AVS Forum Special Member
Join Date: Dec 2001
Location: Middletown, Ohio
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Dunno if this is applicable or useful or not, but just in case ... One issue I have run into with one of my decoders here (Zenith HDV420 ATSC receiver specifically) involving "seemingly" dropped frames(stuttering video/etc - this is all with OTA) has occured when local broadcasters sending 720p have their encoders set so that setting on the encoder such as "repeat field detection"(note: I think that one "specifically" is the "term" used for the setting for certian Harmonic encoders) is turned on .... This is supposed to allow repeated fields to be flagged so that they are drawn by the decoder rather than encoded, but apparently some decoders can't do it properly ... In any case When engineers turned off "repeat field detection" settings on their encoder, the problem went away .. Note that the decoder in the Zenith is the ONLY decoder I have which exhibited this issue ...
Note that the issue only happened during programming sourced from 24fps sources (film, 24p HD video/etc) ... And, it wasn't just network (such as ABC) programming which was effected .... From one Fox affiliate for example, the problem never occured during Fox programming since that is encoded at network level and the splicer "allows it" to effectively bypass the local encoder, but, during syndicated programming sourced from film from that station, the issue occured until they turned off the "repeat field detection" setting on their encoder ... But, from a ABC affiliate, it occured both during Network, syndicated or local programming sourced from 24fps sources ....
BTW, The time compression "issue" previously mentioned is a PITA if you are IVTC'ing and decimiating(or just decimating) frames to return material to 24fps (such as with various AVIsynth filters/scripts which I do for processes such as reencoding using AVC or VC1)....