"High-end" audio from a PDA? - diyAudio
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Old 11th August 2007, 07:08 AM   #1
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Default "High-end" audio from a PDA?

Hi,

I'm planning to build a portable mp3/ogg/aac jukebox with touch screen and I need some help

It needs to be portable and therefore I would like the hardware to consume as little power as possible. That's why I thought of a Windows Mobile system.
My only problem is just that the embedded systems I can find only support questionable audio outputs.

So here's my question:

Is it possible to get a SPDIF signal out of a PDA? Or maybe it is somehow possible to stream it wirelessly la Squeezebox?

Gentlemen, what are my options?

Another nice perspective is also to be able to stream audio from a traditional PDA directly into a Squeezebox
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Old 11th August 2007, 02:41 PM   #2
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I have a Palm TX. It has software to play audio- mp3 and a couple other formats, but no OGG and no flac. There is an upgrade available that will enable ogg playback. The earphone output is not terribly hifi- I can hear thermal noise in it during silent passages and between songs.

The TX has wifi so I can use it to control my squeezebox system but I have not seen anything like softsqueeze for Palm OS that would allow it to receive audio from the server. A pocket PC may be able to run softsqueeze and become a receiver. Using wifi in the TX sucks the battery down pretty fast. I suspect the same would be true in a pocket PC.

For digital out, the TX has USB, Bluetooth, and IR. I'm not a programming type geek so I don't know how you'd access them.

You have a great idea for a project here if you have the tools for the programming (and the skilz!). While you're at it, write a program to allow the TX to access internet radio stations...

I_F
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Old 22nd August 2007, 08:48 PM   #3
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Thanks for the reply!

Unfortunately I lack the programming skils, but it maybe I should look into it

An alternative solution to my problem could be an extreamly low-power XP/Linux system based on the VIA Eden CPU (2,5Watt max).

Still the Windows CE would be better in most aspects (boot time, power consumption)
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Old 23rd August 2007, 12:27 AM   #4
star882 is offline star882  United States
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You could tap into the I2S lines to get a signal. But that would be a lot of work, maybe next to impossible with SMD.
Have you thought about using a Linux-based Gumstix? A PDA would not be optimal since it would also contain a large screen and GPU, which would use lots of power. (That said, a PDA can run for 40 hours or more from 4 CGR18650 cells. For something that commonly available, it's very hard to beat.)
If price is a major concern, you might want to modify an OpenWRT wireless router. You could either use a USB audio chipset or an audio mini-pci card. And with careful selection, they can be small. (For your reference, the board in a WA840G is only a little larger than a credit card.)

Exactly how large should the entire audio player be? How much runtime and storage do you want? What display (if any) should it have? Any special requirements?
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Old 23rd August 2007, 01:12 AM   #5
Daveis is offline Daveis  United States
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Default Re: "High-end" audio from a PDA?

Quote:
Originally posted by Krede
Hi,

I'm planning to build a portable mp3/ogg/aac jukebox with touch screen and I need some help

It needs to be portable and therefore I would like the hardware to consume as little power as possible. That's why I thought of a Windows Mobile system.
My only problem is just that the embedded systems I can find only support questionable audio outputs.

So here's my question:

Is it possible to get a SPDIF signal out of a PDA? Or maybe it is somehow possible to stream it wirelessly la Squeezebox?

Gentlemen, what are my options?

Another nice perspective is also to be able to stream audio from a traditional PDA directly into a Squeezebox

Most MP3 players out of the box will play mp3 and AAC. They are portable with touchscreen. They also use little power.
It might be far easier to tap into the DAC on say an iPod/Create Zen than a Windows PDA.

I was using a Windows PDA and USB host cable and laptop drive combination once. The sound was good and the storage was 100 GB (the size of a laptop drive at the time). Sound was good, but not better than an iPod. The main issue was bulk. It was no longer easy to carry in a single pocket. I needed a separate power cord for the little laptop drive.

Although, once you are using the lossy formats like AAC and MP3 I think that the built in DAC on an iPod would be plenty good.

