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Old 4th January 2013, 06:09 PM   #2041
starn02 is offline starn02  Italy
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More details ....
I installed winXP inside Parallels desktop in the mac, and tried to play from the virtual machine.
I use Foobar, in the same setup as before.
In this configuration the metallic noise is present, but with two differences:
- it happens very soon, not after a long listening session
- it comes more quickly , and fades away more quickly
- the red and green leds are both ON ... that's normal, the control of the board is directly from xp, so the feedback end point is not used

I'm coming to think that the drivers from thesycon are quite peculiar, and probably not completely standard as regards the implementation.
What I'd like to try now is to use the ASIO drivers instead, inside the VM, and see what happens.
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Old 4th January 2013, 10:07 PM   #2042
borges is offline borges  Norway
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No sweat starn02! Thanks for your test report.

I'm away from my debug setup for a few days, so I can't correlate what you're writing to what I've seen in the code lately. Are you able to see the debug messages ('+' and '-') on the RS232?

My Mac's keybaord has arrived and I hope to assemble it on Monday. Crossing my fingers that it works! I'm also borrowing a USB 2.0 analyzer from work. So what I'm hoping is to be able to debug on 3 platforms from the middle of next week. Until then I suggest we hold off a bit since my way of targeting stability on a Mac without owning one has been a bit too much shotgun-in-the-dark tactics with updates to experimental firmware :-)

Could you commit your code with the REC and PLAY leds or upload the file you modified? I'd like to see the code you are referring to!


Cheers
BÝrge
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Old 5th January 2013, 03:36 PM   #2043
starn02 is offline starn02  Italy
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My suggestions for testing ....
- the code that manages data to /from USB endpoints is actually made of 3 parts: one for play, one for feedback endpoint, and one for recording
- which parts actually work is controlled by two flags actually changed by USB commands
- if you can someway have a feedback about which parts are working and which are not (like in my modified code) you will see the different behaviour on different OS/driver combination. In my case I toggle two led off at the beginning of the loop code, and set them on if the code in the play or rec part is executed.

This is in my opinion the key to understand what's wrong. In the case of Windows, for instance, I believe that the information on the feedback endpoint is ignored (both rec and play are working, and I think the driver uses the rec samples number to adapt the size of playback endpoint ....
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Old 6th January 2013, 09:26 AM   #2044
borges is offline borges  Norway
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It's a good idea to differentiate between recording and separate endpoint for sample rate setting. This far I've focused on the separate feedback endpoint, but it's good to know if my code is actually executed on the various OSes.

It should be pretty easy to add some RS232 output message when usb_alternate_setting and usb_alternate_setting_out are modified by the host.


BÝrge
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Old 7th January 2013, 09:27 PM   #2045
borges is offline borges  Norway
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Finally, my Mac is up and running! It's too late here now to do any proper tests, hope to do that in the the following days. Just confirmed that the Audio Widget plays and seems OK. Now I've got both Win7, Mac and Linux test platforms.

Here's something I'll try out in experimental fw next: There's actually room in the fw to create a 40.000 byte buffer where I plan to store gap, sent feedback and received packet lengths for 4.4s of music. Dumping it offline to a terminal over RS232 should be feasible. And I've got high hopes for the USB analyzer I'll borrow.

Oh, and here's a nice pic: The USB-I2S Module installed inside my CD player. (Alex and Roger, do you remember the DI-B board where you helped with the very first AW code? This is what it looks like now :-)


BÝrge
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Old 8th January 2013, 03:39 PM   #2046
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But without high-quality XOs at 22.5792 and 24.576MHz, the USB-I2S is not a high quality converter. Does it possible to put crystals in the USB-I2S Module? They need some complementary component?
Good luck with the tests.
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Old 8th January 2013, 05:40 PM   #2047
borges is offline borges  Norway
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There is room for XOs on the module itself. Just follow the links in my signature and have a look at the module schematics. I used to sell modules with the XOs on. But the mod took me too much time.

BÝrge
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Old 10th January 2013, 08:04 PM   #2048
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Hi all! I just bought one of Borge's AB-1.2 DACs and connected it to a Raspberry Pi. He invited me to post my results here.

Executive summary: It works I'm listening to 24/96 FLAC files as I type this.

Background: I'm working on a music player based on the R-Pi Model B running Debian Wheezy. The player software is mpd. I have a 320GB USB hard disk connected for storage.

My prototype used a cheap USB DAC based on a USB1.1 Tenor chip. After a lot of experimentation, I got it playing bit-perfect at 16 bits, 44.1kHz, but couldn't get any higher without glitches. I did some research and found that the USB 1.1 part of the Pi's USB controller is a little broken.

However, the USB 2.0 part seems to work fine, and Debian Wheezy is based on the new Linux 3.2 kernel, and uses alsa for its sound system. So I figured I might have better luck with the AB-1.2 in its UAC2 mode. And I was right!

Well almost. There is one USB1.1 device left in the system, the keyboard. So I get the occasional audio glitch when pressing or releasing a key. But if I leave the keyboard alone, the sound seems perfect! I listened to a FLAC file of a low frequency sine wave for several minutes and couldn't hear any clicks or stutters.

Thank you Borge and all the other audio-widget developers, for giving me the hi-res audio output I wanted!
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Last edited by scopeboy; 10th January 2013 at 08:07 PM.
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Old 10th January 2013, 10:31 PM   #2049
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Thanks for sharing your experience.
I want to use an RPi as player and thus I'm researching DAC solutions.
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Old 11th January 2013, 01:39 AM   #2050
nikkov is offline nikkov  Russian Federation
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Quote:
Originally Posted by scopeboy View Post
Hi all! I just bought one of Borge's AB-1.2 DACs and connected it to a Raspberry Pi. He invited me to post my results here.
Can you write short instruction how to using R-Pi with audio-widget? It's very interesting theme.
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