ffmpeg baseline compatibility

Baseline profile should be most compatible for any kind of devices. also lower bitrate to lesser than 400kbps.

ffmpeg -y -i test_ad.mp4 -acodec aac -ar 44100 -ab 64k -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -level 3.0 -vb 320k -s 854x480 -r 29.97 h264.mp4