helper functions
Functions |
int | xtract_windowed (const float *data, const int N, const void *argv, float *result) |
| Apply a window function to an array of length N.
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int | xtract_features_from_subframes (const float *data, const int N, const int feature, const void *argv, float *result) |
| Divides the array pointed to by *data into two subframes, and applies a given feature to each subframe, returning them in a single array pointed to by result.
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int | xtract_is_denormal (double const d) |
| Test whether a number is denormal.
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Detailed Description
Declares helper functions, and their parameters.
- Note:
- These functions don't necessarily conform to the prototype used in xtract_scalar.h and xtract_vector.h etc, and as such are intended to be called 'directly' rather than via the xtract[] function pointer array (libxtract.h)
Function Documentation
int xtract_features_from_subframes |
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const float * |
data, |
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const int |
N, |
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const int |
feature, |
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const void * |
argv, |
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float * |
result | |
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) |
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Divides the array pointed to by *data into two subframes, and applies a given feature to each subframe, returning them in a single array pointed to by result.
- Parameters:
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| *data | an array of floats - Parameters:
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| N | the number of elements in the array pointed by *data - Parameters:
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| feature | an integer representing the feature to be applied to each subframe in data. This will be a value as given in the enumeration xtract_features_ (libxtract.h) - Parameters:
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| *argv | a pointer to the argument vector to be passed to the feature extraction function as determined by feature - Parameters:
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It is important to ensure that any _init_*() functions that are called in preparation for functions that are called on subframes are given the subframe size as 'N', and not the frame size. i.e. if xtract_features_from_subframes() is called with N=64, and feature=XTRACT_SPECTRUM, then xtract_init_fft() should be called with N=32. |
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int xtract_windowed |
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const float * |
data, |
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const int |
N, |
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const void * |
argv, |
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float * |
result | |
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) |
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Apply a window function to an array of length N.
- Parameters:
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| *data | a pointer to an array of floats - Parameters:
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| N | the number of elements in the array pointed to by *data - Parameters:
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| *argv | a pointer to a window function as returned by xtract_make_window() - Parameters:
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| *result | a pointer to the first element an array containing the windowed data |
It is up to the caller to generate and free the array containing the window, and to allocate and free memory of size N to hold the data pointed to by *result |
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