Re: [Discuss-gnuradio] Audio underrun when using Audio Sink

[Paul S]

Hi Kevin & Marcus,

thank you for your answers. After a while of testing I've got interesting
results. Firstly, even though it brought 100% CPU load on one core, the
packet encoder is not a problem as the underruns also occured without it.
Anyway, thank you for your suggestion, I'll certainly look into it. Do you
have a link for a thread or something like that where Felix Wunsch mentioned
this? And your example: Does that mean I could use this method on on one
frequency alone?

Secondly, I had about 25% CPU load on all cores for the first flowgraph,
except for when I got these underruns where my CPU load promptly exploded to
100%. However, I'd blame this rise on the underruns themselves as everything
was fine shortly before (maybe because of busy waiting?).
Nevertheless I've splitted the resampler and I am now using 4 resamplers in
a row to get a interpolation of ~100. Both the Socket PDU and the File
Source are producing only occasionally underruns but apart from this they
are doing fine now. Unfortunately the TunSource block is still producing
lots of them (although it's less frequently now). Here's the code for the
TunSource. Maybe you can see what's wrong.


    def work(self, input_items, output_items):        
        out = output_items[0]   
        # Read from tun device 
        packet = tun.read()
        tun.printPkg(packet)
        
        # Extract the header
        header = packet[:20]
        unpacked = unpack('!BBHHHBBH4s4s',header)
        size = unpacked[4]
        buf = packet[32:]
        # cast buffer to (iterable) list
        myarray = list(buf)

        # Counter variable for position in output array
        j = 0
        for i in myarray:
            num = 0
            try:
                num = (numpy.int8(ord(i)))
            except ValueError:
                num = chr(0)
            output_items[0][j] = num
            j = j+1
        return len(buf)


Regards
Paul



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