diff --git a/i_sndfile/i_sndfile.cpp b/i_sndfile/i_sndfile.cpp
index f303bf0973c42978fb3d22c6d68d064c219c3cd2..d633213ec3540fb9a8e5c8a6496ff61ba091828c 100644
--- a/i_sndfile/i_sndfile.cpp
+++ b/i_sndfile/i_sndfile.cpp
@@ -16,13 +16,19 @@ int main(int argc, char**argv){
     SNDFILE *sndfile;
     sf_count_t read_items_nb;
     
+    blc_program_set_description("Record blc_channel input in a sound file");
+    blc_program_add_option(&filename, 'f', "file", "string", "filename of the file to write", NULL);
     blc_program_add_option(&output_name, 'o', "output", "string", "Channel containing the fast fourier transformation", DEFAULT_OUTPUT_NAME);
     blc_program_add_option(&period_str, 'p', "period", "integer", "Period between each sample in ms (0 as fast as possible)", "0");
     blc_program_add_option(&length_str, 's', "size", "integer", "Sample size", "1024");
     blc_program_add_option(&type_str, 't', "type", "INT8|FL32", "Type of the data.", "FL32");
-    blc_program_add_parameter(&filename, "string", 1, "Filename containing the sound", NULL);
     blc_program_init(&argc, &argv, NULL);
     
+    if (filename==NULL){
+    	blc_program_args_display_help();
+    	EXIT_ON_ERROR("You need to specify a filename: -f<filename>");
+    }
+
     type=STRING_TO_UINT32(type_str);
     if (sscanf(length_str, "%ld", &length)!=1) EXIT_ON_ERROR("Reading size '%s'", length_str);
     if (sscanf(period_str, "%d", &period)!=1)  EXIT_ON_ERROR("Reading period in '%s'", period_str);
diff --git a/o_sndfile/o_sndfile.cpp b/o_sndfile/o_sndfile.cpp
index 6dfee71746f4447a3b235b2f20925323905a7ffc..cc766c4d7c00361892bc45d1d5db1aff7ae2f5e6 100644
--- a/o_sndfile/o_sndfile.cpp
+++ b/o_sndfile/o_sndfile.cpp
@@ -11,6 +11,7 @@ int main(int argc, char**argv){
     SNDFILE *sndfile;
     sf_count_t write_items_nb;
     
+    blc_program_set_description("Load a sound file (no mp3) and put the result in the blc_channel");
     blc_program_add_option(&filename, 'f', "file", "string", "filename of the file to write", NULL);
     blc_program_add_parameter(&input_name, "blc_channel-in", 1, "blc channel containing the sound", NULL);
     blc_program_init(&argc, &argv, NULL);