[Ground-station] output of dvbs2_rx app

[Christopher Howard]

Hi, this is likely a very elementary question, but I was playing around
with the dvbs2_rx test app, and was just wondering why the output file
comes out a different size and md5sum than the input file. If I set the
noise default to 0, this does not change the output md5sum. Both files
play just fine and look the same when played. The output ends up
smaller by about 60000 bytes.

$ gnuradio-companion  --version
Gtk-Message: Failed to load module "canberra-gtk-module"
GNU Radio Companion 3.7.10

OS: Debian GNU/Linux 9.8 (stretch) x86_64 
Model: 2347B46 ThinkPad T430 
Kernel: 4.9.0-8-amd64 
Uptime: 12 days, 6 hours, 42 minutes 
Packages: 2178 
Shell: bash 4.4.12 
Resolution: 1600x900, 1280x1024 
DE: GNOME 
WM: GNOME Shell 
WM Theme: Adwaita 
Theme: Adwaita [GTK2/3] 
Icons: Adwaita [GTK2/3] 
Terminal: gnome-terminal 
CPU: Intel i5-3320M (4) @ 3.3GHz 
GPU: Intel Integrated Graphics 
Memory: 3867MB / 7689MB