I've seen small car computers built with Linux and touchscreen displays. The problem there is that you could easily spend $600 or more. For that money you could just buy a laptop computer...

which gets me to my idea... buy a 14" laptop and put a really good USB DAC on it.
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Old 23rd August 2007, 06:06 AM   #6
renfrow is offline renfrow  United States
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You might consider getting an iPod and having it modded.

Tom.
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Old 23rd August 2007, 10:22 PM   #7
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Lots of good answers! Thank you all

I will try to specify the project a bit.

The jukebox will be quite big - it will actually have 4 wheels and some large car batteries to run it. So the difference between a system that consumes 0.5 or 3 watt is negligible. Remember that I also want to use a fairly large touch screen anyway (minimum 5") that too will consume a lot of power. I just don't want a regular mini ITX system eating away 20 watts or more.

The jukebox will be used on festivals (outdoors) so I would like it to be waterproof and to be able to run as long as possible on the car batteries. I have not yet decided how big the battery capacity should be, but I'm counting on no less than 4 full size batteries. The weight of the jukebox should no exceed 50-60 kg though
I'm hoping for several days of music!

I'm not looking for real high-end audio here (that would be a waste) but I would like it to outperform those regular boom boxes and ghetto blasters - not only in volume, but also in audio quality.

Just saw this announcement http://www.engadget.com/2007/08/23/v...gets-official/
That could maybe bring new hope for the XP/Linux based system. That would keep things nice and simple

I also found these: http://www.contendosystems.com/websi...h/products.htm
All-in-one solution - runs Win CE though and I don't know about the audio
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Old 23rd August 2007, 11:59 PM   #8
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I'm not sure how much programming/engineering you want to do on this, but if you're willing to hack some code and don't mind getting your feet wet with the hardware, an industrial Single Board Computer (SBC) might be appropriate for this. Most of the vendors don't list pricing information, but there seem to be lots of appropriate boards out there.

Typically you'll get a ~500MHz ARM, some flash memory and a handful of peripherals (serial ports, VGA, Ethernet, etc.) on a board. Some can run WindowsCE, most can run Linux. You'd probably have to add a DAC and analog output stage yourself though if you chose to use one of these, and thus write the software to control it.

www.kanda.com has inexpensive modules that lack VGA but would otherwise likely be appropriate, for example.

Most of the ones I see consume < 3W in operation and have robust clock scaling and power saving abilities if you were to use them in your software.
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Old 24th August 2007, 10:24 PM   #9
star882 is offline star882  United States
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Quote:
Originally posted by error401
I'm not sure how much programming/engineering you want to do on this, but if you're willing to hack some code and don't mind getting your feet wet with the hardware, an industrial Single Board Computer (SBC) might be appropriate for this. Most of the vendors don't list pricing information, but there seem to be lots of appropriate boards out there.

Typically you'll get a ~500MHz ARM, some flash memory and a handful of peripherals (serial ports, VGA, Ethernet, etc.) on a board. Some can run WindowsCE, most can run Linux. You'd probably have to add a DAC and analog output stage yourself though if you chose to use one of these, and thus write the software to control it.

www.kanda.com has inexpensive modules that lack VGA but would otherwise likely be appropriate, for example.

Most of the ones I see consume < 3W in operation and have robust clock scaling and power saving abilities if you were to use them in your software.
If you're looking for runtime, you would not want to use an analog amplifier. A digital amplifier is much more efficient, and you'll need to supply a digital signal to it.
I think a cheap network appliance like the NSLU2 or WL-HDD would be a good place to start. Just add a USB to I2S or S/PDIF chip (TI makes several) and run the digital amplifier from that.
If you use deep cycle batteries, it wouldn't be hard to engineer it to run for weeks (an average PDA can easily run for months playing video continuously on a few deep cycle batteries). And since it's outdoors, maybe also add small solar panels or windmills?
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Old 25th August 2007, 06:41 AM   #10
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This CF card has spdif, but only inputs, not outputted.

http://www.core-sound.com/pdaudio-cf/2.php

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