Virtualbox 3.0B and USB Microphone

Postings relating to old VirtualBox pre-releases

Virtualbox 3.0B and USB Microphone

Postby reagle » 18. Jun 2009, 14:42

Since the 2* series I've had difficulty with the clipboard, but my USB microphone has worked well with NaturallySpeaking. However, I was not able to test 3.0B for long, and see if my clipboard woes have been solved, as the soundsquality has deteriorated; there are now stutterings/clips.

I'm using 2.2.4-47978_Ubuntu_intrepid with a XP guest, using KDE 3.5.10 and its Klipper. I use a custom kernel to get good sound (CONFIG_PREEMPT=y, CONFIG_HZ_1000=y CONFIG_HZ=1000).
reagle
 
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Re: Virtualbox 3.0B and USB Microphone

Postby reagle » 19. Jun 2009, 15:53

I use virtualization so that I might use NaturallySpeaking on a Linux machine. In the past, in order to get the best audio performance/quality, I would set the virtual machine to a single CPU (taskset 02). However, reading about the SMP support in VirtualBox 3.0, I wondered if using taskset could be part of my problem with stutters/pops. So, I launched VirtualBox normally, and indeed, the quality is better, though by no means perfect.
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Re: Virtualbox 3.0B and USB Microphone

Postby reagle » 23. Jun 2009, 17:28

Since the problem isn't taskset, I wonder if it's related to this: "USB: Support for high-speed isochronous endpoints has been added. In addition, read-ahead buffering is performed for input endpoints (currently Linux hosts only). This should allow additional devices to work, notably webcams"

Could this introduce stutters/drops where none existed before? Is there a wa to disable it for testing? Can anyone confirm this bug?
reagle
 
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Re: Virtualbox 3.0B and USB Microphone

Postby reagle » 24. Jun 2009, 23:40

Problem is still present in 3.0B2, also related to: http://www.virtualbox.org/ticket/3999
reagle
 
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Re: Virtualbox 3.0B and USB Microphone

Postby frank » 25. Jun 2009, 09:25

To be sure: This sound problem did not exist for you with VirtualBox 2.2.4 but with VirtualBox 3.0.0 Beta 1 the problem occurred the first time?
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Re: Virtualbox 3.0B and USB Microphone

Postby reagle » 25. Jun 2009, 15:12

Hi Frank. The problem is present on 2.2.4 *if* you use the generic Ubuntu kernel. But a kernel built with the following low-latency options will give great sound with 2.2.4.

CONFIG_PREEMPT=y
CONFIG_HZ_1000=y
CONFIG_HZ=1000
# CONFIG_NO_HZ

However, the exact same config/kernel with 3.0B1 has clips. It appears I can't attach MP3s, so I'll email them. These were recorded in Audacity on an XP Guest using Intrepid with the low-latency kernel. The problem is worsened with load on the guest (which is present when you are doing speech recognition), so in both clips I'm running super_pi while recording. As you can hear, it makes no difference under 2.2.4.
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