So I've had my new Panny Plasma 60 inch and Onkyo Receiver up and running for a few months now. I have direct tv genie system and a roof top antenna. I have run both an optical and the HDMI ARC audio return channel to the receiver. My research has indicated the ARC over HDMI to be technically better than the optical TOS link so I have enabled the ARC for OTA audio from the TV receiver to get back to the receiver. I see a big inconsistent discrepancy in lip sync between the Over The Air stations in LA. The local CBS affiliate KCBS looks to be in proper sync virtually every time I've looked but the ABC seems a few frames out and other stations are sometimes in and sometimes out.
Having never had such a large screen before I don't have a feel for how long and how typical these out of sync issues have been in the past. I had an SD CRT before this with SD direct TV and roof top antenna and I don't recall noticing so many out of sync channels. I learned at a recent Tektronix seminar that encoders will drift/hop our of sync in steps and the only way to reset the sync is to reboot the encoder. I'm not exactly sure where these encoders fall in the signal distribution chain but they had examples of the varying devices that are inline to transmitter feeds depending on the signal source. Local news cast from the studio vs. network feeds from their sources can run through differing paths at different times of the day etc....
At any rate I feel that if I see KCBS consistently in sync and the ABC affiliate out of sync at the same time when viewing OTA that there must be differences that are happening at the broadcasting sources. If it was my equipment set up, which offers audio delay but I have it set to zero delay, then all stations would be off in the same manner. As it is some are in sync and some out. Sometime I've compared the OTA sync to the same channel on my direct tv receiver and the OTA may be out where as direct tv is in sync and vice versa. I realize the direct tv must have the ability to adjust A/V sync before uplinking so that could account for their signal being correct when OTA is off but are they using an automated process like I've seen at NAB to make the correction? And bottom line are major network affiliates really this sloppy with A/V sync. I know it's happened in the past when equipment at the transmitter shack resets itself from a power spike and things go out of sync. I fight monitor delay in edit bays all the time and protools bays especially when it seems the video cards used have varying delays when playing back different codecs in the protools bay. That's a constant struggle even with my sync check box. Are others seeing these lip sync issues like I am or is there something wrong in my thinking here? If one OTA is always right and many of the others are off in varying degress that has to be the broadcaster side of things. I can't think of reason why my home system would exhibit varying delays between different OTA stations. I do usually change the channel and come back to a problem channel to see if that resets something in the decoder to help with sync. Sometimes it seems to help but most times it's hard to tell.
John Moore
Barking Trout Productions
Studio City, CA
bigfish@pacbell.net
Barking Trout Productions
Studio City, CA
bigfish@pacbell.net
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