HDTV Forum

I receive HD via OTA. When my 1080p Samsung DLP display changes channels it briefly displays details in a strip on the top as to screen ration & audio. With most HD channels it says Dolby Digital. Only on a few programs (such as 24) does my Sunfire Theater Grand 5 AV preamp automatically switch to Dolby. Even when I use the remote to manually change to Dolby it refuses and stays in Stereo or Source Direct mode. Why is this?

Because not ALL shows on the OTA digital stations are in HD, and Dolby.

If you are watching a DTV station then it should have a Dolby Digital encoded audio stream. However, that doesn't mean that it is 5.1. If it is a secondary DTV channel or the local program feed then it is probably stereo. Most prime time scripted shows and HD sporting events are 5.1 and you are probably seeing an indication of this from your A/V receiver. If it is in stereo then how you setup your receiver to handle stereo signals may be giving you the results you see.

Given you have a premium audio system and have paid dearly for it...why would you not spend the money to get HD from
Dish or the cable company to get the audio results you are looking for.

>why would you not spend the money to get HD from Dish or the cable
>company to get the audio results you are looking for.

Note that the small-dish and cable companies take their feed from
the same source as OTA (sometimes by getting a direct feed, and
sometimes by putting up an antenna). They often recompress the
original signal so that it is lower-quality than a direct OTA signal.

why would you not spend the money to get HD from Dish or the cable company to get the audio results you are looking for

That has little do with what the audio carrier is since that generally remains the same regardless of how you receive it. If there should be a difference then the cable or sat distributor is at fault and also an FCC infraction since your local DTV signal is to be distributed in whole just as if you were receiving it over the air.

Gee... on top of that I totally forgot about how they do some heavy bit shaving on the audio figuring you won't notice... unfortunately most don't... that should be reserved for premium channels though because again, per the FCC, the local is to be distributed in it's entirety and that is supposed to include bandwidth. I can also tell you that my cable company is cheating a few locals on that account...

I have the Sunfire Thearer Grand IV and it auto switches to pro logic II (or whatever your default setting is) when a DD signal isn't detected. In a lot of markets FOX isn't carried in HD. For instance, Cablevision in central NJ has all the nets in HD except FOX, which it lists as DTV.

My cable company blames the local channel source as not getting them the feed when 5.1 is available. They also tried to blame my audio source for not being set right, although other channels such as ESPN, Fox and UHD, I have no problems in getting a 5.1.

Please be aware that even if it says Dolby Digital it does not mean the signal is using the full 5.1 channels.

By definition DD is discrete any number of channels up to 5.1, including a mono program.

Your equipment tunes the DD but if it carries only 2.0 (stereo, or Prologic over 2.0) your processor might give you options of how to handle that 2.0, it could extract Pro-Logic out of it and derive the center front and the mono surrounds (L/R, remember they are mono).

But it could also reproduce the 2.0 as just L and R and ignore the matrix (L+R for center, L-R for surrounds), in which case you would believe is not Dolby Digital, when it is, but just using 2.0 out of the 5.1.

Check the manual of your processor as to to to set up the automatic feature of extracting Pro-Logic out of DD 2.0.

DTV was approved as a standard with Dolby Digital, but that is like a carrier approval of up to 5.1 channels, many modern content would be using the full 5.1 of those 6 carriers, a mono movie of 1940 might just be using one.

Best Regards,

Rodolfo La Maestra