Can Tablet PC (android) drive an USB DAC?

KlipschKid

Banned
2007-08-10 8:54 am
Android kernel ? Better than MS ?

Hi,

It's been a few months since the OP asked....and now I wonder what has changed as Android has grown ?

I'm interested to know what the latency of Android is ? How does it compare with Linux, MS and iOS (but no usb on iPad) ? Anyone run any checks ? I typically get around 200u secs using dplact.exe on Win XP.

I'm thinking of getting a slate and plugging in a Teradak Teralink X2 for usb to i2s. Would Android work better than Win7 starter ?

There are quite a few tablets out there due to be released with Android 3.0 Honeycomb and they have usb 2.0 sockets. Here's a link to some of the major players :

Tablets of 2011: What to Look For - TechSpot

Any advice would be greatly appreciated as I know nothing about Android ! I'm sure there are some diyers who are Android fans....

Thanks in advance !
 

KlipschKid

Banned
2007-08-10 8:54 am
Hi,

All I've managed to find out is that it is possible to hack Android OS with Linux code to host a DAC, but it would not, in theory, be any better than simply using a decent Linux build on decent hardware.

So now I'm more interested in the possibility of hacking something like Asus Express Gate (Linux Splashtop) to support a USB DAC and a good software player.

The research continues....
 

KlipschKid

Banned
2007-08-10 8:54 am
Here's an Android platform to work from - the Asus Eee Pad Transformer TF-101 - and they just made the Linux kernel available for download even before the thing hits stores.

ASUSTeK Computer Inc. - Eee - ASUS Eee Pad Transformer TF101

Should be quite easy to add in code to support a usb device like Ti PCM270X ?
I say quite easy but then I have no clue how to do this, so I guess I'll have to teach myself.

A page with some help :

http://www.mjmwired.net/kernel/Documentation/sound/alsa/ALSA-Configuration.txt
 

KlipschKid

Banned
2007-08-10 8:54 am
Hi,

AFAIK Android 3.0 Honeycomb hasn't been released by Google yet - Asus have done it before them. So I think Asus have posted it on the product page of the TF-101 to encourage the Linux community to get coding.

I'm hoping the Eee Pad Transformer's hardware is good enough to allow very low latencies - something I wouldn't have thought likely in a smartphone - which is why this release might get more interest.

So when I say easy, I mean for people with a very good knowledge of Linux. For me, it's gonna be a long road but I'm up for trying.
 
Hi,

AFAIK Android 3.0 Honeycomb hasn't been released by Google yet - Asus have done it before them. So I think Asus have posted it on the product page of the TF-101 to encourage the Linux community to get coding.

I'm hoping the Eee Pad Transformer's hardware is good enough to allow very low latencies - something I wouldn't have thought likely in a smartphone - which is why this release might get more interest.

So when I say easy, I mean for people with a very good knowledge of Linux. For me, it's gonna be a long road but I'm up for trying.

It is only the android kernel. No android libraries that make up android 3.0 are available.

I am afraid android and linux distributions are quite different beasts, AFAIK they have only the modified linux kernel in common. Did you mean to run recording sessions that you are striving for low latency? It would be a very nice mobile DAW indeed. But I am afraid there are no appropriate recording applications available yet.
 

KlipschKid

Banned
2007-08-10 8:54 am
Hi,

Hmmm....I must admit my ignorance. I know they haven't let all their cats out of the bag by releasing the whole OS, but I read that Android uses a Linux kernel plus a Dalvik virtual machine to run Java-based apps, so I thought that Asus must have released the Linux kernel part of the OS so that ppl could start creating apps etc for it ? I downloaded it but I have no idea what to look for being a Linux noob.

The hardware is so tasty that I reckon I'm not the only one who'll want this and it'll only be a matter of time before $5 gets me a download that'll allow a usb dac chip like a PCM2707 to export an I2S from it. Even better if I could then hack this to drive a Tenor 7022L chip for 96/24 I2S output. Someone has already hacked the Xoom....

From my experience with Windows, low latency, esp low DPC latency, is what makes USB audio worthwhile.

My desktop has a low DPC latency of around 20us and that is lower than one sample for a PCM 2707 afaik, so I dunno if Android will actually be any better. But I'm always looking to try anything that might be...

Besides anything else, that Eee Pad + external HDD will keep me entertained with movies/music on long haul flights. It'd be great if it could also drive the PCM2707 in the Gamma2 dac so I could enjoy this and my HD650 on flights too.
 
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so I thought that Asus must have released the Linux kernel part of the OS so that ppl could start creating apps etc for it ?

Android apps are written on the top of the Dalvik VM. The kernel you have downloaded is below the VM. It is certainly good to have the drivers source code available. Asus had to release the drivers source code anyway, since the kernel is licensed under GPL and Asus is distributing the product with their home-made GPL'd drivers. On the other hand, the dalvik apache license does not have this requirement. AFAIK google has not released the user space android 3.0 source code yet and I would expect it is not available to Asus either.

