ffmpeg -i rtmp://ip/live/test -i rtmp://ip/live/test2 -filter_complex "[0:v]setpts=PTS-STARTPTS, pad=iw*2:ih[bg]; [1:v]setpts=PTS-STARTPTS[fg]; [bg][fg]overlay=w; amerge,pan=stereo|c0<c0+c2|c1<c1+c3" -c:v libx264 -crf 23 -preset veryfast -strict -2 -acodec aac -f flv rtmp://live-ams.twitch.tv/app/live_