I've used Tuneskit for 2 videos now, and they claim to not re-encode the video (even though it takes awhile which raised an eyebrow with me) The bit rate and resulting filesize is identical, with the exception being the AAC stereo track. perhaps the stereo audio track is re-encoded and the 5.1 audio and video are just stripped of DRM??? at any rate I have not noticed a perceptible difference in quality but would need to do more tests to be 100% sure. It works with latest itunes and is frequently updated. It is not free however.