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Old 12th January 2013, 04:37 PM   #2061
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the feedback occurs approx. every 10-15 min independent of sampling frequency or access via core audio / native using a Mac with OSX 10.8.2. I used the following frequencies: 44.1, 48, 88.2, 192k. I will post further results of the GPIO output when back in the lab.
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Old 12th January 2013, 05:04 PM   #2062
borges is offline borges  Norway
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Good. I assume you mean that the noise appears every 10-15 mins. That would be consistent with what I'm observing.

BÝrge
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Old 12th January 2013, 10:22 PM   #2063
borges is offline borges  Norway
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I found the error with UAC2 stability on the Mac. In the audio-widget-experimental branch the feedback format is set to what Linux recognizes as 16.16. With the AW firmware this format is NOT recognized by the Mac as proper feedback data.

However, UAC1 on my Mac does not work. The Mac doesn't change the frequency when the firmware detects excessive skew. While this isn't a big problem with functional Mac/UAC2, I'd still like to know why Mac/UAC1 is faulty and try to get it fixed. Any insight on feedback formats in Mac/UAC1 appreciated!

BÝrge
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Old 12th January 2013, 10:26 PM   #2064
borges is offline borges  Norway
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The firmware at audio_widget_20130113.elf contains small bugfixes of the stable branch. It is checked into audio-widget. The feedback format is back at 15.17 so there is no need to change the Windows dll.

UAC2 is stable on Mac/Linux/Win-ASIO. UAC1 is stable on Linux and Windows. The bugs I looked at are:

- USB_WL redefined to USB_PRODUCT_NAME, AW came up as "SDR-Widget" on Mac/UAC1

- Safeguarding outer bonds in UAC2 code had typo/bug and can now execute as intended

- The code which replaces the old Linux quirk performs better on Win-ASIO


Cheers,
BÝrge
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Old 13th January 2013, 03:01 PM   #2065
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On the Mac, iTunes reads the system sample rate when it is first loaded up. If you change the sample rate while iTunes is running, it will continue to output at the old rate, and CoreAudio will resample to the new rate using a "standard quality" (probably not audiophile approved) algorithm.

To get output at the new rate, you have to quit iTunes and run it again.

When iTunes plays files of different sample rates to the rate it detected at startup, it resamples internally using a better quality algorithm than the CoreAudio default one.

Either way, I prefer MPD on the Raspberry Pi.
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Last edited by scopeboy; 13th January 2013 at 03:04 PM.
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Old 14th January 2013, 02:30 AM   #2066
nikkov is offline nikkov  Russian Federation
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Quote:
Originally Posted by linuxworks View Post
its safe to get the latest released raspian
...
Quote:
Originally Posted by scopeboy View Post
As linuxworks says, there are no elite hacks required. Just use the latest Raspbian Wheezy image from here. Downloads | Raspberry Pi The audio driver in it supports the USB-I2S in UAC2 mode.
...
linuxworks, scopeboy, thank you!
I successfully installed mpd and windows client, player started play mp3 file, but without sound. I'll try to understand what I made wrong.
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Old 14th January 2013, 02:33 AM   #2067
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my guess is that it finds the broadcom sound device, first. there's a way to force the usb device to be first and that makes life easier. first device is 'default' for many apps. I don't have the info handy (or my pi's) but I bet its the ordering that is going on. if you hear sound out of the onboard jack, then that was it.

also, you -can- edit the /etc/mpd.conf file and force the next device, by number.
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Old 14th January 2013, 03:24 AM   #2068
1audio is offline 1audio  United States
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Linuxworks, you should post the section of the mpd.conf that worked. This works on X86 for USB:
Code:
#
audio_output {
       type          "alsa"
       name          "USB_Short"
       device        "hw:1,0"    	
}
#
There is a setting that will force USB audio devices to start at 1
In /etc/modprobe.d/alsa-base.conf
options snd-usb-audio index=-2
Should force the USB audio device to load as hw:1
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Old 14th January 2013, 09:43 AM   #2069
jdlvfr is offline jdlvfr  France
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Maybe it can help, alsa devices can also be called by name.
The device name can be found with aplay -l :

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: AB12 [QNKTC USB DAC AB-1.2], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0

The device name is just after the card number, here it is AB12

And the corresponding mpd.conf :

Code:
#
audio_output {
	type		"alsa"
	name		"usb"
	device	"hw:AB12"	
}
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Old 15th January 2013, 01:00 PM   #2070
nikkov is offline nikkov  Russian Federation
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Quote:
Originally Posted by jdlvfr View Post
Maybe it can help, alsa devices can also be called by name.
...
Thak you jdlvfr, 1audio and linuxworks!

I successfully played music from network storage. I'll test different sample frequencies, but 44100 sound is OK
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