Re: Outputting multichannel sound through the optical link??
Re: Outputting multichannel sound through the optical link??
- Subject: Re: Outputting multichannel sound through the optical link??
- From: Stephen Davis <email@hidden>
- Date: Fri, 5 Feb 2010 09:33:47 -0800
On Feb 5, 2010, at 9:22 AM, Simon Thorpe wrote:
> At 11:58 -0500 5/02/10, Paul Davis wrote:
>> On Fri, Feb 5, 2010 at 11:48 AM, Simon Thorpe
>> <email@hidden> wrote:
>>> So, how about this question. Is there any home theatre amplifier out there
>>> that can understand something as dumb as a simple stream of N different PCM
>>> samples?
>>
>> I've not seen one, but I really don't pay any attention to home
>> theater equipment. When I use a multichannel setup at home or in a
>> studio, I plug N different active speakers into the outs of an RME
>> multichannel interface, and i'm more or less done. No "home theater
>> amplifier" involved.
>
> Sure, that's certainly an option - for audio specialists. But again, you have to convert from digital to analog before the amplification. Surely, you must take a hit there?
>
>>
>>> If there is, I guess I might just buy one.
>>>
>>> If there isn't, then the world is mad.... the simplest thing that an
>>> amplifier needs to do is to play straight unencoded audio.
>>
>> with the advent of active speakers this is no longer really true.
>> these days, you (can) handle multichannel audio by plugging speaker N
>> directly into channel N.
>> remember that one way or the other, to get N channels of sound
>> requires either N amplification circuits or some design compromises.
>> my impression is that home theater amplifiers generally go for the
>> compromises but i am sure that varies with price.
>
> Well, I honestly think that something like ONKYO's http://www.eu.onkyo.com/products/TX-NR5007.html isn't making many obvious compromises. It really seems to me to be a very well engineered piece of kit.
>
>>
>>> You mention the possibility of a plug in. Great, tell me more! A little bit
>>> of software that converts a Core Audio multichannel format into something
>>> that can be understood by my amplifier would be perfect. Surely, someone on
>>> the core audio list knows how to do that?
>>
>> i was just speculating. perhaps someone else will comment.
>
> Please do! My checkbook is waiting for the first person who can solve that little programming problem ;-)
>
>>
>>> On the contrary, if anyone anywhere was providing multichannel audiofiles
>>> that I could load into iTunes and play through my home theatre system,
>>
>> you might want to give a little thought to the idea that "home
>> theater" systems are primarily a marketing device. go visit the audio
>> setups of anyone who does multichannel audio for a living (and is not
>> doing "surround sound" mixes for a living) and you won't find any home
>> theater equipment. probably.
>
> Perhaps that's because they can't stream unencoded 7.1 channel 24bit, 192kHz audio directly to a high quality amplifier with an optical input.... (yet!)
>
> You're right that most professionals will not want their nice audio messed up by using some fancy encoding system. So, let's get rid of the encoding. The bandwidth of an optical link is presumably up to sending the data unencoded.... (maybe this could be an issue, I don't know).
As was already mentioned, the S/PDIF optical standard that your receiver understands does *not* have the bandwidth to transport 8 24-bit 192kHz audio. The only two connectors I am currently aware of that can get close are ADAT Lightpipe (optical, limited to 48kHz) and HDMI (electrical).
It is unlikely that you will find an ADAT Lightpipe connector on a home theater receiver. I've never heard of one but it may exist. There are mutlichannel output devices for the Mac that do support it (MoTu Traveler, for example).
I'm not aware of any but, if there were a multichannel FireWire/USB interface for the Mac that had an HDMI output connector, then you could connect that up to a modern receiver that has HDMI inputs.
To recap, there is NO way you're going to get >2-channel *uncompressed* audio out of your Mac's built-in optical output jack.
stephen
P.S. iTunes doesn't support multichannel audio files. _______________________________________________
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