Help Me Understand - Audio and HDMI

[greggerm]

Aaaaaaalright -

I've taken the plunge, and sitting in the living room is a 37" 1080p LCD display. Right next to it is my still-in-progress HTPC, and I am sweating the details of multichannel audio playback, which is making Sage itself seem like childs play.

My audio receiver is a 6-7 year old Yamaha receiver with Dolby Digital and DTS (the original 5.1 formats) capability. Digital in as well as the old-fashioned external decoder line in ports. She's served me very well, and I don't wish to part ways yet - I just blew the checkbook on the TV, so my new component budget is done for the time being.

Here's the million dollar question - when playing back BluRay movies through the HTPC, how will I need to have my system set up in order to hear the best possible sound?

I ask this because I understand the studios have gotten greedy once again and clamped down with their stream encoding, and I am just not totally getting how best to set things up. Without a secure chain, as I understand it the sound will downgrade to a 2-channel matrix, Dolby Pro Logic style.

My Options, as I see it so far...

• HDMI audio and video from computer to television, then use it's digital audio out to run to the receiver.
  
• HDMI video, then SPDIF from computer to receiver.
  
• HDMI video, and punt to multichannel analog audio to the "external decoder in" ports of my receiver.

I've heard of shipping the digital audio via uncompressed LPCM, but is that something that the receiver needs to specifically be able to support?

Do Bluray discs ship with legacy audio streams? Will the encoded Dolby Digital HD and/or DTS-HD streams have the old 5.1 information available for my receiver?

(*Will I be forced to rip, reencode, and THEN watch my movie investments?)

Heck - even if I get a standalone Bluray player, will I still be in the same boat and need to buy a new HDMI/secure stream capable receiver?

Your input is appreciated, as always!

-Greg

[stanger89]

Originally Posted by greggerm

Here's the million dollar question - when playing back BluRay movies through the HTPC, how will I need to have my system set up in order to hear the best possible sound?

Theoretically analog from a good soundcard into the multichannel inputs on your AVR.

I ask this because I understand the studios have gotten greedy once again and clamped down with their stream encoding, and I am just not totally getting how best to set things up. Without a secure chain, as I understand it the sound will downgrade to a 2-channel matrix, Dolby Pro Logic style.

Nope, that's completely incorrect. Without a protected path, audio is limited to a 16bit/48kHz sampling. Almost no movies have audio tracks >48kHz sampling and the difference between 16 and 20/24bit sample depths are negligible.

The important thing to remember is that even though it's "only" 16/48k, it's still uncompressed, so there's none of the lossy-compression degredation that DVD suffered.

My Options, as I see it so far...

• HDMI audio and video from computer to television, then use it's digital audio out to run to the receiver.

That will probably net you stereo.

• HDMI video, then SPDIF from computer to receiver.
• HDMI video, and punt to multichannel analog audio to the "external decoder in" ports of my receiver.

Which one of those will actually sound better will probably require testing. Analog input will bypass bass management/distance correction on your AVR most likely, so you'd want a soundcard that can do that.

I've heard of shipping the digital audio via uncompressed LPCM, but is that something that the receiver needs to specifically be able to support?

You need HDMI 1.1+ for that.

Do Bluray discs ship with legacy audio streams? Will the encoded Dolby Digital HD and/or DTS-HD streams have the old 5.1 information available for my receiver?

DTS-HD MA includes a 1.5Mbps DTS core stream yes. TrueHD, seems like there's not always a corrosponding legacy DD stream. And for PCM discs, there's not always a DD stream either.

(*Will I be forced to rip, reencode, and THEN watch my movie investments?)

Nope.

Heck - even if I get a standalone Bluray player, will I still be in the same boat and need to buy a new HDMI/secure stream capable receiver?

Nope, a Panasonic BD55K or Pioneer 51FD will both decode all the new formats and happilly output them over analog.

[Striker:WG]

Greg,

I am relativley new to Sage, but i've been mucking around with HTPC and Home Theater in general for a while.

I can honestly say that HDCP is the dumbest greediest thing the studios have done in a long time.

I bought my TV about 6 months before HDCP was finalized and put out in full force. Suffice it to say, I had issues when I setup my BluRay ROM in my HTPC.

I found the best solution was to install a software package called "AnyDVD" from a company called Slysoft. There is an HD option to support BluRay and HDDVD as well. Well worth the $100 bucks.

This removes all encryption and protection from the discs on the fly in the background and allows me to play back the discs without issue because of any of this HDCP stuff.

I use AC3Filter to encode analog audio to AC3 and send over SPIDIF to my receiver (which much like yours is a several year old unit that doesn't have HDMI or 7.1). In AC3 Filter I specifiy that Dolby Digital/DTS should just pass-through on the SPIDIF channel and everything works great.

The way my system is physically connected is:

Video: PCI-Express ATI 3870 -> DVI Out -> DVI to HDMI Cable -> HDMI Input on TV

Audio: Realtek Onboard Audio -> SPIDIF Out -> SPIDIF Cable -> SPIDIF Input on Amplifier

Hope this helps.

-Striker-

[greggerm]

Stanger89:

GG - Without a secure chain, as I understand it the sound will downgrade to a 2-channel matrix, Dolby Pro Logic style.

S89 - Nope, that's completely incorrect. Without a protected path, audio is limited to a 16bit/48kHz sampling.

Aah - encouraging! I was hoping it wouldn't be as bad as the tricks they can play on the video path, which I believe has the capability to cut resolutions down significantly.

Analog is probably the way I will go - I have a very healthy amount of DVD rips from my last Sage installation, all done in multichannel AAC audio, which worked flawlessly over the analog outs. The loss in fidelity is not terribly huge, given my audio arrangement. I am not retaining the Dolby Digital stream in my DVD rips so I won't go SPDIF for passthrough.

Striker:

I've never had good luck with AC3Filter working with my "AAC" encoded rips. It would always output in stereo - never the proper 5.1 sound. I'll have to play around with that in time, but my first goal is getting the Sage system up and running as best I can. Wire clutter isn't a huge issue given the location of the systems.

I will be picking up AnyDVD HD before the first of the year, as well as PowerDVD to tie it all together. While I will prefer to rip down my future Bluray purchases, I'm sure I'll pick up one or two that I'll want to watch immediately, so having a software player is key for me.

Thank you both for your input! Appreciated!