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Completely Confused about HDMI Audio


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#1 of 7 Lin Park

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Posted July 24 2007 - 03:36 PM

Been reading many posts here and have managed to completely confuse myself over this issue. What exactly can be accomplished by passing an audio signal via HDMI out of a player (say the Toshiba HD-A2)? And which receiver would one need to take advantage of this method?

Some threads I have read state you can't do anything with it (yet) and some say you can take full advantage of it. Then there are umpteen versions ranging from 1.1 to 1.3. Some receivers have HDMI input (like the Denon 2807) but don't list Dolby TrueHD as an option - are people with these units simply decoding regular DD-EX and DTS tracks? Is a Dolby Digital EX or DTS track on an HD DVD any different than the audio tracks on the standard DVD version of the same movie?

If there is already a posted thread that details and describes all of this please feel free to point me to it.

Sorry for all the questions - maybe I'll go get some sleep now. Posted Image

Thanks,
Lin

#2 of 7 ChristopherDAC

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Posted July 24 2007 - 04:47 PM

Essentially, any version of HDMI will pass up to 8 channels of uncompressed PCM audio at up to 96 kHz 24 bit resolution. The audio can come straight off the disc, in the case of Blu-Ray with PCM, or it can be created in the player by decoding a lossless Dolby TrueHD or DTS-MA HD track on the disc, or a lossy compressed Dolby Digital (and DD Plus) or DTS track, with or without the addition of sounds generated in the player by interactive programming.

Some versions of HDMI will also allow passing compressed audio streams to a suitably-equipped receiver for decoding, but such receivers are practically nonexistent at present.

#3 of 7 Lin Park

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Posted July 25 2007 - 12:27 AM

Seems to make sense so now let's talk specifics then. What would be my options if I were to connect the Toshiba HD-A2 to the Onkyo TX-SR705 which offers the following decoding options: Dolby True HD, DTS-HD Master Audio, Dolby Digital Plus, DTS-HD High Resolution Audio, THX Surround EX®, Dolby Digital EX, DTS-ES™, Pro Logic® IIx, and DTS Neo:6 decoding.

Based on you answer above, it appears I could handle all of the current formats without an issue. Is that the case?

#4 of 7 Garrett Lundy

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Posted July 25 2007 - 04:12 AM

I thought HDDVD-BRD were software disabled to prevent TrueHD from being passed along the chain, and every player had to decode them and use the PCM signal only.
"Did you know that more people are murdered at 92 degrees Fahrenheit than any other temperature? I read an article once. Lower temperatures, people are easy-going, over 92 and it's too hot to move, but just 92, people get irritable."

#5 of 7 Steve Schaffer

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Posted July 25 2007 - 02:47 PM

^^^Absolutely correct. No current BD or HD player can output a raw TruHD or DTSMA or DTSHD bitstream. All players do the decoding internally and output the result as multichannel PCM. BTW, the Onkyo 705 will work fine with multichannel PCM.
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#6 of 7 Lin Park

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Posted July 26 2007 - 01:50 AM

Found some excellent threads and have since become fairly educated on this issues. However, I couldn't find the answer to this one anywhere and it's such a subjective question I hesitate to ask it but here goes:

Which will sound better - the Dolby TrueHD soundtrack decoded inside the Toshiba HD-XA2 and passed via 5.1 analog audio out OR the PCM track passed via HDMI to say the Onkyo 605 and then decoded via DD or DTS?

Thanks!

#7 of 7 Steve Schaffer

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Posted July 26 2007 - 08:25 AM

PCM tracks don't require any "decoding" by the receiver, so all things being equal the sound should be the same.

But all things are not equal. If you use analog outs from the player you will be using the player's bass management and speaker level settings. If you use multichannel PCM from HDMI your receiver will be doing this processing. Usually receivers are better at this than players.
Steve S.
I prefer not to push the subwoofers until they're properly run in.