Raspberry PI -> "nu skool ghetto blaster?"

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Raspberry PI -> "nu skool ghetto blaster?"

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April 22, 2012 at 3:50 pm

#698771
6

General Lighting

@general-lighting

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this is an idea I’ve had in my mind for a while – TBH I’m not brainy enough to build the whole thing but don’t mind sharing the idea (probably not the onlly person who’s thought this anyway)

The Raspberry PI is a small computer with on board audio/graphics which will run some form of Debian Linux.

FAQs | Raspberry Pi

The concept would be to put one of these into a case, add an analogue audio amp/speakers to it, a USB sound input card, and create something like a 80s ghetto blaster you could use for both listening to and transmitting internet radio…

In RX mode it would work like a hardcore lives tuner (could even add a real Hiitachi LCD display to it 😉 and be like a old skool ghetto blaster (one of the larger ones like a portable hi fi)

in TX mode the graphics would output either to HDMI or even PAL composite – contain a low res set of buttons / menus (similar to teletext / BBC micro mode 7 for those old enough to remember) and a double PPM meter so you could easily check levels, plus an accurate clock which can be locked to your national time standard via NTP atomic clocks.

The idea would be you literally plug this box into the program audio feed from your mixer (as the USB card can be selected it could either be analogue balanced/unbalanced or SPDIF provided the card has the debian/ALSA driver, connect it to your online radio station, position the main display where the DJ’s / presenters can see it and start broadcasting. The box itself (depending on processing power) could be used as “squawk box” to monitor either live audio or the streamed audio (it would have to be remote from your mixer to avoid annoyance listening to delayed audio).

I think these would be good for streaming live performances as they could be tucked away anywhere near a broadband feed and wouldn’t need a fragile or bulky computer, and if you don’t have really high res display could use old style idiot box on scart for this, or cheaper LCD TVs…. also the user interface would be designed more like old style audio equipment than a computer…

anyone here interested in developing this sort of idea further? its quite a mission, more than I could do on my own but I think collectively we have the brains here to do it..
April 22, 2012 at 6:00 pm

#954615
1

Tank Girl

@tank-girl

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My mates were like a pack of rabid dogs waiting for the release of pi…
April 22, 2012 at 6:26 pm

#954620
1

YoungOne

@youngone

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Im in for designing a linux interface, i can code a little and i know some basic eletrical stuff.
Also its deffenatly going to be a mission, but id love to help and who knows maybe learn something new.
April 23, 2012 at 8:47 am

#954610
6

General Lighting

@general-lighting

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I tried to tell DJ Pete about this but can’t get onto his forum (it rejects every captcha I enter), anyone else got any way of contacting him?
April 23, 2012 at 9:54 am

#954616
1

barrettone

@barrettone

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My Raspberry Pi SHOULD be arriving this week. I’d be more than happy to volunteer it for this kind of work. I’m a fairly decent coder (though I really should learn more C) and am comfortable with messing around with electronics. If we can get a team of people off here working on this I think we can really get places.
April 25, 2012 at 1:45 pm

#954611
6

General Lighting

@general-lighting

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TBH the playout bit should be easy as I think it runs some form of Debian, and just using a old laptop with Debian out of the box I got a radio player.

the oddcast? TX encoder would have to be ported to this and also checked with the USB soundcard for input (not all play nice)

one thing which would be worth doing is porting the PPM display. This probably is more complex as I’m not sure if the darkwood chaps are sharing the code, but the maths for the PPM meter ballistics must be on the BBC or EBU website somewhere. I haven’t got the head for that sort of DSP programming or maths, though dubstep_joe might ;
April 25, 2012 at 2:37 pm

#954621
1

YoungOne

@youngone

Member
I would just like to add, for playing music it will be easy, i do belive the PI has internal memory, if it doesnt we can always add a small USB drive.
It would be nice to make it touchscreen but i belive it would require extra effort, also for playing from a radio you could use a custom build of VLC as it has its own codecs etc.
April 29, 2012 at 6:08 am

#954622
1

Pat McDonald

@pat-mcdonald

Participant
@General Lighting 477187 wrote:

anyone here interested in developing this sort of idea further? its quite a mission, more than I could do on my own but I think collectively we have the brains here to do it..

