TivoHD playback requirements?


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Anyone from VideoRedo been able to get their hands on the H.264 spec requirements for Tivo playback?

I ask because I am trying to find a way to improve playback of x264 encoded material on the TivoHD. For a long time, a few of us had been struggling with the garbled opening scene when playing h.264 material and it was found that if we mux the audio into the mp4 container before the video, that the playback was normal.

Then, I (in particular) had been complaining about "shimmering" subtitles on x264 encoded material with burned in subs. What was happening was that static images were not getting decoded well. Sometime, the subtitles would display fine and the video looked great. If I paused, or did some sort of trick play where the starting frame didn't decode well, the subtitles (actually the whole image) would move up and down very rapidly to create a shimmering effect. The video would continue to look like this until I pause/trickplay and start on a frame that decoded well. This turned out to be a problem with h.264 playback of 23.976fps material. If I duplicate frames to get back up to 25fps or 29.97 fps, then the playback is fine.

I would like to find a way to get back to 23.976fps material rather than resorting to the somewhat jerky playback of video with duplicated frames. I am wondering if this is a known issue with Tivos (as in, were you aware of this through some spec sheet or something)? Do you have any contact at Tivo that might know this info and maybe know if this is something that could be improved/fixed with a software update?
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