Yet another HDTV + audio setup question

General Questions
#1

We got a new flat screen TV about a month ago (Sharp Aquos 40" LED), and I’m having trouble getting the audio configured the way I want it, so I’m looking for suggestions.

First attempt: I had an HDMI connection from the cable box to the TV. I had a digital audio connection from the cable box to the surround sound receiver. When hooked up this way, the TV picture is about half a second behind the audio.

Second attempt: I removed the digital audio out from the cable box and ran the audio from the TV to the receiver instead. Now the sound is in sync, but I don’t get surround sound - only stereo. I looked in the manual for the TV and it said that I should be able to select between “PCM” and “Dolby Digital”, but I don’t see that option in the menu anywhere.

I went to Sharp’s website to see if there were any support FAQs for this product. I found a FAQ with the question “Why can’t I get Dolby Digital sound on my TV?” The answer is “You can only set the audio output to Dolby Digital when the input is on TV.” In other words, if I’m using HDMI, no surround sound.

So, third attempt: I run a coax cable from the TV out on my cable box to the TV. Yay, surround sound and it is in sync with the picture. Except, apparently, my cable box doesn’t output an HD signal through the coax output - it’s only a SD signal.

So I seem to be screwed here. I can have a hi def picture that is out of sync with the surround sound, or a high def picture that is in sync with stereo sound, or standard def picture with surround sound.

A couple of side questions: is it normal to have a delay with HDMI? My old HDTV was old enough that it only had component video, and I never had the problem with the audio out from the cable box being out of sync. Also, is it normal for an HDTV to not have surround sound output from the HDMI inputs? Should I have gotten the LG or Samsung instead? :wink:

#2

Have you looked up the model on avsforum.com? Odds are there’s a super-secret menu to access where you can sync up the audio to solve the first problem you encountered.

#3

Your best bet is to work on case 1. There shouldn’t be a sync problem between the digital audio out and the HDMI out from the cable box (what model is it BTW)? I’ve used the same configuration in the past, and didn’t have an issue.

Case 2 is somewhat problematic - part of the HDMI protocol is for the display device to inform the signal source what its supported audio formats are - so the TV is telling the cable box that it only supports 2 channel stereo, so the STB is only delivering 2 channel stereo. There may be TVs that accept the full 5.1 signal and downmix it themselves, but you’d have to research (or go to avsforums) to find out which they were. It’s not just selecting the L&R from a 5.1 signal, since most/all of the dialog will be in the center channel subsignal.

Case 3 will never work - the signal from cable box to TV over coax is NTSC, and has no HD capability.

#4

I downloaded the manual for the only model I saw on Sharp’s website for a 40 inch LED AQUOS model. Since you say your TV’s only a month old, hopefully it’s the same model, which is LC-40LE810UN.

When you say, “Ran audio from the TV to the receiver,” do you mean red and white RCA cables? Pages 15 and 28 of the manual state that there’s a DIGITAL AUDIO OUTPUT jack on the back of the TV, right below the four HDMI ports, which appears to be optical. What I’d do: take an optical audio cable, and connect it from that output jack on your TV to the input of your receiver, and leave the HDMI cable running from your cable box to the TV as well. That HDMI cable carries both audio and video, so your TV should pass the digital audio signal along to the receiver. Now that both audio and video are passing through the TV, they should be in sync, and your receiver should be getting surround audio.

#5

What kind of surround sound receiver do you have? Does it have HDMI inputs and outputs? Does it support video pass through?

Here’s how mine is set up. I have an HDMI cable from the sat receiver to the home theater receiver. Another HDMI runs from the output of the receiver to the input on the TV. Both audio and video run through my home theater receiver and I’ve never had an issue with audio/video sync.

The great part about this set-up is that I can do the same with my blu-ray player. When I want to watch a disc I only have to change the input on the home theater receiver. I never have to mess with changing the input on the TV.

#6

Mild hijack: can you define “home theater receiver”? I have one of those Blu-Ray Home Theater systems, with the blu-ray DVD player as the main unit & surround speakers connected to that. Would this unit be considered to be a receiver?

In addition to the audio problems I outlined in another thread, I also have occasional audio delay, which is maddening.