I’ve done that sort of thing with early 90s tech… it’s a lot easier to just rig a mic/pre-amp up to an ADC, sample the music in real time, and react accordingly. It’s less fucking around than trying to interface with EVERY sound deck out there – you would think all you need is a couple of phono jacks but actually, levels always need tweaking, and one little earth buzz on your Pi and the whole venue knows you are a knobhead.

Also, issue with how you broadcast onto the net from the middle of a field or even a cave. The sat dish for an uplink is not a small item.

But… I admire your spirit and inventiveness. I am pretty sure the Pi can be used for plenty of party jobs. Just remember who it’s aimed at though – school kid developers, not industrial innovators.
April 29, 2012 at 8:20 am

#954617
1

barrettone

@barrettone

Member
That’s what industrial developers are for though isn’t it? Take some tools and start messing around with them in ways they didn’t intend. Just look at Xbox Kinect and what that was meant for and what it’s actually used in. Very few limits to human inventiveness, given the right frame of mind!
May 2, 2012 at 4:11 am

#954628
1

DaftFader

@daftfader

Participant
@Pat McDonald 477732 wrote:

I’ve done that sort of thing with early 90s tech… it’s a lot easier to just rig a mic/pre-amp up to an ADC, sample the music in real time, and react accordingly. It’s less fucking around than trying to interface with EVERY sound deck out there – you would think all you need is a couple of phono jacks but actually, levels always need tweaking, and one little earth buzz on your Pi and the whole venue knows you are a knobhead.

Also, issue with how you broadcast onto the net from the middle of a field or even a cave. The sat dish for an uplink is not a small item.

But… I admire your spirit and inventiveness. I am pretty sure the Pi can be used for plenty of party jobs. Just remember who it’s aimed at though – school kid developers, not industrial innovators.

I think the idea is to allow people who don’t have access to a good enough computer who want to stream here or on any similar radio station to be able to do so without forking out a shed load on a new P.C./laptop

Most people I would imagine would be streaming from their “bedroom” so I really doubt anyone’s gonna need a satellite dish, they might as well make a full blown pirate radio station if they are going to go to that length. The whole idea is to make it easier not harder, and even if they are planning on using it out and about you’d use one of these Internet Dongle | Mobile Broadband Dongles (not that either a dongle nor a satellite dish would be much use in a cave).

Recording someone mixing through a mic would sound absolutely terrible.

I’m still not sure what you mean by not being able to interface with every sound deck easily? It’s just a matter of making sure you can send an output of your mixer to it, just like you would to a pc/laptop as you would do normally (the mixer will have an output volume control on it and I assume the idea would be to give it it’s own volume control anyway like any audio equipment.
May 3, 2012 at 4:29 pm

#954623
1

Pat McDonald

@pat-mcdonald

Participant
@DaftFader 478113 wrote:

I think the idea is to allow people who don’t have access to a good enough computer who want to stream here or on any similar radio station to be able to do so without forking out a shed load on a new P.C./laptop

Most people I would imagine would be streaming from their “bedroom” so I really doubt anyone’s gonna need a satellite dish, they might as well make a full blown pirate radio station if they are going to go to that length. The whole idea is to make it easier not harder, and even if they are planning on using it out and about you’d use one of these Internet Dongle | Mobile Broadband Dongles (not that either a dongle nor a satellite dish would be much use in a cave).

[/quote]
Well, depends what you mean by internet broadcast. I was assuming “remote location” as in somewhere without a Wifi broadband coverage, which is sadly still most of the world. Satellite uplink (OK, dish in open air, not inside the cave) gives you internet broadcast from anywhere.

@DaftFader 478113 wrote:

Recording someone mixing through a mic would sound absolutely terrible.[/quote]

Yes it would. I was thinking more about the reaction to music aspect than the radio broadcast aspect.

