Audio and/or video recorder device to wear when walking dog?

In the past several months I have had several unpleasant encounters with strangers while walking my dog in various places. I was wondering what people would recommend for recording purposes of a device I could wear or carry with me in case I needed it for the purposes of personal LEGAL protection? I'm wondering if an audio device would be good enough, or if it should record visual stuff as well. I'm not asking for recommendations on a weapon to carry or anything, there's like a million places for that. I just mean something that could have recorded a couple of bad encounters as of late...I wouldn't want something incredibly bulky, and something that has a clip or strap would be nice. Any recommendations? I looked on amazon but not even sure what category to really look under...

http://www.galls.com/cameras

Thats terrible, sorry to hear. I recommend the pen camera, no one would even know. Hope you and your doggies stay safe, try walking a different route or something. Here's the link below

http://www.amazon.com/s/ref=nb_sb_ss_i_1_10?url=search-alias%3Daps&field-keywords=pen+camera+video+and+audio+recorder&sprefix=pen+camera%2Caps%2C272