Raspberry pie, anybody?

jrebman

New member
I'm starting this thread so that there will be a separate place for those of us who are/want to be playing around with the Raspberry Pie computer for audio playback.  I got my starter kit the other day and this thing is just way cool in how small it is and how much they got on this little card.

As Tom pointed out in the other linux thread, somebody has ported a version of voyage inux and MPD to the RP environment and seems to be makking good progress.  Right now the one big limitation seems to be a firmware/lkernel issue related to the usb hardware and it seems the machine is limited to 16/44.1 playback (if I'm understanding things correctly), but the issue has been sent back to the Raspberry Pie Foundation and they have apparently hired an expert to deal with the issue, so this limitation appears to be temporary, but no fix date is given.

If you are into messing about with small computers, especially for audio use, you should get a starter kit, or stand-alone board and take this thing for a spin.

Another thing that really amazed me about this whole thing is that I actually, for the first time, have access to official documentation and related books through iBooks.  Just for fun I typed "raspberry pie" in the iBooks search and the official RP user's guide came right up, so I downloaded it, opened iBooks, and sure enough, it was fully accessible (on my iPad) and I read through the entire 460 page manual in a day or two.  That in itself was pretty impressive from my point of view, but reading about all the things that comes with the RP and the things people have done with it, the alternative OS builds for it (including a full function media player build), are quite impressive, plus lots of add-on boards and prototyping boards, bridges to arduino boards, etc. was also fascinating.

This little board with a good linear psu, an ethernet connection to a NAS (or usb drive/thumb drive) and a usb dac should prove to be a really sweet, tiny, even portable music server, with remote control possibilities for all kinds of smartphones, iPods, tablets, etc., or if one is really ambitious, a small display screen and some front panel buttons to control it (at this point, it looks like that would all have to be custom built/programmed.)

At $45 for a Rev B board (512 mb ram, 2 usb ports, ethernet port, HDMI port, composite video, 3.5mm stereo audio jack, and i/o connector., it's almost a no-brainer -- if you're into this sort of thing.

Be prepared to do some learning and lots of experimentation and the challenge/frustration of ongoing development though as this is hardly at the point of being a turnkey music streamer at this point.  If you want that, the PCEngines Alix boards are a far more developed, proven and reliable solution, with plenty of online tutorials on how to get them running, and witha good linear power supply, can sound very, very good.

Anybody aside from Tom and I going to get on board with this?  It would be nice if we could get a critical mass of bottleheads working on this, especially if it can be made to be a low cost, reliable server solution to feed the upcoming BH dac.

Cool stuff!

-- Jim
 
Hopefully this thread will eventually get a little traction. I know that Brad, BNAL was interested in experimenting with this. I also recall porcupunctis mentioning that he was going to get a pi to experiment with.

For now I'm using two computers. One Raspberry Pi as a NFS file server and an ALIX computer as an NFS file client. This combination works well for my needs. I like having the External hard drive in the other room for a completely silent system. Have a look at the photo in the link below. The Raspberry Pi is the computer on the bottom that contains my music library. I'm using an iPad to remotely control the headless system.

http://cheap-silent-usb-linux-music-server.blogspot.com/

I plan on poking around the Raspberry Pi MPD route sometime in the near future. However, I just got back from "Cruise To The Edge" yesterday and I'm still on cloud nine. What an awesome experience that was. More on that in the "Cruising with Yes" thread.
 
Grainger49 said:
I'm watching.  Some time I might go to a server.  The problem for me is reading in the 1500 CDs.

I can certainly understand that. My collection is a little bit larger than that. I just started off ripping five to ten per day. I also had a couple of marathon sessions on the weekends. Try starting off with the discs that you listen to the most that way you can start listening right away.

Once you have everything loaded it is so convenient having instant access to your entire library on an iPod, iPad or similar android device. But yeah, it takes some time getting there.
 
