To get information about your video with ffmpeg, you would use the ffrpobe 1) utility (installed with ffmpeg)
ffprobe video.mp4
Example of output where you can see the aspect ratio of 1920×1080
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
title : Video Gifts
artist : Gerard nico
encoder : Lavf58.29.100
keywords : Video-Gifts
Duration: 00:00:39.27, start: 0.000000, bitrate: 3067 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 2933 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
Metadata:
handler_name : Core Media Video
timecode : 00:00:00;00
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s (default)
Metadata:
handler_name : Core Media Audio
Stream #0:2(eng): Data: none (tmcd / 0x64636D74)
Metadata:
handler_name : Core Media Video
timecode : 00:00:00;00
ffprobe -v quiet -print_format json -show_format -show_streams "input.mp4" > "output.json"