How to compose 2 videos by using FFmpeg hstack filter? -

i want compose 2 videos 1 video putting side side. hope set start/stop time each video. final video should h264/aac codec , mp4 format. attached sample videos. https://www.dropbox.com/s/e5eouyrrqsy44ts/1.webm?dl=0 https://www.dropbox.com/s/u0zqie0icxamt3q/2.webm?dl=0

i used following ffmpeg command.

ffmpeg -i 1.webm -i 2.webm -filter_complex "[0:v][1:v]hstack" output.mp4

when run command on terminal of mac os x 10.11, gave me following error.

input 1 height 480 not match input 0 height.

the video smartphone, orientation not correct. please me make composed video ffmpeg.

for set of videos, need

ffmpeg -i 1.webm -i 2.webm -filter_complex "[0:v]scale=480:640,setsar=1[l];[1:v]scale=480:640,setsar=1[r];[l][r]hstack;[0][1]amix" -vsync 0 output.mp4 

the writing application hasn't written stream attributes correctly. videos should tagged 480x640. it's not missing rotation tag, frame context changes.