbSamples; i++)
{
double magnitude = sqrt(fftwOutput[i][0] * fftwOutput[i][0] + fftwOutput[i][1] * fftwOutput[i][1]);
double phase = atan2(fftwOutput[i][1], fftwOutput[i][0]);
std::cout << "mag: " << magnitude << "\n phase: " << phase << "\n";
}
constexpr AVSampleFormat dstFormat = AV_SAMPLE_FMT_S16; constexpr AVSampleFormat dstFormat = AV_SAMPLE_FMT_S16;
swr_alloc_set_opts2(&swrCtx, &frame->ch_layout, dstFormat, frame->sample_rate, &frame->ch_layout, static_cast<AVSampleFormat>(frame->format), frame->sample_rate, 0, nullptr); swr_alloc_set_opts2(&swrCtx, &frame->ch_layout, dstFormat, frame->sample_rate, &frame->ch_layout, static_cast<AVSampleFormat>(frame->format), frame->sample_rate, 0, nullptr);