audio sync issue

[lordshot]

Hello, ever since i bought a new TV ( LG LW4500) ive had some pretty annoying issues with sync... after playing around with the options, tv and med for very long time i figured that what works best is using downmix in both outputs instead of pass trough.

i have connected the med to TV via HDMI, to the receiver directly via optic and coax.

i read in this forum that this could be HDMI lipsync problem, so i tested using only composit instead of HDMI, i tried composit audio and coax/optic.

best result still is via using downmix.

does anyone know the reason for this ? what ever makes it work  better in downmix, why not apply it to pass through ?

[jer1956]

If you select passthrough you are passing the decoding to an external device...and it should be that which adds the delay...even if it's the amp in the TV itself.  Otherwise you could have multiple delays added...as a surround amp would expect to add any delay itself.

[lordshot]

i realize this, but before new tv it worked perfectly =(

[jer1956]

Yes...your new tv is 3D I bet. 

[lordshot]

yes it is =( is it clear whats the problem ?? any solution besides changing TV?

[jer1956]

The problem is 3d tv's expect sources with HDMI 1.3 lip sync to correct for the difference between audio  and video pipelines. Only the latest 3D devices will support that.  That's why you get so many 3D TV and 3D bluray bundles. You can either call this an oversite..or a deliberate con forcing users to buy new sources.

Prior to 3d, TV makers designed their TV's to use CEA-EDID audio delay..so for 20 years sources have worked with TV's without the sync issues earlier plasmas had..or the need for a crude manual correction in the source.


The solution is to add HDMI 1.3 lip sync into  your system.  That can either mean changing many of your sources..or just getting a new HDMI 1.4 surround amp with HDMI 1.3 lip sync.

[lordshot]

so even the new med wont solve the issue i gues...

[jer1956]

Only true 3D sources will have HDMI 1.3 lip sync...becuase they have been designed to deal with this problem created  by the 3D TV makers.  That dosn't include the X2.


But most people wanting 3D also want the latest HD audio...and hence get HDMI 1.4 amps which lip sync. That means all source connected to the amp don't need to correct for thsi...as the amp does it.

The other thing to try is to use 1080i. It would appear the delay needed for 1080i is the one the 3D TV makers offer as the CEA-EDID interlaced delay. So  any source supporting CEA-EDID will delay  the audio by the correct amount.

The most common Progressive source are DVD players..So I wouldn't be surprised if they use 576/480P as the value for the CEA-EDID progressive delay. It certainly isn't 1080P!

There is some lax enginneering going on..becuase with 2D Tv's they made sure every interlaced resolution had the same delay..and the same goes for progressive. Now they just let the delays be what the designs results in...and expect HDMI 1.3 lip sync to correct for it.

[lordshot]

So, as update, soon i will buy a receiver (Pioneer VSX-521-K) i will test how it goes and post here the result to help future people with the same problem.

thanks for the help

[lordshot]

Update:
Bought Pioneer VSX-521 receiver + Pioneer S-HS100 Speakers, audio is perfect or very very close to perfect now, i havent used for long enough to say that everything works, but so far everything good.

i connected Med via HDMI to the receiver, the receiver does all the work from there.


i will update this in a week or maybe 2 to report how its going for me.


VSX-521 is a nice "cheap" entry level receiver, and people who dont have any and wish they had could make a nice investment on this little piece of hardware


i hope this helps other people

[lordshot]

Update: 10 more days happened and i have watched plenty of TV, no problems yet.

looks like this works just fine.

i will make one last report in 2 to 4 weeks, after this i will report only if it doesnt work.

[jer1956]

Thank you for keeping us  up to date. You must have considered the explantion given required a risky investment to some degree.

[lordshot]

well of course its risky since i don't truly understand how CEC and HDMI audio hand shake is working, specially when involving a middle device, i think i will not be the only one that's why i leave as much info as i can, so other people can trust that we can keep the med by buying a receiver.


you know what they say, information is power

[trecky]

best way to fix sync problems is to set your mede8er to 1080i 50hz - works perfect with on my samsung is way out on sync on 1080p etc

hope that helps