HDMI in to TV, optical audio out to receiver, is this setup optimal? - Page 2

Hmm, that makes sense I guess (even though I don't particularly like that it's that way).

The TV digital out at first just output stereo from the STB like its doing from the DVD player. The Comcast STB (RNG110) has a HDMI setting choice of "Auto", "PCM", "Pass" (and disable auto detect). It was set to "Auto" by default. I changed it to "Pass" (and disabled auto detect) and that's when I got my Dolby Digital from the TV Digital out.

I wish the DVD Player had a similar setting. Just doesn't seem efficient to use HDMI (which already has video and digital audio) and then also have to use a separate digital audio out (to get digital audio).

If you studied HDMI standard you'd like it even less.
E.g., xvYCC and Deep Color features, everybody was so excited about, introduced in 1.3. But they are optional: it means even devices which don't have an ability and capacity to support these features can claim 1.3 compliance. And you might not find mentioning of them even in fine print because manufactures are not obligated to disclose this information.
So, claims of "1.3a" or "1.4 compliant" are just a way to charge you extra, unless they explicitly claim xvYCC and/or Deep Color support.

When you attach a device to your TV via HDMI, the device uses HDMI to read the TV's audio and video capabilities. All TV's support stereo PCM, and some TV's have a Dolby Digital decoder. The ones with a Dolby Digital decoder indicate that they can accept both stereo PCM or Dolby Digital.

Remember that the TV cannot tell that an SPDIF cable is attached to it, so in order to output Dolby Digital, it must have the Dolby Digital audio decoder built-in, so that it can play the audio through its built-in speakers. I don't think the TV manufacturers are "going to get on the same page" with this; some will not want to pay the additional cost of a Dolby decoder.

I recently setup a similar configuration for my room mate. His components are a Dolby Digital 5.1 receiver with no hdmi inputs, Best Buy brand 40" LCD HDTV (0 indication of supporting any form or type of Dolby Digital other than stereo) with HDMI inputs and optical out, xbox 360, and hd cable box. I used an hdmi cable from each device which ran to the TV. I then ran a single digital optical cable from the tv to the receiver. I set the tv to send out i believe raw data or PCM from the optical port. Instantly presenting crystal clear dolby digital 5.1 from both devices. It works wonderfully.

You're lucky. Mine didn't work that way. Hooked mine like yours except I have a single digital "coax" out on the TV instead of optical. Had TV out set to "raw" meaning it's just passing whatever signal it's receiving (no need for the TV to have any built in decoders this way). On my TV there is no separate speaker out settings, TV speakers are on all the time regardless, have to mute them to turn them off.

So it's taking the Dolby 5.1 source from HD STB through HDMI cable to TV and passing it along unaltered from TV via digital coax out to my amp and my amp then decodes the Dolby 5.1 signal.

Now hooking up DVD player exactly same way should have the same result but it doesn't. Taking it's Dolby 5.1 source through HDMI to TV and out through same digital coax to amp. This time though something different happens along the way because my amp now can only do Dolby Pro Logic, meaning it's only getting a stereo signal. To get my Dolby 5.1 from the DVD player requires an additional digital out (optical in this case) from DVD player to amp.

Beats me if I can figure what my TV is doing here. I'm probably missing something in all this but I don't know what it is.

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Some TV's have Dolby Digital decoders, and some don't. The TV's with DD decoders present DD capability in their EDID, which they then pass thru their TOSLINK connector. But even this is insufficient with Blu-ray, as many titles do not have Dolby Digital at all; they have stereo and Dolby TrueHD, or they have stereo + DTS + DTS-HD. With these titles, you cannot get surround sound if your only surround option is Dolby Digital.