Dolby Digital switching - Audio Dropout

[MikeR]

Well, I have searched and reviewed as many posts as I could find, but did not locate the specific problem I am having with any HD Channel and Dolby Digital handling.

I dislike adding another thread to a known and already discussed problem, but here it goes.... (mods- please delete if I can be directed to the correct information)

First off, I should state that I am not having any issues with audio during live play or recorded playback.....until

(a) local HD stations switch from 5.1 to 2.0; causing my receiver to lose the DD signal.

(b) DD signal will drop during trickplay (ff/rew/slip/jump back) (live or recorded).

(c) a secondary menu is entered (i.e. "Help" menu); noticed this is where no picture is displayed (does not occur in the "Guide" or "Menu")


Each of the above results in my Onkyo receiver losing the DD signal, resulting in a audible click as it switches between PCM and DD.

This only occurs on the HD channels. Obviously, this problem goes away if I switch DD to "off".

I understand that (a) will result in this click, but it seems to me that the HR20 would handle (b) and (c). Also, the H20 nor the R15, which the HR replaced, exhibited this behavior when listening to DD sources (PPV or HBO).

Question-
Is there anything that can be done to eliminate this "switching" without losing DD capability?

My setup is below. Thanks in advance!

[texasbrit]

Well, I have searched and reviewed as many posts as I could find, but did not locate the specific problem I am having with any HD Channel and Dolby Digital handling.

I dislike adding another thread to a known and already discussed problem, but here it goes.... (mods- please delete if I can be directed to the correct information)

First off, I should state that I am not having any issues with audio during live play or recorded playback.....until

(a) local HD stations switch from 5.1 to 2.0; causing my receiver to lose the DD signal.

(b) DD signal will drop during trickplay (ff/rew/slip/jump back) (live or recorded).

(c) a secondary menu is entered (i.e. "Help" menu); noticed this is where no picture is displayed (does not occur in the "Guide" or "Menu")


Each of the above results in my Onkyo receiver losing the DD signal, resulting in a audible click as it switches between PCM and DD.

This only occurs on the HD channels. Obviously, this problem goes away if I switch DD to "off".

I understand that (a) will result in this click, but it seems to me that the HR20 would handle (b) and (c). Also, the H20 nor the R15, which the HR replaced, exhibited this behavior when listening to DD sources (PPV or HBO).

Question-
Is there anything that can be done to eliminate this "switching" without losing DD capability?

My setup is below. Thanks in advance!

Although it would be nice if the equipment at the station did not create this situation in the fist place, the primary problem is almost certainly with your A/V receiver (or with the settings you are using on the A/V receiver). First, when a channel switches from DD 5.1 to PCM, the digital audio is interrupted "midframe" as it were. Many A/V receivers either mute the audio for a fraction of a second when this switch occurs, or otherwise manage to transition without too much of a glitch. Others make a loud click, or even a screech noise. Sometimes changing the setting you are using for the audio input can solve the problem. On my old Sony receiver changing from "auto" to "DD" solved the problem for me. On my current receiver, "auto" works fine.
I don't know why you should get this problem transitioning from DD 5.1 to DD 2.0, unless the station is doing something strange I would have expected that transition to be seamless. It certainly is on my HR20/Sony receiver setup. Some of my local stations don't use PCM any more, just DD 2.0.

On trick play no audio is output from the HR20 so everything will revert to whatever is the default setting. I don't think there is a way of maintaining the DD 5.1 setting without sending audio.

Going to the help menu on my HR20 does not drop DD 5.1 But whenever you enter a menu or submenu that does not have a picture displayed (and therefore there is no sound) as you have noticed, you will lose DD 5.1, for the same reason. No audio equals no DD 5.1 signal.

[MikeR]

Others make a loud click.....Sometimes changing the setting you are using for the audio input can solve the problem....

Thanks Brit - That would describe my problem exactly. Off to find my manual!

btw, I made an error it should have been "PCM" not 2.0 in my original question.

"local HD stations switch from 5.1 to 2.0"

[jheda]

Mike i have made posts on this subject, hasan was a s helpful as anyone (as he usually is), but i still suffer. And as you see below, i do not have the onkyo, so i dont believe it s yoour reciever.

If you can find hasans post on this, its very intelligent and on point.

Thanks Brit - That would describe my problem exactly. Off to find my manual!

btw, I made an error it should have been "PCM" not 2.0 in my original question.

"local HD stations switch from 5.1 to 2.0"

[MikeR]

Hasan and Brit seem to have covered this subject before.:o

No real solution so far...except the equipment Hasan mentions in this post (http://www.dbstalk.com/showpost.php?p=746061&postcount=5)
or possibly switch the AV receiver to manual/DD as Britt described below.

[MikeR]

I'm home now messing around with trickplay functions.....

