Hi Manu, On Sun, 24 Nov 2013 22:51:33 +0530, Manu Abraham wrote: > Sorry, that I came upon this patch quite late. No problem, better late than never! :) > On Mon, Jun 3, 2013 at 8:51 PM, Jean Delvare <khali@xxxxxxxxxxxx> wrote: > > SNR is supposed to be reported by the frontend drivers in dB, so print > > it that way for drivers which implement it properly. > > Not all frontends do report report the SNR in dB. Well, You can say quite > some frontends do report it that way. Last time I discussed this, I was told that this was the preferred way for frontends to report the SNR. I also referred to this document: http://palosaari.fi/linux/v4l-dvb/snr_2012-05-21.txt I don't know now up-to-date it is by now, but back then it showed a significant number of frontends reporting in .1 dB already, including the ones I'm using right now (drx-3916k and drx-3913k.) With the current version of femon, "femon -H" reports it as 0%, which is quite useless. Thus my patch. > Making the application report it in > dB for frontends which do not will show up as incorrect results, from what > I can say. My code has a conditional to interpret high values (>= 1000) as % and low values (< 1000) as .1 dB. This is a heuristic which works fine for me in practice (tested on drxk, cx22702 and dib3000mc.) I would certainly welcome testing on other DVB cards. I seem to recall that Mauro suggested that values above 40 dB (?) were not possible so we could probably lower the threshold from 1000 to 400 or so if the current value causes trouble. I think the maximum I've see on my card was ~32 dB. If you find a significant number of frontend drivers for which the heuristic doesn't work, and lowering the threshold doesn't help, then I'm fine considering a different approach such as an extra command line parameter. But if only a small number of drivers cause trouble, I'd say these drivers should simply be fixed. Thanks, -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
