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Break out WebRtcNs_IFFT function in ns_core

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This is done in order to make the code more readible and maintainable.
This creates bit-exact output.

BUG=webrtc:3811
R=bjornv@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/24039004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7486 4adac7df-926f-26a2-2b94-8c16560cd09d
This commit is contained in:
aluebs@webrtc.org 2014-10-21 21:27:00 +00:00
parent a5c36b397a
commit 7634c09406
1 changed files with 36 additions and 13 deletions
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49
webrtc/modules/audio_processing/ns/ns_core.c
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@ -778,6 +778,39 @@ static void UpdateBuffer(const float* frame,
}
}
// Transforms the signal from frequency to time domain.
// Inputs:
// * |real| is the real part of the frequency domain.
// * |imag| is the imaginary part of the frequency domain.
// * |magnitude_length| is the length of the spectrum magnitude, which equals
// the length of both |real| and |imag|.
// * |time_data_length| is the length of the analysis buffer
// (2 * (magnitude_length - 1)).
// Output:
// * |time_data| is the signal in the time domain.
static void IFFT(NSinst_t* const self,
const float* real,
const float* imag,
int magnitude_length,
int time_data_length,
float* time_data) {
int i;
assert(time_data_length == 2 * (magnitude_length - 1));
time_data[0] = real[0];
time_data[1] = real[magnitude_length - 1];
for (i = 1; i < magnitude_length - 1; ++i) {
time_data[2 * i] = real[i];
time_data[2 * i + 1] = imag[i];
}
WebRtc_rdft(time_data_length, -1, time_data, self->ip, self->wfft);
for (i = 0; i < time_data_length; ++i) {
time_data[i] *= 2.f / time_data_length; // FFT scaling.
}
}
int WebRtcNs_AnalyzeCore(NSinst_t* inst, float* speechFrame) {
int i;
const int kStartBand = 5; // Skip first frequency bins during estimation.
@ -1204,17 +1237,7 @@ int WebRtcNs_ProcessCore(NSinst_t* inst,
memcpy(inst->magnPrevProcess, magn, sizeof(*magn) * inst->magnLen);
memcpy(inst->noisePrev, inst->noise, sizeof(inst->noise[0]) * inst->magnLen);
// back to time domain
winData[0] = real[0];
winData[1] = real[inst->magnLen - 1];
for (i = 1; i < inst->magnLen - 1; i++) {
winData[2 * i] = real[i];
winData[2 * i + 1] = imag[i];
}
WebRtc_rdft(inst->anaLen, -1, winData, inst->ip, inst->wfft);
for (i = 0; i < inst->anaLen; i++) {
real[i] = 2.f * winData[i] / inst->anaLen; // fft scaling
}
IFFT(inst, real, imag, inst->magnLen, inst->anaLen, winData);
// scale factor: only do it after END_STARTUP_LONG time
factor = 1.f;
@ -1224,7 +1247,7 @@ int WebRtcNs_ProcessCore(NSinst_t* inst,
energy2 = 0.0;
for (i = 0; i < inst->anaLen; i++) {
energy2 += (float)real[i] * (float)real[i];
energy2 += winData[i] * winData[i];
}
gain = (float)sqrt(energy2 / (energy1 + 1.f));
@ -1251,7 +1274,7 @@ int WebRtcNs_ProcessCore(NSinst_t* inst,
// synthesis
for (i = 0; i < inst->anaLen; i++) {
inst->syntBuf[i] += factor * inst->window[i] * (float)real[i];
inst->syntBuf[i] += factor * inst->window[i] * winData[i];
}
// read out fully processed segment
for (i = inst->windShift; i < inst->blockLen + inst->windShift; i++) {