This audio dropout problem does not occur everytime. Why??

[cineplex1]

I'm home now messing around with trickplay functions.....

This audio dropout problem does not occur everytime. Why??

MikeR;

Don't beat your receiver to death just yet. I am having the same issue with a Kenwood Sovereign.

I was on the phone with DTV for an hour. They have no clue. Did a forced download, several RBR's, and 3 whiskeys.

Can't solve it yet.

[hasan]

MikeR,

In terms of the drop out, give your Onkyo receiver a gold star...because the alternative is really ugly. Some HT receiver's don't mute when losing the DD 5.x signal, and they produce some horrendous noise during the transition. Your receiver is doing pretty much what it should (Onkyo).

When the HT receiver is set to autodetect DD 5.x, it needs time to do so. When it is making up its mind, it has two choices: mute the audio, or "guess", which can cause some real annoyances.

The post some referred you to about audio/video sync delay is a different matter..that was referring to lip-sync...if I understand you correctly, you are really describing "audio mode switching" in your Onkyo receiver.

The the audio to the HT receiver is interrupted, then the receiver says: DD 5.1 stream missing...I better do something (if set to autodetect), so, a good receiver will MUTE itself while it's deciding what to do. It makes no difference what causes the loss of the DD stream...it can be a commercial, it can be the pause key, it can be TrickPlay...it's all a matter of timing. If the stream is interrupted longer than the autodetect timing trigger, then the Onkyo is going to mute until it can "define" a signal from the input when it resumes.

The Onkyo response to two conditions you are describing are perfectly normal and unavoidable with current equipment:

1. Commercials drop DD 5.x
2. The source device stops sending audio altogether.

The result is relay clicking in the Onkyo and muted audio. In some other receivers, they don't mute and just throw a bunch of noise at you.


Problem #1 is much worse than #2 for a lot of receivers, as they see a complete change in the digital audio stream, therefore start "hunting", and resetting the audio mode. Some HT receivers tolerate the simple dropping of DD 5.1 without going into "mode seek" better than others.


The "manual" setting mentioned in other posts avoids some of this (in your HT).

There is no easy way out of this. When the DD 5.x signal is lost or is changed, it takes time for things to "sync up" again, and audio to resume. Essentially, it is the current state of the art in HT receivers (which actually is pretty good), and only some crazy kludge by source device manufacturers (like providing a phantom DD 5.x signal when doing TrickPlay) is likely to ameliorate the problem. (I don't see that happening any time soon, if ever).

[MikeR]

Thanks Hasan for the well thought out response. While most of those thoughts were going through my head, it is nice to have some confirmation.

I couldn't imagine having more noise thrown at me. The relay clicking is bad enough.

While thinking about this, the device manufacturers have a few choices -
extend the delay (Onkyo is 2-3 seconds) (delays are typically bad in logic programming, and create other problems)

send a pseudo-signal during transitions (may cause other issues, including compatibility)

not switch until it receives another signal, rather than switch on a "no signal" (set the logic to normally open, not normally closed).

I have not throught these through enough to determine the pros/cons, but the gurus in AV probably have.

why do the manufacturers use a relay? Other than cost, there are other ways to accomplish this.

I found this corresponding comment on the web...
My complaint with the Onkyo 604/674 and the reason it's getting returned to Circuit City is because the video switching relay hardware is LOUD and clicks about a half-dozen times switching between SD & HD and even different types of HD 720p, 1080i, etc

btw, do you set DD to off in the HR20, and use the Onkyo DSPs? I was satisfied with the DSP when it was hooked up to a R15-500; but the 5.1DD sounds much better (due to separation?).

[hasan]

That's a very good question! Old habits (and parts inventory) die hard?

I can think of no sound technical reason to not use solid state relays or another form of solid state switching. It shouldn't be cost. It would require laying out a new circuit board (in all probability), and of course, design changes.

One positive side effect of the relay switching between non-DD5.1 and DD 5.1 is that it is actually good for the relays. Relays keep their contacts clean by "wiping" during each cycle. If this isn't done, the contacts oxidize and you get poor or intermittent relay performance.

Admittedly, it would be better if there were no contacts to wipe, as such (solid state).

[jheda]

I told you Hasan is the man on this subject!!! my yamaha is silent, which is great, and i havent heard the audio on a commerical on NBC mpeg4 since day one. I just switch to 7 channel stereo to hear whats going on...

Good and important thread....

[cineplex1]

I told you Hasan is the man on this subject!!! my yamaha is silent, which is great, and i havent heard the audio on a commerical on NBC mpeg4 since day one. I just switch to 7 channel stereo to hear whats going on...

Good and important thread....

Have we determined just what causes the dolby drop?

Is it the software upgrade, the receriver, or the feed?

I need to know before I have DTV bring a new receiver.:confused: