Re: [Discuss-gnuradio] Lost samples from RTL2832 dongle

[CEL]

Ah, and: Choppy audio from low-buffer streaming applications within VMs
is another common issue with many VM hypervisors.
On Tue, 2018-01-23 at 12:44 +0000, Müller, Marcus (CEL) wrote:
> Hi John,
> 
> my experience, indeed, is that USB passthrough support in VMs is
> suboptimal. So, this could very well be a virtual USB host controller
> problem.
> 
> I'd actually recommend circumventing the issue, e.g. by running rtl_tcp
> on the host machine, and using the appropriate source string in the gr-
> osmosdr source.
> 
> Best regards,
> Marcus
> 
> On Tue, 2018-01-23 at 12:40 +0000, john cooper wrote:
> > Hello GNU people, some help greatly appreciated.
> > 
> > I am a newbie to GNU Radio and have a lost samples problem,  lost from the 
> > USB 2  RF device, seemingly not in the Flowgraph signal chain.
> > 
> > Although I have no hard evidence I am coming to the point of suspecting the 
> > problem lies with the running of GNU under Oracle VM,  hosted by Win 10.
> > 
> > Physical RF device is a  DVB-T+DAB+FM USB dongle, with Realtek RTL2832U and 
> > the R820 device.
> > 
> > System is GNU Radio ( latest version )  running as a guest under Oracle VM, 
> > hosted by Win 10 Pro on a machine with significant system resources.
> > 
> > Oracle version is VM 5.2.6r
> > 
> > Problem is *always* dropped samples from a DVB-T+DAB+FM USB dongle, tens to 
> > hundreds of lost samples.
> > 
> > I have done the following :-
> > 
> >     Added my name to the virtualbox users list.
> > 
> >     added the Virtual Box Extension Pack 5.2.6     to allow USB 2 support 
> > in the VM
> > 
> >     Selected USB2 in the Oracle VM machine.
> > 
> >     Blacklisted the RTL2338 DVB-T  driver  via   
> > /etc/modprobe.d/blacklist-rtl.conf    etc.
> >     
> >     Tested with rtl_test with sample speeds from 2.4e6 down to 0.25 e6
> > 
> >     Several Flowgraphs of various example FM broadcast receivers all have 
> > choppy audio, believed to be due to lost sample from the RF device via USB2 
> > and not seemingly due to mismatch of audio sing sample rates.
> > 
> > 
> > Using only the RTL_SDR source block and Low Pass Filter, plus the WX GUI 
> > FFT Sink and the WX GUI Scope Sink, in a FlowGraph produces spikes in the 
> > Audio which coincide with the suggested sample losses from the physical 
> > dongle.
> > 
> > 
> > Under any and all tests and sample rates the result of rtl_test when ran in 
> > the terminal is a continual stream of lost samples.
> > 
> > 
> > Other information;
> > 
> > running SDR# via the host system ( Win 10 Pro )  is faultless at 2.4e6 
> > sample speed and all lower speeds.
> > 
> > I have also  installed Gqrx in the VM and this system stalls with the 
> > Terminal screen failing to enter the initial set up dialogue screen but 
> > does list in the terminal screen the list of parameters, then hangs.
> > 
> > If anyone has input to the problem, I would be very pleased to hear back 
> > and offer my thanks in advance.
> > 
> > John
> > 
> > 
> >     Virus-free. www.avg.com
> > _______________________________________________
> > Discuss-gnuradio mailing list
> > address@hidden
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
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