Maybe this is old news for some of you, if so sorry. But I think sooner or later someone using Ableton Live for DJ use will ask the standard question: how do I set a specific loop point during playback of music with N bars (N being 1, 2, 4 and so on)?
Well, the thing to learn are the two Set buttons below the bigger Loop button in the envelope view (see image).
When you press the position set button during playback, the current location is recorded and the Loop is automatically enabled with usually a default length to end of track.
When you hit the Length Set button after a while, the length is recorded and the loop point is now looping around this length. To progress, just disable the Loop button and the loop is again non-activated, until you again trigger the next one with the Position Set and Position Length buttons.
The actual resolution, assuming you have global quantization in the loop, will be rounded to the quantization levels. If you have 1 bar quantization, you could hit the length set button immediately after the position set, and it will be a one-bar loop. Same if you have 2-bar quantization, the default resolution will be 2 bars, so you can’t go wrong and define a bad quantization loop range this way.
Now, in real DJ life, you could bind these buttons to your controller so you have one button for loop enable/disable, one for the position set, and one for the length set.