Hello, I try to perform dynamic upsampling on a signal (SR=44,1kHz) to double the sample rate. Here is the code  I wrote to test it.  It works using a raw audio file (cdparanoia -r 1) with a 1Khz sin signal. When I look to my output signal with an oscilloscope it looks quite good but I get some noise (glitches?) that makes it really sound bad. Is there something I do wrong ? Is it a libsamplerate problem ? ************************** ******My code************* ************************** #include <stdio.h> #ifdef HAVE_STDLIB_H #include <stdlib.h> #endif #include <math.h> #include <unistd.h> #include <fcntl.h> #include <sys/types.h> #include <sys/time.h> #include <samplerate.h> int main(int argc, const char *argv[]) {   int TAILLEBUF = TAILLEBUF;   int TAILLEBUF_OUT = TAILLEBUF;   int16_t * p_readbuf= (int16_t *) malloc(sizeof(int16_t)*TAILLEBUF);   float * pf_readbuf= ( float *) malloc(sizeof(float)*TAILLEBUF);   float * pf_writebuf= ( float *) malloc(sizeof(float)*TAILLEBUF_OUT);   int fini=0;   int finiRead=0;   int fd,fdread;    /* sound device file descriptor */     struct timeval tv;   tv.tv_sec = 0;   tv.tv_usec = 120000;   int error;   SRC_STATE * src_state;   SRC_DATA src_data;   src_data.src_ratio = atoi(argv[3]);   src_data.input_frames=0;   src_data.end_of_input = 0;   src_data.data_out = pf_writebuf;   src_data.output_frames=TAILLEBUF_OUT/2;   src_state = src_new(2,2,&error);   /* open sound device I'm working on my own sound card */   fd = open("/dev/AudioDriver/data", O_WRONLY);   if (fd < 0) {     perror("open of /dev/AudioDriver/data failed");     exit(1);   } /*My raw sound file*/   fdread = open("./cdda.raw", O_RDONLY);   if (fd < 0) {     perror("open of cdda.raw failed");     exit(1);   }   fd_set writefds[1];   FD_ZERO(writefds);   FD_SET(fd, writefds);   int k=0;        while (!finiRead) {     /* read TAILLEBUF/2 Frames */     int j;     if(read(fdread,p_readbuf,TAILLEBUF*sizeof(int16_t))!=TAILLEBUF*sizeof(int16_t))             finiRead=1;         int i=0;     /*Convert from 16bit integer to Float*/            for(i=0;i<TAILLEBUF;i++)       {         pf_readbuf[i]=((p_readbuf[i])<<16) ;         }             if(src_data.input_frames==0)       {         src_data.data_in = pf_readbuf;         src_data.input_frames=TAILLEBUF/2;       }     tv.tv_sec = 0;     tv.tv_usec = 120000;     fd_set writefds[1];     FD_ZERO(writefds);     FD_SET(fd, writefds);     while(select(fd+1, NULL, writefds, NULL, &tv)!=1){          tv.tv_sec = 0;       tv.tv_usec = 120000;       fd_set writefds[1];       FD_ZERO(writefds);       FD_SET(fd, writefds);     }     int sent = 0;             if((error = src_process(src_state,&src_data))!=0)printf("error\n");           while(sent < src_data.output_frames_gen)         {           /*Convert my 2-floats frame to an unsigned long frame containing my to channels*/           unsigned long frame;           frame = (unsigned long) ((src_data.data_out[sent]))>>16;           frame |= (((unsigned long) (src_data.data_out[sent+1])) & 0xFFFF0000);           if(write(fd, &frame, sizeof(unsigned long))!=sizeof(unsigned long))         {fini = 1;         }           sent += 2;        }   exit(0); } **************************** **************************** **************************** I hope that you can understand my english and that my code is clear enough for you to help me. Thanks in advance. Mathieu