ffmpeg to twitch, this one with no microphone works perfectly:
ffmpeg -i /tmp/gchd.ts -r 15 -c:v libx264 -pix_fmt yuv420p -preset ultrafast -g 20 -b:v 1000k -c:a libmp3lame -ar 44100 -threads 0 -bufsize 512k -f flv rtmp://live-lax.twitch.tv/app/live_*****

This is one I am trying to make work with my microphone:
ffmpeg -f alsa -ac 1 -i hw:1 -i /tmp/gchd.ts -filter_complex "[0:a][1:a]amerge=inputs=2,pan=stereo|c0<c0+c2|c1<c1+c3[aout]" -map "[aout]" -map 1:0 -r 15 -c:v libx264 -pix_fmt yuv420p -preset ultrafast -g 20 -b:v 1000k -c:a libmp3lame -ar 44100 -threads 0 -bufsize 512k -f flv $OUT

If I remove -map 1:0 I get no video, just an audio stream.