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Old 5th March 2011, 10:44 PM   #1
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Default HDMI for 8-channel audio

Is it the case that HDMI allows a source to send 8 channels of high def PCM?

So a PC with a modern video card (or a suitable Asus Xonar) could use an HT receiver as an 8 channel DAC and power amp system?

I don't have a suitable card at the moment but systems like the Asrock Vision3D and boards like the Gigabyte E350N - both of which claim HDMI 1.4 - are interesting.

How easy is it to drive these channels from a non-video app (not too bothered if its Win7 or Linux for this)?

James
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Old 6th March 2011, 12:05 AM   #2
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Yes, there are cards, drivers, HT receivers and audio software. Windows Media Player 9 supported 7.1, it's up to version 11. GA player claims 8 track.

I haven't tried it or seen it work, I'd be interested to hear from anybody who has.

What material do you intend to play?

w
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Old 6th March 2011, 03:39 AM   #3
qusp is offline qusp  Australia
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there is even a diy board for use with i2s and dxd input dacs. its designed for the ackodac 8 channel sabre dac, but outputs i2s, so dont see why it wouldnt work with other hardware that supports i2s input and multiple channels. supports many other formats too via hdmi
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Old 6th March 2011, 03:29 PM   #4
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Originally Posted by wakibaki View Post
Yes, there are cards, drivers, HT receivers and audio software. Windows Media Player 9 supported 7.1, it's up to version 11. GA player claims 8 track.
...
What material do you intend to play?
Well, whether media player can access it isn't really the point - I want to write a software crossover and play 2-channel audio - so its more important to have ASIO (on Windows) or driver support on Linux that exposes individual channels.

James
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Old 6th March 2011, 03:58 PM   #5
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Isn't HDMI encrypted?
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Old 7th March 2011, 07:30 AM   #6
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Default HDMI encryption

I *think* that (HDCP - is that what you mean?) is at the discretion of the source. But I could be wrong. The Xonar audio card seems to offer 8-channel ASIo on HDCP 1.3 - and I'm wondering if in fact the newer graphics cards which support HDMI 1.4 offer a similar level of access to the data channels.

Possibly I should sniff around in Linux audio channels, but I thought maybe someone here would know.
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Old 7th March 2011, 07:56 AM   #7
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Originally Posted by pinkmouse View Post
Isn't HDMI encrypted?
Typically , but it doesn't have to be. My 1080P divx's are bootleg non-encrypted w/7.1 lossless codec. They already have a blu-ray ripper in certain circles that bypasses HDCP . HDMI 1.3 is backwards compatible to any previous version or even a non-encrypted stream.

If I do play a native Blue-ray , my processor and memory use increase drastically to protect the "content".

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Old 7th March 2011, 07:41 PM   #8
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Originally Posted by jman11964 View Post
I want to write a software crossover and play 2-channel audio.
This shouldn't be too difficult. If you read the WMP9 7.1 writeup on the Microsoft site you will find instructions on creating 7.1 files from individual mono files using Windows Media Mono to Multichannel Wave Combiner 9, a command-line tool available for download.

Your software would require to read an existing .wav file, process the information to extract bass, middle and treble information (and possibly a subwoofer track or tracks) and write out a set of mono files. You would then present these to the combiner, which would produce a file playable with WMP9 and above.

If you care to dig into the 7.1 format, possibly doing some reverse-engineering, you can probably do the whole process in a single application without resorting to the combiner. I haven't dug into it that far but the original .wav header is not very complex, I thought it defaulted to stereo, I could be wrong, but I'm just answering from memory.

Obviously this is not the same as doing the conversion on-the-fly, and it results in files as much as 4 times the size of the originals, but it is quite straightforward, with the exception perhaps of writing the filters, and it should work no problem.

A little application that would allow you to pick the crossover frequencies and write out the result would probably find some users, I might write one myself, although it can't be long before a few start to appear.

w
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Old 11th March 2011, 07:49 PM   #9
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Quote:
Originally Posted by jman11964 View Post
Well, whether media player can access it isn't really the point - I want to write a software crossover and play 2-channel audio - so its more important to have ASIO (on Windows) or driver support on Linux that exposes individual channels.

James
.
Not sure about ASIO drivers, but I can confirm that XBMC running under Linux was able to put out multichannel audio over HDMI on an Acer Revo (Nvidia ION platform). I believe that HDMI audio under Linux should be pretty well supported if you choose your hardware carefully.
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Old 12th March 2011, 02:29 PM   #10
theresa is offline theresa  United States
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Quote:
Originally Posted by jman11964 View Post
Is it the case that HDMI allows a source to send 8 channels of high def PCM?

So a PC with a modern video card (or a suitable Asus Xonar) could use an HT receiver as an 8 channel DAC and power amp system?

I don't have a suitable card at the moment but systems like the Asrock Vision3D and boards like the Gigabyte E350N - both of which claim HDMI 1.4 - are interesting.

How easy is it to drive these channels from a non-video app (not too bothered if its Win7 or Linux for this)?

James
I use my AMD 6850's HDMI output for nearly all audio (except when using headphones) and video with my system. It does up to 7.1 although I only use it for 5.1, not that I've come across any BDs with 7.1 anyway. 7.1 seems to be a failure so far, and I think 3d will be the same.
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