C.Y.M wrote:
IRL, time is constant. But on playback if vdr doesn't clock its data, then desync is quite possible. For example, if there's nothing to "change" for a few video frames, because they're using "stack" compression they won't send an empty frame. So, consider this blackout time in "Lost". The theory is that problems are occurring because they're not sending empty null frames. Also, if they're clocking on video, not audio.
Out of curiosity, I've tried recording one of these flirt phone ad channels, that only send still pictures at extremely low data rates. Playback seemed to be fine more or less, though a/v sync is hard to notice there. The recording length and the video playback speed was more or less correct however.
Another hint: If frames are completely missing in the recording, they also don't account for VDR's absolute recording position and recording length. If there are enough of them, this should be noticeable.
Does VDR store the pcr pid in the recordings? Is the pcr used during playback to clock the data?
Recordings are pure PES packet sequences of video and audio PES packets. PCR is not recorded. On playback, the PES packets are forwarded to the DVB driver without further modification. IMHO the playback sync only uses the PTS of the PES packets, however thats just guessing.
I'm not sure if the PES repacker does anything on recording or if PCR is used only on live. There are not much German channels with PCR on Astra anyway.
(look for VPID with nnn+nnn form in channels.conf)
Cheers,
Udo