owahab/paperclip-ffmpeg — pull request #16 by esbanarango (2013-02-18 00:01:51+00:00)
Title: Validations on parameters values and allow multiple commands on the :vf key

This pull request has two parts.

1. Allow multiple commands on the `:vf` key.
* I came into this _issue_ trying to get a thumb image (jpg) from a video and getting it rotated too. This wasn't posible because in the _pad_only_ process the `:vf` key was being overwritten.
* __Example:__
* Before:
* `-vf transpose=1` <- This command will be overwriting.
* `-vf scale=250:-1,pad=250:250:0:55.0:black`
* Now:
* `-vf scale=250:-1,pad=250:250:0:55.0:black,transpose=1`
2. Validations on parameters values.
* In some cases some keys may come with an empty string or nil.