Glitches in multirec using DVB-S

[alannisota@…]

I get glitches on a recording/LiveTV when switching channels (on the same transponder) using multirec. I traced the problem to this in dvbchannel.cpp:

    if (is_dvbs)
    {
        // make sure we tune to frequency, no matter what happens..
        reset = first_tune = true;

Which causes FE_SET_FRONTEND to be called even when not switching transponders. This causes a momentary glitch in the stream using my card. What is the reason for this code, and can we change/remove it?

[Janne Grunau]

code was added in [10493] to make retuning work

I'll comment it until we find a proper solution.

[Janne Grunau]

t4473.diff should work too. It is forcing only a reset if the card is not locked.

[Janne Grunau]

If someone on irc remembered correctly the forced retune is needed for

Two satellites with the same transponder frequencies. Dish rotates, but no lock, ISTR.

in that case the patch won't help.

[alannisota@…]

the fix that was committed in #15441 works fine for me so far. If the problem is with rotors or switches and retuning to the same transponder, the fix would be to force a reset whenever a switch/rotor command is issued. I'll try out t4473 in the meantime.

[Janne Grunau]

yes, I was working on that. please try ​t4473_v2.diff

[danielk]

The reason for the re-tune is because we temporarily raise the voltage to 17V when rotating a rotor with DiSEqC. Janne's second patch should be the fix the glitches without causing the H/V setting to be incorrect after a rotation of the dish.

[Janne Grunau]

no, as Shane pointed out on irc it won't work since the slave calling the master Tune() with same_input == false.

[Janne Grunau]

​t4473_v3.diff caches the lnb device id and enforces retuning only if it changed.

[alannisota@…]

v3 seems to work for me as well.

[Janne Grunau]

(In [15460]) Fixes #4471, Refs #4477. Force a retune only if the LNB device id has changed.

fixes glitches in recordings when a second virtual DVB tuner changes the channel in the multiplex