Ionic - take a picture with camera and send it to Amazon S3

I am building an app with Ionic framework (angularjs + cordova).

I would like the user to be able to take a picture with his phone camera, and send it directly to an S3 storage on amazon aws.

I know how to take a picture, and get it's base64 and it's URI on the local file system:

ngcordova - camera

I also know how to send a file to S3 through ajax using jquery

Direct upload to S3

Now, the problem is that all the file uploads I found are using an "input type=file". How can I manage to pass the file to the uploader, using its local URI or the base64 encoded string ?