video playing issues

I have many videos I cannot play fine on the iPad.

They are all mp4 encoded with Handbrake.

I tried several ways to play them:

- syncing via iTunes into the "Movies" app

- copying them into OPlayer (and many other third-party apps) documents

- play with Air Video

No way at all.

The issues are: video suddenly stops (or freezes), while audio goes forward, then video restart again, the picture goes green for a second or two, it gets skippy and so on.

The matter is that playing the same videos with iPhone 4 works good. I wonder if that's due to the difference in memory amount between the two devices.

The videos are not too large, in size are 1g approx, they are Standard Definition videos and not HD, ripped from SD DVD or from tv recordings made with Elgato eyetv, SD as well.

Any other encountered problems watching videos on the iPad? Any hint?

Thank you.

Tiziano Solignani