# Dolby Digital vs PCM and commercials losing sound



## georule (Mar 31, 2010)

So I have an HR22 hooked up via HDMI to a Sony STR-DH800 home theater. Some time in the last year or so, I've increasingly noticed that sound has been going away to almost nothing on some (but not all) commercials, some promos ("Next week on Blue Bloods"), and even some primary programming on smaller channels or locally produced content by affiliates (FS North "Becoming Wild", as an example, but not the only one). 

Obviously the promos and locally produced content is more of a concern than the commercials. 

Last night I finally looked at my DirecTV DVR settings, found the Audio page, saw that Dolby Digital was ON and switched it to OFF. Volume problem immediately solved, which I was able to confirm with recorded content, and recreate (and "cure") at will by switching the Audio setting on the DVR.

This does feel like it is a somewhat "new" problem tho (like the last year or so?).

So what am I losing by having Dolby Digital set to OFF on the HR22? My AVR will do "virtual surround", if that means I'm actually just getting stereo now from the DirecTV box when Dolby Digital is OFF.

And of course if a given program seems to be worth it, I can always turn that setting back on temporarily.

Anyway, is this a known problem? Is my AVR (a 2009 model Sony HDMI-switching one) a contributor in the sense that another newer AVR wouldn't have the issue? Is the DVR not doing a good job of detecting something or other in the individual content it's sending to the AVR? Did a software upgrade on the DVR cause this at some point? Does DirecTV plan to do anything about it?

It was a fairly minor annoyance anyway, and just became even more so now that I found that setting in the DVR and can manipulate it if necessary. Just curious what's up with that, what methods others have found to deal with it, and if DirecTV has any plans to address it.


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## texasbrit (Aug 9, 2006)

Your AVR needs to have its input from the DirecTv box set to "auto" so it will switch between DD 5.1 and PCM stereo as the signal changes.


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## TomCat (Aug 31, 2002)

Correct me if I have this wrong, but I think the DD on/off is simply a legacy holdover from before HDMI, meaning it does not do much when connected by HDMI. It's actually unclear what it does now that most audio is AC-3.

This I know for sure, which is that most (if not all HD) channels send only AC-3, which is a variant of DD. This means that if 5.1 channels are available in the source, 5.1 channels will make it through the HDMI cable to your terminal equipment regardless, and if the source is 2.0, there still will be 5.1 channels available, just that only Lf and Rf will be populated with actual audio.

Virtually no HD channel broadcasts a separate 2.0 for the primary audio, because it is the responsibility of the AVR or TV or STB, assuming it can't deliver 5.1, to matrix-decode the 5.1 that arrives into 2.0. The "PCM" mode was originally there for handling that. In a DVR, if you choose the analog outputs, there is one of those matrix decoders there converting the incoming AC-3 to a 2.0 version for those connections. But I am unsure how the DVR uses PCM/DD regarding those connections; obviously it has to decode AC-3 to get normal stereo out.

But virtually every ATSC TV, and I would assume every modern AVR (this being a primary function of an AVR) must have the capability to decode AC-3 audio to DD output and also to matrix-decode to 2.0 for things like the local speakers in the TV, so there is no good reason why that capability would even be considered an option for digital audio out of a DVR. Analog, yes, but the digital protocols nearly always push the full AC-3 as far as they can, meaning they are pushed out of every digital port , including HDMI and SPDIF/optical. So it does not seem that there would even be any logical reason for a method to switch to 2.0 on any digital output port, especially since all of the target devices can decode 2.0 on their own.

There is also a second audio pair usually populated by DVS (Descriptive Video Service) which is the original audio with added narration. At least 15 hours of network fare has to have that, currently, per week. Sometimes the station will not duplicate the main audio on the second pair in local commercials and promos, which leaves a hole if you are listening to the aux audio pair. You can cycle through these options with the green button on your remote, so possibly you got into that mode somehow.

And typically, if your AVR sees 2.0, it will simulate 5.1 for your local amp/speakers using Pro Logic IIx or something of that nature, depending on how you set it up. Honestly, simulating 5.1 from 2.0 is very transparent, and not even detectable from 5.1 in most cases. If the original 5.1 production is done well and there is significant channel separation in how it is produced, actual 5.1 becomes a bit more important.


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## inkahauts (Nov 13, 2006)

I know it makes a difference on the optical and coax outputs. Not sure about hdmi.


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## georule (Mar 31, 2010)

inkahauts said:


> I know it makes a difference on the optical and coax outputs. Not sure about hdmi.


It's definitely making a difference on both coax and hdmi, and I can recreate it at will --no goofy "sometimes" stuff (other than the nature of the content itself, that is). I know it was doing it on coax, because I have a Mits DLP TV that requires a conversion box for 3D and my AVR doesn't handle 3D HDMI switching. So I had to have the HDMI wired to the 3D conversion box and then from there to the TV, and a coax run to the AVR from the HR22. But after realizing that I hadn't actually watched anything in 3D in over a year, and thinking maybe that'd make a difference (after I discovered the difference the Dolby Digital ON was making), I decided to take the 3D box out of the loop entirely, and just go HDMI to the AVR (which works fine so long as there's no 3D involved) without the digital coax.

Issue still exists that way. So it may be an interaction with my AVR of some sort (5 year old Sony), rather than my HR22's "fault", but it's definitely tied to that Dolby Digital ON/OFF in the HR22's settings menu.

I don't plan to be protesting or writing anyone nasty letters about this (particularly now that I've identified the work around), just curious if anyone else had seen it and what they knew about it.

My other big screen TV elsewhere in the house, attached to an HR44, is about to get a brand spanking new 2014 Sony HDMI-switching AVR (STR-DN850), so perhaps it can serve as a test to see if the issue is there too (haven't checked that DVR yet to see if it has the Dolby Digital setting, and if it is currently "ON" or "OFF").


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## dettxw (Nov 21, 2007)

I solved this issue by getting rid of my Denon's. Both of them acted the same way.
No trouble with Pioneer or Onkyo. 
The Denon's were better AVRs but the problem was maddening. No help from Denon tech support either. 
Never did figure out what the real problem was, switching between DD and PCM would just switch the problem between commercials and shows (not every commercial or show of course).
At least switching brands of AVR worked.


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