WereCatf
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Re: SPDIF?

Thu Feb 02, 2012 11:57 am

Does the hardware support SPDIF out and would it be possible to implement an SPDIF-out port on RPi? My surround-sound receiver has no HDMI ports and buying a HDMI -> HDMI + SPDIF cable doesn't work, so implementing a separate SPDIF-port seems like the only possible way of getting 5.1 sound out of RPi.

Of course, USB soundcard would also work, but those are resource-hogs, and on an already resource-constrained system it would be a poor idea to use one such.

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meltwater
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Re: SPDIF?

Thu Feb 02, 2012 12:53 pm

Have a search for I2S (tip use I2S*), many threads about it's possible use (and about if we can hardware hack it to have it available (it got lost!).
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gregeric
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Re: SPDIF?

Thu Feb 02, 2012 1:19 pm

Does your HDMI-connected monitor or TV have optical out? That should route 5.1 to TOSLINK, thereafter you can use a cheap TOSLINK -> SPDIF adapter, or maybe your amp has optical in?

WereCatf
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Re: SPDIF?

Thu Feb 02, 2012 1:28 pm

gregeric said:


Does your HDMI-connected monitor or TV have optical out? That should route 5.1 to TOSLINK, thereafter you can use a cheap TOSLINK -> SPDIF adapter, or maybe your amp has optical in?



No, my TV does not have optical out. And the optical connector on my receiver is already in use anyways.

Tozzi
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Re: SPDIF?

Thu Feb 02, 2012 1:57 pm

I searched for it and found it in a swedish store (I'm from sweden).

http://www.dustinhome.se/delta.....5010150091

It is from Deltaco, so you should be able to find a reseller in you country (Hi there neighbor!)

But then you got DVI-D out instead, is that a problem?

The price in sweden is 1 500kr (around $214 USD), but you should find it cheaper.

Good luck!

WereCatf
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Re: SPDIF?

Thu Feb 02, 2012 2:07 pm

^ Good try, but I'm not going to shell out 170e for such. Heck, I can buy a whole new PC for that or get a 2nd receiver with HDMI. Thanks anyways.

Tozzi
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Re: SPDIF?

Thu Feb 02, 2012 2:15 pm

Haha, you right, but there is more of these out there, and cheaper. I recently found this:

http://www.alibaba.com/product.....e_DVI.html

Me for myself are looking for a HDMI to VGA (old projector), which are a lot harder because of HDMI is digital and VGA analog.. Arrgh..

Tozzi
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Re: SPDIF?

Thu Feb 02, 2012 2:17 pm

Actually found this!

http://www.ebay.com/itm/HDCP-H.....2318b8c735

Got interested for myself..

terual
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Re: SPDIF?

Thu Feb 02, 2012 2:48 pm

As the I²S interface is scrapped (see here: http://www.raspberrypi.org/for.....hange-made), you'll have to use an USB soundcard for now.

But how did you get the idea that an USB sound interface would be a resource hog? For example CD audio is only ~1.4 Mbit/s, which should be easy to cope with.

WereCatf
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Re: SPDIF?

Thu Feb 02, 2012 3:03 pm

terual said:


But how did you get the idea that an USB sound interface would be a resource hog? For example CD audio is only ~1.4 Mbit/s, which should be easy to cope with.


I did mention surround-sound, didn't I? CD audio is stereo, so yes, it requires quite a bit less bandwidth. But you have to remember that already having to move data over USB does consume resources, USB was never designed to be very efficient resource-wise and that's why it's so cheap to implement. Atleast all the USB soundcards I've used have indeed been resource-hogs. On a modern desktop the difference is unnoticeable, but as soon as you plug one in a less-than-modern one you'll likely notice a difference.

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abishur
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Re: SPDIF?

Thu Feb 02, 2012 3:13 pm

Maybe I'm missing something, but you're wanting SPDIF (which is an optical connection), but you also said your optical connector on your receiver is in use already... so how would getting spdif out of the r-pi help you?

I was in the same boat as you on the receiver not taking HDMI but not wanting to shell out hundreds of dollars to upgrade a very nice receiver.  Fortunately, my TV did have digital audio out via an optical cable.  Does your TV offer any sort of digital audio out?  If it does digital coax out instead of an optical toslink cable then maybe your receiver could use that?

I guess what I'm asking here is what surround sound input does your receiver have available?  That might help us give much more useful advice

Side note, the thread terual links to also says it might be possible to get I2S back via some soldering... just sayin'.
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rpt
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Re: SPDIF?

Thu Feb 02, 2012 3:35 pm

SPDIF can be coax as well as optical so I guess she has a spare coax input on her amp.

WereCatf
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Re: SPDIF?

Thu Feb 02, 2012 3:58 pm

Abishur said:

Side note, the thread terual links to also says it might be possible to get I2S back via some soldering... just sayin'.

Aye, I notice that. I'll have to see about it.

Tozzi
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Re: SPDIF?

Thu Feb 02, 2012 4:10 pm

What I understand from her post is this:

She has a coaxial connection free on the amp, no optical.

