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Rockbox General => Rockbox General Discussion => Topic started by: mcmurray on October 15, 2007, 08:28:22 AM

Title: Non-Portable Audiophile Rockbox based DAP
Post by: mcmurray on October 15, 2007, 08:28:22 AM
Hi guys.
I am in the near future beginning design of a high quality desktop DAP that plays everything up to and including 24bit/192khz PCM and FLAC.  Storage will most likely be SATA with capacity exceeding 1Tb.  

I am wondering if there would be any interest from you guys in a non portable player?  Do I have the ok to port Rockbox to my player once the hardware is up and running?

I am also considering making the hardware completely open. i.e. publishing everything as it is designed such as schematics and pcb layouts.  Once I have a working product I will then consider minimising the size for a portable unit.

Tell me what are your thoughts or what features you would require to make an item such as this interesting to you?
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: krazykit on October 15, 2007, 08:35:55 AM
Quote
I am wondering if there would be any interest from you guys in a non portable player?  Do I have the ok to port Rockbox to my player once the hardware is up and running?

Rockbox is licensed under the GPL, so you're more than welcome to port it to any platform you like, so long as the code is also GPL.  Good luck on your project :)
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: mcmurray on October 15, 2007, 08:49:45 AM
Sweet.  Programming was never my strongest attribute but I was looking through the source code last night and it reads quite easily.  I think that resource will be a huge help.  At one point I was contemplating writing the OS from scratch.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: LambdaCalculus on October 15, 2007, 08:59:52 AM
Sounds like a great project! A small desktop-sized jukebox running Rockbox, and storage of upwards of 1 TB... oh so sweet! :)

So what hardware are you looking to design around? Have you got an idea for a CPU, display, and control scheme? Or are you looking for suggestions?
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: mcmurray on October 15, 2007, 09:33:58 AM
At this stage I have some ideas.  High-resolution 24bit playback with a quality DAC/output stage is my main requirement because I have a use for it and right now there is nothing on the market that suits my needs.  I would like the DAC to be on-board but maybe SP-DIF and external DACwill be an option.  I'm considering the Coldfire line of processors.  As for the display and control scheme I envision something simple for the prototype such as a monochrome or greyscale display and standard push buttons for play/pause/navigation etc.  

A fully featured remote might be on the cards once the basic system is working.  

I'm not familiar with the rockbox interface but I will have a play with it soon when I get a portable player.  I am looking for suggestions especially on features and things like control and displays so keep them coming.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: LambdaCalculus on October 15, 2007, 09:43:21 AM
If it's Coldfire you're thinking of, then try to hunt down a DAP that uses the same CPU, such as the iriver H100, H300, or iAUDIO X5 and M5 models. That way, you can get a feel for how Rockbox will perform on the device.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: mcmurray on October 15, 2007, 09:50:10 AM
Will do.  I was thinking about picking up an iAudio x5.  What would be your ideal rockbox CPU?
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: LambdaCalculus on October 15, 2007, 10:02:11 AM
Coldfire. It's well documented, powerful enough to perform software decoding, and already well supported by Rockbox.

If I remember correctly, the Coldfire CPU can be clocked up to 140 MHz, but a little Googling will bring forth the information we seek.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: GodEater on October 15, 2007, 11:05:57 AM
Will do.  I was thinking about picking up an iAudio x5.  What would be your ideal rockbox CPU?

ARM - it clocks higher - so a Freescale something or other would be nice :)
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: etienne on October 16, 2007, 05:06:12 AM
I have a very similar requirement to this.

I run http://www.ambisonia.com, a site that distributes surround sound files in a next-generation format called ambisonics.

I am looking for a harddisk based audio player that is capable of decoding Ambisonic files to multi-channel AV receivers.

The point being that an Ambisonic file can be 'decoded' to any speaker layout (stereo, 5.1 7.1, or even height based systems)... and that the 'decoding' needs to be done in software.... but most users dont want to have to bother with setting up and using their computers. So a Harddisk with a CPU that can do some DSP is perfect.

There are 2 ways that audio streams can get *out* of the system ... analog or digital. digital is clearly cheaper, but analog may be technically easier given that the aim is to get 8 channels out (to arrange speakers in a cube).

It would also be extremely powerful if the harddisk also had Ethernet connectivity with the capability to subscribe to podcasts (this could be managed via a web interface... served by a very simple and small Http server).

Anyway, I'm very interested in this project. Please keep the discussion going.

Etienne
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: mcmurray on October 16, 2007, 05:22:03 AM
Sounds interesting.

