Odd A/V synchronization error

[nak]

Hello,

I have seen a somewhat odd problem that I've not seen or read about here before.

First off, I use GBPVR for OTA (USA) digital/HD receiving/recording with a DVICO ATSC tuner card, and it all works great.

I was using the Cyberlink audio decoder, which worked fine for connecting stereo audio to my TV audio input. However, I was never able to get 5.1 audio out of the optical output of my sound card to connect to my 5.1 receiver using that decoder.

To try to get 5.1 audio, I tried using the AC3filter audio decoder, and was able to get 5.1 audio out of my sound card, with one caveat: When watching live TV, the A/V synchronization is off. The audio runs quite a bit ahead of the video, making it impossible to watch. I messed around with the AC3filter settings, but could never get that fixed.

Then, however, I noticed that if I watched programs that had already been recorded, the A/V sync was perfect! Odd. So, I did the following:

Watch something live. Notice the A/V sync being off. Go to the TV Guide, and start recording that show. Go back to watching live TV, and select that show that is being recorded to watch it as it's being recorded. Magically, A/V sync is perfect! This proves it has nothing to do with the actual content of the show, and has everything to do with whether it's live or recorded. (I think.)

So, for some reason, A/V sync. is perfect for me using that decoder when watching a recorded show, but not a live show.

As a further experiment, I'll watch a show live, then hit 'pause' to put it in time-shift mode, expecting the A/V sync to work since it was now working off a recorded source, but alas, the A/V sync would stay off in this scenario.

This isn't that big a deal, since I only would use the 5.1 audio on occasion, and do most of my watching using the stereo output to my TV using the Cyberlink decoder. If there's something where I'd want to use the 5.1 output to my receiver, like the upcoming Superbowl, I'll just record it and watch it allmost realtime as it's being recorded using the AC3filter, and the AV Sync will be fine.

I'm just confused as to why the AV sync for that decoder works on recorded shows but not when watching live TV?

Any ideas, anyone?

[Carlito]

Did you try different audio renderers as well as decoders?
I don't use 5.1 myself but thought it might be worth a try.

[pBS]

sounds like interaction between sub's filters and your audio....
in watching 'in progress' recordings, it usually uses it's own filters to play,instead of the regular ones used when playing finished recordings..
probably some interaction between those filters..
i would also suggest changing the renderer to either default, or play with the others...i find they make a huge difference in sync on some files..

also, look at the lastgraph to make sure it isn't having to insert other filters to get the ac3 filter to connect...
[if it won't open, just read it with notepad,filters are at top]