Too bad there is no I2S, that would have been handsome to have..

nullstring
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Re: SPDIF?

Thu Feb 02, 2012 5:23 pm

Anyone who has demand for I2S should post in that thread I made to make sure they know how many people have demand for it.

http://www.raspberrypi.org/for.....hange-made

It will give us the best chance of getting them to put it back. =)

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abishur
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Re: SPDIF?

Thu Feb 02, 2012 5:51 pm

Tozzi said:


What I understand from her post is this:

She has a coaxial connection free on the amp, no optical.



That's certainly a good basic assumption, but it's also possible they the individual has 6 unique inputs to get surround sound.  I'm also curious to know if the TV has any sort of digital output.  If it does then finding some way to make use of that might prove to be the most advantageous solution.
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WereCatf
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Re: SPDIF?

Thu Feb 02, 2012 6:25 pm

Abishur said:

I'm also curious to know if the TV has any sort of digital output.  If it does then finding some way to make use of that might prove to be the most advantageous solution.
I ain't at home so I couldn't check. Though I just downloaded the manual for my TV and it does indeed have an optical digital out. However my receiver only has 1 optical input port and it's already in use...

nullstring
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Re: SPDIF?

Thu Feb 02, 2012 7:28 pm

WereCatf said:


Abishur said:


I'm also curious to know if the TV has any sort of digital output.  If it does then finding some way to make use of that might prove to be the most advantageous solution.


I ain't at home so I couldn't check. Though I just downloaded the manual for my TV and it does indeed have an optical digital out. However my receiver only has 1 optical input port and it's already in use...


I would say it's much easier to work around that problem than to get digital out from the RPI... I assume the occupied digital in can't be switched for coaxial for some reason?

If so, $15 will buy you a solution.

http://www.amazon.com/Digital-.....B000I98ZQY

You should, however, test this before hand to see if surround sound will be passthrough the TV from HDMI to the digital out. It's a common problem, and it's a reason many people don't use the digital out from their TV.

WereCatf
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Re: SPDIF?

Thu Feb 02, 2012 7:54 pm

^ Shall try and see. If it works then great, that solves that issue.

612WharfAvenue
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Re: SPDIF?

Thu Feb 02, 2012 8:02 pm

It's also worth noting that even a TV with audio passthrough isn't a cure-all.   For instance, my TV won't pass through DTS streams, and this seems to be a common issue.

Lack of separate digital audio out is the RPi-as-media-player's achilles heel.

henrie
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Re: SPDIF?

Fri Apr 13, 2012 12:05 pm

For instance, my TV won't pass through DTS streams, and this seems to be a common issue.

I can confirm this. I have the top-model Philips 9000-series and it doesn't pass trough dts....

A very nice thing with optical cables is that they can be switch with a cheap mechanical switch... So when you have only 1 input on your receiver there is a solution! (I bought this one myself... not fancy or high-tech but works great)

see http://www.kabelmaxx.nl/optisc.....angen.html

(This is a dutch webshop, but you should get the idea.)

So back to topic: optical output (or cheap way to convert) would be GREAT!!!!

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mahjongg
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Re: SPDIF?

Fri Apr 13, 2012 1:28 pm

WereCatf said:


implementing a separate SPDIF-port seems like the only possible way of getting 5.1 sound out of RPi.


Why do you assume that SPDIF is needed to get surround sound?

5.1 surround sound physically needs only a stereo connection (which the R-PI has in the form of the 3.5mm jack). Surround information is encoded in the phase difference of the stereo signal.

henrie
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Re: SPDIF?

Fri Apr 13, 2012 1:48 pm

Surround information is encoded in the phase difference of the stereo signal.

You're talking 2.1 analoge surround (2 for stereo and 1 for mono surround) known as dolby surround (or prologic). DTS and AC3 have seperate chanels and in the best way each channel is transmitted to a seperate amplifier of your reciever…….

I don't see how you can transmit for example 5.1 (6 seperate channels) trough your stereo mini-jack…

pandapi
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Re: SPDIF?

Fri Apr 13, 2012 3:30 pm

i don't think lack of a dedicated spdif port is a problem.

It can be done over HDMI, so it CAN do it.

If it can't be done on YOUR receiver then you have to work around it or maybe the pi isn't for you.

I would bet that virtually all, if not all, receivers nowadays have HDMI.

Maybe the pi should have a VCR drive in case someone needs it?

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mahjongg
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Re: SPDIF?

Fri Apr 13, 2012 3:56 pm

henrie said:

I don"t see how you can transmit for example 5.1 (6 seperate channels) trough your stereo mini-jack…
Hallo henrie!

No, I'm really talking about 5.1, which has three speakers in the front, and two in the back. The ".1" means there is also a subwoofer (low frequency center speaker).

There are special decoder IC's that transforms a (suitable) stereo signal into the six channels of a 5.1 "surround sound system".

Here is an example:

http://www.electroniq.net/audi.....ystem.html

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