Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 12:07 pm

Hello,

Do the people in here think it will be possible to use a raspberry pi as a multiroom audio system. I’m planning to install a Raspberry Pi in the bathroom, kitchen,… with a 7? or 10? touchscreen. Install an linux application that can read music from my NAS and connect a pair of boxes to the Raspberry Pi. And there it is, my Multiroom Audio system.

What do you think?

(Any info about cheap but good touchscreens (usb) is welcome)

Archangel5089
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Re: Multiroom Audio System

Thu Aug 25, 2011 12:29 pm

Mimo, they actually make something a lot like the R-pi but much more expensive (around $400 for the lower range model) so they do an awesome range of USB touchpad screens to support the idea:

http://www.mimomonitors.com/
(Apparently their technical abilities don't extend to a good website)

I think the cheapest practical one is about £100 (sorry for the cross-currency) but I would hunt around as buying direct probably won't be cheaper. It's not good business to undercut the people you supply on the Internet!

Archangel5089
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Re: Multiroom Audio System

Thu Aug 25, 2011 12:35 pm

I have to say I like the idea of setting up a budget multimedia system throughout the entire house! I'd like to set one up a drop-down touchscreen screen in the kitchen simply so I can stream iPlayer when I cook. I reckon you could do it all with < £150...

Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 12:58 pm

R-pi has an analog output yes?

like you said, only find a low cost touchscreen and it should work.

then find a good linux program to read out the complete library. And good navigation

ShiftPlusOne
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Re: Multiroom Audio System

Thu Aug 25, 2011 1:00 pm

it has analogue output, but I wouldn't use it for music.

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abishur
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Re: Multiroom Audio System

Thu Aug 25, 2011 1:09 pm

Why not? All those awesome iPod tunes everyone has been rocking out to have been thoroughly enjoyed while listening to them via an analog output (headphones and many third party docking stations). Sure it's no digital quality of sound, but it usually enough for providing quality music ;)
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Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 1:22 pm

That's also my idea. When you are in the shower you don' t hear that "less" quality. If i go for a run, it' s also with a jack connector...

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Re: Multiroom Audio System

Thu Aug 25, 2011 1:33 pm

The problem isn't that it's analogue, the problem is that it's low quality analogue. Your iPod is designed with audio quality in mind.

The analogue audio is, I'm afraid, by no means high fidelity audio. Shouldn't be quite as bad as Grandma's phone, though! It's a DSP-accelerated 1-bit DAC with a low-pass filter.

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abishur
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Re: Multiroom Audio System

Thu Aug 25, 2011 1:52 pm

I'm afraid I'm not a big audio guy, so I'm just gonna have to take your word on this one! :)
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Re: Multiroom Audio System

Thu Aug 25, 2011 2:13 pm

I am just going by what Liz said earlier. I am by no means experienced with audio, but if I was to build an audio system, I'd do some research first.

Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 2:42 pm

Hmm, damn ;-)

But, i will buy one and check the sound quality. Later I can buy others to install the audio system. Otherwise I have to "extract" the sound from HDMI to Jack (if i use a sort of computer boxes).?

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Re: Multiroom Audio System

Thu Aug 25, 2011 2:49 pm

I did a quick search on getting HDMI audio in to speakers - you need an AV amp to convert from digital and amplify the signal for speakers - can't find any other way of doing it. I reckon there must be a market for that sort of thing - just a little box with HDMI in and speakers output (or phono/jackplug) out.
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Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 2:58 pm

That would be great, but an extra cost off course. But, we have enough time before the Raspberry Pi comes out and find a solution. :-)

Maybe one of the Devs can say/test if the audio out is "the same" quality like a Ipod audio out/ Smartphone / ...

obarthelemy
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Re: Multiroom Audio System

Thu Aug 25, 2011 6:02 pm

I find I'm more and more using my smartphone + headphones for that. I just keep it on a move around, and with the money saved I can get very nice headphones. Plus, I don't bother the neighbours or occasional guests ?

Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 7:05 pm

In the shower that's difficult ;-)
It is also handy if you are not alone and want a bit of music.

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liz
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Re: Multiroom Audio System

Thu Aug 25, 2011 7:15 pm

There's no variability in HDMI audio quality across different devices - HDMI is HDMI is HDMI, so yes, it'll be comparable to an iPod.
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Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 7:28 pm

@liz

The audio quality off the analogue output is "practical" the same as an output of a smartphone/ipod/... ?

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liz
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Re: Multiroom Audio System

Thu Aug 25, 2011 7:31 pm

Yeah, pretty much. It's not coming from a codec but from filtered PWM, so it's not quite as good as an iPod.
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Argon
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Re: Multiroom Audio System

Thu Aug 25, 2011 7:33 pm

Oke, we will see how good it is.
Now find a solution for a cheap but good touchscreen on usb.

Thank you for the previous answer.

