HDMI DAC

[Chris Hubbard]

Hi All,

I'm about to set up a PC based system for an upcoming show, and need
at least 4 audio outputs. In the past I've used USB from the PC to a
MOTU or similar, and this has been generally OK, although I have
encountered the occasional USB glitch. However, the PC concerned also
has an HDMI output, which in theory contains 8 channels of high
definition audio. So, if one had a multi channel HDMI DAC, one could
avoid USB all together.

Do such devices exist, has anyone actually done this, and if so how
well did it work?

Thanks in advance,

Kind Regards,

Chris Hubbard,
CH Sound Design.
www.chsounddesign.com

[Carlton Guc]

Chris,

>> Do such devices exist, has anyone actually done this, and if so how
>> well did it work?

Currently I do not think there are any HDMI devices out there and I agree w/ you that it should be pretty easy to create one. I've spoken w/ a couple HD manufacturers about this exact question about a year ago and it was suggested to me that there were some technical difficulties in creating such a board, but there was interest in having one created.

You'd think it would be easy as HDMI is designed specifically for media and there are many devices out there already that take a HDMI input and if there are Windows drivers to support such a device, it might just be as easy as grabbing a off the shelf HDMI receiver and plugging it in.

Something like:
http://www.amazon.com/Sony-STRDH520-Channel-Receiver-Black/dp/B004NHCGJO/ref=sr_1_1?s=electronics&ie=UTF8&qid=1327811117&sr=1-1

However I haven't tried it, so I don't know if it'll be easy or not.

Carlton
SR

[Bevan Archer]

I don't know of a device that's built to just decode the audio, but I do have my Desktop PC at home hooked up to my 42" LCD TV via a single HDMI cable and it carries video and audio.  All I had to do was enable HDMI as the audio output.  I don't see any reason you couldn't buy an inexpensive home receiver and make this work, but all your outputs would be unbalanced...

Good luck!!

Bevan

--- On Sat, 1/28/12, Carlton Guc <car...@stageresearch.com> wrote:

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[Adam Fitchett]

A little searching and it seems such a device does exist...

http://www.gefen.com/gefentv/gtvproduct.jsp?prod_id=8202

As to how well it works, I have no idea. I imagine that your computer is seeing the audio over HDMI as nothing more than a multichannel USB device so it might not provide any more stability. I'd be curious to hear your results if you do end up trying this route.

[lindsay smith]

I like the idea but in general HDMI has too many automatic "features" and DRM that I wouldn't use it unless there was a compelling reason to. There is such a thing as an HDMI audio de-embedder made by people like Extron, Kramer and others. Most of these just pull the digital audio off the HDMI stream and output it as an optical SPDIF so you aren't gaining much. Some devices won't send audio out the HDMI output unless they detect video as well. I also think HDMI expects all the audio to be in one stream so it might not work for overlapping cues. The de-embedder and related hardware will probably cost as much, or more, than a decent interface too. (you might be able to tell I've had some issues with HDMI)

Lindsay Smith
Seattle

Hi All,

Thanks in advance,

Kind Regards,

--

[Brad Weber]

Chris said:
>
> I'm about to set up a PC based system for an upcoming show, and need at
> least 4 audio outputs. In the past I've used USB from the PC to a MOTU
> or similar, and this has been generally OK, although I have encountered
> the occasional USB glitch. However, the PC concerned also has an HDMI
> output, which in theory contains 8 channels of high definition audio.
> So, if one had a multi channel HDMI DAC, one could avoid USB all
> together.

There are a number of HDMI audio extractors such as
http://www.extron.com/product/product.aspx?id=hae100&subtype=354&s=4,
http://www.crestron.com/resources/product_and_programming_resources/catalogs
_and_brochures/online_catalog/default.asp?jump=1&model=hd-da-2 and
http://www.atlona.com/Atlona-HDMI-Audio-De-Embedder-with-3D-Support.html.

The question might then be whether the computer lets you see and assign the
HDMI audio as 8 discrete digital audio channels.

Brad Weber
muse Audio Video
Marietta, GA

[ted.p...@gmail.com]

What about FireWire? There's something about hdmi that feels severely untrusty...

[Chris Dietze]

A more expensive solution could be a Denon 7100 series surround preamp, which has eight balanced analog audio outputs and will cooperate with the HDCP protocol inherent in HDMI.

