What would be the optimal compression for SMS?

What would be the optimal compression for SMS?

Optimal X x Y resolution which algo is SMS best at?
Optimal sound compression options.

Yes, you read right, I am asking what would be the ideal settings for SMS to make the best playback experience.

I would really like the answer either in linux command line form or screenshots for GUI apps.

If this question is every answered in a good manner, I would ask this thread to be stickied or the answer to be added to the readme of SMS.