DanielSilva
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Re: Multiroom Audio System

Sun Aug 28, 2011 9:10 pm

An iPod has a dedicated audio codec while the board ( this is me supposing ) just has a very simple 1 bit DAC, the DSP spews out the PWM signals and they are converted into analog signals by a simple low pass filter.

The HDMI cable transports the audio and video streams together so you can't directly convert those digital signals into analog jacks. You need something in between to separate the two streams and convert them into analog signals and it won't be simple and/or cost effective.

The simplest way would be buying an external usb powered audio dongle, you can find one for like 10€. Most of them are based on the c-media chipsets so linux support is usually ootb ( as long as the kernel is compiled with the snd-usb-audio module ).

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Gert van Loo
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Re: Multiroom Audio System

Sun Aug 28, 2011 9:59 pm

Just a note: the output of the 3.5 connector will not be extreme high quality. For that you have to add an audio decoder. But it is the cheapest solution we could come up with.

deggy
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Re: Multiroom Audio System

Mon Aug 29, 2011 2:18 am

This would be an easy setup. I've done similar projects with various hardware hacked-up to act as players (PSPs, Windows and PalmOS PDAs) but never found the ideal solution - and plan to use a RPi for just this application

Here's what I would (will) do:

The RPi will be effectively a massively over-powered mp3 stream player. Put a bare-bones Linux kernel on it booting to a shell and then have a simple binary (like mpg123) connect to an audio stream at boot and try to play it. mpg123 will happily keep connecting to a non-responding stream if given a suitable time-out.

On a server (could be another RPi, could be any computer) run Squeezebox server (formally called Slimserver) which is a free download from Logitech. Effectively this will serve a custom mp3 stream to a unique IP address from http://musicserver:9000/stream.mp3. The Squeezebox server software automatically registers new players by IP address as they connect and you can assign them names. Obviously it includes full music library management too!!

You will need to setup the Client RPi with a very small buffer to achieve responsiveness.

Now you can control the content of the stream sent to the various RPi's from either the server PC of from a tablet or smartphone via Squeezebox servers web interface which is excellent. Squeezebox will push out MP3 audio to the custom stream and change it as you pause and shuffle tracks.

Volume control would be the only issue, but I think you could easily hack up a simple perl script to adjust ALSA volume on players from a browser. Squeezebox server might even be able to re-encode MP3 streams on the fly to change the volume if needed but I have a feeling that this would be a little too laggy.

As for getting the audio out - that's up to how much you want to spend. You could make a enclosure containing the RPi and speakers, you could embed the RPi and some speakers above a suspended ceiling or just make a simple black box to connect to a stereo via 3.5mm line out.

I'll probably make 1 x RPi-based 'boombox' and 1 x RPi-based headless unit to connect to a decent audio system. You could also take a pure digital signal from the HDMI into a suitable amplifier.

pieter
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Re: Multiroom Audio System

Mon Aug 29, 2011 1:24 pm

I've been thinking about using the r-pi for multiroom audio as well.
I'm already using a guruplug as a audiosystem. I bought a usb external soudcard with (among others) a optical spdiff out. The opticial out goes into my living room soundsystem.
On the guruplug I run mpd. Mpd is made with low resources in mind and has a simple protocol to control it (plaintext). There are a lot of mpd clients for (almost) every platform (I use gmpc on the desktop and mpdroid on Android tablets/phones).

Mpd can be configured to use pulseaudio and I want to put a r-pi in every room, connected to a set of speakers. In het mpd-clients I could then select an "output" and music will be streamed to that room :-)

Maybe combine it with forked-daap to serve music to daap-enabled devices.

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jzu
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Re: Multiroom Audio System

Mon Aug 29, 2011 1:39 pm

Believe me, you don't want these C-Sound dongles for a home audio system. They're ok if you want to connect low-quality headphones, but that's about it.

I have an ART USB Phono Plus (http://www.artproaudio.com/pro.....038;id=128). It's got pretty decent quality and features for the price. I've just bought a Behringer USB interface (23€) and I'll give you some feedback once I have tried it.

DanielSilva
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Re: Multiroom Audio System

Mon Aug 29, 2011 2:06 pm

Quote from jzu on August 29, 2011, 14:39
Believe me, you don't want these C-Sound dongles for a home audio system. They're ok if you want to connect low-quality headphones, but that's about it.

I have an ART USB Phono Plus (http://www.artproaudio.com/pro.....038;id=128). It's got pretty decent quality and features for the price. I've just bought a Behringer USB interface (23€) and I'll give you some feedback once I have tried it.


The problem with that is price ... why would you buy something that costs almost 3x more than the board itself ? Specially when you'll need to buy one for each room, the total price would go up considerably. The c-media dongles i referred are good enough for a simple multiroom system ( we aren't expecting high fidelity here ) while still costing just a couple of dollars.

In the $25~$30 i would also look at the Creative X-Fi Go!, it's not bad for the price and it's pretty compact. I just striped the case ( If you're not worried with warranty like me ), de-soldered both usb ports ( dongle and the board i was using ) and soldered some headers instead, fitted everything on a small case.

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