#7

I wouldn’t. With the one weird exception of “ARC system”, it doesn’t “receive” anything. A home theater receiver takes multiple inputs (cable, DVD, bluray, gaming system, iPod, etc.) and is able to switch between them and output sound. Some systems can output different sources into different speakers, creating a “Zone 2” for when you want to pipe music into the kitchen/patio/etc.

#8

Max Torque you are correct about the model. The audio going from the TV to the receiver is from the digital optical output (the glowing red output). HDMI from cable box to TV, digital audio from TV to receiver. This is the configuration where the picture and sound are in sync but only in stereo.

Cell Guy, I’m not sure if the receiver has an HDMI input or not. I’ll have to check when I get home. Considering that the thing has about a hundred jacks on the back, you’d think one would be HDMI but I don’t recall seeing one off the top of my head.

Munch, thanks for the tip on avforums. I’ll take a look.

#9

Messed with this some more after I got home from work. I may have the problem resolved, or at least it doesn’t seem to be as bad as it was.

One thing I forgot to mention in my OP was that when I had the audio out from the cable box going into the receiver, it was a coaxial digital audio cable, not an optical digital audio cable. This was a hold-over from the old HDTV we replaced, which did not have HDMI inputs, only S-video and composite. On the old TV I had composite video and coaxial digital audio, so when we hooked the new TV up I hooked up the HDMI cable from the cable box to TV but left the audio cable in place. This is where we noticed the delay between the video and audio.

The TV does not have a coaxial digital output, only an optical digital output. My stepson had a spare optical cable so that’s what I used to connect the TV’s audio output into the receiver, which is the situation where the sound is in sync but only in stereo.

What I did was removed the digital audio cable from the TV and connected it to the digital audio output from the cable box. So now the way I have it set up is:

  • HDMI from cable box to TV
  • optical digital cable from cable box to receiver

It may be my imagination, but the optical digital audio seems to be a little more in sync with the picture than the coaxial digital audio. Not perfect, but definitely not the half-second or more out-of-sync I was getting before.

Almost forgot to add: Cable Guy, the receiver (a Denon AVR-1907) does not have any HDMI inputs or outputs.

#10

Okay, so when you run the optical audio cable from the TV to the receiver, the sound’s in sync, right?

Check page 28 of your manual again; it describes a place in the TV’s menus (looks like Menu > System Options > Audio Setup) that will let you output either PCM or Dolby Digital from that optical out port. Default is PCM, give DD a try.

Just to be sure: are you certain that the program you’re watching has surround sound? You won’t get sweeping surround effects from every show, or even every channel. Turn to a high-def action movie, that’s probably your best bet for testing purposes.

#11

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#12

Following up on this after monitoring the situation for several days:

I’m now about 99% sure that the audio/video sync issue is a problem with the HDMI output on my cable box. The audio/video coming from the HDMI output seems to be delayed compared to the audio coming out of the digital audio output. Some days the problem seems to be worse than others, but over the last few days it has gotten much worse. The kicker, though, is that last night we were watching a movie on DVD. Since I only have one HDMI cable at the moment, I unplugged the HDMI cable from the cable box output and plugged it into the DVD player output, and had a digital audio cable from the DVD player to the receiver. The audio and video were perfectly in sync through the entire movie. After the movie was over and I plugged the HDMI cable back into the cable box, the picture and audio were out of sync again.

Since I’ve had other odd intermittent problems with my cable box, it looks like I need to call the cable company and see if I can get them to swap it out with one that works better.

By the way Max, that menu option you mentioned which switches between PCM and Dolby Digital is the one I mentioned in my OP that is only available for the TV input, but not for HDMI. Which I still don’t understand why they would make it that way…

#13

Yeah, your STB is the issue then. What make/model # is it? Have you tried unplugging the power & plugging it back in? Sync issues like that are usually software/firmware, so it may just need an upgrade from the headend.

On the last question - what is the signal source for the “TV” input? Does that mean over the air antenna? Here’s the issue with HDMI audio formats - part of the HDMI spec is that a display device (like the TV) will inform the signal source what audio capabilities it has. Some/most TVs are 2 channel stereo only, so they inform the signal source that’s all they can accept, and the source will deliver ONLY the 2 channel PCM, even though there’s a 5.1 Dolby Digital also available. So for your TV to send a 5.1 out its own audio out, it would have to inform the STB that it has 5.1 DD capabilty, which it does not.