Audio lags video

cwmorrow · #1 (**permalink**) 03-20-2007, 08:53 AM

I believe I've seen this problem discussed, but I can't find it in a search.
I have a Fortec Mercury II with a 10' dish, G10 C Band in Arkansas. The audio lags the video by a second or two. What is the solution?
Thanks,
Wayne

wejones · #2 (**permalink**) 03-20-2007, 09:07 AM

Quote:

Originally Posted by cwmorrow

I believe I've seen this problem discussed, but I can't find it in a search.
I have a Fortec Mercury II with a 10' dish, G10 C Band in Arkansas. The audio lags the video by a second or two. What is the solution?
Thanks,
Wayne

Occasionally you might see something like that on a random channel, but it shouldn't be like that in general. If it is like that on all channels, then that is strange. I had a guess that might explain the video lagging, but not for the audio lagging.

Anyway, is this on all channels? If not, and it's a channel listed in Lyngsat, then what channel? If all channels, then how is your system connected? Ie through TIVOs. If audio is AC3, how is it decoded? Ie I've seen video delays when the video goes through a TIVO and the audio goes directly to a stereo, but not the reverse, although if the audio is AC3, and somehow you are using software decoding on a PC or something, I could see the audio being delayed.

Anyway, short, less than a half second offsets are common, but a couple second delays are unusual, unless caused by the connections to the receiver.

elgemcdlf · #3 (**permalink**) 03-20-2007, 09:16 AM

I have found that hitting the pause button then unpausing usually syncs it back up.

wejones · #4 (**permalink**) 03-20-2007, 09:40 AM

Quote:

Originally Posted by elgemcdlf

I have found that hitting the pause button then unpausing usually syncs it back up.

I had forgotten about the pause function on that receiver, since I've disconnected it until I figure out something suitable for AC3. The one time I tried that pause thing, I think it CAUSED a sync problem for me, but that's a good thing to try. I'm also curious about how good the signal is. If there are errors in the signal, the PCR may be corrupted. But I think it's still strange. I can't remember seeing that big of a delay on a live signal except when caused by a TIVO, or the big 18 second delay I got when listening to Sirius audio with NFL games. Had to delay the video with TIVO to sync that.

elgemcdlf · #5 (**permalink**) 03-20-2007, 11:08 AM

I get it from time to time and it drives me crazy watching the mouth move out of sync with audio. No idea why I ever tried the pause but when I did I was back in sync. It would happen from time to time with the Platinum also.

cwmorrow · #6 (**permalink**) 03-20-2007, 08:54 PM

Upon examination, the audio is indeed ahead of the video by two seconds on JLTV, G10R TP 24. There is no problem on the Outdoor Channel, which shares the frequency.
Thanks again,
Wayne

wejones · #7 (**permalink**) 03-20-2007, 09:56 PM

Quote:

Originally Posted by cwmorrow

Upon examination, the audio is indeed ahead of the video by two seconds on JLTV, G10R TP 24. There is no problem on the Outdoor Channel, which shares the frequency.
Thanks again,
Wayne

Strange. I just tuned in that mux. Audio fine with my Ultra, and fine if I stream to my Roku. However, streaming to VLC, I don't get any sound at all, whereas the Outdoor channel is fine through all 3 methods. So it seems like there is something different about that channel. I'll try tomorrow with my Mercury. Interesting.

wejones · #8 (**permalink**) 03-21-2007, 06:53 PM

Quote:

Originally Posted by wejones

Strange. I just tuned in that mux. Audio fine with my Ultra, and fine if I stream to my Roku. However, streaming to VLC, I don't get any sound at all, whereas the Outdoor channel is fine through all 3 methods. So it seems like there is something different about that channel. I'll try tomorrow with my Mercury. Interesting.

Well this is really strange. After spending the day boiling maple syrup, I finally got back to this puzzle. I checked again, and I still cannot play the audio from this channel via VLC, which is an excellent program, that can play just about anything. I checked again with my Ultra, and if plays the audio fine, no delay. So just to complete the comparison, I hooked up the passthru of my ultra to the Mercury-2. Bingo! Audio is really badly out of sync!?!?! There has got to be something very strange about the audio on this channel. If I have time tomorrow, I'm going to save an MPG file from this channel and see if it plays, and/or is out of sync.

EDIT: I recorded a short 30 sec clip with TSREADER. Played the clip back:

via VLC---> No AUDIO ....
via WinDVD---> Audio plays fine
via Nero Media Player----> Audio out of sync
via VideoReDo------> Audio plays fine
re-processed with VideoReDo---->VLC----->Audio plays fine in VLC
weird.

Obviously, there is something strange about the audio on that channel, and obviously different players or CODECS handle it differently.

wejones · #9 (**permalink**) 03-22-2007, 09:59 AM

After pondering this strangeness, I noticed that when playing back my file in VLC, that the progress bar didn't move. Thinking that this must be a timing problem, I checked the original signal. Sure enough, the PMT for this channel doesn't have a program clock reference. Apparently some receivers just assume the PCR data is with the video, and others don't.

Anyway, the solution is simple. Just manuall enter the channel, making sure to use the video PID for the PCR.

cwmorrow · #10 (**permalink**) 03-22-2007, 06:45 PM

Quote:

Originally Posted by wejones

Anyway, the solution is simple. Just manuall enter the channel, making sure to use the video PID for the PCR.

Thanks!
I know how to do that on the old Fortec, the one that won't find this frequency, but not on the Mercury II.

wejones · #11 (**permalink**) 03-22-2007, 07:08 PM

Quote:

Originally Posted by cwmorrow

Thanks!
I know how to do that on the old Fortec, the one that won't find this frequency, but not on the Mercury II.

Look in the Utility section for "Add Channel".

cwmorrow · #12 (**permalink**) 03-22-2007, 07:20 PM

Ah, RTFB.

Thanks, it worked!

(Read the Funny Book.)

cwmorrow · #13 (**permalink**) 03-22-2007, 07:40 PM

Except that when I change channels, it changes back to 8191.

wejones · #14 (**permalink**) 03-22-2007, 08:30 PM

Quote:

Originally Posted by cwmorrow

Except that when I change channels, it changes back to 8191.

Oh well, I thought that would work. Actually I didn't try it on the mercury, I just assumed it would work, since it worked with when I did that with TSREADER going to VLC. I'll have to play with the Mercury more. I don't know.

wejones · #15 (**permalink**) 03-23-2007, 06:13 PM

Well, I finally got a chance to try this again {busy boiling maple syrup}, this time with the Mercury. Sure enough, I add the channel with the PCR PID=VID PID, then go to the channel, and the info is correct, however just like you said, change channels, and go back to it, and it has reverted to 8191. Weird. I even tried deleting both the original and the new channel, and added it again. Same thing. The other weird thing is that 8191 SHOULD tell the receiver to use the video PID anyway.

On the other hand, the out of sync-ness wasn't so bad today, for some reason.