Tvheadend

Mark Clarkstone wrote:

Enable Force old status - Always use the old ioctls to read the linuxdvb status (signal strength, SNR, error counters).

Have tried this. Results are even worse. Only one input provides a reasonable SNR value, the others seem to fail right from the start (see screenshot attached).

Some drivers are not mature enough to provide the correct values using the new v5 linuxdvb API.

Yes, I've read about this before. Does not seem to apply here, since everything worked with TVH 4.0.9 using the same drivers.

Here is the requested trace along with some screenshots to show the status display.

Devices used as identified in the system journal:

adapter 0 (DVB-T #0): Afatech AF9033
adapter 1 (DVB-T #1): DiBcom 7000PC - Hauppauge Nova-TD Stick (52009) [tuner #1 (dual tuner stick)]
adapter 2 (DVB-T #2): DiBcom 7000PC - Hauppauge Nova-TD Stick (52009) [tuner #2 (dual tuner stick)]
adapter 3 (DVB-S #0): Montage Technology M88DS3103 - TechnoTrend TT-connect S2-4600

I've started Tvheadend in its normal configuration, let it scan all DVB-T and DVB-S muxes for EPG data, then selected some channels for live watching (up to 2 simultaneously). Interestingly, the last screenshot shows that I had lost SNR display on only one of the two DiBcom 7000PC DVB-T inputs sitting on the same dual tuner stick (with error-free live video on both).

Hope this helps. If you'd like a trace from a reduced configuration, please let me know.

Here is further analysis and a suggested fix:

The attached C program gathers current SNR readings using the old and new DVB APIs. When invoked during a TVH epggrab run, it looks like this:

# ~/Test/DVB/snr /dev/dvb/adapter3/frontend0

18:08:09 SNR: new=12.041 dB, old=120
18:08:10 SNR: new=12.041 dB, old=120
18:08:11 SNR: new=12.041 dB, old=120
18:08:12 SNR: new=12.041 dB, old=120
18:08:13 SNR: new=N/A, old=0
18:08:14 SNR: new=13.222 dB, old=132
18:08:15 SNR: new=12.787 dB, old=127
18:08:16 SNR: new=13.222 dB, old=132
18:08:17 SNR: new=13.010 dB, old=130
18:08:18 SNR: new=13.424 dB, old=134
18:08:19 SNR: new=13.222 dB, old=132
18:08:20 SNR: new=13.617 dB, old=136
18:08:21 SNR: new=13.010 dB, old=130
18:08:22 SNR: new=13.010 dB, old=130
18:08:23 SNR: new=13.617 dB, old=136
18:08:24 SNR: new=13.222 dB, old=132
18:08:25 SNR: new=13.617 dB, old=136
18:08:26 SNR: new=N/A, old=0
18:08:27 SNR: new=12.787 dB, old=127
18:08:28 SNR: new=12.552 dB, old=125
18:08:29 SNR: new=12.552 dB, old=125
18:08:30 SNR: new=12.787 dB, old=127
18:08:31 SNR: new=12.787 dB, old=127

Conclusions:

1. The new API call sometimes returns an intermediate result of FE_SCALE_NOT_AVAILABLE (presumably if the tuner is not ready yet). According to https://linuxtv.org/downloads/v4l-dvb-apis/frontend-properties.html#DTV-STAT-CNR, this is proper behavior.
2. For the Hauppauge Nova-TD and TechnoTrend TT-connect S2-4600 inputs, the old API call apparently returns a decibel value multiplied by 10 (which does not conform to the API spec and thus constitutes a bug in the driver).

To fix TVH with respect to the new API, I suggest to try the patch attached (untested).

Change improved to avoid switching between dB and relative (%) displays in the UI.

Tested: fixes the bug as intended (see screenshot).

Fix provided as pull request #887 · https://github.com/tvheadend/tvheadend/pull/887

Oliver O wrote:

Fix committed: https://github.com/tvheadend/tvheadend/commit/fb99e1adee13b86cbb5690198daaa7f60e141270

Tested successfully in version 4.1-2189~g3de3244~xenial.

Please close.

commit:fb99e1ad