@DaftFader 478113 wrote:

I’m still not sure what you mean by not being able to interface with every sound deck easily? It’s just a matter of making sure you can send an output of your mixer to it, just like you would to a pc/laptop as you would do normally (the mixer will have an output volume control on it and I assume the idea would be to give it it’s own volume control anyway like any audio equipment.

2 issues to deal with – EMF interference (making sure the Pi or whatever has decent earthed shielding to prevent crosstalk in the audio cables) AND making sure all the earth’s are joined together, with no faults, so that the midpoint of each audio channel is exactly identical. If one piece of equipment has a shitty shield or a bad earth or just a shite design the whole lot hums at mains voltage frequency – which is when you, as the resident geek, look like a knob end (been there, it’s not a fun place to be).
May 3, 2012 at 4:53 pm

#954612
6

General Lighting

@general-lighting

Moderator
Staff
my former employers made a similar device in the late 90s/early 2000s based around single board PC’s – the Raspberry PI can’t be less powerful than these… ironically they were too early to market, before broadband was available and the costs they incurred and resources they used near enough wiped them out.

the idea would be to produce a robust box one end of which goes to the audio, the other goes to a router / switch for a venue which already has broadband. TBH if you are somewhere you need satelllite broadband its mostly likely going to be a place where it would be expensive and maybe even risky to try internet broadcasting and they’d be better off getting voice quality audio out using the existing GSM telephone network (including via ISDN codecs) as this tends not to get controlled as much because its more vital for commercial business!

One of the reasons the PI was delayed was because of EMC compatibility. the end result may or may not be a good thing, depending whether their solution this contaiminates the audio signal earth. Hum is just one of the potential problems – a worse on is contamination of the audio signal with pulses of interference from switched mode PSU, fed down the mains ground. Ground loop problems are something I am well aware of (and so is Daftfader), I spent about 3 months debugging ground loop/noise problems on my kit (admittedly at a level few would noticed but having worked in pro audio for broadcast I am a perfectionist) – one laptop had to have its PSU replaced for one with a europlug (two pins).

One problem (which predates the computer age) is a conflict between getting clean audio and preventing folk from being electrocuted. Nowadays health and safety comes first which TBH isn’t a bad thing, in the old days flaky PA’s and electrocution killed as many musicians if not more than drugs and booze….

however CPC/Farnell sell a variety of low cost transfomers which put a stop to the bulk of these problems and yet don’t destroy the audio frequency response for internet broadcasting.
May 3, 2012 at 5:05 pm

#954629
1

DaftFader

@daftfader

Participant
@Pat McDonald 478293 wrote:

2 issues to deal with – EMF interference (making sure the Pi or whatever has decent earthed shielding to prevent crosstalk in the audio cables) AND making sure all the earth’s are joined together, with no faults, so that the midpoint of each audio channel is exactly identical. If one piece of equipment has a shitty shield or a bad earth or just a shite design the whole lot hums at mains voltage frequency – which is when you, as the resident geek, look like a knob end (been there, it’s not a fun place to be).

Oh you are talking about interference issues, it sounded like you ment the actual wires/format not being compatible, which is obviously not the case.
May 3, 2012 at 9:27 pm

#954618
1

barrettone

@barrettone

Member
I’m still waiting on the postmen to give me my credit-sized computer from Hell. It’s probably still passing CE.
May 4, 2012 at 10:12 pm

#954624
1

Pat McDonald

@pat-mcdonald

Participant
Nah, more like shortage of supply. You will get one. Recall would cost them too much so they want to get it as good they can. I think that’s case from what I hear.

“Compatible” is an iffy concept when dealing with analogue electrical values. Getting them as balanced and slick with all possible connections and variations is an art itself sometimes.

I can’t help but think if you want to stream to the net a dedicated system is better than just a piece of PC software and a home PC- but I also can’t think that a dedicated MP3 recorder, networked to a home PC or regular media swapping, might be less hassle and more reliable than using a Raspbery Pi as part of the recorder. Just my 0.02 cents, I wish you joy of the chase anyway.
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