How to access AWS - Amazon web service's API in wordpress?

I did install the 2 plugins (AWS - Amazon Web Service and S3 offload) in my WordPress CMS in order to upload media to AWS. On the other side, I would like to do trans-coding pro grammatically via my plug-in and now I have a difficult time to find the way to access to aws's api through their plugin.

Please help,

Thank you

via Chebli Mohamed