--Chris Dietze

[Ted Pallas]

I just realized why it feels untrusty - I've seen video move from point A to point B in a number of ways by a number of people, and it only involves HDMI when a DVD player is directly underneath it's display monitor.

I would recommend exploring HDMI for questions like Rob's last week, where you have to get funky on your engineering because of Extenuating Circumstances and you need to maintain A/V sync. That seems more like the application - tools you see will be focused on using hdmi as a combo delivery method, as we've already solved multichannel audio with other digital means.

On Sunday, January 29, 2012, Chris Dietze <cdi...@clearsoundinc.com> wrote:
> A more expensive solution could be a Denon 7100 series surround preamp, which has eight balanced analog audio outputs and will cooperate with the HDCP protocol inherent in HDMI.
>
> --Chris Dietze
>
>

> --
> To create a new topic, send a message directly to theatre-sound-list at googlegroups dot com -- please do NOT reply to an older message and change the subject line!
>
> Take a minute to edit unnecessary text out of your reply. Non-theatre-sound topics should be via private email. To unsubscribe or set your delivery options, see the web page: http://groups.google.com/group/theatre-sound-list
>

--
Ted Pallas
Live Media Designer
Sandwich Construction Consultant
ted dot pallas -at- gmail dot com
516.286.9661

[Jack Hildwine]

FWIW, I've got a 3 year-old HP laptop with HDMI output and a newer
Phillips TV that refuses to output audio from it. It will play with my
Vizio TV. Without spending more time than I already have, the best
answer that I could find was that Phillips has an issue with Nvidia or
the particular chipset in the laptop and mutes the audio from it. I
count this as a FAIL! For hdmi.org and a reason to be wary of this
technology.

Jack Hildwine
Gilbert, AZ

Hi All,

Thanks in advance,

Kind Regards,

--

[Joe Wilson]

On Mon, Jan 30, 2012 at 9:01 AM, Jack Hildwine <jackhi...@cox.net> wrote:
> FWIW, I've got a 3 year-old HP laptop with HDMI output and a newer
> Phillips TV that refuses to output audio from it.

That's our good friend HDCP (High-bandwidth Digital Content
Protection), a copy protection protocol build directly into HDMI. It
is likely that your laptop has a legacy implementation of HDCP that is
being rejected by the newer TV. I'd check to make sure there aren't
any firmware updates available for your video card.

All-in-all, this is another example of how current copy-protection
schemes, while doing little to prevent actual copyright infringement,
restricts lots of legitimate usage.

Cheers!
~joe

_________________________
Joe Wilson, ATD/Sound
Indian River State College

Adding one more "me too" to the
collective internet consciousness.

[Jack Hildwine]

Yes, laptop driver is up-to-date and I updated the TV firmware. That was
a time-warping experience. I remember when TV maintenance involved
replacing a weak high-voltage rectifier tube, cleaning the tuner and
degaussing the CRT!

It could be HDCP and I've also read that based solely on the EDID that
Nvidia blacklists the device and mutes the audio for some
incompatibility issue. Part of the problem is the dearth of information.
These are consumer-class devices on a bidirectional link with
intelligence on both sides. I would hope for at least an error code or
message from either. I could get a Wireshark-like trace of the link and
figure it out myself but I expect plug-and-play.

There are HDMI logos on everything. In the end I blame hdmi.org as
they're apparently too busy licensing overpriced cables than ensuring
that the endpoints play together.

Jack

Cheers!
~joe

--

[Brad Weber]

Jack said:
> It could be HDCP and I've also read that based solely on the EDID that
> Nvidia blacklists the device and mutes the audio for some
> incompatibility issue. Part of the problem is the dearth of
> information.
> These are consumer-class devices on a bidirectional link with
> intelligence on both sides. I would hope for at least an error code or
> message from either. I could get a Wireshark-like trace of the link and
> figure it out myself but I expect plug-and-play.

Here's some free software for reading and managing EDID information from
devices,
http://www.extron.com/product/software.aspx?id=edidmanager&search=EDID.

In one of the classes at last year's InfoComm the instructor mentioned how
they had purchased new monitors and found that they had to keep going into
the computer graphics card setup to get the computers to display correctly.
They finally figured out that the monitor manufacturer had apparently loaded
the EDID information from an older model that had a different native
resolution, thus the display was telling the computer to improperly
configure the graphics output.