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liz
Raspberry Pi Foundation Employee & Forum Moderator
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Re: Some very good audio news

Thu Sep 08, 2011 2:57 pm

Some of our hardware guys have made a really great improvement to the Raspberry Pi as we were expecting to launch it, and best of all, it's not going to cost us anything in parts.

You may remember that we were discussing the audio output from the 3.5mm jack earlier. I know some of you who have media centre-type applications were disappointed that the audio quality from that jack was only going to be equivalent to FM radio. Happily, our very, very smart hardware team has managed to push all the noise out into a frequency that can't be heard by humans (I believe it's also dog-proof), so the audio quality from that jack will now be CD-quality.

This means that you will be able to deal with two high-quality audio streams, one via HDMI and one through that jack. Thanks very much to the hardware team - I don't know precisely who came up with this particular hack, but I'm really, really chuffed you managed it.
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hajj_3
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Re: Some very good audio news

Thu Sep 08, 2011 3:49 pm

that is indeed good news :) Hope to see some photos of the non-alpha boards soon, would be great to see what the final board will look like :)

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liz
Raspberry Pi Foundation Employee & Forum Moderator
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Re: Some very good audio news

Thu Sep 08, 2011 3:56 pm

We're still working through optimising the schematics, so we won't have any artwork for the final boards for at least a couple of weeks. As soon as we do, you guys will be the first to know!
Director of Communications, Raspberry Pi

Arbelzapf
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Re: Some very good audio news

Thu Sep 08, 2011 5:37 pm

I'm very glad to hear about that! Thank you

obarthelemy
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Re: Some very good audio news

Thu Sep 08, 2011 6:05 pm

Thanks team, that's very nice !

linuxboi
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Re: Some very good audio news

Thu Sep 08, 2011 6:21 pm

Thanks, that's great news.

HenryG
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Re: Some very good audio news

Sat Sep 10, 2011 5:15 pm

Is the jack output buffered? I mean, is it only a voltage line-out or is it capable of driving some low-impedance headphones.

Thanks and great work.

Chris
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Re: Some very good audio news

Sat Sep 10, 2011 5:59 pm

Thats great to hear, I was going to make do but my dream of hooking the R-Pi to surround sound will become reality lol. Next, world domination...

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Lob0426
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Re: Some very good audio news

Sat Sep 10, 2011 6:35 pm

CD quality=good news. Nice work, thank them all for us.
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WASD
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Re: Some very good audio news

Sat Sep 10, 2011 9:32 pm

You better make sure it's dog-proof. My dog wants good quality sound.

Ar4
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Re: Some very good audio news

Sun Sep 11, 2011 8:49 pm

Any more specific info about audio? Like output voltage swing (p-p), THD, THD+N or anything else? I hope external USB DAC will work too.

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liz
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Re: Some very good audio news

Sun Sep 11, 2011 9:15 pm

External USB DAC is dependent on driver support, which we're not currently working on - if you can do it or if someone else in the community takes it on as a project, I don't see any obstacles to it working.

Afraid that your other questions are more for the hardware guys than me - things like THD are more on the audio-geekery side of things than we're testing for, as far as I'm aware (audio-geekery is absolutely not a bad thing, that said - it's just not where our mainstream audience is looking for performance). I can say that you probably shouldn't count on the Raspberry Pi as a professional-level audio device.
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Svartalf
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Re: Some very good audio news

Mon Sep 12, 2011 3:06 pm

Quote from liz on September 8, 2011, 15:57
Some of our hardware guys have made a really great improvement to the Raspberry Pi as we were expecting to launch it, and best of all, it's not going to cost us anything in parts.

That's absolutely awesome, Liz. :D

Svartalf
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Re: Some very good audio news

Mon Sep 12, 2011 3:09 pm

Quote from liz on September 11, 2011, 22:15
External USB DAC is dependent on driver support, which we're not currently working on - if you can do it or if someone else in the community takes it on as a project, I don't see any obstacles to it working.

I'd be inclined to think most of those devices conform to the USB audio spec- and if you built the USB audio drivers as part of the support for the distribution, you could get a whole range of things to "just simply work".

stuporhero
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Re: Some very good audio news

Mon Sep 12, 2011 3:32 pm

There is a USB HID (Human Input Device) Standard for Audio (ie USB Headsets, some pro-audio cards have a switch for HID mode) - If someone covered that it would cover the majority of USB audio devices, probably all cheaper ones!

HenryG
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Re: Some very good audio news

Mon Sep 12, 2011 5:19 pm

So, will we be able to plug a pair of headphones or will it be just a line-out?

Svartalf
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Re: Some very good audio news

Mon Sep 12, 2011 8:33 pm

Quote from stuporhero on September 12, 2011, 16:32
There is a USB HID (Human Input Device) Standard for Audio (ie USB Headsets, some pro-audio cards have a switch for HID mode) - If someone covered that it would cover the majority of USB audio devices, probably all cheaper ones!

Heh... That's probably going to be covered- USB devices tend to be "easy" to get over to other processor architectures as long as you're not using inline assembly or doing other "iffy" things like that.

Svartalf
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Re: Some very good audio news

Mon Sep 12, 2011 8:34 pm

Quote from HenryG on September 12, 2011, 18:19
So, will we be able to plug a pair of headphones or will it be just a line-out?

If it gets done...so long as you've got a USB port, either off of the board or an attached hub, you'll be able to plug in nearly anything HID based and largely expect it to work out of the box like it would on an X86 Linux box...

HenryG
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Re: Some very good audio news

Mon Sep 12, 2011 8:42 pm

Quote from Svartalf on September 12, 2011, 21:34

If it gets done...so long as you've got a USB port, either off of the board or an attached hub, you'll be able to plug in nearly anything HID based and largely expect it to work out of the box like it would on an X86 Linux box...

Sorry, I meant from the built-in 3.5mm line-out jack.

Svartalf
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Re: Some very good audio news

Mon Sep 12, 2011 10:55 pm

Heh... It's probably going to be just a line-out. Get some USB headphones... ;)

Ar4
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Re: Some very good audio news

Sat Sep 17, 2011 7:24 pm

PCM270x series chips from TI are good alternative to bulky soundcards. If you use it in bus-powered mode, with only 2-layer pcb it would take as much space as usb-flash.

reggie
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Re: Some very good audio news

Sun Sep 18, 2011 9:51 am

as the r-pi chip has i2s why not use one of the cirrus logic audio chips?

Ar4
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Re: Some very good audio news

Sun Sep 18, 2011 8:31 pm

oh, I never noticed that it do have I2S. Thats really great, though I prefer Burr-Brown chips, gonna check which one performs best.

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jzu
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Re: Some very good audio news

Tue Sep 20, 2011 11:29 am

I hope it's cat-proof, too. This might prove a little more difficult to achieve: http://www.lsu.edu/deafness/He.....nge.html... Do you know what's the frequency, Kenn... um, Liz? ;)

jasongreen
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Re: Some very good audio news

Fri Sep 30, 2011 8:08 pm

I'm imagining R-pi as an audio front end. I wonder if one could be the back end as well with something like ampache? The more I think about it, the more of these I imagine myself buying.

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