[VincePirez]

I know this is an old (and ongoing) topic but I hope someone can give me some additional advice or information.

I've been struggling with 24p issues for a long time now and have been getting by with OpenElec and some manual delay adjustments in advancedsettings.xml. I recently changed AV receiver and decided to revisit this problem. Let me first start by saying that the new AV receiver, with identical HTPC and OpenElec settings, plays things exactly how they were before. I'm almost 100% certain that swapping out the amp (which I did because of its age) has made zero difference here. After a lot of testing, though, I've found that for some reason certain audio formats appear to have different delays associated with them.

If I use passthrough on AC3/Dolby Digital tracks, there is an apparent delay of somewhere around 175ms. This isn't exactly 175ms, but I can't seem to find the "perfect" value that seems to sync up perfectly. Nonetheless, if I disable passthrough and let Kodi decode the AC3 instead, there is no delay and everything is synchronised perfectly. What's odd about this is that DTS passthrough works flawlessly and perfectly in sync. Why does DTS passthrough have no sync problems but AC3/Dolby does? My amp supports it without any problems, and there are no differences in processing for each format.

Obviously I'd prefer my amp to handle the AC3 directly via passthrough, and I know for sure it's capable of handling AC3/Dolby Digital. I can't work out what is causing the delay. It's not my amplifier, as the same thing happens with the old amp. Is passthrough handled differently for different audio formats? Any ideas welcome.