Does anyone know what are two thin horizontal lines in waveform window in audio editors? I want to make my sound louder but wo/clipping, look say here https://www.redsharknews.com/media/k2/items/src/48ed12281ae1f6453d2d5ec95b17e082.jpg, lines at approx. peaks, is this to mark headroom or something else? What if sound crosses it, does it mean clipping will occur? I can see in DAW when sound gets clipped but I'm not sure here.
If you were talking about blue lines, then:
I don't know how to describe that with terminology, but when you play quieter the waveforms is thinner and lies near that line. I believe that line is that defines an audio region minimal dynamic range (again, I'm bad at terminology, but I mean the dynamic range, like my audio interface has a -120 dB dynamic range), so your DAW also has that dynamic range and that line represents -∞ dB, so all audio content which volume level is above the minimal dynamic range is shown as waveform. If that line is mixed with audio content like this (below) then it's called a zero crossing:
So if you see only that line with no audio content – it represent silence (still some extremely quiet noises can occur). I believe you're editing a stereo file, so each channel has it's own (because I've shown in mono).
The lines represent some level. You haven't told us WHICH audio editor you're using, and you haven't shown us the whole screen, so we can only guess WHAT levels.
Here's a more useful screenshot from Wavelab where the labelling shows that the lines are at -6dB. That's a typical level for this sort of line.
The 0dB line, the clipping point, is at the top of the display. Demonstrably, the waveform ISN'T clipped at the -6dB line. It would be at the 0dB line. It's just there as a useful aiming point for the 'bulk' of the signal, leaving room for peaks.