And just FYI, you can buy a refurbed iPod Touch 4g with 8 gb memory (excellent as a remote controller for such a system as we are talking about here) for $150, including the standard Apple warranty.

So getting back to the Pie, there are a couple of scenarios I'm imagining, but at this point I haven't seen anybody doing these things, so they are absolutely not tested and currently aworking approaches.

The first idea I have is to use the HDMI port for music data, instead of USB -- of course I have no idea yet if this will be an improvement or not over usb, but it does have that potential, especially given the current state of the usb kernel issues. HRT now has an HDMI dac that takes an HDMI signal in, strips the sound data out, reassembles the full HDMI packet and can send it on to the display.  This dac also has two hdmi inputs, so you could still send the data from a dvd player or whatever, plus the music data source to it, and then still connect it to your monitor for the picture.  It also does 24/192 PCM, but no idea if DSD will work in this scenario, but probably not, at least not with some serious programming effort.

The second option would be to use the HDMI port with and HDMI tospdif converter, and this will get you an spdif stream for feeding something like the BH dac, which has been said, at first will only have spdif input.

So, the raspberry pie with one of these options (hdmi dac or spdif converter), and a decent linear psu, should get some very nice results.

Of course the possibility of getting the usb issues fixed is pretty likely, so going to a standard usb dac, is also a possibility.  One thing I think would make for a small, compact, very decent sounding dac, fed from a NAS for fileserver, and with a direct audio out, would be to pair the RP with something like the AQ dragonfly, or the new HRT MicroDAC, which is said to be somewhat better sounding than the dragonfly, and cheaper too at $189.  24/96, direct audio out, plus a volume controllled headphone out usign a digitally controled analog volume control, not dithering or bit dropping digital control.  Again, the usb kernel issues would have to be addressed by the RP foundation before this will work beyond 16/44.1.

All of these solutions are based on receiving the data stream over ethernet from a fileserver or NAS, and as Tom has done, an RP will also make a fine fileserver using a usb hard drive for music storage., so even if you had no home ethernet network, you could build one of the dac/spdif options above, feed it from another RP as fileserver, connected with a piece of ethernet cable, and with a usb wireless adaptor connected to the fileserver for remote control.  Relatively inexpensive,, probably a good deal less than even a basic mac mini with a cheap usb dac, and potentially better performance (given less hardware/processing complexity, and other things.  Power supply quality will also figure pretty prominently in the final outcome as well.

Also, forgot to mention it, but the HRT HDMI dac is something like $230, so not terribly expensive as dacs go, and is said to have performance somewhere between the hrt musicstreamer II and musicstreamer II+, and as I said, full 24/192 capability.

Lots of potential here for sure, but none of this is really turnkey at this point and is going to take a good bit of experimenting, tweaking, maybe some hacking, and perserverance to get going, but when done, it should be as easy as distributing preconfigured SD cards with a custom image on them, and assembling the hardware, plugging it all in, andputting it all in some sort of enclosure if desired.

So for the computer timid, you could buy the hardware, and then get an image from one of us on an SD card, follow some basic setup instructions and be ready to go with a very high quality music streamer.

-- Jim
 
I'm also interested in using the RP to connect to my music library.  My goal is to get my library to be accessible on my home network so I no longer need my DAC to be connected to my iMac but rather use the little RP.

Once some solid specs are released on the Bottlehead DAC I'd lke to see  how to incorporate the RP into the DAC enclosure so I can simply connect to my network via ethernet or wifi and stream everything in hi rez.

 
 
One of the items I have been looking at is the WaveIO board to bridge the USB to SPDIF. The DAC I currently use does not support 24/192 USB, so I'm using the SPDIF out on my SB Touch to feed my DAC music at that sample rate.

What is nice about the board is that it appears to support Voyage MPD and the USB power can be bypassed and you can use your own power supply.
 