I wasn't planning on making the unit multi-channel at first but I don't see why it couldn't decode your files and output them digitally.  However you would need to provide complete information about the codec used.

I will keep you up to date on my progress, however my engineering thesis is due soon and is taking up all my spare time at the moment.  After that I'll have plenty of time.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: Multiplex on October 16, 2007, 07:55:06 AM
You don't need real hardware to paly with the Rockbox UI - there are simulators for each of the paltforms, bottom item on this page http://www.rockbox.org/twiki/bin/view/Main/RockboxExtras

It's a sad admission but I might start using the Sim for my DAP as a music player on my PC...
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: GodEater on October 16, 2007, 08:11:12 AM
It's a sad admission but I might start using the Sim for my DAP as a music player on my PC...

Nothing sad about that - I already do...
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: DefineByte on October 16, 2007, 08:45:19 AM
I would love a low-power hard disk based desktop DAP with S/PDIF (with bit perfect output).

Up to this point I've been looking at running a Rockbox sim on a Via Epia based setup but a bespoke design would be brilliant.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: Llorean on October 16, 2007, 08:49:17 AM
Wouldn't a "low power HD-based DAP with S/PDIF" be "The iRiver H100 series"?
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: LambdaCalculus on October 16, 2007, 08:53:13 AM
Wouldn't a "low power HD-based DAP with S/PDIF" be "The iRiver H100 series"?

Yes it would be! :)
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: preglow on October 16, 2007, 08:55:09 AM
The point being that an Ambisonic file can be 'decoded' to any speaker layout (stereo, 5.1 7.1, or even height based systems)... and that the 'decoding' needs to be done in software.... but most users dont want to have to bother with setting up and using their computers. So a Harddisk with a CPU that can do some DSP is perfect.
The Gigabeat series would probably (depending on how fancy shelf filtering you want) be very capable of decoding Ambisonics realtime. They don't seem to come with any digital out capabilities to speak of, though. If you only want basic decoding, the Coldfire based targets will almost certainly be able to do that as well, but the output side of things will probably remain a problem, since not many players are designed for multi-channel use.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: DefineByte on October 16, 2007, 09:10:13 AM
H100s are like hens teeth.

Even if I could find one, there's a few features I'd want that I forgot to mention: support for IR/RF remote controls (either), a decent (ish) sized screen (two line VFD would be great, a DVI or VGA port would also be...great :D), capable of supporting a 2.5" or greater hard disk internally. I think that's it. x)

No-one seems to make such a beast. Surely there's a market out there?
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: Llorean on October 16, 2007, 09:16:08 AM
I constructed my most recent desktop PC, not including monitor, for $280. Admittedly it's a fileserver, and I spent far more on both RAM and processor speed than necessary for a desktop audio player. $100 could be trimmed there, and repurposed for something other than the motherboard's onboard sound (though I believe it has digital out, honestly in its duty I didn't check).

For stationary digital audio devices, I'm betting there's not *too* much market for "more expensive, yet less useful." Though there are the gumstix for something a bit smaller than a small form factor PC.
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: DefineByte on October 16, 2007, 09:30:18 AM
An ATX/mATX PC would certainly be the cheapest way forward but one of my main concerns is power usage (I forgot to mention fanless in the previous list too). I'd ideally like to shoot for around or below 30 watts if possible (not including the 7" LCD I've been eyeing up.). Via have 1 watt x86 CPUs that I'm waiting on but lower power would be excellent.

I've looked into the Gumstix before but I didn't notice a model with S/PDIF. I guess I could go the USB audio route. They're not really in the ideal form factor anyway (I forgot something else, would be good if it looked nice too).
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: GodEater on October 16, 2007, 11:48:55 AM
I constructed my most recent desktop PC, not including monitor, for $280.

Would you mind sharing (off forum if you like) what you bought? My PC is starting to blow hard when it walks up mild slopes and is in need of replacing....
Title: Re: Non-Portable Audiophile Rockbox based DAP
Post by: saratoga on October 16, 2007, 05:24:12 PM
I constructed my most recent desktop PC, not including monitor, for $280. Admittedly it's a fileserver, and I spent far more on both RAM and processor speed than necessary for a desktop audio player. $100 could be trimmed there, and repurposed for something other than the motherboard's onboard sound (though I believe it has digital out, honestly in its duty I didn't check).

Hell just mod an Xbox.  XBMC already does all the formats rockbox has, FLAC included, and it has digital out.  Should be less then $100 bucks used these days.  And it takes a 3.5" disk, a CD/DVD or an ethernet cable.