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Diffstat (limited to 'third_party/resample/src/filterkit.h')
| -rw-r--r-- | third_party/resample/src/filterkit.h | 159 |
1 files changed, 0 insertions, 159 deletions
diff --git a/third_party/resample/src/filterkit.h b/third_party/resample/src/filterkit.h deleted file mode 100644 index c0d5e97c..00000000 --- a/third_party/resample/src/filterkit.h +++ /dev/null @@ -1,159 +0,0 @@ -/*:filterkit.h */ - -#include "stdefs.h" - -/* - * LpFilter() - Calculates the filter coeffs for a Kaiser-windowed low-pass - * filter with a given roll-off frequency. These coeffs - * are stored into a array of doubles. - * writeFilter() - Writes a filter to a file. - * makeFilter() - Calls LpFilter() to create a filter, then scales the double - * coeffs into an array of half words. - * readFilter() - Reads a filter from a file. - * FilterUp() - Applies a filter to a given sample when up-converting. - * FilterUD() - Applies a filter to a given sample when up- or down- - * converting. - * initZerox() - Initialization routine for the zerox() function. Must - * be called before zerox() is called. This routine loads - * the correct filter so zerox() can use it. - * zerox() - Given a pointer into a sample, finds a zero-crossing on the - * interval [pointer-1:pointer+2] by iteration. - * Query() - Ask the user for a yes/no question with prompt, default, - * and optional help. - * GetUShort() - Ask the user for a unsigned short with prompt, default, - * and optional help. - * GetDouble() - Ask the user for a double with prompt, default, and - * optional help. - * GetString() - Ask the user for a string with prompt, default, and - * optional help. - */ - -void LpFilter(double c[], int N, double frq, double Beta, int Num); -/* - * reference: "Digital Filters, 2nd edition" - * R.W. Hamming, pp. 178-179 - * - * LpFilter() computes the coeffs of a Kaiser-windowed low pass filter with - * the following characteristics: - * - * c[] = array in which to store computed coeffs - * frq = roll-off frequency of filter - * N = Half the window length in number of coeffs - * Beta = parameter of Kaiser window - * Num = number of coeffs before 1/frq - * - * Beta trades the rejection of the lowpass filter against the transition - * width from passband to stopband. Larger Beta means a slower - * transition and greater stopband rejection. See Rabiner and Gold - * (Theory and Application of DSP) under Kaiser windows for more about - * Beta. The following table from Rabiner and Gold gives some feel - * for the effect of Beta: - * - * All ripples in dB, width of transition band = D*N where N = window length - * - * BETA D PB RIP SB RIP - * 2.120 1.50 +-0.27 -30 - * 3.384 2.23 0.0864 -40 - * 4.538 2.93 0.0274 -50 - * 5.658 3.62 0.00868 -60 - * 6.764 4.32 0.00275 -70 - * 7.865 5.0 0.000868 -80 - * 8.960 5.7 0.000275 -90 - * 10.056 6.4 0.000087 -100 - */ - -int writeFilter(HWORD Imp[], HWORD ImpD[], UHWORD LpScl, UHWORD Nmult, UHWORD Nwing); -/* - * Write a filter to a file - * Filter file format: - * file name: "F" Nmult "T" Nhc ".filter" - * 1st line: the string "ScaleFactor" followed by its value. - * 2nd line: the string "Length" followed by Nwing's value. - * 3rd line: the string "Coeffs:" on a separate line. - * following lines: Nwing number of 16-bit impulse response values - * in the right wing of the impulse response (the Imp[] array). - * (Nwing is equal to Npc*(Nmult+1)/2+1, where Npc is defined in the - * file "resample.h".) Each coefficient is on a separate line. - * next line: the string "Differences:" on a separate line. - * following lines: Nwing number of 16-bit impulse-response - * successive differences: ImpD[i] = Imp[i+1] - Imp[i]. - * ERROR codes: - * 0 - no error - * 1 - could not open file - */ - -int makeFilter(HWORD Imp[], HWORD ImpD[], UHWORD *LpScl, UHWORD Nwing, - double Froll, double Beta); -/* - * makeFilter - * ERROR return codes: - * 0 - no error - * 1 - Nwing too large (Nwing is > MAXNWING) - * 2 - Froll is not in interval [0:1) - * 3 - Beta is < 1.0 - * 4 - LpScl will not fit in 16-bits - */ - -int readFilter(char *filterFile, - HWORD **ImpP, HWORD **ImpDP, UHWORD *LpScl, - UHWORD *Nmult, UHWORD *Nwing); -/* - * Read-in a filter - * Filter file format: - * Default file name: "F" Nmult "T" Nhc ".filter" - * 1st line: the string "ScaleFactor" followed by its value. - * 2nd line: the string "Length" followed by Nwing's value. - * 3rd line: the string "Coeffs:" on separate line. - * Nwing number of 16-bit impulse response values in the right - * wing of the impulse response. (Length=Npc*(Nmult+1)/2+1, - * where originally Npc=2^9, and Nmult=13.) Each on separate line. - * The string "Differences:" on separate line. - * Nwing number of 16-bit impulse-response successive differences: - * ImpDiff[i] = Imp[i+1] - Imp[i]. - * - * ERROR return codes: - * 0 - no error - * 1 - file not found - * 2 - invalid ScaleFactor in file - * 3 - invalid Length in file - */ - -WORD FilterUp(HWORD Imp[], HWORD ImpD[], UHWORD Nwing, BOOL Interp, - HWORD *Xp, HWORD Inc, HWORD Ph); - -WORD FilterUD(HWORD Imp[], HWORD ImpD[], UHWORD Nwing, BOOL Interp, - HWORD *Xp, HWORD Ph, HWORD Inc, UHWORD dhb); - -int initZerox(UHWORD tempNmult); -/* - * initZerox - * ERROR return values: - * 0 - no error - * 1 - Nmult is even (should be odd) - * 2 - filter file not found - * 3 - invalid ScaleFactor in input file - * 4 - invalid Length in file - */ - -/* - * zerox - * Given a pointer into a sound sample, this function uses a low-pass - * filter to estimate the x coordinate of the zero-crossing which must ocurr - * between Data[0] and Data[1]. This value is returned as the value of the - * function. A return value of -100 indicates there was no zero-crossing in - * the x interval [-1,2]. Factor is the resampling factor: Rate(out) / - * Rate(in). Nmult (which determines which filter is used) is passed the - * zerox's initialization routine: initZerox(Nmult) - */ -double zerox(HWORD *Data, double Factor); - -BOOL Query(char *prompt, BOOL deflt, char *help); - -unsigned short GetUShort(char *title, unsigned short deflt, char *help); - -double GetDouble(char *title, double deflt, char *help); - -char *GetString(char *prompt, char *deflt, char *help); - -#define GetUHWORD(x,y,z) GetUShort(x,y,z) - |