Use FFmpeg to resize and generate .mp4 & .webm videos from any source video.

gistfile1.txt

/** 
Scaling
 - Scale can be used as is which will set the height to 560 but keep aspect ratio for width.
 - Other options include setting both with & height
 - Watch out for sizing errors when not divisible by 2
**/

/** MP4 1st pass **/
ffmpeg -i input.mov -vcodec libx264 -vprofile high -preset veryslow -b:v 225k -maxrate 300k -bufsize 1000k -vf scale=-1:560 -threads 2 -pass 1 -an -f mp4 /dev/null

/** MP4 with audio 2nd pass **/
ffmpeg -i input.mov -vcodec libx264 -vprofile high -preset veryslow -b:v 225k -maxrate 300k -bufsize 1000k -vf scale=-1:560 -threads 2 -pass 2 -acodec libvo_aacenc -b:a 128k -f mp4 output_file.mp4

/** MP4 without audio 2nd pass **/
ffmpeg -i input.mov -vcodec libx264 -vprofile high -preset veryslow -b:v 225k -maxrate 300k -bufsize 1000k -vf scale=-1:560 -threads 2 -pass 2 -an -f mp4 output_file.mp4

/* Generate single image from first frame of video, scale and save as jpg */
ffmpeg -i input.mov -vframes 1 -vf scale=-1:560 testimg.jpg

/** webm 1st pass **/
ffmpeg -i input.mov -codec:v libvpx -quality good -cpu-used 0 -b:v 225k -qmin 10 -qmax 42 -maxrate 300k -bufsize 1000k -threads 2 -vf scale=-1:560 -an -pass 1 -f webm /dev/null

/** webm 2st pass with audio **/
ffmpeg -i input.mov -codec:v libvpx -quality good -cpu-used 0 -b:v 225k -qmin 10 -qmax 42 -maxrate 300k -bufsize 1000k -threads 2 -vf scale=-1:560 -codec:a libvorbis -b:a 128k -pass 2 -f webm output.webm

/** webm 2st pass without audio **/
ffmpeg -i input.mov -codec:v libvpx -quality good -cpu-used 0 -b:v 225k -qmin 10 -qmax 42 -maxrate 300k -bufsize 1000k -threads 2 -vf scale=-1:560 -pass 2 -f webm output.webm

You might need some kind of libraries or something ffmpeg is trying to use which you need to install. Just an idea, I'm not for sure though.

Use -2 instead of -1 and the error will go away

It did not 😕 I got the following error:

Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height

Edit Actually I had to use : -codec:a copy for the webm with audio