Optical - audio out of sync

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simon14

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Topic # 66237 15-Aug-2010 18:37

I connected my HD tv up to my surround sound system via the optical out on the TV into the optical in on the home theatre system, but the sound is out of sync with the picture. This is also evident when i turn the TV volume up and have the surround sound volume up at the same time - the TV sound comes out before the surround sound.

If i run the surround sound through the AV audio out on the TV into the av audio in on the surround sound system, the sound is in sync on the surround sound system so it's only out of sync using the Optical cable.

My question is, is this being caused by my Panasonic surround sound system or is it to do with optical technology itself? I know it's not the TV causing the latency in sound because the sound coming out from the TV directly is fine and sound being sent from to tv to the surround sound system via av out leads is also fine.

I'd really like to use the optical out as we just had freeview HD installed and i would like to benefit from the 5.1 surround sound.... as the av cables only do 2 channel audio, not surround sound.

Also have a similar issue with the ps3. When i use "optical out" on the ps3 into "optical in" on the surround sound, movies/games are in sync but Singstar mics are out of sync. For example, if i say something into the singstar mics, it will come out the speakers a split second later. If i run the ps3 through av audio out, it's instant and there is no sound delay at all.

Beginning to think it's an issue with Optical in general but would like to hear what others think??

xarqi

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Reply # 367947 15-Aug-2010 19:43

I'd be looking for an "Optical audio delay" setting that needs tweaking, either in the TV, or the HT system. You've specified the sound system as "Panasonic", but exactly which model? Likewise the TV.

illicit

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Reply # 367950 15-Aug-2010 19:46

Turn off ALL picture processing (dynamic contrast, film mode, black enhancer etc etc)

then report back here with results

Oblivian

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Reply # 367951 15-Aug-2010 19:47

So you have an EXTERNAL Freeview decoder via HDMI to the TV then trying the optical out from the tv?

I'm picking from the quick google, for that method you have to mess with the audio over HDMI routing options. That, or its needing to downmix the audio to stereo over optical. One tv I saw mentioned didn't do (5.1) passthrough (which you will need)

You may find your tv is still outputting the analogue audio signal as apposed to the decoers stream?

Might need to list input/output configuration to give a clearer picture on where the TVs sources are likely to be coming from

simon14

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Reply # 368058 16-Aug-2010 06:08

Thansk fro the replies.

TV has Freeview built INTERNALLY, i'm not using an external box - so the optical leads are going straight from tv into surround sound system.

Will report back on make and models when i'm home later this evening - however TV is Sony and surround sound is Panasonic.

I'll turn off all picture processing and let you know what happens.

simon14

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Reply # 368059 16-Aug-2010 06:12

illicit: Turn off ALL picture processing (dynamic contrast, film mode, black enhancer etc etc)

then report back here with results

Thinking about this further.... this would make sence if sound from the surround sound was coming out before the TV's sound - that would indicate there is a manual time delay in the sound from the TV to keep up with a delay in the picture being processed. This is not the case though, the sound delay is not from the TV but from the surround sound system so i don't think it has anything to do with picture processing or anything but will give it a go anyway.

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Reply # 368292 16-Aug-2010 18:19

simon14:
illicit: Turn off ALL picture processing (dynamic contrast, film mode, black enhancer etc etc)

then report back here with results

Thinking about this further.... this would make sence if sound from the surround sound was coming out before the TV's sound - that would indicate there is a manual time delay in the sound from the TV to keep up with a delay in the picture being processed. This is not the case though, the sound delay is not from the TV but from the surround sound system so i don't think it has anything to do with picture processing or anything but will give it a go anyway.

is the sound coming BEFORE or AFTER the picture? Thats probably the most important thing to know in order to determine where the problem is.

I used to run into the problem where the soundtrack was ahead of the picture with my samsung plasma. I fixed the issue by sending in the exact native resolution so that the plasma didnt have to perform any scaling. The sound was fine when coming back out of the samsung's rca points, but not if i sent it straight to HT amp. Obviously the samsung was adding its own delay to internal audio when performing picture processing.

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illicit

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Reply # 368309 16-Aug-2010 18:54

simon14:

Thinking about this further.... this would make sence if sound from the surround sound was coming out before the TV's sound

My bad, read your post the wrong way around - I thought the sound was coming out of the stereo BEFORE the TV.

simon14

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Reply # 368355 16-Aug-2010 20:45

Just to confirm, the sound is coming out AFTER the picture - so it's nothing to do with the processing time of the picture.

The sound comes out perfect from the TV itself and perfectly from the surround sound unit itself with AV cables but the sound comes out AFTER the picture using optical out into the surround sound system, so it's something to do with the optical out.

Have not had time to confirm Panasonic surround sound model number but tv is SONY KDL55EX500

Oblivian

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Reply # 368358 16-Aug-2010 20:57

This may sound silly, and hopefully you already checked.. is your fancy new TV actually currently on the digital tuner, not the analogue one.
(soon tell, images will be stretched/squashed and not true 16:9)

The digital may well be piping the digital audio from the digital stream, but if you are watching the analogue video at the time.. there will be a delay for sure. Standard RCA audio wouldn't suffer this as it will be a what-you-are-watching output. There's no processing being done

Analogue vs digital signals can be up to 10sec out of range depending on the decoding process.

I know the parental units 2x panasonics have a button on the remote to switch analogue/digital sources.

(of course this wont help your PS3 issues)

xarqi

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Reply # 368366 16-Aug-2010 21:20

I've found a manual for the TV online and there's nothing in there about setting an audio delay. The nearest was a setting in the Home/Sound menu where you can change the optical out to either Auto or PCM, It says the first is for Dolby Digital compatible devices and the second for everything else. You could try the different settings and see if there's any effect.

simon14

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Reply # 369025 18-Aug-2010 07:17

TV is tuned through Digital, not analogue.

I have tested both Auto and PCM with no luck.

I think it may be a setting with the surround sound - but then bluray movies via ps3 are in sync via optical out of ps3 into optical in on surround sound so that kind blows that theory.

Jaxson

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Reply # 369159 18-Aug-2010 10:25

So basically this only happens when you send optical out signals from the TV to the amplifiers optical in?

Fault with TV's optical out, have you googled that model number for possible other users with same problem?

Do you still have the delay problem running a standard stereo rca analogue audio lead from the TV to the amplifier?

Is there some special hidden setup menu perhaps that allows for optical delay times?
Do you get this same problem on TV3 dolby digital shows, like lie to me, csi's etc that are in 5.1?

simon14

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Reply # 369172 18-Aug-2010 10:39

Jaxson: So basically this only happens when you send optical out signals from the TV to the amplifiers optical in?

Fault with TV's optical out, have you googled that model number for possible other users with same problem?

Do you still have the delay problem running a standard stereo rca analogue audio lead from the TV to the amplifier?

Is there some special hidden setup menu perhaps that allows for optical delay times?
Do you get this same problem on TV3 dolby digital shows, like lie to me, csi's etc that are in 5.1?

No delay when running standard stereo rca analogue audio from tv to amp. Only a slight delay when running optical from tv to amp.

I can tell there is a delay because i have the volume on the tv up and the volume on the amp up... the amp is slightly behind. When having vol on tv up and vol on amp up using rca cables, it's exactly the same with no delay.

No known issues with this tv regarding to optical issues.... it better not be a tv fault, it would be a hassle to try and fix.