What options are there for cloud based FFMPEG processing? Just like Imgix and Cloudinary are image editing as a service platforms, are there any online platforms that provide ffmpeg as a service so we can run ffmpeg commands on their server?

At the moment I'm running my FFMPEG commands on AWS Lambda but we are hitting a dead-end because of it's limitation of 1.5GB RAM and 300 seconds duration.

Some of our video processing take upto 1.5GB RAM and it shuts down the server.
Actually you can use Cloudinary for video processing as well.

Cloudinary's API allows you to build manipulation URLs and embed a HTML5 video player with all the video sources and settings.

Original videos are stored in the cloud and you can then dynamically create multiple resized, cropped and manipulated videos on-the-fly and deliver them via dynamic URLs or use code to either add video tags or build the URLs.

For example if  you want to resize a video to a width of 150 pixels and a height of 100 pixels, the dynamic URL will look like this:

 http://res.cloudinary.com/demo/video/upload/w_150,h_100/dog.mp4


You can also rotate the video by any arbitrary angle in degrees with the angle parameter (a in URLs). For example rotating a video by 90 degrees:

 http://res.cloudinary.com/demo/video/upload/a_90/dog.mp4


If you want to add text overlays, use the text: property of the overlay parameter ( l_text: in URLs), followed by the font name and size (separated with an underscore), a colon, and then the text string to display. 
For example, to overlay the text string "Sample Video" in the Arial font with a size of 40 pixels:

l_text:arial_40:Sample Video.