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Refactor FFT helpers (#5309)

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* Do not check if unsigned int is negative

* Reduce scope of some local variables

* Use right types for iterators

* Check conditional returns first

* Remove unused functions

* Utilize a range-based for loop opportunity
This commit is contained in:
Hussam al-Homsi
2020-03-11 15:07:02 -04:00
committed by GitHub
parent 0196f31509
commit 85e0574138
2 changed files with 20 additions and 119 deletions
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12
include/fft_helpers.h
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@@ -103,16 +103,4 @@ int LMMS_EXPORT absspec(const fftwf_complex *complex_buffer, float *absspec_buff
int LMMS_EXPORT compressbands(const float * _absspec_buffer, float * _compressedband,
int _num_old, int _num_new, int _bottom, int _top);
int LMMS_EXPORT calc13octaveband31(float * _absspec_buffer, float * _subbands,
int _num_spec, float _max_frequency);
/** Compute power of finite time sequence.
* Take care num_values is length of timesignal[].
*
* @return power on success, else -1
*/
float LMMS_EXPORT signalpower(const float *timesignal, int num_values);
#endif

127
src/core/fft_helpers.cpp
View File

@@ -35,13 +35,12 @@
*/
float maximum(const float *abs_spectrum, unsigned int spec_size)
{
float maxi = 0;
unsigned int i;
if (abs_spectrum == NULL) {return -1;}
if (spec_size <= 0) {return -1;}
if (spec_size == 0) {return -1;}
for (i = 0; i < spec_size; i++)
float maxi = 0;
for (unsigned int i = 0; i < spec_size; i++)
{
if (abs_spectrum[i] > maxi) {maxi = abs_spectrum[i];}
}
@@ -61,13 +60,11 @@ float maximum(const std::vector<float> &abs_spectrum)
*/
int normalize(const float *abs_spectrum, float *norm_spectrum, unsigned int bin_count, unsigned int block_size)
{
int i;
if (abs_spectrum == NULL || norm_spectrum == NULL) {return -1;}
if (bin_count == 0 || block_size == 0) {return -1;}
block_size /= 2;
for (i = 0; i < bin_count; i++)
for (unsigned int i = 0; i < bin_count; i++)
{
norm_spectrum[i] = abs_spectrum[i] / block_size;
}
@@ -89,9 +86,9 @@ int normalize(const std::vector<float> &abs_spectrum, std::vector<float> &norm_s
*/
int notEmpty(const std::vector<float> &spectrum)
{
for (int i = 0; i < spectrum.size(); i++)
for (float s : spectrum)
{
if (spectrum[i] != 0) {return 1;}
if (s != 0) {return 1;}
}
return 0;
}
@@ -103,22 +100,21 @@ int notEmpty(const std::vector<float> &spectrum)
*/
int precomputeWindow(float *window, unsigned int length, FFT_WINDOWS type, bool normalized)
{
unsigned int i;
if (window == NULL) {return -1;}
float gain = 0;
float a0;
float a1;
float a2;
float a3;
if (window == NULL) {return -1;}
// constants taken from
// https://en.wikipedia.org/wiki/Window_function#AList_of_window_functions
switch (type)
{
default:
case RECTANGULAR:
for (i = 0; i < length; i++) {window[i] = 1.0;}
for (unsigned int i = 0; i < length; i++) {window[i] = 1.0;}
gain = 1;
return 0;
case BLACKMAN_HARRIS:
@@ -142,7 +138,7 @@ int precomputeWindow(float *window, unsigned int length, FFT_WINDOWS type, bool
}
// common computation for cosine-sum based windows
for (i = 0; i < length; i++)
for (unsigned int i = 0; i < length; i++)
{
window[i] = (a0 - a1 * cos(2 * F_PI * i / ((float)length - 1.0))
+ a2 * cos(4 * F_PI * i / ((float)length - 1.0))
@@ -152,7 +148,7 @@ int precomputeWindow(float *window, unsigned int length, FFT_WINDOWS type, bool
// apply amplitude correction
gain /= (float) length;
for (i = 0; i < length; i++) {window[i] /= gain;}