I downloaded it but I have no idea what to look for being a Linux noob.

Even a seasoned linux developer would fight hard with adding alsa usb audio support to android kernel.

The hardware is so tasty that I reckon I'm not the only one who'll want this and it'll only be a matter of time before $5 gets me a download that'll allow a usb dac chip like a PCM2707 to export an I2S from it. Even better if I could then hack this to drive a Tenor 7022L chip for 96/24 I2S output.

I think eventually someone (or google itself) will port the existing usb audio 1.0/2.0 drivers. I think android uses the small embedded alsalib (salsa) and the userspace (i.e. the dalvik VM) should not require any major changes.

From my experience with Windows, low latency, esp low DPC latency, is what makes USB audio worthwhile.

My desktop has a low DPC latency of around 20us and that is lower than one sample for a PCM 2707 afaik, so I dunno if Android will actually be any better. But I'm always looking to try anything that might be...

See my tests of usb resilience in linux http://www.diyaudio.com/forums/pc-based/93315-linux-audio-way-go-23.html#post1719044 . I do not think you need low system latency for reliable usb playback on properly coded and easily configurable system. You cannot do any of the changes I did with winxp, perhaps that is the reason you are having usb audio dropouts on unoptimized windows PCs.
 
H,

Thanks for the help - I get it ! Also thanks for directing me to the posts about Linux timings. I've been working my way through that thread but for a noob it is very long and not exactly plain English ;-) I'm keen to learn, but woah, I'm in at the deep end it seems.

The reason I said DPC was important is because of my experience with different PCs. Without any doubt, the best USB-sourced sound came from ones with low DPC. My desktop rocks, my old notebook barely hummed in tune. So I'm looking around for a replacement that can/could do decent audio.

Do you reckon Android can/could do it ?
 
I do not want to start the discussion of latency vs. sound quality (USB or PCI), but in my opinion the difference in sound of your NTB and PC was caused by quality of the USB +5V lines. Typically notebooks have poor/noisy PSUs.

As I do not believe latency nor operating system has any effect on USB sound quality, there is no reason why android could not do. Plus tegra in the Eee Pad is a very powerful hardware for audio playback.
 
Hi,

Like you, I also found USB power to be a problem. I have checked on my scope and the lines have a broadband of noise which is totally unsuitable for audio. Thankfully there is the adum4160 usb isolator so I can give the usb devices clean power and keep them isolated from the PC. There's a very obvious improvement in SQ.

I built an AMB sigma11 using a max6250 vref for one of the adum4160 I have - it's about the best power a USB device can get.
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The only difficulty with usb isolation is that it won't work with asynch devices like the M2Tech HiFace. In systems with high dpc, an asynch device clearly sounds better; but with low dpc, asynch is not any better imho. So, from my limited experience and listening tests, DPC does matter. I also think onboard chips ( as spdif sources ) and PCI soundcards are better than usb in some cases, but I really cannot say this with any authority because my comparisons have been apples and oranges. Have you done any testing ?

I completely agree that hardware is very important. I'm not sure about the processor (not tested this) but for sure a high FSB is very definitely better !

It's worth pointing out that some of the differences are very slight indeed, and others are instantly and immediately obvious. Different OS, DPC, etc have been very small differences but drivers, power quality, isolation etc are, by comparison, huge improvements.

Tom
 
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There is an open issue at Google to implement the USB AUDIO feature, and use an external DAC on Android devices.

It needs 1200 votes to enter the top ten, and there are 950 votes today... Let's see if the votes are increased after posting this on DiyAudio (this thread has 8554 views so far) :)

Please, click "vote for this issue" at the bottom of the page :)

Issue 24614 - android - Enable USB audio on the Galaxy Nexus (or any Android 4.0 device) - Android - An Open Handset Alliance Project - Google Project Hosting
 
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Still not done a year later ? Clearly not of interest to them eh ?

Well, I logged in and added my comment and star, but no need, as I found the Nokia N8 supports pcm270X devices so that's been my portable digital source for the last year. It plays flac through folderplay too.

So I use the N8 with an AMB y2 dac with Tent lab clocks and an adum isolator to power the y2. I doubt an Android source will sound any better ?
 
Hi,

I tried the Windows 8 Consumer Preview the other day. I'm sure people here know about it but in case they don't, it's a free download from Microsoft and their site has a licence key too in the FAQ, valid to sometime in 2013.

Windows 8 Consumer Preview

DNJXJ-7XBW8-2378T-X22TX-BKG7J

http://windows.microsoft.com/en-US/windows-8/download

Anyway, the Metro UI sucks on a notebook or desktop ( for example no start button, and the shut down is hidden in settings which is a pop up on the rhs of the screen ) but it will probably work well with a touch screen so I think I'll give Android a miss ( despite loving the Galaxy SII ) and go from using my N8 to a Win8 mini-tablet/phone.

My main concern about Win8 was the install took up a huge amount of Gb. Not so much a footprint as a crater.
 
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