yvkdreamer, there's nothing that can be done to calm down someone else. But if that person decides to do so, they can work to bring themselves under control. I know this first-hand. It took a personal epiphany for the right perspective to work on myself. I purchased a stack of anger management books and studied. I found techniques which worked for me.
Now, to get on topic with the forum: Meditation did help, but not in ways that a lot of advice suggested.
Many sources claimed that meditation alone, mindfulness meditation or simply clearing one's head, would improve temper. That did not work for me. However, I used visualizations, mantras (many which I made myself), breathing techniques, energy manipulation (I didn't know about grounding and centering as such before I came here, but it made sense because I was already doing something similar), and other similar things to let go before I blew up, or to bring myself back quickly if I went over the line.
But it all comes down to the person making the decision to change. Nobody else could change me. I had to do the work myself.
I went on holiday with my sister and taught her a simple spell to unset your mind from such spells its seems to have worked as she is now a more joyful person to be around.
I don't really do spells, but I can say this: A calm setting makes calm people. Find out what triggers their outbursts, and take them away from it, or limit their exposure to it. If they are just naturally angry, then perhaps you ought not hang around them.
Many people get violent when angry. Some hit out at people; some smash crockery. Anger is really fear and frustration.Treating the anger by being calm in the presence of it can often work. When the angry person has calmed down is the time to talk to them about it. When they are angry, it is a waste of breath! Best to get out of the way!