Tom,

Still suffering the after-effects of the cruise? :-)  I did mention that with the RP you could use an HDMI to spdif converter for the BH dac and others, like Brad's that he just mentioned, that don't have a usb option, or won't go to full resolution with usb.  Again, this is not tested, just theoretically possible with the RP with it's HDMI port.

AAlso, comparing specs of the RP to the Alix, I can't help but wonder if the RP may make a better platform in the long run, based on some basic specs:  RP is 700 mhz, Alix is 500 (for 2D2 board which is what I'm using), basic ram is 512 mb for Rp and 256 for Alix, and if I recall, sd card is a bit faster than CF card..  Of course this is nowhere near the full story, but it will be interesting to compare them when done.

-- Jim
 
I just skimmed a post on another forum saying the raspberry pi has i2s headers. Would that open up the possibility of bypassing usb and going directly to a dac board that accepts i2s as an input? I know several diy dac board have this capability. Exciting?!
 
I may be wrong about this, but I'm not sure i2s and I2C are the same thing -- the RP has the latter.  If this is the same as I2S, yes, that could be really interesting, though dacs with direct i2s inputs are not very common and for the most part tend to be fairly expensive.

If you can confirm this, do let us know.

-- Jim
 
Ah, didn't notice one was i2c the other i2s. From Wikipedia, they sound very different, but I'm no expert. Maybe one is a subset of the other.

Or maybe someone can develop code to bit-bash i2s through the gpio pins. That's as techno babble as I can get, but there's some truth in it.
 
Count me in. I might not have time to play this week much but I have seen some webpages where users have used MPD and a python script to play internet radio.  I know there are successful media servers (XMBC) but most use that for streaming video / movies.  I would imagine it would play music as well. 

I thought it might be as simple as using the audio out to the preamp but I guess not.  Still I have a brand new RPi and no project yet so what the heck.  I'll spend a little time digging and count me in.

John
 
Hi John,

Welcome... again.Good to have another hand on board.  I'm not exactly sure when I'm going to get busy on this as bot this and the alix will be going on in the background while I continue some work on other things, but that also gives more time for the usb issues to get resolved byt the rPi foundation., and I may just give the HRT HDMI dac a shot in the mean time as well.

-- Jim


 
Looks like HRT has a few new products out.  I really enjoyed my HRT II+ so I can imagine the new HD model will be fantastic.  The HDMI stream is also very interesting to me. 

Jim, I'm curious how you intend to use the HDMI stream with the RPi. 
 
Hi Tom,

The Raspberry Pie has an HDMI port on it (just at the rear of the ethernet connector), and with a little configuring of devices for the music stream, it should be possible to send the PCM file through the HDMI port.  Note, I said "should be" as I've not done this and will have to do some research on this to start, and then see what may need to be done to optimize it.  I plan to run headless,but I'm also guessing that you could use the video out as well, but I myself will most likely not be trying that.  The x.11 GUI/gnome are not really accessible to me so I'm going to stick with a remote SSH console interface using my macbook air over ethernet.

Note I will also be using the Raspyfi voyage linux distro with MPD for music playback.

Yes, it's about time the streamer HD came out -- that one has been promised "next quarter" for a couple of years now.  My guess is that it will be a solid performer for it's approx $450 price.  If I weren't already in possession of so many dacs, I'd likely get one myself.  I'd also very much like to hear the new Micro dac as well.  I was hoping the micro dac would work directly with an iPad and camera connector kit, but it looks like that is not the case.

-- Jim
 
Looks like there is i2s but there are serious doubts about the quality. The discussion is beyond me, but that seems to be what they are saying:

http://www.diyaudio.com/forums/digital-line-level/233230-raspberry-pi-i2s-output-asynchronous-usb-i2s.html
 
Just saw this article on ArsTechnica:

http://arstechnica.com/information-technology/2013/04/airplaying-music-and-video-from-ipad-to-raspberry-pi-its-as-easy-as/

This article makes it sound pretty easy.  Easy as pi maybe.
 
Back
Top