[BUG] UDP throughput seems too low based on expected data types?

[kristian1108]

Describe your environment

I'm using an RTLSDR dongle on the latest branch of RTLSDR-Airband (at this time, commit e7cd0ece5b3f1a1c054d926bcecefa8166a3af62).

I'm on my Mac OSX 14.1.1 Sonoma, with Apple M1 silicon.

What happened?

When I set up a UDP stream, I'm getting 8kb/s through the socket.

What you expected to happen?

I would expect to get 32kb/s through the socket based on this documentation: https://github.com/charlie-foxtrot/RTLSDR-Airband/wiki/Configuring-UDP-outputs

NFM disabled: 8000hz, 32-bit float samples = 8000 samples x 4 bytes per sample = 32 kilobytes per second.

Steps to Reproduce

src/rtl_airband -c ../../bladerf-conf/rtl_airband.conf -f -e

Your rtl_airband.conf file

devices:
({
  type = "rtlsdr";
  index = 0;
  gain = 20.0;
  centerfreq = 128.5;
  channels: (
    {
     freq = 128.175;
     modulation = "am";
     squelch_threshold = -100;
     outputs: (
          {
           type = "udp_stream";
           dest_address = "127.0.0.1";
           dest_port = 8081;
           continuous = true;
          },
          {
           type = "file";
           continuous = true;
           directory = "/Users/me/code/bladerf-conf";
           filename_template = "hello";
          }
      );
     }
  );
});

Note the output in the .mp3 file sounds just fine, but I'd love to have the live stream. Thank you!!

[SullivanChrisJ]

With NFM enabled I get the full data rate 16kHz 32-bit floats. I haven't tried with NFM disabled, and NFM is what I use it for. How are you measuring the output? I noticed at one point in working with this output that I needed the receive buffer to be large enough to hold the full UDP packet size of 2000 floating point values (8K bytes). Maybe your buffer is 2K bytes?