FFmpeg: Useful Commands
Created:Flags
Some common audio/video related flags or arguments to FFmpeg commands and what they mean.
General:
-i = input
Audio/Video:
NOTE: a || v are interchangeable
-an or -vn = remove either audio or video
-b:a or -b:v = bitrate, great for reducing a HQ video to work on mobile (example: -b:v 20m)
-r = frame rate (video)
-c:a or -c:v = refers to a command relating to the codec, so if you want to copy one of those codecs you can write: -c:v copy which is passthrough for video
Commands
Remove Audio:
ffmpeg -i input.mp4 -c:v copy -an output.mp4
Extract Audio (use preferred codec):
ffmpeg -i video.mp4 -vn -c:a copy -acodec pcm_s16le output.wav
Add Audio To Video:
ffmpeg -i input.mp4 -i input.wav -c:v copy -c:a aac -b:a 320k output.mp4
or
ffmpeg -i input.mov -i input.wav -c:v copy output.mov
Adjust the Volume (percentage or db works) :
ffmpeg -i input.mp4 -vcodec copy -af "volume=-15dB" -b:a 320k output.mp4
Adjust Length to the shortest audio or video:
ffmpeg -i input.mp4 -i audio.aac -shortest -c:v copy -c:a copy output.mp4
Scale a video for performance:
ffmpeg -i input.mp4 -s 1920×960 output.mp4
Scale a video by video filter for reducing size:
ffmpeg -i input.mp4 -vf scale=iw*.5:ih*.5 output.mp4
Convert to DNxHD for Pro Tools
ffmpeg -i input.mp4 -c dnxhd -s 1280x720 -r 24000/1001 -pix_fmt yuv422p -b 90M OUTPUTNAME.mov
360 Video Manipulation
Stereoscopic to Monoscopic:
Over-under (top-bottom):
ffmpeg -i input.mp4 -vf crop=h=in_h/2:y=0 output.mp4
Side-by-side (left-right):
ffmpeg -i input.mp4 -vf crop=h=in_w/2:y=0 output.mp4
360 Video Rotation
Where 100 is the desired amount of vertical pixels you want to offset from right to left, shifting the image toward the right:
ffmpeg -i /path/to/input.mov -filter_complex "[0:v][0:v]overlay=100:0[bg]; [bg][0:v]overlay=100-W,format=yuv420p[out]" -map "[out]" -an -codec:v libx264 -crf 23 -preset medium /path/to/output.mp4
if you want to shift by an angle use the following:
width_of_video / 360 = pixels_per_degree
pixels_per_degree * degrees_you_want_shifted = number_of_vertical_pixels_rounded