for (unsigned int i = 0; i < length; i++) {window[i] /= gain;}
return 0;
}
@@ -166,12 +162,10 @@ int precomputeWindow(float *window, unsigned int length, FFT_WINDOWS type, bool
*/
int absspec(const fftwf_complex *complex_buffer, float *absspec_buffer, unsigned int compl_length)
{
int i;
if (complex_buffer == NULL || absspec_buffer == NULL) {return -1;}
if (compl_length <= 0) {return -1;}
if (compl_length == 0) {return -1;}
for (i = 0; i < compl_length; i++)
for (unsigned int i = 0; i < compl_length; i++)
{
absspec_buffer[i] = (float)sqrt(complex_buffer[i][0] * complex_buffer[i][0]
+ complex_buffer[i][1] * complex_buffer[i][1]);
@@ -189,33 +183,28 @@ int absspec(const fftwf_complex *complex_buffer, float *absspec_buffer, unsigned
*/
int compressbands(const float *absspec_buffer, float *compressedband, int num_old, int num_new, int bottom, int top)
{
float ratio;
int i, usefromold;
float j;
float j_min, j_max;
if (absspec_buffer == NULL || compressedband == NULL) {return -1;}
if (num_old < num_new) {return -1;}
if (num_old <= 0 || num_new <= 0) {return -1;}
if (bottom < 0) {bottom = 0;}
if (top >= num_old) {top = num_old - 1;}
usefromold = num_old - (num_old - top) - bottom;
int usefromold = num_old - (num_old - top) - bottom;
ratio = (float)usefromold / (float)num_new;
float ratio = (float)usefromold / (float)num_new;
// for each new subband
for (i = 0; i < num_new; i++)
for (int i = 0; i < num_new; i++)
{
compressedband[i] = 0;
j_min = (i * ratio) + bottom;
float j_min = (i * ratio) + bottom;
if (j_min < 0) {j_min = bottom;}
j_max = j_min + ratio;
float j_max = j_min + ratio;
for (j = (int)j_min; j <= j_max; j++)
for (float j = (int)j_min; j <= j_max; j++)
{
compressedband[i] += absspec_buffer[(int)j];
}
@@ -223,79 +212,3 @@ int compressbands(const float *absspec_buffer, float *compressedband, int num_ol
return 0;
}
int calc13octaveband31(float *absspec_buffer, float *subbands, int num_spec, float max_frequency)
{
static const int onethirdoctavecenterfr[] = {20, 25, 31, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, 2500, 3150, 4000, 5000, 6300, 8000, 10000, 12500, 16000, 20000};
int i, j;
float f_min, f_max, frequency, bandwidth;
int j_min, j_max = 0;
float fpower;
if (absspec_buffer == NULL || subbands == NULL) {return -1;}
if (num_spec < 31) {return -1;}
if (max_frequency <= 0) {return -1;}
/*** energy ***/
fpower = 0;
for (i = 0; i < num_spec; i++)
{
absspec_buffer[i] = (absspec_buffer[i] * absspec_buffer[i]) / FFT_BUFFER_SIZE;
fpower = fpower + (2 * absspec_buffer[i]);
}
fpower = fpower - (absspec_buffer[0]); //dc not mirrored
/*** for each subband: sum up power ***/
for (i = 0; i < 31; i++)
{
subbands[i] = 0;
// calculate bandwidth for subband
frequency = onethirdoctavecenterfr[i];
bandwidth = (pow(2, 1.0/3.0)-1) * frequency;
f_min = frequency - bandwidth / 2.0;
f_max = frequency + bandwidth / 2.0;
j_min = (int)(f_min / max_frequency * (float)num_spec);
j_max = (int)(f_max / max_frequency * (float)num_spec);
if (j_min < 0 || j_max < 0)
{
fprintf(stderr, "Error: calc13octaveband31() in fft_helpers.cpp line %d failed.\n", __LINE__);
return -1;
}
for (j = j_min; j <= j_max; j++)
{
if (j_max < num_spec) {subbands[i] += absspec_buffer[j];}
}
} //for
return 0;
}
/* Compute power of finite time sequence.
* Take care num_values is length of timesignal[]
*
* return power on success, else -1
*/
float signalpower(const float *timesignal, int num_values)
{
if (num_values <= 0) {return -1;}
if (timesignal == NULL) {return -1;}
float power = 0;
for (int i = 0; i < num_values; i++)
{
power += timesignal[i] * timesignal[i];
}
return power;
}