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Discussion Starter · #1 ·
I'm running an LG LST-4200A OTA, with the audio connected via optical cable to my Sony receiver. Set for Dolby Digital output.


I'm noticing that on a LOT of HDTV shows that I watch, the audio is slightly out of sync with the video. Actor's lips move just slightly before they speak, etc.


The first time I noticed that was on an episode of Grey's Anatomy. I posted in my local reception area thread (Detroit), and some others had noticed it as well, so I apparently it wasn't my setup.


Since then, though, I've noticed it on MANY shows across many networks. It almost seems like the audio is out of sync more often than it's in sync.


Is this a common issue in HDTV transmissions at this time, or could I have a hardware issue? I noticed while watching a rerun of "House" the other night that it was exceptionally bad - part way through the show, the signal unexpectedly dropped for about 1 second, then returned and things were synced up much better (I wonder if the station reset something). Anything I can troubleshoot to definitely rule out my hardware?


I've tried setting the output to PCM in the 4200A, but that didn't make a difference.


Thanks,
 

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I saw the same problem the other week. I receive Fox east from NY via D* and run my optical and the video via component through my Yamaha AV receiver. I hadn't noticed it on any other shows though. I am a little puzzled as to why this should happen. If I was running the video direct to the TV and bypassing the AV receiver I could maybe understand it.

It must be out of sync when it comes off the satellite. Having said that, the new line of Yamaha receivers have the ability to delay the audio for this very reason.

From Yamahas web site:


Other RX-V2500 Features


Accurate Touch Volume Control

192 kHz/24-Bit DACs for All Channels
Audio Delay for Adjusting Lip-Sync (0–240 ms)

Analog Mixdown


Alan
 

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try turning your set top box off, then back on, works for me whenever the audio sync is off.... especially if i have been flipping around amongst all the channels
 

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In most cases, it happens after an error in transmission of the signal. Though the signal is actually still in sync as it is received, it gets out of sync locally as it is converted to your video output format and audio processing.


For example, my Dish 6000 will loose sync after a transmission issue on the video/audio out put, but at the actual signal path in the unit where 169time and R5000HD mods are, they continue to capture the signal in sync.


Changing the channel will bring them back together.


However, I have seen some actual times that BEV and D* have had the OTA HD Networks out of sync in the past.


Though most times you will find it to be an error that caused the mpeg decoding locally to loose sync.
 

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Quote:
Originally Posted by EnglishRebel
I saw the same problem the other week. I receive Fox east from NY via D* and run my optical and the video via component through my Yamaha AV receiver. I hadn't noticed it on any other shows though. I am a little puzzled as to why this should happen. If I was running the video direct to the TV and bypassing the AV receiver I could maybe understand it.

It must be out of sync when it comes off the satellite. Having said that, the new line of Yamaha receivers have the ability to delay the audio for this very reason.

From Yamahas web site:


Other RX-V2500 Features


Accurate Touch Volume Control

192 kHz/24-Bit DACs for All Channels
Audio Delay for Adjusting Lip-Sync (0–240 ms)

Analog Mixdown


Alan
Some TVs take a finite amount of time to process (and sometimes convert) the video portion of the signal. However, they usually delay the internal audio to match. This is fine if you are using just the TV's built-in audio and speakers. If you feed audio from an external source, such as a satellite STB to your A/V receiver, it will likely come out AHEAD of the video.

Both the Yamaha RX-V1500 and RX-V2500 have audio delay to take care of this. There is also an audio delay box from the UK that does this, if you can't justify springing for a top-of-the-line A/V amp. Sell price is about 200 bucks.
 

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Discussion Starter · #7 ·
Thanks for all the information.


My current setup is that I feed the audio out optically from the 4200A to my Sony receiver (model number escapes me at the moment - it's an STR-DE835, purchased around 1999).


Video is fed directly to the TV via component cables.


When I notice the audio lag, changing channels doesn't help. I've also tried shutting off the 4200A then turning it back on, and haven't noticed that helping.


When I watch analog cable TV, I have the analog signal going directly into the tv, and the audio out from the tv connected to the receiver (I have the speakers on the TV shut off completely). I never have this issue when watching analog cable.


Could it be that delay is introduced by the receiver, perhaps when it's decoding DD? I need to keep track of when we notice this issue, and see if it's primarily with DD 5.1 shows.


Is this a case where I should be feeding the video through the receiver to keep it in sync (I don't believe my reciever has that capability, certainly not with component output)?
 

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Quote:
Originally Posted by fcondron
Is this a case where I should be feeding the video through the receiver to keep it in sync (I don't believe my reciever has that capability, certainly not with component output)?
I would be surprised if the Sony did not have component inputs and outputs. I used to have a Sony STR unit and if I remember correctly it had them although at the time I didn't use them as my Sony TV only had SVideo in.

