Does a DVR track frame rates or does it treat it simply as data? [...]
Video is encoded to a frame rate, but I believe trickplay always needs to land on a "key" frame, which is the first frame in a sequence of frames that whatever compression is being used determines is most important to encode with as little loss of quality as possible.
That's why it sometimes appears after stopping FFX1, which has no autocorrection applied to it, that the video still jumps backwards before resuming play. I believe that happens when the closet key frame to the stopping point is before
the resume point, and the HR needs to "back-up" to find it. Otherwise, if it always jumped to the next
keyframe, there would be a risk of a dropped word of dialog.
MPEG-2 by it's nature is encoded with more key frames than MPEG-4, which is why MPEG-2 file sizes are larger. As a result, tho, MPEG-2 trickplay is smoother.
I think trickplay is an area where the HR's were being unfairly compared to the DirecTiVo, because the HR10 only had to deal with MPEG-2 files. Comparing MPEG-2 to MPEG-4 trickplay is really comparing apples to oranges.