Thorsten Mühlfelder | 5 May 10:32 2011
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Improving USB audio sound quality on the Dockstar

Hi,

I'm using a high quality USB audio device (Burr-Brown Japan PCM2702) with my 
Dockstar. I've configured mpd to use the hardware interface without dmix 
because dmix seems to be broken on the ARM platform.

But there is one problem left: sometimes clicks and pops can be heard. They 
appear randomly up to 2 times a minute. My impression is that hard disk data 
transfer causes them, because using "hdparm -t" makes the situation worse. On 
the Dockstar all USB devices are connected via hub to the same USB 
controller:
# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 001 Device 003: ID 0bc2:2120 Seagate RSS LLC 
Bus 001 Device 005: ID 08bb:2702 Texas Instruments Japan Speakers

Is it possible to give the USB audio data transfers a higher priority?

--

-- 
Thorsten Mühlfelder
Salix OS: www.salixos.org
Thorsten Mühlfelder | 5 May 10:40 2011
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Re: Improving USB audio sound quality on the Dockstar

Am Thursday 05 May 2011 10:32:52 schrieb Thorsten Mühlfelder:
> Hi,
>
> I'm using a high quality USB audio device (Burr-Brown Japan PCM2702) with
> my Dockstar. I've configured mpd to use the hardware interface without dmix
> because dmix seems to be broken on the ARM platform.
>
> But there is one problem left: sometimes clicks and pops can be heard. They
> appear randomly up to 2 times a minute. My impression is that hard disk
> data transfer causes them, because using "hdparm -t" makes the situation
> worse. On the Dockstar all USB devices are connected via hub to the same
> USB controller:
> # lsusb
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
> Bus 001 Device 003: ID 0bc2:2120 Seagate RSS LLC
> Bus 001 Device 005: ID 08bb:2702 Texas Instruments Japan Speakers
>
> Is it possible to give the USB audio data transfers a higher priority?

Another idea is that network traffic may cause this because eth0 has higher 
priority IRQ than USB:
thorsten <at> dreamtheater:~$ cat /proc/interrupts 
           CPU0
  1:   68571661   orion_irq  orion_tick
  5:          2   orion_irq  mv_xor.0
  6:          2   orion_irq  mv_xor.1
  7:          2   orion_irq  mv_xor.2
  8:          2   orion_irq  mv_xor.3
 11:   94038944   orion_irq  eth0
(Continue reading)

Andrzej Telszewski | 5 May 10:42 2011
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Re: Improving USB audio sound quality on the Dockstar

On 05/05/2011 10:32 AM, Thorsten Mühlfelder wrote:
> Hi,
> 
> I'm using a high quality USB audio device (Burr-Brown Japan PCM2702) with my 
> Dockstar. I've configured mpd to use the hardware interface without dmix 
> because dmix seems to be broken on the ARM platform.
> 
> But there is one problem left: sometimes clicks and pops can be heard. They 
> appear randomly up to 2 times a minute. My impression is that hard disk data 
> transfer causes them, because using "hdparm -t" makes the situation worse. On 
> the Dockstar all USB devices are connected via hub to the same USB 
> controller:
> # lsusb
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
> Bus 001 Device 003: ID 0bc2:2120 Seagate RSS LLC 
> Bus 001 Device 005: ID 08bb:2702 Texas Instruments Japan Speakers
> 
> Is it possible to give the USB audio data transfers a higher priority?
> 

Hi,

You might try 'chrt', but you need to find the process(es) ID(s)
responsible for all the audio stuff. Eventually, check here:

http://subversion.ffado.org/wiki/IrqPriorities

but it's rather about real-time Linux.

(Continue reading)

Claudio Cavalera | 5 May 14:48 2011
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Re: Improving USB audio sound quality on the Dockstar

On 05/05/2011, Andrzej Telszewski <atelszewski <at> gmail.com> wrote:
> On 05/05/2011 10:32 AM, Thorsten Mühlfelder wrote:
>> Hi,
>>
>> I'm using a high quality USB audio device (Burr-Brown Japan PCM2702) with
>> my
>> Dockstar. I've configured mpd to use the hardware interface without dmix
>> because dmix seems to be broken on the ARM platform.
>>
>> But there is one problem left: sometimes clicks and pops can be heard.
>> They
>> appear randomly up to 2 times a minute. My impression is that hard disk
>> data
>> transfer causes them, because using "hdparm -t" makes the situation worse.
>> On
>> the Dockstar all USB devices are connected via hub to the same USB
>> controller:
>> # lsusb
>> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
>> Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
>> Bus 001 Device 003: ID 0bc2:2120 Seagate RSS LLC
>> Bus 001 Device 005: ID 08bb:2702 Texas Instruments Japan Speakers
>>
>> Is it possible to give the USB audio data transfers a higher priority?
>>
>
> Hi,
>
> You might try 'chrt', but you need to find the process(es) ID(s)
> responsible for all the audio stuff. Eventually, check here:
(Continue reading)


Gmane