While using rtl_sdr i noticed that there was no direct sampling support, despite the rtl-sdr library supporting it, so i wrote a patch:

diff --git a/src/rtl_sdr.c b/src/rtl_sdr.cindex 2c93b57..15a4212 100644 --- a/src/rtl_sdr.c +++ b/src/rtl_sdr.c @@ -55,6 +55,7 @@ void usage(void)   "\t[-b output_block_size (default: 16 * 16384)]\n"   "\t[-n number of samples to read (default: 0, infinite)]\n"   "\t[-S force sync output (default: async)]\n" + "\t[-D direct sampling (default: 0, 1 for I branch, 2 for Q branch)]\n"   "\tfilename (a '-' dumps samples to stdout)\n\n");   exit(1);  } @@ -112,6 +113,7 @@ int main(int argc, char **argv)   int n_read;   int r, opt;   int gain = 0; + int direct_sampling = 0;   int ppm_error = 0;   int sync_mode = 0;   FILE *file; @@ -121,8 +123,8 @@ int main(int argc, char **argv)   uint32_t frequency = 100000000;   uint32_t samp_rate = DEFAULT_SAMPLE_RATE;   uint32_t out_block_size = DEFAULT_BUF_LENGTH; - - while ((opt = getopt(argc, argv, "d:f:g:s:b:n:p:S")) != -1) { + + while ((opt = getopt(argc, argv, "d:f:g:s:b:n:p:S:D:")) != -1) {   switch (opt) {   case 'd':   dev_index = verbose_device_search(optarg); @@ -149,6 +151,9 @@ int main(int argc, char **argv)   case 'S':   sync_mode = 1;   break; + case 'D': + direct_sampling = atoi(optarg); + break;   default:   usage();   break; @@ -200,7 +205,8 @@ int main(int argc, char **argv)  #endif   /* Set the sample rate */   verbose_set_sample_rate(dev, samp_rate); - + /* Set direct sampling*/ + verbose_direct_sampling(dev, direct_sampling);   /* Set the frequency */   verbose_set_frequency(dev, frequency);