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Could anyone help on how to call this function which will compute a moving median from an input array and return an output array with replaced median values
into this simple program which uses sndfile.hCode:void CWaveBuf::BMedian35(short* lpSource, short* lpDest, short cx) { short offsetnextpoint = m_waveFormat.scan_count;// number of chans within source buffer short nbspan = TransformBufferSpan[13]; // nb of points within moving windows /2 // usually we use = 30; ie 61 points total. Our spikes are defined over 60 points. short offsetspan = offsetnextpoint * nbspan; // offset between center of window & end short NN = nbspan*2 +1; // nb of points within window short *parray = new short[NN]; // temporary array // init parray = consecutive points (image of the data points) int i=0; // index variable short* lp = lpSource; // pointer to origin of source buffer lp -= offsetspan; // first point of the moving window for (i = 0; i < NN; lp += offsetnextpoint, i++) // load parray *(parray+i) = *lp; // with buffer values // sort parray into ascending order using heapsort algorithm // // "l"= index which will be decremented from initial value down to 0 during // 'hiring' (heap creation) phase. Once it reaches 0, the index "ir" will be // decremented from its initial value down to 0 during the 'retirement-and- // promotion' (heap selection) phase. int l = nbspan + 1; // temp index int ir = NN - 1; // temp index int j; // temp index short val; // temp storage for (;;) // pseudo-loop over parray { // ------------------------- if (l > 0) // still in hiring phase { l--; val = *(parray + l); } else // in retirement-and-promotion phase { val = *(parray+ir); // clear a space at the end of the array *(parray+ir) = *(parray); // retire the top of the heap into it ir--; // decrease the size of the corporation if (ir == 0) // done with the last promotion { *(parray) = val; // the least competent worker of all break; // exit the sorting algorithm } } // ------------------------- i = l + 1; // wether we are in the hiring or promotion, we j = i + i; // here set up to sift down element raa to its // proper level while (j-1 <= ir) { if (j-1 < ir) if (*(parray+j-1) < *(parray+j)) j++; // compare to the better underlining if (val < *(parray+j-1)) // demote val { *(parray+i-1) = *(parray+j-1); i = j; j = j + j; } // this is val's level. Set j to terminate the else // sift-down j = ir + 2; } *(parray+i-1) = val; // put val into its slot } // end of initial sort short newvalue; // temp variable used in the loop short oldval; // temp variable used in the loop short offset2span = 2*offsetspan+offsetnextpoint;// offset first to last pt/window lp= lpSource + offsetspan; for (cx; cx>0; cx--, lp += offsetnextpoint, lpDest++) { newvalue = *lp; // new value to insert into array oldval = *(lp-offset2span); // value to discard from array // locate position of old value to discard // use bisection - cf Numerical Recipes pp 90 // on exit, j= index of oldval // int jhigh = NN-1; // upper index int jlow = 0; // mid point index while (jlow <= jhigh) { j = (jlow+jhigh)/2; if (oldval > *(parray+j)) jlow = j +1; else if (oldval < *(parray+j)) jhigh = j-1; else break; } // insert new value in the correct position // case 1: search (and replace) towards higher values if (newvalue > *(parray + j)) { for (j; newvalue > *(parray + j); j++) { if (j == NN) break; *(parray+ j) = *(parray + j + 1); } *(parray + j-1) = newvalue; } // case 2: search (and replace) towards lower values else if (newvalue < *(parray + j)) { for (j; newvalue < *(parray + j); j--) { if (j == 0) { if (newvalue < *parray) j--; break; } *(parray + j) = *(parray + j -1); } *(parray + j+1) = newvalue; } // case 3: already found! else *(parray + j) = newvalue; // save median value in the output array // m_waveFormat.binzero : binary value of the zero volt. For ex, for 12 bits binary encoded data, zero is // encoded as 2048. *lpDest = *(lp-offsetspan) - *(parray+nbspan) + (short) m_waveFormat.binzero; } delete parray; }
All i'm trying to do is replace the process _data function call with the WaveBuf::BMedian35 function, it's just im not sure what parameters to use, i realise some code will have to be changed in the function such as the m_waveFormat.scan_count, but its just the correct use of the function that im worried about,Code:/* #include <stdio.h> /* Include this header file to use functions from libsndfile. */ #include <sndfile.h> /* This will be the length of the buffer used to hold.frames while ** we process them. */ #define BUFFER_LEN 1024 /* libsndfile can handle more than 6 channels but we'll restrict it to 6. */ #define MAX_CHANNELS 6 /* Function prototype. */ static void process_data (double *data, int count, int channels) ; int main (void) { /* This is a buffer of double precision floating point values ** which will hold our data while we process it. */ static double data [BUFFER_LEN] ; /* A SNDFILE is very much like a FILE in the Standard C library. The ** sf_open function return an SNDFILE* pointer when they sucessfully ** open the specified file. */ SNDFILE *infile, *outfile ; /* A pointer to an SF_INFO stutct is passed to sf_open. ** On read, the library fills this struct with information about the file. ** On write, the struct must be filled in before calling sf_open. */ SF_INFO sfinfo ; int readcount ; const char *infilename = "input.wav" ; const char *outfilename = "output.wav" ; /* Here's where we open the input file. We pass sf_open the file name and ** a pointer to an SF_INFO struct. ** On successful open, sf_open returns a SNDFILE* pointer which is used ** for all subsequent operations on that file. ** If an error occurs during sf_open, the function returns a NULL pointer. ** ** If you are trying to open a raw headerless file you will need to set the ** format and channels fields of sfinfo before calling sf_open(). For ** instance to open a raw 16 bit stereo PCM file you would need the following ** two lines: ** ** sfinfo.format = SF_FORMAT_RAW | SF_FORMAT_PCM_16 ; ** sfinfo.channels = 2 ; */ if (! (infile = sf_open (infilename, SFM_READ, &sfinfo))) { /* Open failed so print an error message. */ printf ("Not able to open input file %s.\n", infilename) ; /* Print the error message from libsndfile. */ puts (sf_strerror (NULL)) ; return 1 ; } ; if (sfinfo.channels > MAX_CHANNELS) { printf ("Not able to process more than %d channels\n", MAX_CHANNELS) ; return 1 ; } ; /* Open the output file. */ if (! (outfile = sf_open (outfilename, SFM_WRITE, &sfinfo))) { printf ("Not able to open output file %s.\n", outfilename) ; puts (sf_strerror (NULL)) ; return 1 ; } ; /* While there are.frames in the input file, read them, process ** them and write them to the output file. */ while ((readcount = sf_read_double (infile, data, BUFFER_LEN))) { process_data (data, readcount, sfinfo.channels) ; sf_write_double (outfile, data, readcount) ; } ; /* Close input and output files. */ sf_close (infile) ; sf_close (outfile) ; return 0 ; } /* main */ static void process_data (double *data, int count, int channels) { double channel_gain [MAX_CHANNELS] = { 0.5, 0.8, 0.1, 0.4, 0.4, 0.9 } ; int k, chan ; /* Process the data here. ** If the soundfile contains more then 1 channel you need to take care of ** the data interleaving youself. ** Current we just apply a channel dependant gain. */ for (chan = 0 ; chan < channels ; chan ++) for (k = chan ; k < count ; k+= channels) data [k] *= channel_gain [chan] ; return ; } /* process_data */
Anyones help is greatly appreciated
