Bug/fix: Auto gain disables when web page loads

[tronba]

Hi, noticed a bug when playing with a fork, got some AI assist, and think we found a fix. Hope it can be of help.

Problem: Auto gain works initially, but gets disabled as soon as you open the web interface. You then have to toggle it off and on to get it back.

Cause: In rtl_fm_python.c, the lib_get_tuner_gains_count and lib_get_tuner_gains functions both call rtlsdr_set_tuner_gain_mode(dongle.dev, 1) which switches the device to manual mode. The web page calls these functions to populate the gain dropdown menu.

Solution: Remove the rtlsdr_set_tuner_gain_mode lines from both functions since they're only meant to query available gains, not change the gain mode.

In lib_get_tuner_gains_count, remove: rtlsdr_set_tuner_gain_mode(dongle.dev, 1);
In lib_get_tuner_gains, remove: r = rtlsdr_set_tuner_gain_mode(dongle.dev, 1);

[th0ma5w]

Thanks for this ... I think I remember there being a corner case where you can't itemize the list of gains without it being in manual mode especially on older sticks I think? And I didn't want to manage the state of a late population of the drop down ... and I think I called it a day there originally on this project hahah.

When using the API or script directly this behavior doesn't happen of course. I would like to perhaps make sure we're up to date with the latest rtl_fm.c, perhaps figure out a way not to distribute that with this project, and perhaps switch to a newer or simpler JS stack? I'll keep this open for now, I appreciate the work, and I hope these changes work for you in your fork and on your hardware? I will take some time to test as well.