However having said that, I think you will still have the same problem because I still do. I guess the only solution is to feed video and audio direct to the TV and let the TV take care of the problem (per Carl33) but then you loose the ability to have DD.

Alan
 

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Discussion Starter · #9 ·
Quote:
Originally Posted by EnglishRebel
I would be surprised if the Sony did not have component inputs and outputs. I used to have a Sony STR unit and if I remember correctly it had them although at the time I didn't use them as my Sony TV only had SVideo in.

However having said that, I think you will still have the same problem because I still do. I guess the only solution is to feed video and audio direct to the TV and let the TV take care of the problem (per Carl33) but then you loose the ability to have DD.

Alan
Trust me, no component inputs/outputs. I just verified it by looking at a .pdf copy of the manual. Only composite RCA-style (single for video) and a few s-video jacks.


I certainly don't want to run the audio direct to the tv and use the tv speakers - that greatly defeats half the advantage of HDTV (the 5.1 surround). I can't believe everyone using HDTV with an audio receiver and 5.1+ setup is just living with the audio being out of sync...


I'm fairly certain that the audio is BEHIND the video, but I'll try to verify that tonight.


More info that just occurred to me - I also have a HTPC that we record shows with (only recording off of analog cable). It's connected similarly - component video straight to the TV, audio goes to the coax digital input on the receiver utilizing PCM. I've never noticed an audio sync problem when watching shows via that. I'm becoming more and more convinced that I only see the delay issues when watching HDTV shows that utilize 5.1/DD.
 

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Frank

I will also try and see if audio lags video or vice versa - it's a little difficult to tell though because it's such a short delay. I only get the problem on HD shows. House was from Fox NY via satellite but I also get the same problem when watching some HBO movies in HD. I will check to see if I get the delay when watching HD OTA but I'm fairly certain I don't. I too don't understand why more people are not posting the problem here.

Alan
 

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I have noticed the audio sync problems from time to time, but it has only been with the D* channels. Changing channels does not fix the problem. I have not had any problems with any of the OTA channels.


Receivers used: Samsung TS-360 and H10-250.
 

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Well I watched a rerun of House last night on Fox NY via satellite (the program where I originally noticed the lip sync problem) and it was perfectly in sync. So the problem must be intermittent leading me to believe it's the satellite feed.

Anyone got any more comments?

Alan
 

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Discussion Starter · #13 ·
Same here - I watched most of that House episode (OTA in the Detroit area) and saw no issues. I also checked out a few other shows. Medium seemed perfectly in sync as well (but wasn't DD 5.1, which most of the shows with audio sync problems seem to be). Seventh Heaven DID seem slightly out of sync, but I was going crazy trying to figure out if the audio was lagging, or if it was the video.


I'd expect that if it were my hardware or setup, I'd see the problem all the time. I'm just finding it hard to believe that if it's a transmission issue, there aren't more posts on this forum complaining about it. It seems to hit a good two-thirds of programs we watch, and is very annoying.



And here I was all set to get a new Panasonic digital receiver to see if that would help. Maybe I'll find a way to justify it anyway. :)
 

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Discussion Starter · #15 ·
Quote:
Originally Posted by Foxbat121
Nobody mentioned what kind of TV you have here? For example, Samsung DLPs are notorious for A/V sync problems.
I have a Sony HS30 rear-projection set, about 5 years old. It's getting it's signal via component input.
 

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Sammy gets A/V sync issue regardless of input types. A/V sync is tough to get rid of if it happens in source device (STB or DVD player) because of the nature of randomness in the delay.
 

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Discovery on D* is ALWAYS considerably out of sync for me but I hardly notice any on the other channels. I always assumed it was the broadcast since it's only one channel.
 

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What I find frustrating is that, while I have a H/K AVR435 that can artifically delay the audio, my problem is that I ALWAYS have an audio lag in the first place. Here's what I'm running (component feed):


D* H10 ------> AVR435 ------> InFocus 7205


I've used the HDMI output (DVI to 7205) to bypass the AVR435, which didn't make any difference. While I do notice more audio lag on some channels compared to others, the problem is generally pervasive across all channels.


Anybody else have a similar setup/problem?
 

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Quote:
Originally Posted by turt
Discovery on D* is ALWAYS considerably out of sync for me but I hardly notice any on the other channels. I always assumed it was the broadcast since it's only one channel.
I noticed the same thing for Dicovery HD in my Cox cable. Maybe it is the problem with the broadcast.
 

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I have an LG 52" DLP. I haven't noticed any sync issues on Discovery HD Theater just on Fox E. In fact I was watching Rick Steves last night and it seemed okay.

Alan
 
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